ISSN 1000-3304CN 11-1857/O6
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High Performance Ambipolar Polymer Semiconductors and Transistors
Yun-long Guo
四校 , doi: 10.11777/j.issn1000-3304.2020.19221
[Abstract](195) [FullText HTML](70) [PDF 2422KB](7)
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Organic polymer semiconductors and field-effect transistors (OFET) are the frontier interdisciplinary research directions of chemistry, materials, semiconductors and microelectronics. Polymer semiconductors are the important research contents in this field, among which ambipolar semiconducting polymer materials, which have the double carrier transport ability, have received extensive attention in the academic field. This unique property gives ambipolar semiconducting polymers many applications, such as low-cost logic circuit, organic light-emitting transistors (OLETs), low-energy cost memory device, and near infrared detectors. In this feature article, the research progress of ambipolar polymer semiconductors and transistors is summarized. First, we give brief introduction of the configuration of OFETs and its related parameters. And then, our research work in designing new ambipolar polymers based on bis-acceptors or enhancing acceptor ability with withdraw group are introduced. In fact, except designing of polymer structures, solution-process methods are also very important for low-cost and large-area organic devices. Therefore, different solution-processing technologies, such as spin-coating, sheer-coating, bar-coating, inkjet printing, screen printing, and slot-die, are discussed for achieving high performance OFETs. Further, functional application of D-A ambipolar polymer semiconductors in inverter circuit, OLETs, and memory devices are mainly described in this paper. Finally, the scientific problems and development direction in the research process of ambipolar polymer semiconductors and devices are also discussed.
Patterning of Polymer Functional Materials and Their Applications in Optoelectronics
Yue Geng, Han-fei Gao, Yu-chen Wu, Lei Jiang
四校 , doi: 10.11777/j.issn1000-3304.2020.19218
[Abstract](353) [FullText HTML](153) [PDF 2892KB](15)
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Optoelectronic devices based on semiconductor polymers have attracted extensive attention due to their solution processability, light weight, flexibility and low cost. The fabrication of polymer optoelectronic devices with high integration and performance requires controllable patterning technology. The past decade has witnessed the rapid development of different strategies, which focus on patterning conducting polymers with high precision and resolution. Herein, we summarized processing and patterning methods including photolithography, moulding and printing, and our patterning techniques based on the superwetting interface, which introduced a capillary force to steer the dewetting dynamics and mass transport process. The asymmetric-wettability topographical surfaces were integrated onto a 3D template by a selective modification process. For a topographical template with periodically arranged micropillars, two dewetting mechanism were allowed. We then briefly summarized the recent researches and developments of these polymer patterning technologies in the fields of field-effect transistors, photodetectors, vapor sensors, light-emitting diodes and solar cells. Finally, an outlook is provided with regard to the concerns and challenges for the future study on the mechanism and the integrated optoelectronic devices of conducting polymer in this field. We speculate that this article could serve as a trigger for future development in the fields of polymer functional materials pattern.
Polymer Dielectrics and Their Nanocomposites for Capacitive Energy Storage Applications
Sang Cheng, Yu-shu Li, Jia-jie Liang, Qi Li
四校 , doi: 10.11777/j.issn1000-3304.2020.20001
[Abstract](428) [FullText HTML](222) [PDF 2520KB](29)
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Electrostatic capacitors with extremely fast discharge speed and ultra-high power density, are an important class of energy storage element in advanced electrical and electronic systems. Polymer dielectrics are widely employed as capacitor dielectric materials because of their high breakdown strength, the ability to self-heal, low loss and low cost. However, polymer dielectrics usually show low energy density and poor thermal stability, which restrict their applications in high power electronics and compact power modules. In order to improve the energy density and temperature capability of polymer dielectrics, we have carried out a series of study. This review focuses on our recent progress in developing high-performance polymer-based dielectric materials and in understanding the corresponding dielectric phenomena. The main content includes the synthesis and characterization of PVDF-based ferroelectric polymers, copolymers and nanocomposites, and polymer-based high temperature dielectrics, as well as the investigation of interfacial property in the polymer matrix/inorganic nanoparticle composite system. At the end of this review, we summarize the existing challenges and propose the future directions in the field of polymer-based capacitor dielectrics.
Hierarchical Structures of Self-assembled Liquid Crystals and Their Applications
Qing-yi Guo, Sai-bo Wu, Yan Qian, Wei Hu
四校 , doi: 10.11777/j.issn1000-3304.2020.20002
[Abstract](273) [FullText HTML](497) [PDF 4739KB](8)
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Liquid crystals, featured by self-assembly property and stimuli responsiveness, have attracted intensive attention not only in fundamental material sciences, but also in advanced functional applications. At different phases, liquid crystals exhibit distinguished structures, such as layered focal conic domains and oil streaks in smectics, lying or standing helical structures in cholesterics, and cubic lattices stacked by double-twisted structures in blue phases. These hierarchical structures present novel optical, mechanical and electromagnetic characteristics, which can be further modulated by external stimuli. In recent years, high-quality liquid crystal hierarchical structures have been realized in large scales via optimizing material components and introducing external confinements. Multi-dimensional manipulations of these hierarchical structures have been achieved by adopting various external stimuli. A series of remarkable applications of such liquid crystal hierarchical structures in particle manipulation, surface modification and optical devices have been demonstrated. This paper reviews the latest research progress in above fields and aims to extend the understanding of soft matter architectures.
Smart Antibacterial Surfaces with Switchable Function to Kill and Release Bacteria
Qian Yu, Hong Chen
六校 , doi: 10.11777/j.issn1000-3304.2020.20031
[Abstract](393) [FullText HTML](251) [PDF 2306KB](61)
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The adhesion of bacteria and the subsequent formation of biofilms on the surfaces of biomaterials cause a series of adverse consequences, resulting in serious problems in both human healthcare and industrial applications. Therefore, endowing the surfaces with antibacterial capabilities has attracted considerable interests and development of antibacterial surfaces has become an active field of research. The traditional antibacterial strategies are mainly focused on killing bacteria attached on the surfaces, however, neglecting many problems raised from the accumulation of dead bacteria and debris such as degradation of biocidal efficiency and secondary contamination. Aiming to solve these problems, a promising smart antibacterial strategy based on switchable function between bacteria-killing and bacteria-releasing was proposed. Based on this strategy, a series of smart antibacterial surfaces have been developed to kill the attached bacteria and then trigger the on-demand release of dead bacteria from the surface by regulation of bacteria-surface interactions, so as to maintain the effective antibacterial activity for long-term applications. In this feature article, we summarize our achievements and the recent progress in the field of smart antibacterial surfaces. These surfaces have been divided into three categories based on the methods for applying biocidal agents on to the surfaces: (1) the surfaces with permanently immobilized biocidal agents; (2) the surfaces with reversibly incorporated biocidal agents; and (3) the surfaces without common biocidal agents but with physically biocidal activity. In the end, we provide a brief perspective of the future research directions in this promising area.
Evolution of Conductive Network in Nickel/Polyurethane Composites under Tensile Strain
Ke Tian, Hua Deng, Qiang Fu
六校 , doi: 10.11777/j.issn1000-3304.2020.19228
[Abstract](257) [FullText HTML](165) [PDF 1458KB](15)
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An unconventional resistivity-strain behavior — the resistivity of nickel/polyurethane composites decreases by more than six orders of magnitude under 20% tensile strain was observed for the first time, while the conductive network evolution mechanism responsible for such unusual behavior is still unclear. In this work, the frequency dependence of various parameters of two nickel/polyurethane composite systems with contrary strain sensing behaviors was investigated by means of impedance spectra (IS) to achieve better understanding. Through further analysis using fitting parameters of Nyquist plot, the changes in the resistance of aggregates and the resistance between aggregates under tension were calculated and two different evolution modes of conductive network for both composite systems were proposed. It is illustrated that the percolation behavior occurred under tension for the composite with 27.5 vol% filler concentration due to the dimensional change of these aggregates, which is named as stretch-induced percolation. However, no continuous conductive network is constructed in the matrix within the whole strain range for composite with 25 vol% filler loading, because such content is much lower than that in the percolation region. This study provides a new understanding for the variation in conductive network of conductive polymer composites (CPCs) during stretching, and offers a new strategy to investigate the evolution of conductive network in CPCs.
Research Progress of Cathode Binder for High Performance Lithium-ion Battery
Ya-li Wang, Bing-xue Liu, Guo-feng Tian, Sheng-li Qi, De-zhen Wu
四校 , doi: 10.11777/j.issn1000-3304.2019.19215
[Abstract](243) [FullText HTML](120) [PDF 2613KB](16)
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Developing high-performance battery systems requires the collaborative optimization of every battery components, including electrodes, electrolyte, separators and binder systems. The strategies of synthesizing electrode materials and developing novel electrolyte system are widely investigated. Cathode binder, a crucial material to maintain structure stability of cathode, plays an essential role in efficiently enhancing energy density and ensuring safety of lithium ion battery. In recent years, designing advanced binder systems has attracted researchers’ attention. In this account, the research progress on material and structural design of cathode binder and application about cathode binder of lithium ion battery are reviewed comprehensively. The effects that cathode binders play on stabilizing cathode material, promoting reduction of battery internal impedance and regulating electrochemical performances of lithium ion battery are primarily introduced. Meanwhile, the characteristics of the oil-soluble binder represented by poly(vinylidene fluoride) (PVDF), polyimide (PI), functional polymer binder and the water-soluble binder represented by poly(acrylic acid) (PAA) and carboxymethyl cellulose (CMC) are concluded in detail. PVDF has good chemical stability and adhesion, but suffers from large swelling ratio; PI has excellent high temperature resistance and good mechanical properties, but the cost is relatively high; functional polymer binder has good electrical conductivity and can effectively suppress the shuttle effect of Li-S lithium batteries, but the preparation process is complicated; PAA is flexible, but mechanical properties are poor; CMC has good dispersibility and large mechanical strength, but it needs to be matched with styrene-butadiene rubber due to the large brittleness. Furthermore, combining with the existing research reports, methods of designing advanced cathode binder systems are concluded to provide valuable guidance for the performance optimization. The development prospects and application exploration are also discussed.
Post-sulfonation for Precisely Controllable Preparation of Main-chain Type Sulfonated Poly(phenylquinoxaline)s and Their Properties for Proton Exchange Membrane
Lu Liu, Kang-cheng Chen
五校 , doi: 10.11777/j.issn1000-3304.2019.19203
[Abstract](241) [FullText HTML](318) [PDF 1384KB](10)
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A series of main-chain type sulfonated poly(phenylquinoxaline) (SPPQ) were prepared by post-sulfonation of PPQs, which were synthesized from copolymerization of 4,4′ -bis(4-(2-phenylethylenedione)phenoxybiphenyl and 4,4′ -bis(2-phenylethylenedione)diphenylether with 3,3′ ,4,4′ -tetraaminobiphenyl under different molar ratios. They were confirmed by the model compounds that sulfonic acid groups were precisely introduced to the 2,2′-position of the biphenyl fragment with high electron cloud density on SPPQ backbone. Therefore, sulfonic acid groups can be predicablely introduced to the polymer main-chain under mild conditions by the combination of monomer molecular structure design and post-sulfonation proceeding. Relative viscosity of these SPPQs was higher than 3.8 dL/g, indicating their high molecular weight. SPPQ-based proton exchange membranes (PEMs) were prepared by solution casting method. Their properties such as ion exchange capacity (IEC), water uptake, swell ratio, oxidative stability, mechanical properties and proton conductivity were investigated. The TGA results indicated that SPPQ PEMs had good thermal stability with the desulfonic acid groups temperature at about 320 °C and the decompose temperature at about 550 °C. All SPPQ PEMs showed water uptake less than 39% and in-plane swelling ratio linearly increased with increasing IEC and temperature, with the values ranging from 2.1% – 13%. For example, SPPQ-5 with the IEC value up to 2.21 meq/g showed excellent dimensional stability with only 11% and 13% in-plane direction and thickness direction of the swelling ratios at 80 °C, respectively. Free radical oxidative stability test in Fenton reagent showed that the breaking time of SPPQ PEMs decreased with increasing IEC. For example, the SPPQ-1 (1.29 meq/g) has breaking time of over 150 h at 20 °C, whereas the value decreased to 81 h for SPPQ-5 (2.21 meq/g). Proton conductivity of SPPQ PEMs were increased obviously with the increase of temperature and IEC, and the maximum proton conductivity reached 64 mS/cm. The proton conductivities are much lower than that of Nafion NR212, due to the formation of acid-base groups between sulfonic acid groups and quinoxaline groups and the obviously low water uptake of the PEM.
Preparation and Characterization of Functionalized POSS Derivatives and Multi-arm Star-shaped Polyesters
Yi-wei Liang, Peng Liu, Shu-xing Yin, Jing-rui Liu, Ming-zu Zhang, Jin-lin He, Pei-hong Ni
四校 , doi: 10.11777/j.issn1000-3304.2019.19210
[Abstract](446) [FullText HTML](229) [PDF 1464KB](36)
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A set of functional POSS derivatives and star-shaped POSS-cored polyesters are presented. Three POSS derivatives POSS-8OH, POSS-16OH and POSS-8NH2 are prepared by thiol-ene “click” reaction of octavinyl polyhedral oligomeric silsesquioxane (OVPOSS) with 2-mercapto-ethanol, 1-thioglycerol and cysteamine hydrochloride. Their chemical structures are confirmed by 1H-NMR, 13C-NMR, and FTIR analyses. Subsequently, POSS-8OH and POSS-16OH are used to initiate the ring-opening polymerization (ROP) of ε-caprolactone (ε-CL) and 2-ethoxy-2-oxo-1,3,2-dioxaphospholane (EOP), resulting in hydrophobic 8-arm (POSS-8PCL) and 16-arm (POSS-16PCL) star-shaped poly(ε-caprolactone), as well as hydrophilic 8-arm star-shaped poly(ethyl ethylene phosphate) (POSS-8PEEP). Three star-shaped POSS-8PCL with different arm lengths are synthesized by changing the feed ratio of the monomer to initiator. As a demonstration, the chemical structure of POSS-8PCL-2 is confirmed by using FTIR, 1H-NMR and 13C-NMR analyses. TGA test indicates that the initial decomposition temperature and decomposition mode are influenced by the molecular weights of POSS-8PCL. In order to compare the thermal stability of star-shaped PCL with a POSS core or an organic core, tripentaerythritol (TPE) is used to initiate the ROP reaction of ε-CL to give eight-arm PCL (TPE-8PCL) with an organic core. TGA test demonstrates that inorganic POSS core has better support to maintain melt stability of 8-arm star-shaped PCL than organic TPE core. The chemical structure and molecular weight information of POSS-16PCL are characterized by FTIR, 1H-NMR and 13C-NMR analyses, as well as GPC test. TGA analysis shows that the initial decomposition temperature is around 200 °C, the decomposition behavior also displays an apparent two-stage mode, and the residue derived from POSS segment is about 3.6% at 700 °C. Finally, POSS-8OH is used to initiate the ROP reaction of EOP to obtain POSS-8PEEP. The chemical structure and molecular weight information of POSS-8PEEP are confirmed by FTIR, 1H-NMR and GPC analyses. Furthermore, TGA analysis demonstrates that the thermal stability of POSS-8PEEP is weaker than star-shaped PCL and the initial decomposition temperature is decreased to about 100 °C. The decomposition of POSS-8PEEP shows a more apparent multi-stage mode and about 19.8% residue is left at 700 °C. This work reports a facile method for the preparation of functional POSS derivatives and star-shaped POSS-cored polymers.
Effects of Annealing Temperature and Active Layer Thickness on the Photovoltaic Performance of Poly(3-hexylthiophene) Photodetector
Shi-jia Gao, Xin Wang, Yu-lin Zhang, Sai Zhang, Wen-qiang Qiao, Zhi-yuan Wang
四校 , doi: 10.11777/j.issn1000-3304.2019.19206
[Abstract](547) [FullText HTML](368) [PDF 1006KB](71)
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Poly(3-hexylthiophene) (P3HT) with good electronic transmission capacity is one of promising material for organic photodetector. Compared with organic solar cells, the research of photodetector based on P3HT is deficient, especially in how to improve the light absorption efficiency and electronic transmission ability of active layer. Here, bulk heterojunction photodetectors with a structure of ITO/PEDOT:PSS/P3HT:PC61BM/C60/Al were prepared by using P3HT as a donor and fullerene derivative (PC61BM) as an acceptor. The change of active layer thickness plays an important role in the effective transfer of photogenerated charge to the electrode. Although increasing the thickness of active layer can increase the light absorption efficiency, it may also lead to the recombination of electrons and holes in the process of long distance transmission. In addition, annealing condition is the key to the film forming process. Adjusting the annealing temperature can control the self-assembly of active layer, thus obtaining the ideal nano-size phase separation structure and reducing the recombination probability of photoexcitons. Therefore, the active layer thickness in P3HT devices varied at 120, 160, 180 and 200 nm and the devices were annealed at 100, 120, 130, 140 and 150 °C in order to probe the effect of these variables on photodetector performance. It was found that the device with a 180-nm thick active layer, after being annealed at 150 °C, exhibited the maximal responsivity of 268 mA/V at 550 nm and more than 200 mA/W in the wavelengths of 470 − 610 nm under the bias of −2 V. Furthermore, the same device showed a linear dynamic range of 95 dB after annealing at 120 °C. Our study demonstrates that the thickness of active layer is of great importance to the light absorption efficiency and the device performance, while the annealing treatment can significantly affect the morphology of active layer, as evidenced by AFM study, which reduces the recombination probability of holes and the electrons and thus improves the photodetector performance.
Effect of Sodium Dodecyl Sulfate on the Rheological Behavior of Poly(vinyl alcohol) Aqueous Solution
Shao-shen Xu, Miao Du, Yi-hu Song, Zi-liang Wu, Qiang Zheng
三校 , doi: 10.11777/j.issn1000-3304.2019.19178
[Abstract](646) [FullText HTML](433) [PDF 1087KB](48)
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Rheological behaviors of poly(vinyl alcohol) (PVA) aqueous solution are influenced remarkably by the intermolecular hydrogen bond interaction in the semi-dilute solution region. Owing to the hydrogen bond network, 10 wt% PVA aqueous solution exhibits a high viscosity which limits the development of its solution processing method to some extent. Sodium dodecyl sulfate (SDS), as a surfactant, can destroy the hydrogen bond interaction, thus playing a certain viscosity-reducing role. Based on measuring the critical aggregation concentration (CAC) and critical micelle concentration of SDS in 10 wt% PVA aqueous solution (CMCP), the steady and dynamic rheological behaviors of PVA-SDS aqueous solution were studied in detail. The concentrations of SDS (csur) can influence the rheological behavior of PVA aqueous solution in different ways at various regions. ① csur < CAC, the apparent viscosity (ηa) of the solution doesn’t change a lot as the csur changes. ② CAC < csur < CMCP, ηa decreases as the csur increases. Particularly, ηa reaches the minimum while csur = CMCP and a wider second platform is displayed in this area. ③ csur > CMCP, SDS form micelles that act as physical cross-linking points, and the dynamic storage modulus (G′) of the composite solution also increases significantly. The changes in the hydrogen bond network of the PVA solution was indirectly characterized by the changes of the hydration number measured by Differential Scanning Calorimeter. After introducing SDS, the number of bound water (n) decreases due to the interaction between SDS and PVA. However, n almost keeps constant when csur > CMCP. The viscous activation energy also shows a similar change. When csur is much larger, the micelles formed by SDS in water are conducive to the formation of physical cross-linking network, which contribute more to the solution elasticity, leading to the increase of G′ (greater than that of dynamic loss modulus). Compared with the dilute solution, SDS has a greater viscosity reduction effect on the PVA semi-dilute solution.
High-performance Thin Film Composite Forward Osmosis Membrane with Polydopamine/Polyethyleneimine (PDA/PEI) Co-deposition Interlayer
Shao-fei Wang, Yuan Yu, Qing-yun Wu
六校 , doi: 10.11777/j.issn1000-3304.2019.19193
[Abstract](650) [FullText HTML](330) [PDF 1388KB](32)
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Forward osmosis (FO), as a promising membrane separation technology, has attracted much attention, whose performance is strongly dependent on the structure and property of FO membrane. Thin film composite (TFC) FO membrane, consisting of a thin film and a porous substrate, is commonly used for FO process due to its high water permeability. Nevertheless, TFC FO membrane still suffers from a trade-off between water permeability and salt rejection, which limits the further application of FO process. Recently, constructing an interlayer between the thin film and the porous substrate has been reported as an effective way to improve the performance of TFC membranes. Herein, a novel TFC FO membrane was prepared by using a polydopamine/polyethyleneimine (PDA/PEI) co-deposition interlayer on cellulose triacetate (CTA) porous substrate followed by an interfacial polymerization. The surface structures and properties of CTA substrates and TFC membranes were systematically investigated by FTIR/ATR spectroscopy, scanning electron microscopy, atom electron microscopy, solute rejection method, and water contact angle test. Compared with CTA substrate and PDA modified CTA substrate, the surface of CTA substrate deposited by PDA/PEI interlayer becomes smooth and has a narrow surface pore size distribution as well as small surface pore size of (30.0 ± 4.1) nm. Meanwhile, the polyamide film formed on the PDA/PEI co-deposition interlayer presents a uniform leaf-like structure and excellent hydrophilicity. Therefore, TFC FO membrane with PDA/PEI co-deposition interlayer achieves an improved water flux of (7.1 ± 2.3) L/(m2·h), rising by 57.6% compared with nascent TFC FO membrane; a low reverse salt flux of (1.4 ± 0.1) g/(m2·h), and a small specific salt flux of (0.2 ± 0.06) g/L, decreasing by 83.9% and 90.6%, respectively. It means that PDA/PEI co-deposition interlayer facilitates to improve both water permeability and selectivity of TFC FO membrane. This work proposes an effective modification method for improving the performance of TFC FO membrane by using PDA/PEI co-deposition interlayer.
Study of Cationic Copolymerization of Isobutylene and p-(Chloromethyl)styrene
Ke Yang, Qiang Liu, Shuai Wen, Shu-xin Xu, Chen-qi Shi
六校 , doi: 10.11777/j.issn1000-3304.2019.19179
[Abstract](773) [FullText HTML](404) [PDF 1495KB](72)
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Cationic copolymerization of isobutylene (IB) and chloromethylstyrene was investigated with n-hexane (Hex)/dichloromethane (CH2Cl2) (V/V = 6/4) as solvent, TiCl4, AlEt1.5Cl1.5, AlEt2Cl, AlCl3 as co-initiators and water or cumyl alcohol as initiators. The molecular weight, molecular weight distribution (MWD) and structure composition of the resulting copolymers were analyzed by gel permeation chromatography (GPC) and 1H-NMR spectroscopy. The reactivity ratios were determined by Kelen-Tüdős and Yezreielv-Brokhina-Roskin formula, and the copolymerization mechanism was proposed. It was found that co-initiators with strong Lewis acidity, such as AlEtCl2, AlEt1.5Cl1.5 and AlCl3 can catalyze intermolecular alkylations to form gels while no gel formed with the relatively weaker TiCl4. The chloromethylstyrene with para-substituent, i.e., p-(chloromethyl)styrene (p-CMS) was found to have a low reactivity during the copolymerization with IB (rIB = 4.67, rp-CMS = 0.70) while the ortho-isomer exhibited no activity. The chemical structure of resulting copolymers indicated that p-(chloromethyl)styrene cannot initiate the polymerization of IB which may be due to its low initiation rate compared to the highly active cumyl group at p-CMS/IB molar ratio of 4.11. However, the benzyl chloride group in the formed copolymer chain can slowly initiate polymerization of IB and p-(chloromethyl)styrene, forming branched structures. The content of p-(chloromethyl)styrene increased with increasing molecular weight and monomer conversion. Systematic research on the branched structure, rheological properties and other physical properties of the resulting copolymers is in progress.
Effect of Hydrogen on Copolymerization between Dichlorosilane-functionalized Nonconjugated α,ω-Diolefin and Propylene
Xue-min Yin, Ya-wei Qin, Li-yang Zhang, Shuai Ma, Jin-yong Dong
六校 , doi: 10.11777/j.issn1000-3304.2019.19187
[Abstract](577) [FullText HTML](282) [PDF 1145KB](32)
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Dichlorosilane functionalized nonconjugated α,ω-diolefin and propylene copolymers, prepared by heterogeneous Ziegler-Natta catalysts, have been newly found to trigger dehydration condensation reaction among/between polypropylene chains to form long-chain branched (LCB) structures in the presence of water. Hydrogen is often used as a chain transfer agent to regulate the molecular weight of the polymer in olefin polymerization. Therefore, whether or how hydrogen affects the insertion of the di(5-hexenyl)dichlorosilane in the polymerization of propylene is a topic worthy of study. Herein, the copolymerization of di(5-hexenyl)dichlorosilane and propylene has been investigated based on MgCl2/TiCl4 catalyst (9,9-bis(methoxymethyl)fluorine (BMMF), as internal electron donor) in bulk polymerization conditions. The polypropylene microstructure was analysed by changing hydrogen content while the amount of di(5-hexenyl)dichlorosilane was fixed. It was found that hydrogen significantly improved the activity of catalyst and reduced the molecular weight of polymer. The 1H-NMR results show that the pendant double bonds in the polypropylene chain decreased from 0.12 mol% to 0.05 mol%, illustrating that hydrogen inhibited the insertion of di(5-hexenyl)dichlorosilane in the polymerization. The higher the hydrogen content, the lower the insertion of di(5-hexenyl)dichlorosilane in the polypropylene chain, which corresponds to the decreasing density of long-branched chains in the polymer. Analysis of the insoluble portion of the polymer in the xylene showed that there is no gel in the presence of hydrogen. The creep test results exhibit that the value of Mb/Mw increases from 0.70 to 0.95, which quantitatively indicates that the long-chain branching density in the polymer decreases with the increasing hydrogen content. The long-branched chain density in polymer decreases with the increasing hydrogen content, which is also confirmed by the results of small amplitude oscillatory shear rheology test.
Ring-opening Alternating Copolymerization of Epoxides/Cyclic Anhydrides Catalyzed by (Salen)TiIVCl2 Complexes
Shuai Li, Yu-Bo Wang, He-Yuan Ji, Chong-Min Chen, Xiao-Lu Chen, Li Pan, Bin Wang
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20049
[Abstract](174) [PDF 1129KB](15)
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In this work, tetravalent titanium complexes with salen-type ligands were synthesized, characterized and tested as catalyst for the ring-opening alternating copolymerization (ROAC) of epoxides and cyclic anhydrides. These (salen)TiIVCl2 complexes are structurally different from the typical (salen)MIIICl complexes (M= Al, Co and Cr), in which two Cl- groups and no vacant coordination site exist in the axial positions. In the presence of bis(triphenylphosphine)iminium chloride (PPNCl), these (salen)TiIVCl2 complexes could effectively catalyze the ROAC of phthalate anhydrides (PA) and cyclohexene oxide (CHO), affording perfectly alternating polyester. The Lewis acidity of TiIV complexes and structures of cocatalyst affected significantly on the catalytic activities. Chain initiation investigation indicated that the copolymerization was initiated by the axial Cl- group in (salen)TiIVCl2 complex rather than the nucleophile in the cocatalyst, which is very different from the mechanism proposed for ROAC catalyzed by (salen)AlIIICl/PPNCl binary system. Meanwhile, (salen)TiIVCl2/PPNCl system exhibited broad monomer adaptability, allowing for preparation of polyesters with structural diversity via copolymerization of some common cyclic anhydrides and epoxides. Our present work demonstrated a rare example of cyclic anhydride/epoxide copolymerization catalyzed by (salen)TiIVCl2 complex.
Copolymerization of Styrene Derivatives and Isoprene Catalyzed by Half-Sandwich Scandium Complex
Yang-zhi Duan, Lei Jiang, Kai-ying Diao, Fang Guo
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20027
[Abstract](151) [PDF 0KB](2)
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The copolymerization of isoprene and styrene derivatives such as p-chlorostyrene (St-Cl) and 4-dimethylsilyl styrene (St-SiHMe2) catalyzed by the half-sandwich scandium complex (C5Me4SiMe3)Sc(CH2C6H4NMe2-o)2 have been studied in this paper. The microstructures and thermal properties of the obtained copolymers were characterized by NMR, GPC and DSC. These results showed that the IP/St-Cl and IP/St-SiHMe2 copolymers with controllable IP content (21 mol% - 95 mol%), high molecular weight (Mn = 3.1×104 - 15.9×104) and narrow molecular weight distribution (Mw/Mn = 1.21 - 1.92) were conveniently obtained by changing the feed ratio of IP and styrene derivatives in chlorobenzene at room temperature, in which the IP was in 1,4- and 3,4-structure units and the styrene derivatives had a syndiotactic structure. The electronegativity of substituents on the styrene derivatives directly affected the copolymerization activity and the comonomer distribution sequences in the resulting copolymers. The copolymerization activity of IP and St-SiHMe2 (105 g polymer molSc-1 h-1) was much higher than that of the copolymerization of IP and St-Cl (104 g polymer molSc-1 h-1), and the incorporation content of St-SiHMe2 was also higher than that of St-Cl under the same conditions. The copolymerization of IP and St-Cl afforded gradient copolymers with a glass transition temperature (Tg = -1 - 5 C) originating from poly(IP) segment and a melting point (Tm = 314 - 318 C) originating from syndiotactic poly(St-Cl) segment. The copolymerization of IP and St-SiHMe2 afforded the random copolymers with a single Tg (12 - 82 C ) which increased with the enhance of St-SiHMe2 content (13 - 79 mol%).
Preparation of High-Melt-Strenght, High-Impact-Strength Polypropylene by α-Alkenylmethyldichlorosilane-Mediated Heterophasic Copolymerizaiton of Propylene
Zhang Zhijian, Wang Li, Zu Fenghua, Hong Liuting, Qin Yawei, Dong Jinyong
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20017
[Abstract](85) [PDF 0KB](0)
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As one of the most important thermoplastic polymer materials, polypropylene, PP, is mainly flawed on mechanical properties by low impact strength, which is particularly significnat at low temperatures, and on melt processibility by low metl strength. It is thus an interesting scientific issue for propylene polymerization and PP structure design research to seek ways that simultaneously improve on these two paramount property attributes. In this paper, we introduce an α-alkenylmethyldichlorosilane-mediated heterophasic copolymerization of propylene approach to address the issue. By engaging in the heterophasic copolymerization, α-alkenylmethyldichlorosilane is able to promote resultant PP/EPR copolymers to be long chain-branched through an end hydrolysis treatment. The heterophasic copolymerization of propylene by this way affords phase-separated PP impact copolymers of long chain-branched structure, which is thoroughly confirmable by GPC and rheology as well as morphology (SEM) measurements. The LCBed PP impact copolymers simultaneously posses high melt strength and strong strain-hardending effect in extensional rheology test and high impact resistance in mechanical properties test.
Study on Structure Design and Electromagnetic Shielding Properties of Polymer Nanocomposites
Xinyu Wu, Hao-Bin Zhang
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20015
[Abstract](130) [PDF 0KB](9)
Abstract:
Lightweight polymer nanocomposites with excellent processability and chemical resistance have been becoming research focus of electromagnetic interference (EMI) shielding materials. The EMI shielding performance of polymer nanocomposites greatly depends on electrical conductivity, which is in turn determined by the transport efficiency through the conducting network. However, it still remains a great challenge to construct high-quality conducting pathway in polymer matrices with least filler content by matrix-filler interface and rational structural design. Research on the key scientific issues of polymer nanocomposites was conducted, and some interesting results were achieved including: 1) Developed several approaches for the design and tailoring of filler dispersion and matrix-filler interfaces and successfully prepared a series of high-performance electrically conductive polymer nanocomposites with low percolation threshold; 2) Proposed some routes for constructing preformed three-dimensional architectures for conductance/shielding, facilitating the structural and functional integration design of polymer nanocomposites; 3) The construction of multi-interface structures in polymer nanocomposite enables the balance of high EMI shielding performance and lightweight feature. This perspective summarizes our recent research advances, and forecasts the future challenges and opportunities of polymer nanocomposites for electromagnetic shielding.
Molecular Design and Device Performance of Thermally Activated Delayed Fluorescent Polymer Materials
Lei Hua, Shou-ke Yan, Zhong-jie Ren
最新录用 , doi: 10.11777/j.issn1000-3304.2020.19224
[Abstract](264) [PDF 1611KB](17)
Abstract:
Thermally activated delayed fluorescence (TADF) polymer materials have achieved rapid development since their application in organic light emitting diodes (OLEDs). So far, various TADF polymer materials with different molecular structures and excellent properties have been reported, of which external quantum efficiency of OLEDs have achieved to 23.5%. They possess all-organic chemical structures without heavy metals, 100% theoretical internal quantum efficiency, and the advantages of large-area manufacturing by solution process. Nevertheless, when using polymers to develop low-cost display or device, there are still many problems to be overcome, such as, the lower quantum efficiency compared to small molecules, efficiency roll-off at high brightness, and poor device stability. Herein, we summarize the research progress of TADF polymers with different structures, and especially review our research work on linear TADF polymer design and their OLEDs device performance. In addition, the problems and future development of TADF polymers were also discussed in the end.
Study on the Amyloid-Like Fibrinogen-Based Nanofilm
Qing-min Yang, Yong-chun Liu, Li-xin Chen, Peng Yang
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20051
[Abstract](39) [PDF 1763KB](4)
Abstract:
The fibrinogen nanofilm was prepared by using the reaction between fibrinogen and the reducing agent tris(2-carboxyethyl) phosphate hydrochloride (TCEP) and resultant amyloid-like aggregation. The kinetics of the reaction between fibrinogen and TCEP and the change of its secondary structure were investigated by optical characterization methods such as fluorescence spectrum and far ultraviolet-circular dichroism. The structure of the thin film was characterized by transmission electron microscopy. The concentration of fibrinogen, the pH value and concentration of TCEP buffer on the thickness of the film were investigated by atomic force microscope and optical ellipsometer. The film stability was characterized by atomic force microscopy. Finally, the antifouling ability of the film was characterized by platelet adsorption and protein adsorption. The experimental result shows that by controlling the reaction conditions, the film thickness was controlled, and the film showed excellent stability in different environments. More important, the thin film showed certain resistance to platelet adsorption and model biofluid mixtures (e.g., fetal bovine serum, milk), which is expected to be utilized in the field of surface modification as a new generation of bio-based antifouling materials.
Research progress and perspectives of sandwich-structured electrolytes for rechargeable lithium batteries
Ting-ting Liu , Jianjun Zhang, Zhe Yu, Han Wu, Jin-ning Zhang, Ben Tang, Guang-lei Cui
最新录用 , doi: 10.11777/j.issn1000-3304.2019.19196
[Abstract](305) [PDF 0KB](8)
Abstract:
Abstract High-performance electrolyte is necessary to improve safety issues and electrochemical performance of rechargeable lithium batteries. Sandwich-structured electrolyte, a novel class of electrolyte system, possess special two, three or more layers of symmetrical or asymmetrical structures. For different rechargeable lithium batteries and functional applications, sandwich-structured electrolytes can deliver specific and optimal functions by regulating multilayer material structure and preparation process. Up to now, such sandwich-structured electrolytes have been widely used in high-voltage lithium batteries, solid-state lithium batteries, lithium metal batteries and high-energy lithium-sulfur batteries. In addition, sandwich-structured electrolytes exhibit multiple functionality: 1)(1) enhancing ionic conductivity; (2) improving interfacial compatibility; (3) suppressing the shuttling of polysulfides. More importantly, the development of sandwich-structured electrolytes is extremely rapid especially in recent years, showing a very promising application prospect in the field of rechargeable lithium batteries. Herein, this paper mainly summarizes the types, preparation process and research advances of sandwich-structured electrolytes in high-performance rechargeable lithium batteries. At the end of the review, we also discuss the challenges and future development of sandwich-structured electrolytes. It will undoubtedly act as a great reference and theoretical guidance for researchers engaged in high-performance electrolytes for rechargeable lithium batteries.
Polymeric materials for the regulation of tumor immune microenvironment
Weimin Miao, Jiasi Wu, Qisong Tong, Yongcong Huang, Jinzhi Du
最新录用 , doi: 10.11777/j.issn1000-3304.2020.19227
[Abstract](165) [PDF 0KB](9)
Abstract:
With great success of cancer immunotherapy in clinical practice, extensive attentions have been attracted to improve the efficacy of anti-tumor therapy by inducing anti-tumor immune response. However, there exists a complicated immunosuppressive tumor microenvironment within tumor tissue, which includes the presence of a variety of immune suppressive cells, such as regulatory T cells (Tregs), myeloid-derived suppressor cells (MDSCs) and tumor associated macrophage (TAMs), etc., as well as large amounts of cytokines and chemokines, metabolites, etc. secreted by immune cells and tumor cells. By regulating or reversing the immunosuppressive microenvironment, anti-tumor efficacy can be effectively improved. For a long period of time, polymeric materials have been used as important drug delivery carriers, but their applications in the regulation of tumor immune microenvironment are still in an infant stage. In this review, with brief introduction of the characteristics of tumor immune microenvironment, we systemically summarized the progress of polymeric materials in improving the efficacy of cancer treatment through the regulation of tumor immune microenvironment in recent years.
Controlling the Condensed Structure of Polythiophene and Polyselenophene-based All-Conjugated Block Copolymers
Yue Yin, Dalong Zhai, Shuwen Chen, Xin Shang, Lixin Li, Juan Peng
最新录用 , doi: 10.11777/j.issn1000-3304.2020.19220
[Abstract](176) [PDF 0KB](5)
Abstract:
Block copolymers can microphase separate into a variety of well-defined nanoscale structures. Conjugated polymers are a kind of semi-rigid macromolecules with special mechanical, conducting, and optoelectronic properties. All-conjugated block semiconducting copolymers have gained immense interest because they combine the optoelectronic properties of conjugated polymers with the fascinating self-assembly properties of block copolymers. In this paper, we introduced some research progresses on poly(3-alkylthiophene) and poly(3-alkylselenophene)-based all-conjugated diblock copolymers, focused on controlling the condensed structure of these two systems in our group. By tuning their molecular structures such as main/side chains, the length of alkyl side chains, and side substitutions, etc., and post-treatment in their solution and film states such as changing solvents, aging, thermal and solvent annealing, etc., the synergy and competition between two basic phase transitions, that is, their microphase-separated behavior and crystalline behavior were systematically studied and clarified. As a result, their condensed structures were efficiently tuned. Furthermore, their optoelectronic properties such as charge mobilities based on their different condensed structures were investigated to build up the relationship among their chemical structures, condensed structures, and device performance. As poly(3-alkylthiophene) and poly(3-alkylselenophene) are model systems with simple molecular structures, the rules and knowledge about controlling their condensed structures obtained from these model systems are expected to be applied to other conjugated systems with more complexed molecular structures and better properties.
Controllable Phase Morphology of EPR in Polypropylene Heterophasic Copolymerization by Dichlorosilane-Functionalized Nonconjugated α,ω-Diolefin
Xue-min Yin, Ya-wei Qin , Li Wang, Jian-jun Yi, Jin-Yong Dong
最新录用 , doi: 10.11777/j.issn1000-3304.2019.19213
[Abstract](182) [PDF 0KB](0)
Abstract:
Heterophasic copolymerization of propylene in-reactor based on Ziegler-Natta catalyst is one of the major methods for preparing PP/EPR heterophasic copolymer. Compared with the traditional physical blending method, PP /EPR heterophasic copolymer can achieve the evenly dispersion of EPR phase in PP matrix with smaller phase domain size. However, for linear EPR, it is prone to flow and aggregate during the polymerization, resulting in adhesion between / among polymer particles. In addition, the PP /EPR heterophasic copolymer will undergo significant phase separation during melt processing, and the EPR droplets will aggregate into larger rubber particles. Moreover, the longer the melting processing time, the more serious the phase separation of PP phase and EPR phase, and the larger the size of rubber particles. Therefore, the control of PP/EPR copolymer particle morphology and EPR phase morphology is particularly critical. In this paper, the dichlorosilane functionalized nonconjugated α,ω-diolefin, Di(5-hexenyl)dichlorosilane, is introduced into the polymerization and make it participate in the random copolymerization of ethylene / propylene to form cross-linking of EPR, which is an effective method to solve the above problems. The results show that the dichlorosilane functionalized nonconjugated α,ω-diolefin is introduced to form cross-linked EPR, the flow and aggregation of EPR droplets are effectively controlled. The surface morphology of PP/EPR copolymer particles was observed by SEM showed that all samples have a good particle morphology. The TEM and AFM test results show that the EPR is evenly dispersed in the PP matrix with a small phase domain size. As a result, the mechanical properties of PP/EPR copolymer are greatly improved.
Influence of Grafting Point Distribution on Self-Assembly Morphology of ABA Triblock Copolymer Brush
Ji-hua Xu , Yin-qi Chen, Yu-hua Yin, Run Jiang, Zheng Wang, Bao-hui Li
最新录用 , doi: 10.11777/j.issn1000-3304.2019.19204
[Abstract](273) [PDF 1719KB](17)
Abstract:
School of Physics and Electronics, Shandong Normal University, Jinan 250358; School of Physics, Nankai University, Tianjin 300071
Direct polymerization of Lysine and Furfural via Ugi reaction
Yue Tao, Jin-long Chen, Shi-Xue Wang, You-hua Tao
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20025
[Abstract](159) [PDF 0KB](8)
Abstract:
Lysine and furfural are naturally available renewable resources, and along with dwindling petroleum and eventual depletion of fossil resources, the controlled synthesis of bio-based polymers derived from lysine and furfural has recently become a growing research focus. However, their simple and general polymerization still remains a key challenge. Herein, we demonstrate that natural lysine and furfural monomers can be polymerized via Ugi reaction in a step-growth fashion, which leads to the polypeptoids with a number average molecular weight (Mn) up to 10.0 kg/mol, under mild conditions (open to air, room temperature, and catalyst free). Importantly, polymerization can be carried out in water, avoiding the use of toxic solvents. The structures of resultant polypeptoids were confirmed by 1H and 13C NMR spectroscopy. All of the signals attributable to the repeating unit of the polypeptoid that should be produced by the Ugi reaction are visible. Moreover, the MALDI-TOF MS analysis of the resulting product consists of an array of peaks separated by a 407.2 Da interval, which corresponds to the molar masses of the repeating unit. The MALDI-TOF MS result is consistent with the proposed mechanism of Ugi reaction. These polypeptoids exhibit a Tg value of 116 °C, and do not show melting transition. Indeed, the renewable feedstocks and simple concepts described here offer an attractive framework from which the Ugi reaction can be applied to prepare lysine and furfural based polymers.
Application of PEDOT in the Fields of Electromagnetic Interference Shielding
Han Gao, Yang Zhang
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20071
[Abstract](47) [PDF 1562KB](1)
Abstract:
With the explosive development of modern electronic information technology, electromagnetic interference (EMI) has become increasingly prominent. The development of EMI shielding materials with excellent comprehensive performance has captured enormous scientific attention. Poly (3,4-ethylenedioxythiophene) (PEDOT) exhibits the characteristics of simple molecular structure, small energy gap and high electrical conductivity. These outstanding features provide a new perspective on the construction of high-performance electromagnetic shielding materials. At the same time, with the comprehensive investigations of EMI shielding properties and advances in synthesis technology, PEDOT is compounded with other functional components. Through rational components selection and structural design, the enhanced synergy of electromagnetic attenuation characteristics between the components is achieved. PEDOT will fulfill requirements of ‘thin thickness, low density, strong shielding capability, wide shielding bandwidth’ of advanced electromagnetic shielding materials. Thus, PEDOT-based materials can meet the high EMI shielding demands of flexible display, smart wearable devices, high-frequency devices, high-precision electronic equipment and other applications. Many researches have been devoted to this topic and numerous achievements have been realized over these years. This review surveys the recent advances of PEDOT-based electromagnetic shielding materials. The synthesis approaches of PEDOT are introduced first. Then, the construction strategies for representative PEDOT-based composites using conductive, magnetic and non-electromagnetic components are summarized. Their prominent and unique electromagnetic characteristics are discussed. Particularly, the relationship between the electromagnetic components, structure and electromagnetic characteristics are summarized. The EMI shielding mechanism and performance optimization approaches are also detailed. Finally, some problems existing in the current research are presented, as well as the suggestions and challenges regarding future research needs.
DNA nanostructures in the study of molecular interactions
Hao Li, Yaya Hao, Fei Wang, Gang Liu, Lihua Wang
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20055
[Abstract](50) [PDF 0KB](0)
Abstract:
Exploring molecular interaction mechanisms is vital for a better understanding of life activities. In recent years, with the development of DNA nanotechnology, researchers have been using DNA nanostructures to study molecular interactions. According to the simple base-pairing rules between single strands, DNA nanostructures can be designed and constructed precisely by self-assembly. With high programmability and addressability of DNA nanostructures, the system to be observed could be located on DNA nanostructures through different strategies such as DNA hybridization and covalent interactions. The arrangement, type, and the number of target molecules can be precisely controlled. Thus, DNA nanostructures offer a template for observing molecular interactions. With the designability and high rigidity, DNA nanostructures could be utilized as frames with certain mechanical properties. By spatially organizing anchored molecules, nanoscale microenvironment could also be regulated on the platform of DNA nanostructures. In addition, DNA nanotechnology could be combined with various single-molecule techniques such as fluorescent imaging, atomic force microscopy, allowing single-molecule study with DNA nanostructures. In this review, we provide an overview of the construction of observing platforms with DNA nanostructures and the applications of DNA nanostructures in the study of molecular interactions. Finally, we summarize and prospect the development of DNA nanotechnology in this field.
Preparation and self-healability of Silicone Elastomer with Dual-crosslinked Network
Zhu Liu, Peng Hong, Hong-ping Xiang, Zi-ying Huang, Qing-hong Luo, Xian-jun Yang, Xiao-xuan Liu
最新录用 , doi: 10.11777/j.issn1000-3304.2019.19207
[Abstract](341) [PDF 0KB](8)
Abstract:
Silicone elastomer with self-healability can be developed by effectively constructing reversible dynamic bonds (i.e., covalent and non-covalent). Due to the low bond energy of dynamic bonds, the mechanical properties of the silicone elastomers are general poor. Besides, the self-healing silicone elastomers are usually not transparent due to their compatibility. To solve this problem, colourless and transparent sulfhydryl silicone oils (PDMS–SH) are firstly prepared by hydrolysis-condensation reaction. Then a transparent silicone elastomer with fast UV curing rate and excellent self-healability can be prepared by reversible-irreversible hybrid dual-crosslinked networks which is constructed by the photo-induced click reaction of PDMS-SH and vinyl-terminated silicone oil (VPS), as well as the thermal reversible dynamic cross-linked network of carboxyl- and amino-modified silicone oil. If the irradiation intensity is 70 mW/cm2, the dosage of Darocur1173 is 1.0 wt.% and the molar ratio of –SH/–Vi is 1.5/1, the thiol-ene photopolymerization has high conversion and rate of polymerization, and will not be affected by ion cross-linked network. The increasement of ion cross-linked network can effectively reduce the activation energy Ea and is favorable for the stress relaxation. Meanwhile, movement, dissociation and recombination of dynamic ion reversible network, as well as the formation of dual network structure can be benefited from heat treatment, so the improvement of healing efficiency will be more easily achieved. Importantly, the prepared silicone elastomer with a transmittance of 93% in visible light and healing efficiency over ~90 % after multiple healing cycles can be acquired, Therefore, a feasible approach is provided to impart reversible ionic association induced self-healing silicone materials.
Conjugated-polymer Nanoparticle for NIR-II Fluorescence Imaging Guiding NIR-II Photothermal Therapy
Ting Huang, Yan Chen, Peng-fei Sun , Qu-li Fan , Wei Huang
最新录用 , doi: 10.11777/j.issn1000-3304.2019.19192
[Abstract](504) [PDF 1099KB](28)
Abstract:
To improve the quality of fluorescence imaging and effectiveness of photothermal therapy, We designed a novel conjugated-polymer(BDT-TTQ) with a narrow band gap for NIR-II fluorescence and NIR-II photothermal effect. In addition, we prepared nanoparticle(BDT-TTQ NPs) through nanoprecipitation method for in vivo application. With strong absorption in the NIR-II region of 1000-1200 nm, the BDT-TTQ NPs can realize fluorescence image during 1200-1400 nm excited by 1064 nm laser. And the BDT-TTQ NPs can achieve high-resolution NIR-II fluorescence imaging of living blood vessels in mice. In addition, the nanoparticle (BDT-TTQ NPs) exhibits excllent photothermal conversion at 1064 nm laser and high efficiency of tumor cells ablation in vitro and in vivo.
Living Anionic Synthesis of Eight-arm Star-shaped Block Copolymer and Study on Its Hydrogenation
Bin Wang, Ming-zu Zhang, Jin-lin He , Pei-hong Ni
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20035
[Abstract](230) [PDF 0KB](4)
Abstract:
The preparation and characterization of eight-arm star-shaped block copolymer (PS-PI)8POSS and study on its hydrogenation is reported in this paper. Firstly, living polystyrene-b-polyisoprene block copolymer chain (PS-PI-Li) was synthesized in benzene via high-vacuum living anionic polymerization with styrene and isoprene as the monomers and sec-butyllithium as the initiator. Subsequently, octavinyl polyhedral oligomeric silsesquioxane (OVPOSS) was used to react with slightly excess PS-PI-Li in benzene to prepare an eight-arm star-shaped block copolymer (PS-PI)8POSS. After obtaining purified (PS-PI)8POSS by fractionation precipitation using toluene and methanol as the solvent/nonsolvent pair, the chemical structures and molecular weight information of (PS-PI)8POSS and precursors were characterized by proton nuclear magnetic resonance (1H-NMR), Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). Finally, the hydrogenation of (PS-PI)8POSS was carried out with p-toluenesulfonyl hydrazide (TSH) in xylene under a nitrogen astmosphere. Four kinds of hydrogenated eight-arm star-shaped (PS-HPI)8POSS were respectively synthesized by changing the feeding amount of TSH. The chemical structures of hydrogenated copolymers were characterized by means of FTIR, 1H-NMR and GPC. 1H-NMR analysis indicated that (PS-HPI)8POSS-4 and (PS-HPI)8POSS-8 samples obtained by using 4 and 8 mole equiv TSH were almost completely hydrogenated, while (PS-HPI)8POSS-2 sample using 2 mole equiv TSH displayed a few residual double bonds of PI block. GPC analysis demonstrated that only (PS-HPI)8POSS-8 showed less degradation and narrower polydispersity compared with other (PS-HPI)8POSS samples. To explore the effect of reaction time on hydrogenation, some samples were taken out at different time during hydrogenation reaction. With the aiding of 1H-NMR and GPC analyses, the (PS-HPI)8POSS samples collected at different time points were characterized. The 1H-NMR result indicated that hydrogenation of (PS-PI)8POSS was completed after 12 h reaction. In order to compare the thermal stability of (PS-PI)8POSS and (PS-HPI)8POSS, TGA tests were conducted. TGA analysis indicated that the 5% initial decomposition temperature of (PS-HPI)8POSS reached to 410 ~ 420 C, which was higher than that for (PS-PI)8POSS (~ 360 C). Besides, the quick decomposition temperature of (PS-HPI)8POSS was above 470 C, which was much higher than that for (PS-PI)8POSS (~ 405 C). This work reports a fast and efficient method for the preparation of eight-arm star-shaped block copolymer, which could be further hydrogenated to enhance its thermal stability. This kind of novel star-shaped block copolymers containing both hard and soft segments may find potential application in thermoplastic elastomers.
Precise Macroscopic Supramolecular Assembly
Mengjiao Cheng , Feng Shi
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20016
[Abstract](156) [PDF 0KB](1)
Abstract:
Macroscopic supramolecular assembly (MSA) is a recent progress of supramolecular science. The intrinsic feature of MSA is an interfacial assembly event between two macroscopic building blocks modified with massive supramolecular interactive motifs. Because of increased groups and interactive area, MSA assembly normally results in a few thermodynamic metastable structures, leading to many imprecise assemblies and poor ordering of the finally assembled structures, which is not favourable for high performance of bulk supramolecular materials and corresponding applications. Therefore, developing strategies to achieve precise MSA for the construction of ordered supramolecular structures, has remained as a challenge of further development of MSA. This feature article has introduced the concept of MSA and its corresponding assembly mechanism, elaborated precise assembly ideas based on two aspects regarding energy landscape of MSA process, i. e. (1) the difference in thermodynamic stability of precise and imprecise assemblies, and (2) control over assembly kinetics and pathways, summarized the current proposed precise assembly strategies accordingly to realize assembly of fine structures, which has a high matching degree over 90% of assembled interface, and further envisioned potential applications of precise MSA in fabricating tissue scaffolds.
The Applications of Molecular Bottlebrush in Nanomedicine
Ziyang Sun, Huaan Li, Huahua Huang, Yi Shi , Yongming Chen
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20021
[Abstract](160) [PDF 0KB](1)
Abstract:
Molecular bottlebrush is one kind of unimolecular nanomaterials that connected by covalent bonds, which has better cyclic stability in complex physiological environment than other nanomaterials obtained by supramolecular self-assembly. In addition, the nanomaterials with the shape of sphere, rod and worm can be obtained by adjusting the relative length of the backbone and side chain of molecular bottlebrush, that providing a research platform for studying the physiological behavior of nanomaterials with the same chemical composition but different morphologies. Herein, this review aims to summarize the recent research progress in the application of molecular bottlebrush in the field of nanomedicine, such as small molecule drug delivery, gene loading and biological imaging, and the future development and challenges of molecular bottlebrush in nanomedicine field have also been discussed.
Highly Sensitive Two-dimensional Photonic Crystal Hydrogel Cu2+ Sensor
Chen-hui Liu, Gen-qi Liu , Chen-rui Ren, Hong-kai Shi, Ke Xue, Yun-lei Cao, Huan-huan Li, Jian-xun Liu
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20030
[Abstract](71) [PDF 0KB](0)
Abstract:
Two-dimensional polyvinyl alcohol hydrogel (PVA 2DPCH) was prepared by using two-dimensional photonic crystal array of polystyrene as template and glutaraldehyde as cross-linking agent. Then the mercaptopolyvinyl alcohol two-dimensional photonic crystal hydrogel (PVA-SH 2DPCH) was obtained through thiolization modification of polyvinyl alcohol (PVA), with mercaptoacetic acid as esterifying agent. The response behavior of PVA-SH 2DPCH to Cu2+ was studied by the Debye ring method. The results showed that PVA-SH 2DPCH had a high-sensitive response to Cu2+. The gel shrunk in Cu2+ solution, and its Debye ring diameter (D) increased with the increase of the concentration of Cu2+. When the concentration of Cu2+ increased from 0 to 10-15mol/L, its Debye ring diameter increased by 0.45cm; when the concentration continued to 10-7mol/L, its Debye ring diameter (ΔD) increased by 0.85cm. To conclude, when the concentration of Cu2+ is in the range of 10-15mol/L to 10-7mol/L, the Debye ring diameter change (ΔD) of PVA-SH 2DPCH has a linear relationship with the concentration of Cu2+ (c), and the linear regression equation is ΔD = 1.195 + 0.0493 × logc, (ΔD/cm, c/mol/L), R2 = 0.99899. With the prepared PVA-SH 2DPCH as a Cu2+ sensor, and the Debye ring method is adopted to characterize the concentration of Cu2+ in the solution. Featured by marker-free and visible detection, the Debye ring method is simple but highly efficient, which provides the possibility for real-time detection of Cu2+ in the field.
Surface Modification and Properties of UHMWPE Fibers by ZnO Nanorods
Han Zhao, Qing Shang, Meng Yang, Shuai Jin, Yang-yang Wang, Ning Zhao, Xiao-pin Yin, Cai-ling Ding, Jian Xu
最新录用 , doi: 10.11777/j.issn1000-3304.2020.19229
[Abstract](153) [PDF 0KB](2)
Abstract:
Dense and uniform arrays of ZnO nanorods were successfully formed on the surface of ultra high molecular weight polyethylene (UHMWPE) fiber via low temperature hydrothermal method. The resultant microstructure could effectively enhance the interfacial bonding strength between the fiber and the resin due to its ability to form a mechanical meshing structure with the resin. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD) were used to analyze the structure and properties of UHMWPE fibers before and after modification, and the monofilament pull-out experiment was performed to characterize the interfacial shear strength (IFSS) between the fiber and epoxy resin, exploring the effects of reaction time and precursor concentration on interface properties. The results showed that this gentle modification process has little effect on the intrinsic properties of the fiber, and the IFSS could be 58% higher than that of the unmodified fiber. In addition, the UHMWPE fabric was modified by the similar method, and the puncture work was improved by 20% for the UHMWPE@ZnO fabric. The puncture work was further improved by 42% when tannic acid was introduced at the interface to enhance the binding force between ZnO nanorods and fiber surface.
Dynamic and Rheological Behavior of Particle Crosslinked Vitrimers
Shi-yi Chen, Wei You, Wei Yu
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20013
[Abstract](241) [PDF 0KB](7)
Abstract:
Dynamically cross-linked polymers mainly introduces dynamic reversible covalent bonds into the polymer network to enable the materials to undergo structural rearrangement and then obtain processability. Therefore, it has considerable application prospects in polymer materials. In addition to designing new reaction systems, some researchers have also tried to use nanoparticles as the crosslinking agents to prepare dynamic cross-linked polymer nanocomposites. They mainly focused on the preparation of new dynamic cross-linked materials through the surface modification of nanoparticles in order to make them successfully participate in crosslinking reactions. Afterwards, the traditional melt remodeling and stress relaxation behavior are used to study their dynamic behavior and processability. However, they lack an in-depth discussion of the dynamic characteristics of dynamic cross-linked polymers, especially the influences on the dynamic behavior from the size differences of crosslinking agents (molecular crosslinking agents and nano-particle crosslinking agents). Thus, this paper used dynamic rheology to study the differences among particle-crosslinked vitrimer, molecular crosslinked vitrimer and particle-filled polymer composites under linear and nonlinear conditions. Compared with molecular cross-linked system, the relaxation modulus at the ends of particle cross-linked system was mainly derived from particle diffusion motion. And the reversible covalent network had a weaker contribution on the modulus and slowed down the rate of particle diffusion. Compared with the particle-filled system, the nanoparticles in the particle cross-linked system can escape from the particle cage after the dissociation of dynamic covalent bond.
Study on Adhesion Mechanism of Resorcinol Formaldehyde Cobalt Salt Adhesive System in Tire Skeleton Materials
Hao Yin , Yan-zhe Song , Yun-feng Li, Meng-cheng Du, Jian-guang Pang, Xin-yan Shi
最新录用 , doi: 10.11777/j.issn1000-3304.2019.19184
[Abstract](229) [PDF 0KB](0)
Abstract:
In order to verify and further explore the mechanism of adhesion of the adhesive resin and cobalt salt to the tire and the copper-plated steel cord,.The conventional adhesive resin R80 and two new adhesive resins HT1005 and H620 were selected to analysis mechanism of adhesion through structural analysis,rubber vulcanization characteristics,T extraction test, a new adhesive layer strength test method and adhesive layer characterization method.The results show that the polar adhesive resin containing hydroxyl groups will be auto-phase-separated due to thermodynamic incompatibility with the polarity difference of non-polar natural rubber when vulcanized. The adhesive resin migrates to the interface layer between the rubber and the copper-plated steel wire to produce a resin-rich layer between the rubber and the copper-plated steel wire. Since the crosslinking temperature of the binder resin is about 140 °C, it will reach when the rubber vulcanization temperature is cross-linked with S, a cross-linking reaction occurs. The network modulus of the binder resin is higher than that of the rubber vulcanization network, which enhances the adhesion strength between the copper-plated steel wire and the rubber, and form a modulus transition layer between the copper-plated steel wire and the rubber A modulus transition layer between the rubber and the rubber further enhances the adhesive layer.
Regulation of adhesion between polymer solid-liquid composite interface and liquid
Shu-man Cheng, Pu Guo, Li-ping Heng
最新录用 , doi: 10.11777/j.issn1000-3304.2020.19226
[Abstract](154) [PDF 0KB](3)
Abstract:
Interface adhesion is one of the most important properties of polymer composite materials, adhesion between solid and liquid can be seen everywhere in human life, agriculture and industry, such as oil-water separation, droplet manipulation, lab on the chip, high efficiency heat exchanger, and water collection. Hence, accurate regulation of interface adhesion plays a vital role in promoting the development and application of such materials. This paper mainly reviews adhesion regulation of polymer solid-liquid interface from three aspects: stability, directivity and intelligence. The first aspect mainly focus on improving anti-adhesive stability and mechanical stability of the polymer solid-liquid composite surface by introducing nanoscale layered structures and hetero-structures into surface microstructure. The second aspect summarizes directional adhesion of polymer solid-liquid composite interface, which was designed by combining the directional polymer surfaces and lubricants. The third aspect focus on intelligent regulation of interface adhesion, which was achieved by introducing smart response element into the polymer solid-liquid composite interface and then reversible regulation of the adhesion between the interface and liquid under the external field was realized. Finally, the existing problems of this fields are summarized and their future development directions are forecasted.
Research Progress on Polymer Crystallization Confined within Nano-porous AAO Templates
Guo-ming Liu , Guang-yu Shi, Du-jin Wang
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20003
[Abstract](167) [PDF 0KB](2)
Abstract:
The crystallization of polymers under nano-confinement has attracted great attention in recent years. Anodic aluminum oxide (AAO) template with uniform nano-cylinders provides an ideal model system for constructing one-dimensional nano-confinement environments. For crystalline polymers under confinement, the nucleation mechanism, crystal orientation, crystallization kinetics, crystallinity, and polymorphic preference are very different from those of the bulk. In the present paper, the research advances on the crystallization mechanism under confinement in AAO templates are summarized with an emphasis on the research results from the authors' group. The results are divided into four sections. (1) Nucleation. There is still a lack of a strict criterion for nucleation mechanism, especially the discrimination between homogeneous and surface nucleation. The frequently reported “multiple nucleation events” are proved to be results from percolation due to surface residual layer. The interaction between the polymer and the AAO wall plays an important role in the nucleation of poly(lactic acid). (2) The anisotropic crystalline growth. This section deals with the factors that govern the orientation, including the kinetic selection model, thermodynamic stability and interfacial interactions. (3) Crystallization kinetics. The Avrami index decreases under confinement. First-order kinetics is observed for polymers within AAO. The Avrami index that is remarkably smaller than 1 can be explained by the competition growth of multiple nuclei with different growth rates within one pore. (4) Crystallinity and polymorphic preference. The metastable crystalline modifications that are not favored in bulk become more pronounced under confinement within AAO, which provides a method to prepare functional nano-fibers. The questions to be solved on this topic are proposed.
Revealing the Relationship between the Biocompatibility and the Bound Water of Poly(ethylene glycol) by Single-Molecule Force Spectroscopy
Jun Xu, Nan-pu Cao, Yao-xin Xiao, Zhong-long Luo, Yu Bao , Shu-xun Cui
最新录用 , doi: 10.11777/j.issn1000-3304.2019.19219
[Abstract](239) [PDF 490KB](12)
Abstract:
Poly(ethylene glycol) (PEG) has become the “superstar” in the field of biological materials due to its excellent biocompatibility. However, the molecular mechanism underlying its biocompatibility is still unclear. In this work, we have investigated the relationship between the biocompatibility and the bound water of PEG by single-molecule force spectroscopy. To discern the effect of bound water on PEG in an aqueous solution, the single-chain inherent elasticity of PEG should be determined first as a reference. The inherent elasticity of PEG is obtained in a small-sized nonpolar organic solvent, nonane, which is confirmed by the quantum mechanical calculations-based freely rotating chain model (QM-FRC model). Then, SMFS experiments have been performed in phosphate-buffered saline (PBS) to study the effect of bound water on PEG. The shoulder plateau in the force-extension (F-E) curve of PEG obtained in PBS should be caused by the rearrangement of the bound water (water bridge) during the PEG elongation. This assumption has been confirmed by the two states QM-FRC model (TSQM-FRC model), which takes into account the effect of the water bridge. This bound water rearrangement will consume additional energy (Ew) besides that for the inherent elasticity of the chain. This Ew is calculated to be ~ 1.59 kBT/unit (3.93 kJ/mol) by integrating the area between the F-E curves of PEG obtained in PBS and nonane, which is closed to those of biomacromolecules. Inspired by the relationship between the low Ew and the behaviors of biomacromolecules, we have speculated the relationship between the biocompatibility and the bound water of PEG. (1) Like those of biomacromolecules, this Ew makes sure that the conformational transition of PEG in blood or cell will not consume (or produce) too much energy. Thus, the energy disturbance caused by PEG can be borne by the organism. (2) An appropriate Ew can prevent the aggregation of biomacromolecules and PEG. Biomacromolecules can self-assemble into the high-level structure after partial dehydration. If PEG has no bound water (Ew = 0), PEG may aggregate with the partially dehydrated biomacromolecules and then cause a serious of consequences. In one word, the Ew closed to those of biomacromolecules may be an important factor for the excellent biocompatibility of PEG.
Controllable Synthesis and Catalysis Application of Conducting Polymer/Noble Metal Nanoparticle Hybrids
Chuanqiang Zhou, Jie Han , Rong Guo
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20010
[Abstract](201) [PDF 3644KB](12)
Abstract:
Conducting polymer/noble metal nanoparticle hybrids have aroused increasing interest due to their potential application in fields of catalysis, sensing, surface-enhanced Raman, photo-thermal therapy and so on. The incorporation of conducting polymers with noble metal nanoparticles can produce new hybrids showing distinct properties that are not observed in the individual components. In general, the strategies in the synthesis of conducting polymer/noble metal nanoparticle hybrids involve the direct mixing of conducting polymers and noble metal nanoparticles; redox reaction between conducting polymers and noble metal ions; redox reaction between aniline monomers and noble metal ions; as well as aniline monomer polymerization in the presence of noble metal nanoparticles. Noble metal nanoparticles either support on surfaces of conducting polymer nanostructures or embed in conducting polymer matrix. The objective of our research focus on the controllable synthesis of polyaniline/noble metal nanoparticle hybrids with compact interactions, which will show potential application as advanced nanocatalysts in diverse catalytic reactions. The purpose of this review focus on our works in recent years on the synthetic strategies and catalysis application of polyaniline/noble metal nanoparticle hybrids. The supported polyaniline/noble metal nanoparticle hybrids can be synthesized through the redox reaction between polyaniline and noble metal ion, where the configuration of hybrids and size of supported noble metal nanoparticles are determined by polyaniline nanostructures and functional doping acids. The embedded polyaniline/noble metal nanoparticle hybrids can be synthesized through the redox reaction between aniline monomer and noble metal ion, where the functional substituents in aniline monomer play the determining role in lowing the size of noble metal nanoparticles in hybrids. In addition, the polymerization of aniline monomer on surfaces of noble metal nanoparticles can also lead to embedded polyaniline/noble metal nanoparticle hybrids with compact interaction. Polyaniline/noble metal nanoparticle hybrids have been successfully applied as nanocatalysts in nitrophenol reduction, alcohol oxidation, Suzuki-Miyaura cross-coupling, and Ullmann reactions. In particular, a novel yolk-in-shell nanostructure of polyaniline/Au hybrids have been emphasized and the synergistic catalytic effect of polyaniline for Au nanoparticles has been discussed.

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高分子学报2020年3月第3期目录
2020, 50(3).
[Abstract](108) [PDF 2320KB](11)
Abstract:
下载PDF文件可查看本期的封面、目录和图文摘要。
Atomic Force Microscopy Studies of Polymer Crystallization in Thin Film: Understanding the Formation Mechanism and Tuning the Properties
Bin Zhang
2020, 51(3): 221-238. doi: 10.11777/j.issn1000-3304.2019.19185
[Abstract](851) [FullText HTML](425) [PDF 4038KB](103)
Abstract:
Over the past decade, besides fundamental concepts, single-crystal engineering of functional polymers and its applications have attracted increasing attention. With the advances of multiparametric and multifunctional characterization, atomic force microscopy (AFM) not only can image the surface topography of polymer crystals in nanoscale while simultaneously mapping the physical properties, like the electrical and thermal properties, but also provides a unique way of linking molecular structures, crystallization conditions and post-treatment to properties. Furthermore, the nanoscale control afforded by scanning probe lithography (SPL) has prompted the development of a regulation of the polymer aggregation structures and surface patterns in thin films. To explicitly probe the mechanism of polymer crystallization, single layer lamella and few layer lamellae in thin films as a model system, combined with AFM can provide information on polymer nucleation and growth with high spatial and temporal resolution. On the other hand, to promote a better understanding of the nature of heterogeneities of metastable state within the lamellae, lamellar thickening/melting and self-seeding, the effects of annealing temperature and time on lamellar thickness of metastable folded-chain crystals have been investigated in polymer thin films.
Sustainable Polymers Based on Natural Terpenes
Jie Hao, Yu-xia Gao, Hou-rui Chen, Jun Hu, Yong Ju
2020, 51(3): 239-266. doi: 10.11777/j.issn1000-3304.2019.19180
[Abstract](1066) [FullText HTML](521) [PDF 6068KB](198)
Abstract:
Sustainable polymers are a class of materials derived from renewable resources and exhibit closed-loop life cycles. The development of sustainable polymers has been an important research topic to meet the need of nonpetroleum-based materials and to reduce the dependence on fossil fuel over the past decades. Terpenes is a kind of natural products with extensive supply sources and has multiple reactive sites and chiral centers. They can be divided into cyclic monoterpenes, linear monoterpenes and polycyclic terpenes according to the number of isoprene units and skeleton ring in their molecular structures. Such structural characteristic can not only simplify the synthesis of sustainable polymers, but also be used to design sustainable polymers with accurate structure at the molecular level according to a variety of demands. Moreover, natural terpenes can endow sustainable polymers with unique stereochemical structures, good biological activity and biocompatibility, thus broadening their applications in surface coating, biological medicine, and tissue engineering. From the perspective of structural design, there are three main ways to construct natural terpene-based sustainable polymers: (1) main-chain sustainable polymers can be obtained by self-condensation polymerization or co-condensation of terpenes or their derivatives; (2) side-chain sustainable polymers can be obtained by homopolymerization or copolymerization of terpenes with unsaturated functional groups or terpene monomers modified by unsaturated moieties; (3) sustainable polymers end-capped with terpenes can be obtained by modifying the polymer chain end with terpenes or their derivatives. It should be noted that the structure discrepancy between natural terpenes may require different design strategies to create functional sustainable polymers. This paper reviews the progress of natural terpene-based sustainable polymers in recent decades in the order of cyclic monoterpenes, linear monoterpenes and polycyclic terpenes. The main resources, monomer design strategies and polymerization methods of natural terpenes, as well as the characteristics, advantages and potential applications of natural terpene-based sustainable polymers are discussed.
Synthesis of Main-chain Azobenzene Liquid Crystalline Copolyester with Cide Hydroxyl Group and Its Photoresponsive Behavior
Ya-ting Peng, Tao Wang, Hang Li, Rong Yang, Jin-chun Li
2020, 51(3): 267-276. doi: 10.11777/j.issn1000-3304.2019.19177
[Abstract](715) [FullText HTML](406) [PDF 1625KB](64)
Abstract:
A series of main-chain azobenzene liquid crystalline copolyesters containing side hydroxyl group (Az-LCP) were synthesized with 4,4'-bis(6-hydroxyhexyloxy)biphenyl (BHHBP), 4,4'-bis(6-hydroxyhexyloxy)azobenzene (BHHAB), diethyl malate (DM) and phenyl succinic acid (PSA) by random copolymerization. Chemical structure of the Az-LCPs was characterized by proton nuclear magnetic resonance (1H-NMR) and gel permeation chromatography (GPC). And the phase transition behavior of the Az-LCPs was characterized by differential scanning calorimeter (DSC), and X-ray diffraction (XRD). Az-LCPs showed a nematic phase with a glass transition temperature (Tg) around room temperature. With increasing BHHAB monomer, the Tg and nematic-isotropic transition temperature of Az-LCPs decreased from 25.6 °C and 96.4 °C to 19 °C and 88.2 °C, respectively, showing a trans-cis photoisomerization effect of Az-LCPs. Then monodomain azobenzene liquid crystalline networks (Az-LCNs) were prepared by uniaxial stretching at nematic phase first, postcrosslinking in the hexamethylene diisocyanate solution for 12 h. Moreover, the orientation degree decreased with increasing BHHAB monomer into Az-LCP due to the decreasing Tg and π-π stacking interaction. While being crosslinked with HDI, the Tg of Az-LCNs increased up to 40 °C, meanwhile, the nematic-isotropic phase transition became broad and almost disappeared as the BHHAB monomer increased. All the Az-LCNs showed a UV-light induced bending and vis-light induced unbending behavior at room temperature except Az-LCN4 which contains 50% BHHAB monomer. Crosslinking duration of Az-LCNs also exhibited an influence on the photoresponsive bending/unbending behavior. With increasing crosslinking duration, the bending angle increased first and then decreased. In addition, the maximum bending angle and photoresponsive speed of Az-LCNs decreased with increasing thickness of the Az-LCNs films. Az-LCP1 with 10% azobenzene content and cross-linking for 12 h exhibits excellent photoresponsive behavior with a high bending angle of 88° and the fastest photoresponsive speed.
Synthesis of Carboxyl-terminated Polyolefins via Metathesis Degradation-hydrogenation of Diene Rubbers
Xi-xi Wang, Lu Dai, Su-yun Jie, Bo-geng Li
2020, 51(3): 277-286. doi: 10.11777/j.issn1000-3304.2019.19171
[Abstract](730) [FullText HTML](419) [PDF 1845KB](55)
Abstract:
The carboxyl-terminated polydiene is a kind of widely used telechelic liquid rubber, which is commonly used as adhesive for solid rocket propellant, material bonding, sealant, electric insulation or as modifier of epoxy resins. Taking diene rubbers as raw materials, the carboxyl-terminated polydienes were synthesized via olefin metathesis degradation of diene rubbers catalyzed by Grubbs II catalyst ( G2 ) in the presence of maleic acid as a chain transfer agent (CTA). The carboxyl-terminated polyolefins were further prepared by the subsequent chemical hydrogenation with p-toluenesulfonyl hydrazide/tri(n-propyl)amine reagents. The influences of reaction conditions on the molecular weight and molecular weight distribution of products, including reaction time, reaction temperature, molar ratios of C=C/catalyst and C=C/chain transfer agent, were investigated. The results indicated that the molecular weight of products could be controlled by varying the molar ratio of C=C/catalyst or C=C/chain transfer agent. It turned out that the catalyst was highly active for the metathesis degradation of diene rubbers even if there was no existence of chain transfer agents. The structures of carboxyl-terminated polydienes and polyolefins were characterized by nuclear magnetic resonance spectroscopy (1H-NMR) and carbon spectrum (13C-NMR), infrared spectroscopy (FTIR) and gel permeation chromatography (GPC) and their thermal properties were investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). It’s worth noting that the trans-1,4 content of carboxyl-terminated polybutadiene via metathesis degradation greatly increased and the corresponding cis-1,4 content decreased, thus affecting the properties of polymers. After hydrogenation, the carboxyl-terminated polyolefins had better thermal stability than the carboxyl-terminated polydienes.
Surface Modification of Ultra-high Molecular Weight Polyethylene Fiber by Catechol-tetraethylenepentamine
Han Zhao, Qing Shang, Meng Yang, Shuai Jin, Yang-yang Wang, Ning Zhao, Xiao-pin Yin, Cai-ling Ding, Jian Xu
2020, 51(3): 287-294. doi: 10.11777/j.issn1000-3304.2019.19172
[Abstract](667) [FullText HTML](406) [PDF 1246KB](55)
Abstract:
In recent years, research on interface modification based on dopamine has been greatly developed, but the high price of dopamine limits its practical application. Cheap catechol-tetraethylenepentamine (Cat-TEPA), similar to dopamine, can spontaneously polymerize and then deposit on the surface of various materials, exhibiting strong adhesion, reactivity, and no selectivity to the substrate. Surface modification based on Cat-TEPA has become a universal method suitable for practical applications. In this paper, ultra-high molecular weight polyethylene (UHMWPE) fiber was modified by Cat-TEPA. Transmission electron microscopy (TEM), infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and the static contact angle investigations were used to characterize the structure and performance of the modified fibers. The interfacial shear strength (IFSS) between the fiber and the epoxy resin before and after modification was measured by monofilament extraction experiment. The effects of reactant ratio and reaction time on interface properties were explored and the optimal modification conditions were determined. The results show that Cat-TEPA modification does not affect the crystallization and thermal stability of the fiber, and the surface wettability of the fiber is improved after modification. An optimal IFSS increase of about 44% has been obtained when the molar ratio of Cat-TEPA is 1:4 and reaction time is 24 h.
Enhanced Energy Storage Performance of Polyimide-based Nanocomposites by Introducing Two-dimensional Nanosheets
Fu-rong Li, Jian-ying Zhao, Hai-quan Guo, Lian-xun Gao
2020, 51(3): 295-302. doi: 10.11777/j.issn1000-3304.2019.19164
[Abstract](637) [FullText HTML](360) [PDF 1211KB](67)
Abstract:
Increasing demands to improve the energy storage density of polymer dielectric materials have spurred the development of polymers with enhanced permittivity and improved dielectric breakdown. The introduction of high permittivity fillers can effectively improve the polymer permittivity, but it is also easy to cause the reduction of breakdown strength, which affected the improvement of the energy storage density of polymer materials. In this study, the polyimide-based nanocomposite films were fabricated via the in situ polymerization with high permittivity barium titanate (BT) nanoparticles and two-dimensional nanosheets exfoliatred from hydrotalcite (HT) as fillers . The permittivity of PI/BT films gradually increased with the increaseing content of BT nanoparticles. However, the breakdown strength decreased significantly with the increase of BT content. Therefore, the energy storage density of PI/BT composite films showed a remarkable decrease. However, with a small amount of two-dimensional nanosheets of hydrotalcite adding to the PI/BT composite films, the breakdown strength of the composites showed an obvious increase trend. The breakdown strength of the PI/BT film conntaining 30% BT increased by 32.8% when only 1% two-dimensional nanosheets were added. The improvement effect of two-dimensional nanometer sheet on the breakdown strength of PI/BT composite material is the same under different BT contents. Therefore, the penetration strength of PI/BT composite film can be effectively improved by adding two-dimensional nanocrystalline sheets, thus increasing the energy storage density. This is due to the fact that two-dimensional nanosheets can effectively improve the dispersion of high content nanoparticles in the polymer matrix, thus improving the properties of composites related to the dispersion of nanoparticles. Experimental results showed that by introducing two different morphology fillers, the permittivity and breakdown strength of PI/BT/HT composite films can be improved. With the addition of 20% BT and 1% HT, the energy storage density of PI/BT/HT composite film can reach 2.58 J/cm3, which is 14.6% higher than that of the composite film with only 20% BT. This method of simultaneously adding two different morphology fillers such as nano particles and two-dimensional nanosheets into the polymer matrix was expected to be applied in more fields of nanocomposite materials, especially in fields with high content of nano particles.
Preparation and Properties of Recyclable High-performance Epoxy Resins and Composites
Dong Wang, Li-ying Li, Hong-jun Ke, Kong-li Xu, Shan Lu, Wen-hua Gong, Huan Zhang, Guo-yong Wang, Ying-min Zhao, Ning Zhao
2020, 51(3): 303-310. doi: 10.11777/j.issn1000-3304.2019.19167
[Abstract](730) [FullText HTML](478) [PDF 1365KB](96)
Abstract:
Aiming at the demands for recyclable resins and composites in practical applications, high performance recyclable epoxy resins with excellent comprehensive properties are prepared using methyl teterahydrophthalic anhydride as the curing agent and zinc acetylacetonate hydrate as the catalyst. The effects of anhydride and catalyst concentrations on the structure, thermal and dynamic properties of epoxy vitrimers are systematically explored to achieve the resin formulation optimization. With the decrease of anhydride concentrations, the cross-linking densities decrease, and the epoxy vitrimers show decreased glass transition temperature (Tg) but enhanced dynamic properties, which is attributed to the sufficient hydroxyl groups in structure that could trigger the transesterification exchange reactions with ester bonds. The increase of catalyst concentrations can also lead to enhanced dynamic properties as a result of the accelerated transesterification rates. The epoxy vitrimer with epoxy/anhydride/catalyst ratios of 1:0.5:0.05 displays optimal comprehensive performance with intermediate thermal properties and excellent dynamic properties. Based on the dynamic transesterification reaction, the epoxy vitrimers can be well reprocessed by the physically hot pressing methods at 180 °C for 6 h under a pressure of 10 MPa, and the recycling efficiency can be up to 80%. Moreover, the epoxy vitrimer-based carbon fiber reinforced composites are prepared by the resin transfer molding (RTM) technique. The prepared carbon fabric composites show a tensile strength of 479 MPa and tensile modulus of 58 GPa, revealing comparable mechanical properties to those of traditional thermoset composites. After heating the composites in ethylene glycol solvent at 180 °C for 8 h, the clean carbon fiber fabric with the same dimension as fresh ones can be reclaimed due to the dissolution of epoxy vitrimer binder in alcohol solvent via transesterification. In addition, the collected dissolved polymers can form vitrimers again by evaporating the EG solvent in open air at 180 °C for 12 h. It is demonstrated that the carbon fibers and epoxy polymers can both be fully recycled from the composites by the alcohol solvent dissolution method.
Investigation of the Transformation Dynamics of Diblock Copolymers Assemblies in Reverse Solvent via Computer Simulation
Chun-yang Yu, Shan-long Li, Ke Li, Yong-feng Zhou
2020, 51(3): 311-318. doi: 10.11777/j.issn1000-3304.2019.19173
[Abstract](634) [FullText HTML](388) [PDF 1281KB](59)
Abstract:
It has become a very mature and effective method to construct complex nanostructures by the self-assembly of amphiphilic block copolymer in solution or in bulk. A large number of studies have been reported that the assembly morphology of amphiphilic block copolymer can be accurately controlled by adjusting the block ratio, concentration, block compatibility and solvent conditions. Meanwhile, compared with the solution self-assembly method, the combination of substrate restriction and solvent annealing provides another way for the construction and regulation of complex nanostructures. However, due to the limitations of experimental methods, two basic problems have not been resolved. The first one is that, after the solvent selectivity was changed, the structural transformation dynamics of micelle were not clear. The second one is that, the current studies are only limited to the structural transformation process of spherical micelles in different solvents, the structural evolution kinetics of other shaped micelles or vesicles in the reverse solvent or at interface have not been reported. Thus, it is necessary to address these issues through computer simulation. In this paper, the transformation dynamics of diblock copolymers assemblies in reverse selective solvent were disclosed using dissipative particle dynamics simulation. Simulation results show that after the change of solvent selectivity, the large spherical micelles were respectively transformed into the reverse spherical micelle in solution and the ring-like micelle at the interface. The simulation results were in agreement with the available experimental result. In addition, the simulation results also predicted that after the change of solvent selectivity, the ring-like micelle, the wormlike micelle and the vesicle were transformed into the reverse ring-like micelle, the reverse ring-like micelle and multimicelle aggregate in solution, respectively, while they were transformed into the branched wormlike micelle, the multilayer nanoparticle and the patch nanoparticle at the interface, respectively. The current work provide important guidance for the design and preparation of novel nanostructures.
  • Editor: Xi Zhang

    Establishment Time: 1957

    Adminidrated by: Chinese Academy of Sciences

    Sponsors by: ICCAS
     Chinese Chemical Society

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