ISSN 1000-3304CN 11-1857/O6
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Sustainable Polymers Based on Natural Terpenes
Jie Hao, Yu-xia Gao, Hou-rui Chen, Jun Hu, Yong Ju
六校 , doi: 10.11777/j.issn1000-3304.2019.19180
[Abstract](267) [FullText HTML](98) [PDF 7147KB](60)
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.
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](224) [FullText HTML](124) [PDF 1087KB](13)
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.
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
一校 , doi: 10.11777/j.issn1000-3304.2019.19164
[Abstract](314) [FullText HTML](129) [PDF 1084KB](36)
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 stydy, 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.
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
六校 , doi: 10.11777/j.issn1000-3304.2019.19173
[Abstract](300) [FullText HTML](125) [PDF 1281KB](19)
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.
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](229) [FullText HTML](92) [PDF 1388KB](7)
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](430) [FullText HTML](202) [PDF 1495KB](59)
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](202) [FullText HTML](93) [PDF 1145KB](19)
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.
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
六校 , doi: 10.11777/j.issn1000-3304.2019.19177
[Abstract](348) [FullText HTML](210) [PDF 1625KB](40)
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.
Preparation and Properties of Recyclable High-performance Epoxy Resins and Composites
Dong Wang, Li-ying Li, Hong-jun Ke, Kong-li Xu, Shan Lu, Wenhua Gong, Huan Zhang, Guo-yong Wang, Ying-min Zhao, Ning Zhao
六校 , doi: 10.11777/j.issn1000-3304.2019.19167
[Abstract](345) [FullText HTML](199) [PDF 1359KB](54)
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.
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
六校 , doi: 10.11777/j.issn1000-3304.2019.19172
[Abstract](368) [FullText HTML](200) [PDF 1246KB](32)
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.
Synthesis of Carboxyl-terminated Polyolefins via Metathesis Degradation-hydrogenation of Diene Rubbers
Xi-xi Wang, Lu Dai, Su-yun Jie, Bo-geng Li
六校 , doi: 10.11777/j.issn1000-3304.2019.19171
[Abstract](350) [FullText HTML](231) [PDF 1845KB](40)
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.
Atomic Force Microscopy Studies of Polymer Crystallization in Thin Film: Understanding the Formation Mechanism and Tuning the Properties
Bin Zhang
六校 , doi: 10.11777/j.issn1000-3304.2019.19185
[Abstract](334) [FullText HTML](183) [PDF 3644KB](56)
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.
Synthesis and Properties of a Novel Conjugated Acceptor Material for Organic Solar Cells Based on Indacenobis(dithieno[3,2-b:2′,3′-d]pyran)
Xin Ke, Ling-xian Meng, Xiang-jian Wan, Xin Zhang, Mei-jia Chang, Chen-xi Li, Yong-sheng Chen
一校 , doi: 10.11777/j.issn1000-3304.2019.19131
[Abstract](676) [FullText HTML](346) [PDF 925KB](57)
We designed and synthetized a new non fullerene acceptor with an A-D-A structure, named IDTO2HT-2F, based on indacenobis(dithieno[3,2-b:2′,3′-d]pyran) for organic solar cells. The dithieno[3,2-b:2′,3′-d]pyran will improve the electron-donating capability of the unit and lift the highest occupied molecular orbital (HOMO). Thus, the band gap decreases, making the maximum absorption peak red-shift. Theoretical calculation based on density functional theory (DFT) proved the feasibility of this molecular design. The molecule IDTO2HT-2F has a narrow bang gap of 1.30 eV with the solid absorption edge extended to 956 nm, which is complementary to that of the polymer PM6 film. The broad absorption of the active layer ensures the photovoltaic device to produce high photocurrent. With 0.5% DIO additive and thermal annealing at 120 °C for 10 min, the organic solar cell based on the acceptor IDTO2HT-2F and the polymer PM6 exhibits a power conversion efficiency (PCE) of 10.85% with a short circuit current density (Jsc) of 20.61 mA cm−2, an open-circuit voltage (Voc) of 0.86 V and a fill factor (FF) of 0.62. The results indicate that the strategy of introducing pyran into the molecular backbone is an effective way to tune the absorption and energy level of the molecules, which is also a promising method to design new non fullerene acceptors.
The Microstructures and Molecular Interactions in Multiphase Polymers: Insights from Solid-State NMR Spectroscopy
Rong-chun Zhang
六校 , doi: 10.11777/j.issn1000-3304.2019.19175
[Abstract](462) [FullText HTML](219) [PDF 4727KB](71)
In recent decades, solid-state nuclear magnetic resonance (NMR) spectroscopy has been playing an important role in the characterization of polymer materials. To some degree, it has become one of the indispensable tools for studying the microstructures, segmental dynamics and inter-/intra-molecular interactions and elucidating the structure-functionality-property relationship of multiphase polymer materials, because the anisotropic spin interactions in the molecules can be selectively manipulated via various radiofrequency pulse sequence design. As a result, NMR can provide important information on a length scale from 0.1 nm to 100 nm and a time scale from 1 ns to 100 s. Herein, in this current review article, we will review some of our recently developed solid-state NMR approaches specifically for applications in polymers, including quantitative determination of compositional contents, characterization of crosslinking/entanglement density and inhomogeneity of the network, hydrogen bonding interactions between segments, and so on. A variety of typical examples, including self-healing supramolecular rubbers, thermal reversible polyurethanes, dual-cross-linked hydrogels, elastomers, etc., are given in detail, showing how various solid-state NMR approaches were implemented to quantitatively characterizing the structures, molecular interactions, and crosslinking network. Furthermore, due to the presence of heterogeneous dynamic in multiphase polymers, the applications of traditional solid-state NMR techniques are sustainably limited, and we also developed corresponding novel solid-state NMR approaches to overcome the limitations and enhance the spectral resolution and signal sensitivity.
Cationic Surfactant Sensor Based on Polyacrylic Acid Two-dimensional Photonic Crystal Hydrogel
Xia-tong Qin, Gen-qi Liu, Chen-hui Liu, Jian-xun Liu, Huan-huan Li, Yun-lei Cao, Xiao-dong Fan
六校 , doi: 10.11777/j.issn1000-3304.2019.19170
[Abstract](341) [FullText HTML](174) [PDF 1082KB](29)
A polyacrylic acid two-dimensional photonic crystal hydrogel (PAA 2D-PCH) was prepared with acrylic acid as monomers, ethylene glycol dimethylacrylate as cross-linkers, 2,2-diethoxyacetophenone as initiators and polystyrene two-dimensional photonic crystal with bright diffraction under visible light illumination as a template, and its stimulating response properties to cationic surfactants were investigated. The results indicated that the PAA 2D-PCH had a sensitive response to cationic surfactants, while no response to anion, nonionic and zwitterionic surfactants. When the concentration of CPC, CPB and CTAB was increased from 0 to 4 × 10−3 mol/L, the diameter of Debye ring increased by 5.95, 5.50 and 4.95 cm, respectively, and the particle spacing decreased by 390, 364, and 341 nm, respectively. In the anionic surfactant, nonionic surfactant and zwitterionic surfactant solution, the diameter of Debye ring of the PAA 2D-PCH showed almost no change. The selective recognition of cationic surfactants by PAA 2D-PCH stemed from the electrostatic interaction between the negatively charged carboxylate ions and the cationic surfactants in the phosphate buffer solution of pH = 7.4, causing the PAA 2D-PCH shrunk, the particle spacing reduced, the diameter of the Debye ring increased, and the diffraction wavelength blue shifted. Study on the response behavior of PAA 2D-PCH to cationic surfactants by Debye ring method is easy to operate and has the characteristics of reusability and visualization, which is expected to be used for the determination of cationic surfactants in water.
Applications of Polymeric Micro/Nanoparticles in Engineered Vaccines
Hua Yue, Guang-hui Ma
六校 , doi: 10.11777/j.issn1000-3304.2019.19143
[Abstract](509) [FullText HTML](256) [PDF 2741KB](65)
With the increasing demand for preventing and controlling of new/sudden diseases, major infectious diseases and malignant tumors, vaccines that based on traditional experience await updated. In terms of the unique physio-chemical advantages, polymeric micro/nano particles have become the research hotspots in the field of biomedical delivery. However, the rational integration of the micro/nano particles into vaccine delivery system is a huge challenge. On the basis of our research on the preparation and application of polymer micro/nano particles, an advanced strategy that co-assembles the particle "chassis" and subunit vaccines into one engineered vaccine is proposed. During the 20-year systematic study, new functions of polymeric particles are developed, and important mechanisms for the enhanced cellular/mucosal immunity are clarified. Apart from the chassis with conventional physiochemical property, other chassises with lysosomal escape merit, unique properties (deformability or mobility), or " Immunoticket” advantage have been exploited. The present paper not only summarizes our work but also involves international research progress, which sheds light upon the engineered vaccine chassises for their on-demand design concept, relative mechanism and development
Preparation and Characterization of Electrospinning Crosslinked Gel Polymer Electrolytes
Yun-ni Chen, Qin Xiao, Qing-yin Li, Shi-jie Ren
六校 , doi: 10.11777/j.issn1000-3304.2019.19149
[Abstract](407) [FullText HTML](219) [PDF 1449KB](44)
Gel polymer electrolytes (GPEs) for lithium ion batteries (LIBs) have attracted great attention due to their high ionic conductivity and safety, but it is still a great challenge to develop GPEs which can be used at high temperature in specific applications, such as oil drilling, mining, military and aerospace electronics. Cross-linking is one of the efficient methods for enhancing the thermal stabilities of GPEs. In this work, crosslinked gel polymer electrolytes (e-CGPEs) were made by electrospinning and Friedel-Crafts alkylation reaction. First of all, electrospun polymer membranes (e-PMs) were prepared by electrospinning technique with poly(vinylidene fluoride) (PVDF) as the matrix and polystyrene-b-poly(ethylene oxide)-b-polystyrene (PS-PEO-PS) triblock copolymer as the additive. Then the styrene units in e-PMs were crosslinked by Friedel-Crafts alkylation reaction to give electrospun crosslinked polymer membranes (e-CPMs). e-CPMs were activated by absorbing electrolytes to give crosslinked gel polymer electrolytes (e-CGPEs). The effects of PS-PEO-PS content (3%, 5%, 10%, 20%) on the properties of e-CPMs and e-CGPEs were also discussed. The results show that the content of PS-PEO-PS can affect the crystallinity, electrolyte uptake and crosslinked degree of e-CPMs, which may have influences on the ionic conductivity. Owing to the abundant crosslinked networks, high-temperature dimensional stabilities of e-CPMs are much better than that of electrospun PVDF membrane and commercial polypropylene (PP) membrane. All e-CPMs show almost no dimensional shrinkage at 160 °C, indicating that e-CPMs can be efficient precursors of GPEs used at high temperature. e-CGPEs have better electrochemical performances than the PVDF-based GPE (e-PVDF), due to their high porosity, electrolyte uptake and ionic conductivity. Among all the e-CGPEs, e-CGPE 5% with proper PS-PEO-PS content and crosslinked degree possesses the highest ionic conductivity of 6.52 mS/cm at room temperature. The half-cell assembled by e-CGPE 5% shows a discharge specific capacity of 83.5 mAh/g at 2 C. e-CGPEs also exhibit excellent cycle and rate performances. e-CGPE 5% has a capacity retention of 99.7% after 100 cycles at 0.1 C. All the results suggest that e-CGPEs have potential application value in high-efficiency lithium ion batteries which could be used at high temperature. And this work also provides a new path for the preparation of crosslinked gel polymer electrolytes with high efficiency and good performance.
Measuring the Strength of S/Se Based Dynamic Covalent Bonds
Jia-hao Xia, Hong-bin Li, Hua-ping Xu
六校 , doi: 10.11777/j.issn1000-3304.2019.19166
[Abstract](697) [FullText HTML](428) [PDF 1391KB](71)
Sulfur, selenium-containing bonds, including disufide bond (SS), diselenide bond (SeSe), and selenide-sulfide bond (SeS), are an important type of light responsive dynamic covalent bonds. Among them, SS and SeS bonds can undergo exchange reaction with the irridiation of UV light, while SeSe bond only requires visible light due to its weaker bond energy. The purpose of this research is to use atomic force microscope-based single molecule force spectroscopy (AFM-SMFS) measurement to reveal the reasons behind the responsiveness and stability of S/Se related dynamic covalent bonds. In this study, quartz substrates modified by SS or SeSe bond were prepared via surface modification. Specifically, the quartz substrates were first washed with a mixture of sulfuric acid and hydrogen peroxide (volume ratio is 7:3), and then processed with oxygen plasma to obtain a hydrophilic surface. The surface then reacted with 3-aminopropyltriethoxysilane to form amino groups at the top, which further reacted with disulfide or diselenide containing diacid to afford SS or SeSe bond-modified substrates. The structures of the surfaces were comfirmed by water contact angle (WCA), atomic force microscopy, X-ray photoelectron spectroscopy (XPS), and time of flight secondary ion mass spectrometry. Based on the light induced exchange reaction, wettabilities of the substrates were able to adjusted and were characterized by WCA and XPS. By exchanging with thiol or diselenide containing polymer, the polymer chain-attached substrates linked by a single bond of either SS, SeS, or SeSe could be obtained. The rupture forces of the three bonds were measured by SMFS. At a pulling speed of 200 nm/s, the rupture forces of SeSe, SeS and SS bonds were (1100 ± 300), (1320 ± 330), and (1450 ± 300) pN, respectively, indicating their strengths decreased as SS > SeS > SeSe. This result was consistent with the thermodynamic stability ranking of the three bonds. SMFS results illustrated that the strength of the dynamic covalent bond is between that of non-covalent interaction and that of robust covalent bond (e.g. C―C bond), which accounts for its balance of responsiveness and stability.
Particle Morphology Control of Polypropylene Heterophasic Copolymer at Increased EPR Content by Simultaneous Cross-linking
Meng-jia Zhang, Li Wang, Liu-ting Hong, Ya-wei Qin, Jin-yong Dong
三校 , doi: 10.11777/j.issn1000-3304.2019.19115
[Abstract](776) [FullText HTML](308) [PDF 1372KB](54)
Heterophasic copolymerization of propylene based on MgCl2-supported Ziegler-Natta catalysts, that is, sequential propylene homopolymerization or copolymerization with minor amount of ethylene followed by ethylene/propylene random copolymerization for EPR, is a major polymerization technique in polypropylene industry, whose products, depending on their EPR contents, include high impact PP (hiPP, where EPR weight fraction is normally less than 40%) and thermophastic olefin elastomer (TPO, where EPR weight fraction is higher than 50 wt%). Compared to hiPP, the production of TPO is rather more challenging, for increased EPR contents makes it very difficult to prevent EPR from overflowing to the surfaces of the polymer particle, which will mess up with the particle morphology and lead to serious reactor fouling issues, affecting the production continuity. How to control the particle morphology at increased EPR contents with EPR being authentically contained inside without contaminating the surfaces has become a key scientific issue in further developing heterophasic copolymerization of propylene to TPO. This paper reports that the solution may lie in a simultaneous cross-linking of EPR using nonconjugated α,ω-diolefin during its polymerization. It is shown that simultaneous cross-linking can alter EPR’s viscoleastic properties to a great extent, exponentially increasing its low-shear viscosity and elasticity. As a result, EPR no longer poses as aggregated volatile droplets but rather large-size phase domains are formed by hot-compression; instead, it features dispersed particles discrete to each other. In turn, no overflowing of EPR occurs to the polymer particle surfaces. This research provides a solution for heterophasic copolymerization of propylene and polypropylene thermoplastic elastomer with high EPR content.
Investigation of Chiral Recognition Mechanism of Polysaccharide Derivatives Based on Molecular Simulation
En-ting Deng, Wan-ying Bi, Bo Liu, Li-li Zhang, Jun Shen
六校 , doi: 10.11777/j.issn1000-3304.2019.19116
[Abstract](415) [FullText HTML](215) [PDF 975KB](11)
As one of the most powerful and popular chiral stationary phases (CSPs), phenylcarbamate derivatives of cellulose and amylose exhibit high chiral recognition ability and have realized efficent enantioseparation for almost 80% chiral compounds. To develop novel enantioseparation materials with high chiral recognition ability, it is of crucial importance to elucidate the chiral recognition mechanism for CSPs. Based on this, cellulose tris(phenylcarbamate) and amylose tris(phenylcarbamate) were synthesized by traditional esterification method in this study. The structures and degrees of substitution of the polysaccharide derivatives were characterized by 1H-NMR, implying that the obtained cellulose and amylose deivatives possessed regular higher order structures and almost complete substitution of phenylcarbamate pendants at three positions on the glucose units. The obtained polysaccharide derivatives were then coated on aminopropyl silica gel to prepare the chiral stationary phases (CSPs). The chiral recognition abilities of the derivatives were evaluated by the high performance liquid chromatography (HPLC) based on the separation of racemic 1-(9-anthryl)-2,2,2-trifluoroethanol (Rac-1). Then, based on the molecular mechanics and the molecular dynamics, molecular simulation of the higher order sturucture of polysaccharide derivatives were performed using Materials Studio software. The optimized conformation for the interaction between polysaccharide derivatives and enantiomers of Rac-1 was achieved by the molecular simulation according to the FTIR and XRD results. The molecular simulation results agreed well with the chiral recognition ability and elution order of enantiomers by HPLC. It indicated that the chiral recognition was significantly dependent on the synergistic interactions between polysaccharide derivatives and enantiomers of Rac-1 at the chiral grooves formed by the carbamate substituents and aromatic rings of the polysaccharide derivatives with different stabilities. This study may contribute to a better understanding for the chiral recognition mechanism of polymer-based CSPs.
Synthesis and Performance of a Double Network Self-healing Elastomer Based on Hydrogen Bonds and Diels-Alder Crosslinks
Yan Peng, Yu-jia Hou, Qiao-qiao Shen, Hui Wang, Gang Li, Guang-su Huang, Jin-rong Wu
六校 , doi: 10.11777/j.issn1000-3304.2019.19140
[Abstract](669) [FullText HTML](428) [PDF 1065KB](73)
Intrinsic self-healing elastomers, which can automatically heal themselves after damage without the addition of other reagents, have recently attracted increasing attention. However, a trade-off commonly exists between high mechanical properties and high self-healing efficiency, which is always the bottle-neck in advancing these high performance self-healing elastomers. To solve this problem, a high performance and high self-healing efficiency elastomer was developed in this work based on hydrogen bonds and Diles-Alder (DA) crosslinks. Firstly, a monomer (HM) functionalized with amido bond and carbamic acid ester for the generation of hydrogen bonds was synthesized by N-butyl isocyanate and N-(2-hydroxyethyl)acrylamide. Next, one-pot free-radical copolymerization of HM, butyl acrylate (BA), and furfuryl methacrylate (FMA) was carried out to afford a linear copolymer, which was only cross-linked with hydrogen bonds. Finally, bismaleimide (BMI) was used to crosslink the linear copolymer through DA reaction. A double network self-healing elastomer with two kinds of crosslinks, i.e. hydrogen bonds and DA bonds, was thus prepared. The heating-up and cooling down FTIR spectroscopy was used to characterize the hydrogen bonds, while the existence of DA bonds was proved by FTIR, DSC, and DMA techniques. When an external force was applied, the hydrogen bonds broke firstly to dissipate energy, which helped to increase the toughness by about 6.2 times, the tensile strength by about 12.3 times, and Young’s modulus of the elastomer by about 26 times. Meanwhile, DA crosslinks endowed the elastomer with certain elasticity and the capability of fast shape recovery. Moreover, thanks to the reversible ability of hydrogen bonds and DA crosslinks, the elastomer exhibited a high self-healing efficiency up to 98%.
Reinforcing Styrene-Butadiene Rubber with Deformable Domains and Related Mechanisms
Li-jie Zhang, Jing Huang, Si-wu Wu, Zheng-hai Tang, Bao-chun Guo
六校 , doi: 10.11777/j.issn1000-3304.2019.19135
[Abstract](535) [FullText HTML](277) [PDF 1420KB](42)
In the present work, based on the coordination capability of nitrile groups in nitrile rubber (NBR) with metal ions, a novel type of rubber material with sacrificial domains was designed. Specifically, copper sulfate (CuSO4) and vulcanization package were introduced into styrene-butadiene rubber (SBR)/NBR blend by mechanical mixing and hot pressing. As a result, SBR with sulfur crosslinkings are formed as continous phases while the NBR mainly crosslinked by Cu(II)-nitrile coordination bonds are acted as dispersed phases, which are used as deformable domains to reinforce SBR. With the increasing concentration of coordination bonds in dispersed phase, both strength and modulus of the rubber improve rapidly. When 20 wt% NBR was introduced, the strength and modulus of SBR are increased by 2.6-fold and 3.2-fold, respectively. The significant reinforcing effect of this system is attributed to the strong yet deformable domains. The strong domains have hydrodynamic effect, which greatly improve the moduli of the samples. On the other hand, upon external stress, the loading can be rapidly transferred from SBR matrix to the domains owning to strong interfacial interactions, forcing the domains to develop high-elastic deformation prior to the rupture of SBR chains and dissipate mechanical energy, thus significantly enhancing the toughness of the rubber. This forced high-elastic deformation in domains can be recoverd through relaxation at a high temperature to fully restore the mechanical properties. Overall, this work provides a new way for the reinforcement of non-polar rubber through the design of deformable domains.
Systheisis of Vanadium Complexes Bearing Tridentate β-Ketoimine Ligands and Their Catalytic Capabilities towards Ethylene (Co)polymerization
Ling-pan Lu, Kai-ti Wang, Yi Liu, Jia-jun Wu
六校 , doi: 10.11777/j.issn1000-3304.2019.19128
[Abstract](666) [FullText HTML](346) [PDF 893KB](32)
Vanadium catalysts always show outstanding catalytic properties towards ethylene (co)polymeriztaion, while the high-valent vanadium species would be deactivated because of the generation of inactive or less active low-valent species at elevated temperature and/or in prolonged time. As proved, introducing of bulky groups into the ligands is benefit to improving the catalytic properties of vanadium complexes. Herein, in order to well control the oxidation state of vanadium species, a series of tridentate β-ketoimine type vanadium(III) complexes bearing cyclic skeleton {[(R)X(C6H4)N=CH(C6H5)C10H7O]VCl2(THF): 2a , R = CH3, X = S; 2b , R = CF3, X = S; 2c , R = Ph, X = S; 2d , R = tBu, X = S; 2e , R = Ph2, X = P; 2f , R = Ph, X = O}, were synthesized and characterized. Because of the constrained effects of the cyclic skeleton and the stabilizing effects of the bi-chelating ring, these synthesized catalysts showed high activities and improved stabilities in ethylene (co)polymerization. In the presences of Et2AlCl and ethyl trichloroacetate, catalysts 2a2f showed 8.16 − 19.9 kgpolymer/(mmolV·h), 7.68 − 26.9 kgpolymer/(mmolV·h) and 4.80 − 42.2 kgpolymer/(mmolV·h) of catalytic activities towards ethylene polymerization, ethylene/norbornene (NBE) copolymerization and ethylene/exo-1,4,4a,9,9a,10-hexahy-dro-9,10(1′,2′)-benzeno-1,4-methanoanthracene (HBM) copolymerization, respectively. All of the resultant polymers exhibited a unimodal distribution, indicating that these vanadium catalysts showed single-site catalytic behaviour, even at elevated temperatures (50 − 70 °C). Catalysts 2b , 2d , 2e and 2f showed "positive" comonomer effects in both ethylene/NBE copolymerization and ethylene/HBM copolymerization. Besides, 2a and 2c also exhibited positive comonomer effects in ethylene/HBM copolymerization. Cyclic olefin copolymers possessing high molecular weights (NBE: 43.1 − 66.4 kg/mol; HBM: 90.2 − 138 kg/mol) and high comonomer incorporations (NBE: 30.9 mol% − 42.1 mol%; HBM: 14.7 mol% − 25.0 mol%) were obtained facilely via direct copolymerization. The glass transition temperature is dominantly affected by the cyclic olefin incorporations and the steric hindrance of the cyclic olefin. Compared with the ethylene/NBE copolymers, the obtained ethylene/HBM copolymers showed much higher glass transition temperatures (NBE: 84 − 105 °C versus HBM: 173 − 188 °C).
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](0) [PDF 0KB](0)
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.
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](75) [PDF 0KB](2)
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.
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
最新录用 , doi: 10.11777/j.issn1000-3304.2019.19210
[Abstract](45) [PDF 1272KB](7)
A set of functional POSS derivatives and star-shaped POSS-cored polyesters are prepared and characterized. Octavinyl polyhedral oligomeric silsesquioxane (OVPOSS) is first reacted respectively with 2-mercapto-ethanol, 1-thioglycerol and cysteamine hydrochloride by thiol-ene “click” chemistry to get three kinds of POSS molecules with hydroxyl groups, dihydroxy groups and amino groups, denoted as POSS-8OH, POSS-16OH and POSS-8NH2. The chemical structures of these POSS derivatives are confirmed by nuclear magnetic resonance (1H- and 13C-NMR) and Fourier-transform infrared spectroscopy (FTIR). 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) under the catalysis of stannous octoate or 1, 8-diazabicyclo[5.4.0]-undec-7-ene (DBU), 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 length are synthesized by changing the feed ratio of the monomer to initiator. GPC analysis demonstrates that POSS-8PCL samples possess symmetrical monomodal peak and the trace of polymers with higher feed ratio show an apparent shift to higher molecular weight part compared with that with lower feed ratio. As a demonstration, the chemical structure of POSS-8PCL-2 is confirmed by using FTIR, 1H NMR and 13C NMR analyses. TGA tests indicate that the initial decomposition temperature and decomposition mode are influenced by the molecular weights of POSS-8PCL. For example, the initial decomposition temperature of POSS-8PCL-1 is about 150 C and the TGA curve displays apparent two-stage decomposition pattern. However, with the increase of molecular weights, the initial decomposition temperature of POSS-8PCL-2 and POSS-8PCL-3 are increased to about 200 C and the two-stage decomposition modes become weaker. In addition, it is also found that the residues with different contents are left at 700 °C. In order to compare the thermal stability of star-shaped PCL with POSS core or 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 of POSS-16PCL is characterized by FTIR, 1H NMR and 13C NMR analyses. The molecular weight information of POSS-16PCL is analyzed by GPC test and it shows a symmetrical monomodal peak and relatively low dispersity. TGA analysis indicates 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 a hydrophilic eight-arm star-shaped poly(ethyl ethylene phosphate) (POSS-8PEEP). The chemical structure and molecular weight information of POSS-8PEEP are confirmed by FTIR, 1H NMR and GPC analyses. The GPC curve using DMF as eluent shows a monomodal peak and relatively low dispersity, but the peak is not quite symmetrical maybe due to the weak signal of polyphosphoesters in GPC test. 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.
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](0) [PDF 0KB](0)
School of Physics and Electronics, Shandong Normal University, Jinan 250358; School of Physics, Nankai University, Tianjin 300071
Effects of Annealing Temperature and Active Layer Thickness on the Photovoltaic Performance of P3HT Photodetector
Shi-jia Gao, Xin Wang, Yu-lin Zhang, Sai Zhang, Wen-qiang Qiao , Zhi Yuan Wang
最新录用 , doi: 10.11777/j.issn1000-3304.2019.19206
[Abstract](86) [PDF 888KB](4)
Bulk heterojunction photodetectors with a structure of ITO/PEDOT:PSS/P3HT:PC61BM/C60/Al were prepared by using poly(3-hexylthiophene) (P3HT) as a donor and fullerene derivative (PC61BM) as an acceptor. The active layer thickness in devices varied at 120 nm, 160 nm, 180 nm and 200 nm and the devices were annealed at 100 ℃, 120 ℃, 130 ℃, 140 ℃ and 150℃ in order to probe these variables on photodetector performance. It was found that the device with a 180-nm thick active layer, after being annealed at 150 ℃, exhibited the maximal responsivity of 268 mA/V at 550 nm and > 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 ℃. Our study demonstrates that the thickness of active layer is critically important to the light absorption efficiency and hence the device performance, while the annealing treatment can significantly affect the morphology of active layer, as evident by AFM study, which reduces the recombination probability of holes and the electrons and thus improves the photodetector performance.
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](87) [PDF 0KB](1)
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](146) [PDF 1099KB](15)
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.
Patterning of Polymer Functional Materials and Their Applications in Optoelectronics
Yue Geng, Han-fei Gao, Yu-chen Wu , Lei Jiang
最新录用 , doi: 10.11777/j.issn1000-3304.2020.19218
[Abstract](1) [PDF 0KB](0)
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.
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
最新录用 , doi: 10.11777/j.issn1000-3304.2019.19203
[Abstract](45) [PDF 0KB](0)
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 ratio. 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 main-chain. 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 were higher than 3.8 dL/g, indicating high molecular weight of them. SPPQ-based proton exchange membranes (PEMs) were prepared by solution casting method. Their properties such as ion exchange capacity (IEC),water uptake, swell ratio, mechanical properties, 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 ℃ and the decompose temperature at about 550 ℃. All SPPQ PEMs showed water uptake less than 39% and in-plane swelling ratio linearly increased with increasing of IEC and temperature with the values in the range of 2.1% ~13%. For example,the swell ratios of 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 at 80 ℃, respectively. Free radical oxidative stability test in Fenton reagent showed that the breaking times of SPPQ PEMs decreased with increasing of IEC. For example, the SPPQ-1(1.29meq/g) have over 150 h of breaking times at 20 ℃, whereas the value decreased to 81 h for SPPQ-5(2.21meq/g). Proton conductivity of SPPQ PEMs were increased obviously with the increase of temperature and IEC, the maximum proton conductivity was 64 mS/cm. The proton conductivities are much lower than 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.
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](26) [PDF 0KB](0)
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.

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2020, 51(1).
[Abstract](56) [PDF 2643KB](11)
2020, 51(1).
[Abstract](671) [FullText HTML](465) [PDF 182KB](90)
Strain-induced Crystallization of Long Chain Polyamide and Its Copolymers
Li-li Wang, Ping Zhu, Xia Dong, Du-jin Wang
2020, 51(1): 1-11. doi: 10.11777/j.issn1000-3304.2020.19165
[Abstract](580) [FullText HTML](294) [PDF 3091KB](76)
As a special species of polyamide, long chain polyamide (LCPA) provides combined performances of polyolefin and polyamide due to its chemical structure with long methylene chains segments between two neighbor polar amide groups. During the processing or application, strain-induced crystallization (SIC) has a significant effect on the mechanical strength and elasticity of LCPA and LCPA based its copolymers. It is of great importance to further study the microstructural evolution mechanism for the design and production of LCPA and its copolymers under the external field. With a focus on the SIC, this feature article mainly summarizes our group’s work on SIC of LCPA since 2010 and some related studies of other researchers, including the phenomenon of SIC observed in LCPA and its copolymer, the influencing factors of SIC and the corresponding rules, the correlation between SIC and the mechanical properties, and the characterization technics as well.
Studies on Homo- and Co-polymerizations of Polar and Non-polar Monomers Using Rare-earth Metal Catalysts
Dong-mei Cui
2020, 51(1): 12-29. doi: 10.11777/j.issn1000-3304.2020.19142
[Abstract](710) [FullText HTML](603) [PDF 3626KB](98)
The homo- and co-polymerizations of polar and non-polar monomers, since they can remain the stereo-regularity of the non-polyolefin precursors and meanwhile introduce polar groups into the non-polar polyolefins to improve their surface properties or bring unpredicted new functionalities, have attracted great attention of both academia and industries. However, polar groups are Lewis-basic while the catalysts employed in the polymerizations are usually Lewis acidic, which are prone to interact with the catalytic metal center to poison the catalysts, thus the study on homo- and co-polymerizations has been a challenging project. To date, many achievements have been obtained, and the following research should focus on realizing the homopolymerizations of polar monomers, increasing the activity and insertion ratio of the polar monomer in the copolymers, regulating the polar monomer composition and distribution along the copolymer macromolecular chains and isolating high molecular weight and practically available products. In this review, we summarized the recent developments of our group on the homo- and co-polymerizations of polar monomers, in particular polar styrenes and conjugated dienes with styrene, ethylene, butadien, isoprene and other popular nonpolar olefins, aiming to provide the readers novel strategies for designing new catalysts and polar monomers, as well as the unprecedented mechanisms.
Preparation and Bio-medical Applications of Dynamic ChemistryBased Self-healing Hydrogels
Yong-san Li, Yan-shuang Xu, Lei Tao, Yen Wei
2020, 51(1): 30-38. doi: 10.11777/j.issn1000-3304.2020.19144
[Abstract](887) [FullText HTML](527) [PDF 4343KB](190)
Self-healing hydrogel is a new generation smart material that has drawn great attention among researchers from multiple cutting edge areas. Self-healing hydrogels are continuously enriching our knowledge in developing new materials and changing our lives. In the recent decades, thanks to numerous dedicated researchers, series of self-healing hydrogels have been explored through dynamic chemistry and supramolecular interactions, which have been applied in interdisciplinary areas for controlled release of drugs, 3D cell culture, and scaffolds of tissue engineering, etc. Self-healing hydrogels can be injected as solid gels instead of liquid precursor, then self-heal in situ. Thus, self-healing hydrogels have been utilized as a new type of injectable carrier to deliver drugs. This method effectively avoids unwanted cargo loss throughout the cycling and dramatically improves the delivery efficiency of drugs. Thus, self-healing hydrogels have been studied in recent research as great therapeutic carrier for tumour therapy and wound-healing. This review aims to summarize some recent research progresses in the preparation of self-healing hydrogels based on different dynamic covalent bonds. The bio-medical applications of self-healing hydrogels including tumour therapy and wound-healing have also been introduced. The future development and challenges of dynamic chemistry based on self-healing hydrogels have also been discussed.
Typical Polymer Fiber Materials: An Overview and Outlook
Sen-long Yu, Heng-xue Xiang, Jia-liang Zhou, Tian Qiu, Ze-xu Hu, Mei-fang Zhu
2020, 51(1): 39-54. doi: 10.11777/j.issn1000-3304.2020.19148
[Abstract](1184) [FullText HTML](656) [PDF 3014KB](211)
High molecular material (or abbreviated as polymer) is the substantial foundation of human survival and development, which is regarded as the important symbol of social civilization. Polymer materials usually can be divided into plastic, fiber and rubber according to the application fields and molecular weight. Among them, polymer fibers are defined as the thin strip shaped materials with the length-diameter ratio larger than 1000 (usually a nanoscale or micron-scale diameter) and certain tensile strength and toughness. With the development of society and the progress of science and technology, the application fields of polymer fibers are gradually expanded from traditional home textile and clothing to advanced fields such as aerospace, biomedicine, environment, energy and so on. Therefore, the product connotations and applications of polymer fiber materials are expanding continually, which are the basic materials of national economy, the strategic materials of national defence, the frontier materials of emerging industries. In this work, we briefly introduced the development history of polymer fiber materials firstly, which have experienced the natural fiber, artificial fiber, synthetic fiber, functional fiber and high-performance fiber stages in turn. Then, the present situation of several representative polymer fiber materials (such as common fiber-poly(ethylene terephthalate) fiber, high performance fiber-poly(phenylene sulphide) fiber, biomass fiber-poly(lactic acid) fiber) were introduced systematically based on our group’s research work, including the development history, fabrication methods, chemical and physical structures and properties, modification technologies and application fields. In the end, we put forward the future prospect of polymer fiber materials combined with the social development demand. Based on the interdisciplinary integration and technological breakthroughs of materials, information, biology, machinery and other disciplines, the polymer fiber material (called Next Generation Fiber) with multiple components, multiple structures and multiple functions will become future development trend, which are characterized by green, super performance and intelligence.
Interface Properties in Polymer/Single-chain Nanoparticle Composite
Hu-jun Qian, Zhong-yuan Lu
2020, 51(1): 55-65. doi: 10.11777/j.issn1000-3304.2020.19152
[Abstract](656) [FullText HTML](378) [PDF 4702KB](102)
It is a practical method to control the property of polymer material by incorporating nanoparticles. Recently polymer/nanoparticle composites have drawn increasing attention in the polymer field. Although researchers have made apparent progresses in the property regulation of polymeric materials by incorporating nanoparticles, progress in the development of the corresponding theory is, however, greatly inhibited, due to the lack of proper characterization approach, especially on the interaction mechanism between various nanoparticles and matrix polymers mainly at their interface area. This mini review summarizes recent simulation results of our research group, especially on a polymer/nanoparticle composite system where nanoparticles are single-chain crosslinked polymer nanoparticles with the same chemical composition as matrix polymers. In particular, after a thorough discussion of the structure and dynamic properties at nanoparticle/polymer interface region, it is clear that the interface in this system, where nanoparticle and matrix polymer interact effectively, has approximately the same size as nanoparticle itself. This interface size has no dependence of matrix polymer chain length. We hope that this conclusion can be helpful for the further development of relevant theory for polymer/nanocomposite systems.
Material Research Progress of the Sustainable Polymer-Cellulose
Bo Duan, Hu Tu, Li-na Zhang
2020, 51(1): 66-86. doi: 10.11777/j.issn1000-3304.2020.19160
[Abstract](846) [FullText HTML](477) [PDF 12825KB](193)
The “Green Chemistry” has become the strategy direction of research and development of the world in the 21th century. Cellulose, as the most abundant natural polymers, is a very important renewable resource and the main industrial raw material. The cellulose shows many great advances including biocompatibility, biodegradability, high structure stability. However, due to the large amounts of inter- and intra-hydrogen bonding among the cellulose molecules, the cellulose has a dense structure and is very hard to be processed through dissolution or melt, which limit the further exploitation of the cellulose resource. The traditional organic solution of the cellulose often has the problem of high cost and pollution. In recent decades, with the development of the “Green” solvent (alkaline/urea, ionic liquid, etc.) and the cellulose nanotechnology, the researchers have greatly expanded the cellulose application in biomedical, energy storage, optical fields in addition to the traditional spinning and papermaking industry. This review mainly introduces the new methods (“bottom to up” and “up to down”) for the exploitation of cellulose based materials in recent years through the following four sections: (1) the regenerated cellulose based materials from the “green” solution-alkaline/urea aqueous and ionic liquid; (2) the preparation and self-assembly of the nanocellulose; (3) the development and utilization of the wood nanotechnology; (4) bacterial cellulose based functional materials.
A Discussion on the Origins and Development of Polymer Physics
Yu-liang Yang, Hong-dong Zhang
2020, 51(1): 87-90. doi: 10.11777/j.issn1000-3304.2020.19162
[Abstract](1289) [FullText HTML](579) [PDF 3850KB](116)
In this paper, we briefly review the origins and growth of polymer physics from our perspective. It is proposed that the theory of rubber elasticity can be regarded as a starting point of polymer physics. It reveals why many mainstream theories can work and play key roles in the history of polymer science. We hope researchers may take their impetus from the achievement of classic and modern polymer physics.
Regioselective Polymerization of α-Methylene β-Butyrolactone: Synthesis of Linear and Cyclic Polyesters
Yue-chao Xu, Hui Zhou, Xiao-bing Lu
2020, 51(1): 91-97. doi: 10.11777/j.issn1000-3304.2020.19145
[Abstract](766) [FullText HTML](587) [PDF 1088KB](65)
Regioselective polymerization of α-methylene β-butyrolactone (MβBL) to afford polyesters with various topological structures was achieved by the use of different catalysts or initiators. With azodiisobutyronitrile (AIBN) as initiator, polymerization selectively occurred at the C=C bond to produce linear poly(α-methylene-β-butyrolactone) (PMβBL) with the remain of β-butyrolactone unit. Achiral Salen aluminum complexes afforded linear syndiotactic-enriched polyesters with controllable molecular weight and a narrow polydispersity, in which ring-opening polymerization selectively occurred at the acyl C―O bond of MβBL and the C=C bond was remained. Strong organic bases, such as 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), exhibited high activity for ring-opening polymerization of MβBL under mild condition, affording linear polyesters. Simple sodium iodide mediated MβBL polymerization predominately produced crystalline cyclic polyesters with a melting point of 145.4 °C, in which the ring-opening mainly concerned the alkyl Cβ―O bond cleavage. This study demonstrates that the synthesis of various topological materials with different properties can be achieved by regioselective polymerization of functional monomers with the exquisite choice of catalyst or initiator.
Synthesis and Property of Novel Functionalized Polytetrahydrofuran-b-polyisobutylene-b-polytetrahydrofuran Triblock Copolymers
Fang Zhang, Hang-tian Zhang, Tian Yang, Bo Kong, An-ru Guo, Qi Zhang, Yi-xian Wu
2020, 51(1): 98-116. doi: 10.11777/j.issn1000-3304.2020.19151
[Abstract](540) [FullText HTML](252) [PDF 2402KB](58)
The functionalized polyisobutylenes (PIBs) carrying allyl-Br or allyl-NH2 with different molecular weights and narrow molecular weight distribution, could be successfully synthesized via controlled/living cationic polymerization of isobutylene (IB) in n-hexane/CH2Cl2 mixed solvents at −80 °C. Controlled/Living cationic ring-opening polymerization (ROP) of tetrahydrofuran (THF) was achieved with Allyl-Br/AgClO4 initiating system at 0 °C. Two kinds of novel functionalized PTHF-b-PIB-b-PTHF triblock copolymers were designed and synthesized via combination with controlled/living cationic polymerization of IB and controlled/living cationic ROP of THF. Terminal hydroxyl functionalized HO-PTHF-b-PIB-b-PTHF-OH triblock copolymers (expressed as FIBF-OH) were successfully synthesized by using the PIBs with difunctional allyl-Br terminal groups (Br-PIB-Br) as macroinitiators to initiate living cationic ROP of THF in the presence of AgClO4 to create living PTHF+-b-PIB-b-PTHF+ chains and then terminating by H2O molecules. On the other hand, PTHF-b-HN-PIB-NH-b-PTHF triblock copolymers containing hydrogen bonds at the connection point of PTHF and PIB segments (expressed as FIBF-NH) were also successfully synthesized via efficient nucleophilic substitution reaction between living PTHF+ chains and amine groups in H2N-PIB-NH2. Due to the dynamic incompatibility between polar PTHF segments and nonpolar PIB segments and the crystallization of PTHF segments, PTHF-b-PIB-b-PTHF triblock copolymers exhibit an obvious microphase separation micromorphology. It is recognized that the chemical structure in the PTHF-b-PIB-b-PTHF triblock copolymers makes a great contribution to the formation of hydrogen bonding and thus the supramolecular network. The crystallization of PTHF segments could be improved even in FIBF-NH with relatively short PTHF segments, e.g. Mn,PTHF = 0.7 kg·mol−1. FIBF-NH could be completely self-healing at 25 °C for 10 min after cutting on its surface. However, the cutting on FIBF-OH surface was difficult to heal even at 30 °C for 3 days. Moreover, the PTHF-b-PIB-b-PTHF triblock copolymers could be used as drug carrier by interactions between PTHF segment and drug. The drug carrier microspheres exhibit pH-sensitive drug-release rate in PBS with different pH values. The novel functionalized PTHF-b-PIB-b-PTHF triblock copolymers combined the respective good properties from PIB and PTHF segments would have their potential applications as biomedical and smart-healing functional materials.
Chain Entanglement Regulation of Sintered Ultrahigh Molecular Weight Polyethylene and Its Effect on Properties
Peng Dong, Ke Wang, Jun-fang Li, Qiang Fu
2020, 51(1): 117-124. doi: 10.11777/j.issn1000-3304.2020.19159
[Abstract](576) [FullText HTML](304) [PDF 1235KB](103)
Ultrahigh molecular weight polyethylene (UHMWPE) shows outstanding toughness, wear resistance and chemical inertness as a high performance polymer. However, extremely high entanglement degree results in high viscosity and processing difficulties, which greatly limits the applications. To address this issue, the new single-site Z-N catalysts have been used to regulate the growth and cohesion of molecular chains during the polymerization of ethylene in recent years, by which nascent UHMWPE with low entanglement degree and excellent processing capability can be obtained. With such UHMWPE nascent powder, different sintering temperatures (Ts) of 170, 190 and 220 °C were set, respectively, then a isothermal crystallization step with precise temperature control was added, and the effect of chain entanglement on the structures and properties of sintered UHMWPE was investigated. Through the tensile tests at 160 °C, it was confirmed that UHMWPE chains significantly reentangled when Ts = 220 °C, resulting in high degree of entanglement; while the initial low entanglement state can be sufficiently reserved when Ts = 170 °C, Me reached 12.3 kg/mol. Therefore, the samples with distinct different entanglement states can be obtained. DSC results have shown that low entanglement degree was beneficial to the formation of crystal lamellae with higher melting temperature (up to 141 °C) and high crystallinity (up to 65%) through isothermal crystallization steps, which was close to the level of nascent UHMWPE powder. Moreover, it proved that the integrated mechanical performance of the product sintered at 170 °C was significantly improved. The yield strength was increased by up to 72%, the tensile strength by 139%, the elastic modulus by 162%, and the elongation at break by 36%, realizing simultaneously strengthening and toughening of sintered UHMWPE materials. This provides a new strategy for the high performance UHMWPE sintered products from the perspective of chain entanglement regulation.
  • Editor: Xi Zhang

    Establishment Time: 1957

    Adminidrated by: Chinese Academy of Sciences

    Sponsors by: ICCAS
     Chinese Chemical Society


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