最新刊期
      卷 37 ， 期 3 ， 2017

        Feature Articles

      • Chen Ping,Xiong Xu-hai,Xia Lian-lian,Zhang Li-ying,Yu Qi,Liu Si-yang
        Issue 3, Pages: 399-410(2017) DOI: 10.11777/j.issn1000-3304.2017.16168
        摘要：Three types of chain-extended bismaleimides with aromatic hetero-cycle structure (PBMI, FBMI, ZBMI) were synthesized, and their chemical structure and thermal properties were characterized by nuclear magnetic resonance (NMR) spectroscopy, infrared (IR) spectroscopy, differential scanning calorimeter (DSC), thermo-gravimetric analyzer (TGA) and dynamic mechanical analyzer (DMA), respectively. PBMI, a phthalide-containing bismaleimide, was prepared with phenolphthalein, o-cresolphthaleine and thymolphthalein as initial raw materials. With increasing number and volume of substituent groups, the solubility of PBMIs in common organic solvents was enhanced while their reactivity reduced. Three cured PBMI resins showed excellent thermal stability and heat resistance. Their glass transition temperatures (Tg) and the temperatures of 10% weight loss, both decreased with the number of alkyl chain substituents to aromatic rings, were in the range of 324-364℃ and 454-495℃, respectively. The cured PBMI with only methyl groups demonstrated an optimal moisture resistance. FBMI, a fluorene-containing bismaleimide, was subdivided into ether-type FBMI and ester-type FBMI. The melting point of the ether-type FBMI was lower than that of the ester-type FBMI, and the reactivity of the two resins were comparable with each other. The heat resistance and moisture resistance of the cured products of the former were superior to those of the latter. In addition, the incorporation of methyl groups into the molecular skeleton of the two types of FBMI resulted in a decrease of above-mentioned properties. The Tg values of the four FBMI cured products were all above 350℃ and the maximal Tg value reached above 400℃. ZBMI, a 1,3,4-oxadiazole-containing bismaleimide with asymmetric molecular structure, was designed and synthesized based on the characteristics of synthetic process of 1,3,4-oxadiazole moiety. Three ZBMI monomers exhibited good solubility and different reactivity of two end-capped unsaturated double bonds. Their cured products with fully aromatic heterocyclic structure were characterized by higher thermal stability and the initial decomposition temperature of 500℃.  
        关键词：Bismaleimide;Phthalide/fluorene cardo;1, 3, 4-Oxadiazole;Heat resistance;Moisture resistance   
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        发布时间：2021-03-19

        Reviews

      • Yang Ting-ting,Zhou Zhu-xin,Zhang Yi,Liu Si-wei,Chi Zhen-guo,Xu Jia-rui
        Issue 3, Pages: 411-428(2017) DOI: 10.11777/j.issn1000-3304.2017.16221
        摘要：Polyimides (PIs) are a class of representative high-performance polymers possessing a number of merits, such as high thermal stability, good mechanical and electrical properties, superior dimensional stability, and designable structures. They have important potential applications in the fields of organic optoelectric industries. However, traditional polyimides are in general non-luminescent. Studies of polyimides as light-emitting materials are rare. The photoluminescence quantum efficiency reported is quite low, mainly due to the strong inter- and intra-molecular charge-transfer (CT) interaction of polyimides, which greatly restricts their applications as light-emitting functional layer in the organic optoelectric fields. In order to better understand the general rules of light-emitting behavior of polyimides, and to broaden their application fields in the organic light-emitting diode, this review gives a presentation on the photoluminescence mechanism of polyimides that have been developed, including the formation of locally excited (LE) state and charge transfer (CT) state in the typical donor-acceptor polyimide structures, and the influence for both of the states on their respective photoluminescence process. The recent advances of photoluminescence polyimides as well as the methods to improve the fluorescence quantum yield of polyimides are also provided. Reviewing the polyimides with high photoluminescence quantum yield is focused mainly on the introduction of heterocyclic chromophores (like triphenylamine, pyridine, coumarin, dioxazole, porphyrin etc.) and fused-ring chromophores (like naphthalene, anthracene, pyrene, perylene, fluorene,etc.) into the main chain or the side chain of the aromatic polyimides. These methods would improve more or less the luminescence intensity without sacrificing the comprehensive properties of the polyimides, but there still be a long way to go as the fluorescence may be weakened by the condensed stacking of the chromophores. In another aspect, some researchers also introduced chromophores into semi-aliphatic polyimides, and found it an efficient way to develop highly fluorescent polyimides, because these aliphatic structures in the polymer backbone would effectively limit the intra-CT interactions, and finally form LE emission. However, the overall properties of these semi-aliphatic functional polyimides would be greatly decreased, and their work functions were difficult to match with the metal electrodes, which would greatly limit their applications. Therefore, to obtain the key technologies for the controllable preparation of highly-efficient luminescent polyimides and the controllable adjustment of the luminescent color would be the most important research directions in the near future, which would be of great interest to develop the applications in the fields of photo electronic devices, energy saving and environmental protection for high-performance and high-efficiency light-emitting polyimides.  
        关键词：Polyimide;Photoluminescence;CT interactions;Structure;Recent advances   
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      • Zheng Zhong,Song Yi-hu,Zheng Qiang
        Issue 3, Pages: 429-453(2017) DOI: 10.11777/j.issn1000-3304.2017.16187
        摘要：Fumed silica (FS) has become irreplaceable for a wide range of applications such as adhesives, coatings, lithium battery, and liquid armor, etc., especially when serving as the rheological agent. However, it is a great challenge to control the rheological behavior of polar liquids like reactive polar oligomers when employing FS, because complicated interactions between the surfaces of FS and polar molecules could make it difficult for formula design and rheological performance adjustment of industrial products. In this work, synthesis and classification of typical FS are introduced, followed by representative applications of FS as rheological agents in the field of oligomer nanocomposites (ONCs). Then four interactions between nanoparticles:van der Waals attraction, electrostatic repulsive force, steric repulsive force and hydrogen bonding attraction that are crucial to rheological behaviors of ONCs are elaborated in detail. Meanwhile, the rheological behaviors of both dilute and concentrated ONCs, particularly the FS/polar oligomer nanocomposites, are summarized, and the rheological responses of dense dispersions are concluded into two categories:(i) flocculated system and (ii) non-flocculated system. Both flocculated and non-flocculated behaviors are related to particle-oligomer and particle-particle interactions, and their typical rheological responses including thixotropy and shear thickening, as well as their influencing factors are also stated and compared. Furthermore, researches in interfacial layer structures between nanoparticles and ONCs are thoroughly overviewed on the basis of a summary on the measurement and control of interfacial layer structures, and the relationship between rheological behavior and interfacial structures of ONCs (FS filled systems in particular) are comprehensively expounded. Combined with the recent progress in FS filled polar oligomers about rheology and interface, two important research directions are proposed for ONCs at last:one is how to establish direct relationships between the interfacial layer structure and the interactions for nanoparticles and polar oligomers, and the other is how to precisely regulate and control the rheology of FS/oligomer nanocomposites by elaborate design of interfacial structures.  
        关键词：Fumed silica;Polar oligomer;Rheological behavior;Molecular relaxation;Interfacial design   
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        发布时间：2021-03-19

        Research Article

      • Yan Xue-sheng,Xu Jun,He Jin-lin,Zhang Ming-zu,Dai Li-xing,Ni Pei-hong
        Issue 3, Pages: 454-463(2017) DOI: 10.11777/j.issn1000-3304.2017.16128
        摘要：The preparation of star-shaped polymers using incorporation of living anionic polymerization with polyhedral oligomeric silsesquioxane (POSS) is rarely reported. In this study, two types of POSS-cored star-shaped polymers were obtained by one-step addition reaction. Firstly, the living (polyisopryl)lithium (PI-Li) and living polystyrene-block-polyisoprene block copolymer chain (PS-PI-Li) were synthesized by high-vacuum living anionic polymerization. Meanwhile, a POSS derivative with one hydroxyl and seven vinyl groups (VPOSS-OH) was prepared by the addition of triflic acid to commercial octavinyl POSS with eight vinyl groups (V8T8). Subsequently, the mono-hydroxyl functionalized seven-arm star polymers were prepared by directly adding living PI-Li or PS-PI-Li to VPOSS-OH in benzene. The purified star-shaped polyisoprene 7PI-POSS-OH and star-block copolymer 7(PS-PI)-POSS-OH were obtained after fractionation precipitation, and then characterized by nuclear magnetic resonance (1H- and 13C-NMR), gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectroscopy, respectively. By changing the feed ratio of the monomer to initiator, the polymers with different degree of polymerizations were synthesized. The compositions of the polymers were calculated by comparison of the integrals of the characteristic signals from 1H-NMR spectra. GPC analysis indicated that the trace of the crude products showed an apparent shift to smaller retention time compared with that of the base PI or PS-PI. The fractionated samples had symmetric peaks and relatively narrow polydispersity. MALDI-TOF MS tests demonstrated that the base PS gave a single molecular weight distribution, and the observed molecular weight was in good agreement with the calculated value. The similar result was also found for the base PS-PI. However, the MALDI-TOF MS spectra were not obtained for the fractionated star-shaped polymers, possibly because of their high molecular weights. TGA analysis showed that the thermal decomposition temperature of 7PI-POSS-OH and 7(PS-PI)-POSS-OH was higher than the base PI and the block copolymer PS-PI. In addition, it was also found that about 6% of residue left at 600℃, which may be due to the incorporation of POSS segment. The process reported here may serve as an alternative approach to produce functional star-shaped polymers by changing the structure of the initiators and the monomers.  
        关键词：Living anionic polymerization;Polyhedral oligomeric silsesquioxane;POSS;Star-shaped polymer   
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        发布时间：2021-03-19
      • Wang Yue,He Nai-pu,Lu Zhen-wu
        Issue 3, Pages: 464-470(2017) DOI: 10.11777/j.issn1000-3304.2017.16138
        摘要：Two types of atom transfer radical polymerization (ATRP) initiators containing disulfide pyridine structure were synthesized and characterized by 1H-NMR. The results revealed that disulfide pyridine was successfully introduced to the end or the middle of the ATRP initiator molecule. N,N-diethyl-acrylamide (DEAAm) was initiated by the ATRP initiators using ATRP to prepare the end-functional (end-functional pDEAAm) and the middle-functional poly(N,N-diethyl-acrylamide) (mid-functional pDEAAm), respectively. Both the end- and mid-functional pDEAAm were characterized by1H-NMR and gel permeation chromatography (GPC). 1H-NMR results showed that disulfide pyridine was successfully introduced into the end-group of pDEAAm chain to form theend-functional pDEAAm or the middle of the chain of pDAAm to give the mid-functional pDEAAm, respectively. GPC results showed that the molecular weight of the end-functional pDEAAm and the mid-functional pDEAAm with narrow distribution was controlled by ATRP. Polydispersity index (PDI) of the end-functional pDEAAm was 1.21, and that of the mid-functional pDEAAm was 1.23. The molecular weight of the mid-functional pDEAAm was higher than that of the end-functional pDEAAm. The results suggested that ATRP initiator with two initiating sites increased the molecular weight of the pDEAAm. Furthermore, the temperature-responsive behaviors of polymers in the aqueous solutions were tested by UV-visible spectrophotometer. Both types of pDEAAms showed excellent temperature-sensitivity in aqueous solution. The lower critical solution temperature (LCST) of the pDEAAms was identified as 28℃. Below the LCST, pDEAAms were completely dissolved in water. In contrast, above the LCST of pDEAAms, phase separation appeared in the polymers aqueous solutions. The position of disulfide pyridine structure in pDEAAms chain did not influence the temperature-responsive behavior of the polymers aqueous solutions. Both pDEAAm are expected to be useful to prepare block copolymers and to bind site-specifically to biomacromolecules. In particular, the mid-functional pDEAAm will be useful to prepare the star-polymers and the multi-armed polymers.  
        关键词：Atom transfer radical polymerization;Poly(N, N-ethyl-acrylamide);Temperature-responsive   
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      • Wu Qiong,Xu Peng-xiang,Wang Li-quan,Cai Chun-hua,Lin Jia-ping,Lu Ying-qing,Tian Xiao-hui
        Issue 3, Pages: 471-481(2017) DOI: 10.11777/j.issn1000-3304.2017.16120
        摘要：Micelles and hydrogels, generally prepared at different concentrations in waters, arouse great interest due to their wide application. However, it is inconvenient and difficult to prepare the micelles and hydrogels at the same concentrations. In this work, different states of a same copolymer, such as micelle solutions and hydrogels, are prepared via the polymerization of the pre-assembled acrylic acid and styrene with the same monomer compositions at the same concentrations. The influence of initiator (azodiisobutyronitrile) concentration on the structures of the aggregates is investigated, and the corresponding molecular structures of the copolymers are studied by nuclear magnetic resonance and dynamic thermomechanical analysis, whereas the morphology of the aggregates is characterized by scanning electron microscope and transmission electron microscope. As a supplement to the experiment, dissipative particle dynamics simulation is further performed to reveal the aggregate structures and the corresponding molecular structures of the copolymers. It is found that, under the same concentration of acrylic acid and styrene, the system with a higher initiator concentration (7.0×103 mol/L) tend to form stable spherical micelles of 50 nm diameter, in which the copolymers have longer blocks; while that with a lower initiator concentrations (such as 7.0×104 mol/L) tend to form network hydrogels, in which the copolymers have alternated and shorter blocks. Both the dynamic thermomechanical analysis and the simulation results demonstrate that the diblock copolymers and multiblock copolymers are synthesized at the higher and the lower initiator concentration. The different aggregate structures are originated from the different molecular structures. In addition, rheological characterization techniques are employed to investigate the rheological properties of the solutions and the hydrogels to clarify the relations between the properties and the molecular/aggregate structures. The rheological characterization showed the shear thinning non-Newtonian behaviour for both the micelle solutions and the hydrogels, and the gel-point of hydrogels was determined to be at the concentration of 22 wt%. It is found that the hydrogels are recoverable after destruction by large amplitude oscillatory shear. The work can serve as an example to clarify the role of the polymer microstructure in determining the material properties and to provide guides for constructing materials with the similar composition but different aggregate structure.  
        关键词：Self-assembly;Polymerization;Gels;Micelles;Dissipative particle dynamics   
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        发布时间：2021-03-19
      • Luan Shu-juan,Xu Jing,Qi Pei-lan,Wang Kai,Wang Ying-ying,Song Shi-yong
        Issue 3, Pages: 482-490(2017) DOI: 10.11777/j.issn1000-3304.2017.16133
        摘要：In some pH-sensitive drug delivery systems, hydrazone bonds frequently appeared in the side chains of the polymers as connections to doxorubicin (DOX). Introducing hydrazone bond onto the backbone of an amphiphilic copolymer to form pH-responsive hydrazone-containing micelles will realize the encapsulation of a broad spectrum of hydrophobic drugs. As a proof of concept, this work began with rational designing of mPEG-based macro-initiators and followed by ring-opening polymerization to construct hydrazone-containing biodegradable block polymers. A series of hydrazone-containing biodegradable copolymers (mPEG-Hz-PLA) of different molecular weights were synthesized. The diblock copolymers bear both hydrophilic PEG chain of fixed length and hydrophobic PLA chain of varied lengths. The resulting copolymers then self-assembled to form stable micelles with mean diameters below 100 nm. The study showed that these pH-sensitive polymeric micelles has a critical micelle concentration (CMC) of 5.46×104 mg/mL or less. Notable size change of the hydrazone-containing micelles were found after incubation in acidic media (pH=4.0 and 5.0), while no size changes were observed for the polymeric micelles without hydrazone bonds. Doxorubicin (DOX) was used as the model drug and loaded into the core of micelles, leading to the micelles with a larger size (100-200 nm) than the blank ones. The drug loading content (DLC) and drug loading efficiency (DLE) of the micelles increased slightly along with the length of PLA. In vitro drug release study showed that DOX loaded in mPEG-Hz-PLA micelles were released more rapidly and more sufficiently under acidic conditions compared with non pH-sensitive micelles. Under pH=7.4, DOX released from both pH sensitive micelles and non-sensitive ones were less than 30% in 24 h. At pH 4.0, more than 70% of DOX was released from the pH-sensitive micelles while less than 45% of DOX released from the non-sensitive micelles in 24 h. MTT assay in HeLa and RAW264.7 cells lines showed enhanced antitumor ability for the DOX loaded pH sensitive micelles following 48 h incubation, compared with free DOX or non-sensitive micelles, while no obvious cytotoxicity was detected for the blank micelles. The hydrazone-containing micelles have great promise as a safe and effective carrier for antitumor drug delivery.  
        关键词：mPEG-Hz-PLA polymer;Micelles;pH-Sensitive;Drug release   
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      • Shi Fu-kuan,Zhong Ming,Zhang Li-qin,Liu Xiao-ying,Xie Xu-ming
        Issue 3, Pages: 491-497(2017) DOI: 10.11777/j.issn1000-3304.2017.16162
        摘要：The grafting polymerization of acrylamide (AM) on the surface of vinyl hybrid silica nanoparticles (VSNPs) leads to the formation of nanobrush gelators. The gelators can link with each other by the hydrogen bond among the grafted polyacrylamide (PAM) chains as physical crosslinking points, and thus the multifunctional VSNPs as analogous covalent crosslinking points to construct dually crosslinked single network nanocomposite under the form of physical hydrogels (NCP gels), which exhibit high strength and super stretchability. Under stretching, the hydrogen bonds in the PAM NCP gel could dissipate energy and homogenize the network by their break and recombination process; VSNPs could retain the original configuration of the gel and work as transferring centers to homogenize the stress distribution in the gel network. As a result, the synergy of the dual crosslinking points ensures the PAM NCP gel to exhibit high strength and super stretchability. Polyvinylalcohol (PVA) is hydrophilic and compatible with PAM. PVA could physically interact with PAM by forming hydrogen bonds and also crystallize after freezing-thawing (FT) process. To further improve the strength and toughness of the NCP gels, the mixtures of PVA and the PAM/VSNP gelators are prepared and then treated by FT process. Thus PVA interacted with the grafted PAM chains could form micro-crystals, playing the role of new junction points to crosslink further the gel network. Thereby hierachically crosslinked PAM NCP gels are obtained. According to the characterization of Raman spectra and DSC, it is verified that PVA could form micro-crystal and interact with PAM by hydrogen bond, leading to toughen NCP gel network. Compared to the PAM NCP gel, the PVA/PAM NCP gels exhibit greatly improved mechanical properties due to the enhanced synergy of the hierachical crosslinking points. The tensile strength and fracture energy of the gels are enhanced from 313 kPa to 557 kPa and from 1.41×104 J/m2 to 4.65×104 J/m2, respectively.  
        关键词：Polyvinylalcohol;Micro-crystal;Hierarchical crosslinking;High strength;Poly(acrylamide) hydrogel   
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        发布时间：2021-03-19
      • Yuan Yi,Mu Ruo-jun,Yang Dan,Tan Xiao-dan,Huang Rong-xun,Li Chong-gao,Xie Bing-qing,Wang Min,Pang Jie
        Issue 3, Pages: 498-505(2017) DOI: 10.11777/j.issn1000-3304.2017.16141
        摘要：Nanofiber films froms different proportion of konjac glucomannan (KGM)/poly(vinyl alcohol) (PVA) have been synthesized using electrospinning and used for sustained drug release. KGM was crosslinked with PVA to form a composite liquid, which was used as spinning solution to prepare KGM-PVA film by electrospinning. The drug release behavior of KGM-PVA nanofiber membrane was studied using 5-ASA as model drug. The microstructure of the composite nanofiber films was characterized by scanning electron microscope (SEM) and Fourier transform infrared spectrometer (FTIR), while the thermal properties were analyzed by differential scanning calorimeter (DSC). The sustained-release of the model drug from the nanofiber films was studiedin vitro and with a mathematical model of drug release. It was observed that a uniform nanofiber with no node was synthesized when about 76% of KGM in the nanofibers film was used. Under this condition, thermal stability was enhanced as well. The structure characterization illustrated that the nanofiber membrane of the composite KGM-PVA was formed by stacking of the numerous nanofibers. Intermolecular reaction between KGM and PVA led to an enormous change in the structure and the function of the composite films in comparison with other KGM derived films. A relatively large specific surface area was formed during the formation of the network structure in the nanofiber film, which favored drug adsorption. The in vitro experiment results revealed that nanofiber film containing 5-aminosalicylic acid in PBS buffer of pH=7.4, performed well sustained-release and the cumulative release rate was about 45% after 25 h. The results also showed sustained-release from the nanofiber films was better fitted with Higuchi model. This study indicated that KGM/PVA nanofiber film developed by electro spinning provided a theoretical base for the development of the carrier for sustainable drug-release.  
        关键词：Konjac glucomannan;Polyvinyl alcohol;Electrostatic spinning;Nanofiber film;Drug sustained release   
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        发布时间：2021-03-19
      • Wei Meng-juan,Guo An-ru,Wu Yi-xian
        Issue 3, Pages: 506-515(2017) DOI: 10.11777/j.issn1000-3304.2017.16152
        摘要：A series of novel poly(γ-benzyl-L-glutamate)-g-(polytetrahydrofuran-b-polyisobutylene) graft-block copolymers, PBLG-g-(PTHF-b-PIB), have been successfully synthesized via combination of living anionic polymerization with living cationic polymerization. The grafting density (GD) along PBLG backbone in PBLG-g-(PTHF-b-PIB) graft-block copolymers was mediated by changing the molar ratio of living -PTHF-b-PIB chains to-NH-functional groups in PBLG backbone. The well-defined PBLG-g-(PTHF-b-PIB) copolymers with different grafting densities (GD) (9%~65%) and different chain lengths (polymerization degree, DPb) (71.43~93.65) of -PTHF-b-PIB block segment branches were achieved. The chemical structure of the PBLG-g-(PTHF-b-PIB) copolymers was confirmed by FTIR, 1H-NMR and TGA characterization with grafting densities (GD) ranging from 9% to 65%. Circular dichroism (CD) and FTIR spectra showed that some of the PBLG-g-(PTHF-b-PIB) copolymers maintained α-helical structure from PBLG. The effects of GD and DPb of the -PTHF-b-PIB branches on the Tg, PBLG, α-helical secondary structure and enthalpy of α-helical transition of PBLG backbone were investigated by DSC. It has been found that the signal strength of α-helical secondary structure from the PBLG backbone gradually decreased while both Tg, PBLG and enthalpy of α-helical transition of PBLG backbone gradually increased with increasing GD or DPb in the branches. The effect of DPb on confined crystallization of PTHF segments in the PBLG-g-(PTHF-b-PIB) copolymers was also investigated by changing molecular weight of PTHF segments while keeping the same molecular weights of the PBLG backbone and PIB segments in branches. It was observed that both the melting point of the crystalline from PTHF segments (Tm,PTHF) and its melting enthalpy increased with increasing the molecular weight of PTHF segments in branches. Moreover, it is also shown that the crystallization of PTHF segments in PBLG-g-(PTHF-b-PIB) copolymers was obviously weakened by increasing the grafting density (GD) from 9% to 45% by keeping the same molecular weights of PBLG backbone and PIB segments in branches.  
        关键词：Poly(γ-benzyl-L-glutamate);Polyisobutylene;Polytetrahydrofuran;Graft copolymer;Secondary structure   
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      • Wu Yuan-peng,Zhou Chang-liang,Xue Shi-shan,Li Chuan,Lin Yuan-hua,Zheng Zhao-hui,Ding Xiao-bin
        Issue 3, Pages: 516-523(2017) DOI: 10.11777/j.issn1000-3004.2017.16142
        摘要：Magnetic and porous materials with effectively oil-absorbing and magnetic responsive properties were prepared through a facile way from carboxymethyl cellulose sodium (CMC) modified polyurethane foam. Polyurethane foam was first washed and immersed into CMC aqueous solution to modify the polyurethane foam by CMCs. The modified foam was then dipped into aqueous FeCl3 solution for further modification by Fe3+ through the interaction between Fe3+ and the carboxy groups of CMC. The composite porous materials were put into a teflon autoclave and the temperature was elevated to 230℃ and heated for 4 h to obtain magnetically porous materials. The as-prepared materials were characterized by optical microscope (OM), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and contact angles. The results from OM and SEM showed that the materials were indeed porous. FTIR indicated that CMC and Fe 3+ were present on the polyurethane foam sequentially. XRD pattern showed that Fe3+ changed to Fe3O4 during the heating process. The effects of heating temperature and concentrations of CMC, FeCl3 solution on oil-absorbing and magnetic responsive performance of the magnetic materials were investigated in details. The materials were hydrophobic and the contact angle of water droplet on the foam surface was determined to be 115.9°. The magnetic and porous foam was oleophilic and absorbed about 10 times of its own weight for crude oil and engine oil. It absorbed also a series of solvents, including hexane, xylene, cyclohexane, toluene, ethyl acetate and chloroform. The absorption rate was in general very fast and could be used for treating oil spills. The density of the porous material was low (0.036 g/cm3), so that they were floating on the surface of water, good for absorbing spilled oils. The as-prepared samples were magnetic, and the oil saturated samples could be easily separated by using an exterior magnet. What was more important was that the porous materials were reusable more 20 times without obvious decrease in their oil-absorption capacity.  
        关键词：Polyurethane foams;Carboxymethyl cellulose sodium;Magnetic porous materials;Oil-absorbing property   
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      • Li Sha-sha,Hao Xiao-gang,Jia Jin-lan,Hou Cai-ying,Guan Tao-tao,Wang Zhong-de
        Issue 3, Pages: 524-533(2017) DOI: 10.11777/j.issn1000-3304.2017.16148
        摘要：Polypyrrole/multi-walled carbon nanotubes (PPy/MWCNTs) conductive fillers and their polyurethane (PU) composites were synthesized via chemical oxidative polymerization of pyrrole (Py) on the surface of carboxylated MWCNTs in the presence of FeCl3 oxidant at 0℃. The effects of Py dosage on the properties of PPy/MWCNTs and on their PU composites were investigated. FTIR results suggested that an interaction force existed between the -COOH carboxylated groups of MWCNTs and the NH groups of PPy. Thermogravimetric analysis (TGA) demonstrated that carboxylated MWCNTs made a noticeable improvement in thermal stability compared with PPy. Test of scanning electron microscopy (SEM) showed that Py polymerization of occurred on the surface of the carboxylated MWCNTs and Py content changed the aspect ratio of PPy/MWCNTs. Deconvolution of the C1 peak of X-ray photoelectron spectroscopy (XPS) suggested that an increase in Py dosage led to a first increase and then decrease in the content of sp2 and sp3 hybrid carbons, with a decrease in the ratio of doping nitrogen. Accordingly, the electrical conductivity of PPy/MWCNTs increased first and then decreased. The highest conductivity was obtained when Py content was 20% based on the weight of the carboxylated MWCNTs. The change in PPy doping and the aspect ratio of PPy/MWCNTs played a significant role in the properties of PPy/MWCNTs/PU composites. Increasing Py dosage resulted in an improvement in the water resistance of the PPy/MWCNTs/PU composites, with a decrease in their tensile stress, storage modulus and glass transition temperature. The conductivity of PPy/MWCNTs/PU showed a similar trend to that of PPy/MWCNTs, and the highest electrical conductivity was obtained with Py content of 15%. It is suggested that PPy/MWCNTs possess better thermal stability, electric conductivity and reinforcing properties than PPy, and their PU composites have good processability, mechanical properties and electrical conductivity.  
        关键词：Polypyrrole;Multi-walled carbon nanotubas;Polyurethane;Composites   
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      • Hu Mei-shao,Ni Jiang-peng,Liu Dan-qing,Wang Lei
        Issue 3, Pages: 534-541(2017) DOI: 10.11777/j.issn1000-3304.2017.16121
        摘要：A series of novel branched poly(aryl ether benzimidazole) (OPBI) with 1,3,5-benzenetricarboxylic acid (BTA) as branching agent were synthesized and applied as proton exchange membranes for high temperature fuel cell. The introduction of branching points and aryl ether groups gave the branched OPBIs unique three-dimensional structures for acid absorption. Consequently, the proton conductivity was improved. The structure of branched OPBI was characterized by Fourier transform infrared spectroscopy (FTIR) and1H-NMR spectra. The branched OPBI proton exchange membranes was directly produced by the solution casting process. Acid doping level (ADL), proton conductivity, solubility, thermal and oxidative stability, and mechanical properties of the proton exchange membranes were studied in detail. As the branching degree increased, the phosphoric acid (PA) doping level, proton conductivity and oxidative stability of the branched membranes were clearly improved. Compared with linear p-PBI and OPBI proton exchange membranes, the branched OPBI membranes had more free volume for acid absorption. The PA doping level of branched OPBI membranes with a 9% degree of branching exhibited the highest ADL of approximately 9.2 PA PRU-1, which was approximately 1.4 times greater than that of the linear OPBI membranes. The proton conductivity of the 9% branched OPBI membrane reached 0.0314 S/cm at 180℃, which was nearly 1.8 times greater than that of the linear PBI membranes. Compared with linear PBIs, an excellent solubility of branched OPBI was observed. The improved solubility of branched OPBI in common solvents such as DMSO, DMAc at room temperature, may be derived from the introduction of aryl ether and the branching point. Moreover, branched OPBI membranes showed excellent thermal stability (decomposition temperature >500℃) and oxidative stability (weight loss <12% in Fenton's reagent for 60 h). Even though the mechanical properties of branched OPBI membranes need further improvements, all of these properties indicate that branched OPBI membranes are promising candidates for high temperature proton exchange membranes fuel cells (HT-PEMFC).  
        关键词：High temperature fuel cell;Proton exchange membrane;Poly(aryl ether benzimidazole);Branched structure;Phosphoric acid doping level   
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        发布时间：2021-03-19
      • Zhang Xu-feng,Yu Jin-guang,Wu Yun-qi-qi-ge,Yi Xiao-su
        Issue 3, Pages: 542-548(2017) DOI: 10.11777/j.issn1000-3304.2017.16135
        摘要：A novel bio-based epoxy resin system, which aimed to be used for hot melt prepreg curing at mid-temperature, was developed from epoxy resin (E51), using rosin-sourced acid anhydrides as curing agent and imidazole as latent catalyst. The temperature-time-transition property of the thermosetting resin wit bio-sourced material was studied. The cure kinetics of the rosin-based resin system was investigated by dynamical differential scanning calorimeter (DSC). The parameters of the cure reaction were obtained by a phenomenological model fitting, which gave 9.68 kJ/g for the activation energy, 1.28×1015 s-1 for the constant factor and 2.483 as the reaction order, respectively. The relationship between the curing degree and the reaction time at varied temperature was established according to the model used. At temperature above 100℃, the curing degree increased quickly with time. On the contrary, at temperature below 100℃, the curing degree increased slowly with time. For example, the resin system was cured for 180 min at 130℃, the curing degree reached 90% or higher. These results indicated that the resin can realized mid-temperature curing with good stability. Furthermore, the glass transition temperature of bio-based epoxy system was measured using DSC and dynamic mechanical analysis (DMA), and their dependence on the curing degree was obtained based on DiBenedetto equation by regression analysis and the glass temperature transition curves. Moreover, the gelation behavior of the bio-based resin system was studied using a cone plate viscometer. An equation between gel time and temperature was obtained by conducting linear regression analysis. The cure degree and glass transition temperature at gelation, calculated by phenomenological model and DiBenedetto equation, were 0.386 and 26.22℃, respectively. Finally, the equivalent curing degree, glass temperature transition and gelation were plotted versus time and the temperature-time-transition (TTT) diagram was formed for the bio-based resin system, which might serve as a powerful tool for manufacturing composite materials or semi-finished products. From this TTT diagram, the state of the resin system could be known at any temperature for any time, and the applicable laminate processing conditions by hot press method was therefore determined.  
        关键词：Bio-based;Epoxy resin;Cure kinetics;TTT diagram   
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        发布时间：2021-03-19
      • Lu Yang,Qu Li-jian
        Issue 3, Pages: 549-555(2017) DOI: 10.11777/j.issn1000-3304.2017.16125
        摘要：The present study applies the numerical self-consistent field theory (SCFT) to the polymer solution confined in a sphere, which is relevant for many technological and biological applications. This paper focuses on the adsorption/depletion transition of the polymer chains near the inner surface of the confining spherical shell. Dependence of the density profiles of the confined polymers on the radius of the confining wall, the polymer-wall interaction, and the mean polymer concentration are analysed from the numerical results of SCFT. It is found that the polymer segments distribute uniformly near the centre of the confining sphere and inhomogeneously near the confining shell. When the radius of the confining sphere is large enough, the confined polymers behave similarly to those near a flat plane. The lower the mean concentration of the confined polymer segments is, the more sensitive the thickness of the adsorption or depletion layer is to the sphere radius. The density profiles of the polymers and the thickness of the adsorption or depletion layer indicate that the adsorption/depletion transition can take place under specified conditions. The transition depends on the dimension of the confining sphere, the polymer chain length, the mean concentration, as well as the polymer-wall interaction. A linear relationship between the critical polymer-wall interaction parameter at the transition point and the reciprocal value of the chain length is observed from the numerical results of SCFT. Similar behaviour has also been found in the polymer chains near a flat plane. However, the slope and the intercept of the linear relationship here are functions of the radius of the sphere when the confining effect comes into play. It is found that higher critical attraction energy between the polymers and the wall is needed for adsorption/depletion transition to occur for smaller confining sphere. In other words, it is more difficult for the adsorption/depletion transition to occur.  
        关键词：Self-consistent field theory;Adsorption;Depletion;Confinement   
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        发布时间：2021-03-19
      • Zhao Xue-ning,Yin Jian,Lu Cong-hua
        Issue 3, Pages: 556-562(2017) DOI: 10.11777/j.issn1000-3304.2017.16169
        摘要：We reported a simple method to fabricate gradient patterns on polymer-based films, which was based on the non-lithographic surface wrinkling. Namely, a polydimethylsiloxane (PDMS) soft substrate was mechanically pre-strained with a "triangular block" beneath the strained PDMS sheet, followed by surface oxidation with ultraviolet ozone (UVO) and/or oxygen plasma (OP). A thin silica-like (SiOx) stiff layer was generated after the surface oxidization. Thus the surface wrinkling was induced on the as-formed film/substrate system of SiOx/PDMS bilayer when the pre-strain of the PDMS substrate was released slowly. It was found that aligned surface wrinkles with a uniform wavelength were yielded on the OP-exposed PDMS substrate. However, gradient patterns were obtained when the PDMS substrate was treated by UVO. The introduction of the "triangular block" beneath the strained PDMS sheet led to a change of the distance between the PDMS substrate and the UVO light, and thus an increased decay of UVO light intensity along with the exposed PDMS sheet happened. As a result, the gradient thickness of the SiO x layer was formed on the resulting SiOx/PDMS bilayer and the corresponding gradient wrinkles were generated,since the wrinkle wavelength was closely related to the thickness of the stiff film. In contrast, the thickness of the as-formed SiOx layer was uniform during the OP exposure. It was noted that, for the single UVO exposure, a large pre-strain was required to induce the surface wrinkling on the UVO-exposed PDMS substrate. Interestingly, compared with the single UVO treatment, the combined UVO/OP surface oxidation treatment (e.g., UVO-OP and OP-UVO treatment) did not need the large pre-strain on the PDMS substrate. Furthermore, the wavelength range of the obtained gradient wrinkles was extended greatly. Consequently, different gradient patterns with well-defined microstructures were finely tuned by a simple manipulation of the exposure order and the exposure duration of the combined UVO/OP applied to the pre-strained PDMS substrate. Based on the systematical results, we revealed the underlying physics that was related to the formation of the current gradient wrinkle patterns.  
        关键词：Gradient patterns;Polydimethylsiloxane;Oxygen-plasma treatment;Ultraviolet-ozone treatment;Surface wrinkling   
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        发布时间：2021-03-19
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