Synthesis and characterization of poly(isobutylene‐co‐isoprene)‐derived macro‐monomers

Allylic halide displacement from brominated poly(isobutylene‐co‐isoprene) (BIIR) by carboxylate nucleophiles is used to prepare elastomer derivatives containing pendant polymerizable functionality. These solvent‐borne substitutions are conducted under homogeneous and phase‐transfer catalyzed reaction conditions to synthesize acrylate and vinylbenzoate esters in high yield. The resulting macro‐monomer derivatives are shown to crosslink efficiently with peroxide initiation to give high modulus, thermoset products that cannot otherwise be accessed from isobutylene‐rich elastomers. The extent of cure, as measured by the storage modulus of the vulcanizate, scales with RCH=CH₂ content, and can be extended by co‐oligomerization of pendant unsaturation with that contained within multifunctional coagents. An alternate approach involving the introduction of pendant sulfonyl azide functionality is described, wherein thermal decomposition to nitrene intermediates supports an efficient crosslinking process. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Simulation-based design of thermally-driven actuators using liquid crystal elastomers

Liquid crystal elastomers (LCEs) are a class of soft functional materials which exhibit complex mechanical responses to external stimuli. Their promise for technological applications is difficult to realise in practice due to the complexity of design, fabrication and performance quantification of these materials. In order to address these issues, simulation-based methods are necessary to both enhance and accelerate the design process, compared to traditional experimentation alone. This work presents such an approach using a hyperelastic solid mechanics model and experimental measurement of material parameters for a thermotropic LCE. The simulation method is validated using existing experimental data of the thermomechanical response of an LCE-based cantilever resulting from a hybrid-aligned nematic texture imposed during crosslinking. The validated method is then used to perform a proof-of-concept design process of an LCE multilegged gripper in order to determine optimal design parameters for gripper performance. The simulation method and results presented in this work represent a significant step towards simulation-based design of LCE materials, which has the potential to overcome the complexity and cost of the LCE design process.     

甲基丙烯酸三丁基锡酯共聚甲基丙烯酸甲酯的竞聚率测定方法准确性探讨

甲基丙烯酸三丁基锡酯共聚甲基丙烯酸甲酯的竞聚率测定方法准确性探讨赵秉熙陈文明陈道勇阎立峰（中国科学技术大学应用化学系合肥２３００２６）朱清仁（中国科学院结构成分开放实验室合肥２３００２６）韩哲文陆志豹（华东理工大学材料科学系上海２００２３７）关键词...     

Applications of Hybrid Polymers Generated from Living Anionic Ring Opening Polymerization

Increasingly precise control of polymer architectures generated by “Living” Anionic Ring-Opening Polymerization (Living AROP) is leading to a broad range of commercial advanced material applications, particularly in the area of siloxane macromers. While academic reports on such materials remain sparse, a significant portion of the global population interacts with them on a daily basis—in applications including medical devices, microelectronics, food packaging, synthetic leather, release coatings, and pigment dispersions. The primary driver of this increased utilization of siloxane macromers is their ability to incorporate the properties of silicones into organic structures in a balanced manner. Compared to organic polymers, the differentiating properties of silicones—low T_g, hydrophobicity, low surface energy, and high free molal space—logically lend themselves to applications in which low modulus, release, permeability to oxygen and moisture, and tactile interaction are desired. However, their mechanical, structural and processing properties have until recently precluded practical applications. This review presents applications of “Living” AROP derived polymers from the perspective of historical technology development. Applications in which products are produced on a commercial scale—defined as not only offered for sale, but sold on a recurrent basis—are emphasized. Hybrid polymers with intriguing nanoscale morphology and potential applications in photoresist, microcontact printing, biomimetic soft materials, and liquid crystals are also discussed. Previously unreported work by the authors is provided in the context of this review.     

聚氨酯弹性体的形态结构和电性能研究不同起始反应温度的 …

以聚醚多元醇、丁二醇和甲二异氰酸酯为原料，在不同起始反应温度下（不用催化剂）合成了一系列硬段含量为３０％的聚氨酯弹性体（ＰＵ），它们的起始反应温度分别为２０℃（Ｓ－１）、４０℃（Ｓ－２）、６０℃（Ｓ－３）和８０℃（Ｓ－４）。用示差扫描量热分析、傅立叶变换红外光谱和透射电镜研究了它们的形态结构。研究结果发现：随着初始反应温度的升高，试样Ｓ－１的相分离程度较大，Ｓ－２次之，Ｓ－３的相分离程度较小，但Ｓ     

Molecular modeling of cellulose in amorphous state. III. An innovative elastomeric crosslink system

The flexibility of molecular structures of rubber materials was evaluated using molecular modeling techniques to develop new crosslink agents which improve deformation recovery of cellulose without significant loss of the mechanical strength. Among the studied structures Poly(propylene oxide) (PPO) pentamer appears to be the most flexible and coiled one. Our calculation results showed that, cellulose crosslinked with PPO pentamers had similar deformation recovery to that crosslinked with DMDHEU. No conformation transitions were observed in these crosslinks when cellulose models were extended to 15% strain, which is consistent with the previous result that conformation transitions in crosslinks should be avoided upon extension to achieve a good recovery on crosslinked cellulose. In addition, PPO crosslinks did not significantly affect the breaking strain of cellulose based upon the cavity volume calculations, and they helped to remove the stress concentration among cellulose chains as suggested by the results of hydrogen bonding analysis. Thus, breaking strength of cellulose might not be significantly affected by PPO crosslinks as well. The preliminary experimental results confirmed above observations. Therefore, PPO pentamer appears to be a promising elastomeric backbone structure of crosslinking agents. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1821–1833, 2007     

Tributyltin hydride and 1-ethylpiperidine hypophosphite mediated intermolecular radical additions to 2,4,6-trichlorophenyl vinyl sulfonate

2,4,6-Trichlorophenyl vinyl sulfonate smoothly undergoes intermolecular radical addition under mild initiation conditions mediated by tributyltin hydride and 1-ethylpiperidine hypophosphite (EPHP) to generate a range of functionalised alkyl sulfonamide precursors. This methodology can be used to prepare bifunctional pentafluorophenyl/2,4,6-trichlorophenyl sulfonates in good yields.     

Chemical modification of metallocene‐based polyolefinic elastomers by acrylic acid and its influence on physico‐mechanical properties: Effect of reaction parameters,crystallinity and pendant chain length

In this investigation, solution grafting of acrylic acid (AA) in presence of benzoyl peroxide (BPO) was carried out onto metallocene‐based “poly(ethylene‐octene) elastomers” (POE) as well as “poly(ethylene‐butene) elastomers” (PBE), to impart polarity on the non‐polar rubbery matrix and also to study the effects of crystallinity and pendant chain length on the “grafting percentage” and “percent gel yield” at optimized conditions for all the POE and PBE systems. Reaction parameters were optimized on the basis of the relative proportions of graft and gel formations obtained through %weight gain, Fourier Transform infrared spectroscopy and elemental analysis. The effect of grafting at its maximum level on various physico‐mechanical properties was also thoroughly investigated by using X‐ray diffraction (XRD), differential scanning calorimetry (DSC), mechanical, dynamic mechanical (DMTA), and thermogravimetric analysis (TGA) and the properties were correlated with the structure of the modified polymers. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5529–5540, 2007     

Melt-processed polymer multilayer distributed feedback lasers: Progress and prospects

Reflecting recent progress in the functionalization of roll-to-roll processed polymer multilayers, this review describes the development and characterization of versatile large-area multilayer distributed feedback (DFB) lasers. These developments are reviewed in the broader context of microresonator lasers, with a brief tutorial on the theory and experiment needed to understand their unique features. Of particular interest is the broad tunability of these DFB lasers by simple modification of their structure, mechanical stretching, and temperature. Prospects for commercialization of polymer multilayer DFB lasers are also discussed. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 251–271     

单轴拉伸下液晶高弹体力学行为的热力序耦合特性

论文利用液晶高弹体的应力-应变本构方程和力-序耦合方程,研究了沿指向矢单轴拉伸下液晶高弹体力学行为的热力序耦合特性.由于力-序耦合,有序度在拉伸作用下变大,从而影响了液晶高弹体的应力-应变关系,使得应力在相同伸长下变小.不同温度下应力受到有序度影响的程度不同.由于有序度随温度升高而减小,当工程应力不变时,伸长随着温度升高而减小;当伸长不变时,应力随着温度升高而增大;伸长随温度的变化关系和应力随温度的变化关系都呈非线性.