FRG: Synthesis, Properties, and Simulations of Semi-Flexible and Ionomer Elastomers

精心定制的合成，新的物理特性测量分析，和新的计算机模拟方法已经开发出理想的简单网络，如那些由柔性有机硅，聚（二甲基硅氧烷）的研究。 该项目包括使用这些技术来研究更复杂结构的弹性体：即来自半柔性链和离聚物链的弹性体。 聚（二乙基硅氧烷）网络，其弹性链具有更硬的骨干比相应的二甲基硅氧烷，因为它们的较大的乙基侧基，表现出有趣的无定形介相转变单轴变形时。 氘核磁共振，X-射线，和计算机模拟研究，提出了阐明的中间相的分子结构，过渡的动力学，和网络结构的作用，对发病的过渡。 另一方面，在模型离聚物链的合成和我们的中性弹性体的性能的理解的进展的最新发展，使一些模型的基于正戊烷的离聚物弹性体的系统研究非常有前途。 这样的研究将作为理解离聚物网络行为和新型材料合成的基础。弹性体材料，特别是基于硅酮的弹性体，在药物递送系统中、在通过膜分离的空气的富氧中以及作为纳米器件制造中的印模（stamp）（举几个例子）中发现了广泛的应用。 该项目涉及基于对其化学结构进行微小修改的新型有机硅弹性体的合成和表征。 这些改性导致新的物理性质，例如由更硬的聚合物链制成的弹性体中的相变和由轻微带电的“离聚物链”制成的弹性体中的两亲性（水和有机溶剂两者的吸收性）。 这些新材料可用作“智能”材料（如开关和自增强弹性体）和环境补救中的有机污染物吸收剂。

Carefully tailored synthesis, new analysis of physical characterization measurements, and new computer simulation methods have been developed for the study of ideal simple networks such as those made of a flexible silicone, poly(dimethylsiloxane). This project consists of using these techniques to study elastomers of more complex structures: namely elastomers from semi-flexible chains and from ionomer chains. Poly(diethylsiloxane) networks, whose elastic chains have a stiffer backbone than the corresponding dimethylsiloxane because of their larger ethyl side groups, exhibit an intriguing amorphous-mesophase transition upon uniaxial deformation. Deuterium NMR, X-ray, and computer simulation studies are proposed to elucidate the molecular structure of the mesophase, the kinetics of the transition, and the role of the network architecture on the onset of the transition. On the other hand, recent developments in the synthesis of model ionomer chains and advances in our understanding of the properties of neutral elastomers make a systematic study of some model siloxane-based ionomer elastomers very promising. Such a study will serve as the basis for an understanding of ionomer network behavior and the synthesis of novel materials.%%%Elastomeric materials, and in particular silicone-based elastomers, find a wide range of applications in drug delivery systems, in oxygen enrichment of air by membrane separation, and as stamps in the fabrication of nano-devices, to give a few examples. This project is concerned with the synthesis and characterization of new classes of silicone elastomers based on small modification of their chemical structure. These modifications lead to new physical properties such as phase transitions in elastomers made from stiffer polymer chains and amphiphilicity) absorbance of both water and organic solvents) in elastomers from slightly charged " ionomer chains. These new materials can find applications as "smart" materials (e.g. switches and self-reinforced elastomers) and as absorbents of organic pollutants in environmental remediation.