Effect of Chemical Structure and Molecular Architecture on the Properties of Polymer Networks

小行星9706066 该重点需求组项目涉及弹性体性能的基础研究。 拟议的研究包括三管齐下的方法，涉及：1）仔细的合成和表征; 2）使用氘NMR; 3）Monte Carlo模拟。 该小组将使用末端连接化学以系统的方式改变所制备的网络的结构，并研究这种变化对网络的机械和溶胀性能的影响。 氘核磁共振实验将被用来探测网络的分子结构和压缩下的网络链段取向序参数。 最后，将开发蒙特卡罗模拟方法来检查固化后获得的分子结构，网络的溶胀机制和前体分子的链刚度的影响。 实验结果、模型预测和模拟结果将进行比较，以验证或改进现有模型，并在必要时提出新模型。 聚（二乙基硅氧烷）（PDES）网络的这些研究将有助于阐明一个长期存在的问题，在应变网络中的段-段相互作用的性质，因为PDES表现出介相结构以上的玻璃化转变。 这项研究是在弹性体材料和网络的技术重要领域，并将有助于提供其分子水平的结构和性能的基本理解。 ***

9706066 Cohen This Focused Reqearch Group project involves fundamental studies of elastomer properties. The proposed research consists of a three-pronged approach involving: 1) careful synthesis and characterization; 2) use of deuterium NMR; and 3) Monte Carlo simulations. The group will use end-linking chemisty to vary the architecture of the prepared networks in a systernatic way and to examine the effect of this variation on the mechanical and swelling properties of the networks. Deuterium NMR experiments will be used to probe the molecular architecture of the networks and the segment orientational order parameter of networks under compression. Finally, Monte Carlo simulation methods will be developed to examine the molecular structures that are obtained after curing, the swelling mechanisms of the networks and the effect of the chain stiffness of the precursor molecules. Experimental results, model predictions and simulation results will be compared to validate or improve existing models as well as propose new models if necessary. These studies on poly(diethylsiloxane) (PDES) networks will help elucidate a long standing issue about the nature of segment-segment interactions in strained networks because PDES exhibits a mesophasic structure above its glass transition. %%% This research is in the technologically important area of elastomeric materials and networks and will help provide fundamental understanding of their molecular-level structures and properties. ***