Reorientational Dynamics and Intermolecular Cooperativity in Crosslinking Polymers

9710480 Mijovic该资助涉及交联聚合物中偶极运动动力学的基本研究。 玻璃形成材料的动力学目前是科学界相当活跃的主题，但迄今为止还没有关于由于化学反应而经历结构的时间演变的系统的动力学的全面研究报告。 化学反应的进步改变了材料的本质，并为分子运动动力学的研究增加了新的维度。 化学成分、物理特征和形态的变化伴随着节段运动或松弛的时间尺度的连续变化。 当一个信号（本研究中的电场）被施加到聚合物上时，许多分子片段必须一致响应。 这需要分子水平上的合作，因此，基本的论点应该开始的命题，即弛豫过程是由分子间的合作。 本研究的主要目的是研究交联过程中偶极动力学的变化，并利用其结果：1）描述网络形成过程中各个阶段各种弛豫过程的分子起源; 2）建立网络的化学和物理状态与偶极动力学的联系方法;和3）提供了一个解释的网络动力学的分子间的协同性。 所提出的方法是一个跨学科的性质，并将允许在交联聚合物的再取向动力学和分子间协同性的基本理解。 预计这项研究完成后，将提供一个分子水平的洞察力的聚合物，经历了一个时间演变的结构作为化学反应的结果的再取向动力学。 ***

9710480 Mijovic This grant concerns a fundamental investigation of the dynamics of dipole motions in crosslinking polymers. Dynamics of glass-forming materials are currently a subject of considerable activity in the scientific community, but no comprehensive study has been reported hitherto on the dynamic of systems that undergo a temporal evolution of structure as a result of chemical reactions. The advancement of chemical reactions alters the very nature of the material and adds a new dimension to the study of dynamics of molecular motions. Changes in the chemical composition, physical characteristics and morphology are accompanied by a continuous variation in the time scale for segmental motions or relaxations. When a signal (electric field in this study) is applied to a polymer, a number of molecular segmental must respond in unison. That requires cooperation on the molecular level, and hence the fundamental argument should begin with the proposition that the relaxation processes are governed by intermolecular cooperativity. The principal objectives of the research are to investigate the changes in dipole dynamics during crosslinking and utilize the results to: 1) describe the molecular origin of various relaxation process at all stages during network formation; 2) formulate a methodology for relating the chemical and physical state of the network to dipole dynamics; and 3) provide an interpretation of network dynamics in terms of intermolecular cooperativity. %%% The proposed methodology is of an interdisciplinary nature and will permit a fundamental understanding of reorientational dynamics and intermolecular cooperativity in crosslinking polymers. It is expected that the research, when completed, will afford a molecular-level insight into the reorientational dynamics of polymers that undergo a temporal evolution of structure as a result of chemical reactions. ***