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. ***
