Specific Interactions in Polymer Systems

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The two co-PI's will continue research on the effect of specify interactions on the phase behavior of polymer blends. One part of the proposed work concerns the completion of work initiated a few years ago on the effect of chain architecture on the number of like and un-like contacts in solutions and blends where the components contain functional groups that hydrogen bond to one another. These systems are particularly amenable to study because infrared spectroscopy can be used to count the number of contacts in well-chosen systems. Work in progress involves the effect of branching in hyperbranched and dendrimer-like polymers, mesh size in cross-linked networks and microphase separation in blends involving block copolymers. The second part of the proposed research involves the application of a new technique, a two-dimensional Fourier transform infrared/dielectric spectrometer. Dielectric relaxation measurements have been used for many years as a probe of the dynamics of polymer chains, through the detection of the transitions and relaxations that are a result of various types of coupled or local motions. Infrared spectroscopy provides a probe of molecular level structure and, in certain systems, intermolecular interactions. Clearly, a technique (or, more accurately, a hybrid-technique) that can measure the temperature and frequency range of various transitions and relaxation's, while simultaneously probing the functional groups involved and the degree to which their motions are coupled, would be an extremely powerful analytical tool. It is expected that this instrument will open up various new areas of research and undergraduate students will be involved in "scouting" experiments as part of their senior projects to help explore and establish these. At the same time, this hybrid spectrometer will be used to explore problems associated with the major thrust of our research that could not be tackled previously, particularly the dynamics of functional groups and polymer chains in associating systems.%%%This new area of research has considerable potential for enhancing both research activities and education. In terms of the former, the development of the technique should allow the functional groups involved in relaxations and transitions in various materials, not just polymers, to be explored. In terms of education, through the mechanisms of involving undergraduates in the research, seminars on technique development and incorporating this instrument into our undergraduate laboratories, the importance of combining methods of investigation and techniques in order to tackle complex problems will be taught and emphasized.