US-Czechoslovakia Research on Dynamic Light Scattering from Block Copolymer Liquids near the Order-Disorder Transition

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This U.S.-Czechoslovakia research project between Dr. Timothy P. Lodge of the University of Minnesota-Twin Cities and Dr. P. Stepanek of the Czechoslovak Academy of Sciences will be to perform extensive experimental examination of the dynamics of block copolymer liquids. Their focus will be the weak segregation regime, defined to incorporate order-disorder transition and the adjunct ordered and disordered states. The researchers will use dynamic light scattering to investigate both block copolymer melts and solutions, especially: chain length and concentration; block copolymer composition; the segment-segment interaction parameter; and temperature. They will pay particular attention to the number, angular dependence, and identification of the modes which appear in the experimental correlation functions. The large characteristic time constants involved will pose challenges which demand various exploratory stategies. The researchers will interpret the results in the framework of emerging theoretical descriptions, anticipating that dynamical mean-field approximations are unlikely to be adequate. These measurements will complement rheological, rheo-optical, tracer diffusion, and small-angle scattering studies at the University of Minnesota. This project in chemistry fulfills the program objective of advancing scientific knowledge by enabling leading experts in the United States and Eastern Europe to combine complementary talents and pool resources in areas of strong mutual interest and competence.