The dynamics of polymers in polymer solutions have not been probed in great enough detail to provide a coherent picture of the behavior of these polymers, especially in more concentrated solutions. To help understand this behavior further, we have prepared a series of backbone-labeled polymers including poly(n-butyl acrylate)-d1 (PNBA). These provide a basis for comparison of the behavior among a group of related polymers. The dynamics have been probed by using deuterium relaxation times. Since the relaxation times are relatively fast and the quadrupolar relaxation mechanism is well understood, data from this technique provide a convenient means for comparison of dynamics for different acylates. We have chosen to use the relaxation times T1 and T2 as the basis set because they probe the spectral densities of the polymers at rather different frequencies (vide infra). We have previously reported the dynamics of poly(iso-propyl acrylate) (PIPA) in chloroform solution. At that time we found that the relaxation times measured could not be adequately evaluated by the motional models tested at that time. Our original results showed that the models yielded results which were not physically realistic and resulted in, for example, correlation times getting slower with increasing temperatures. This problem has now been solved for the logχ2 model by the proper normalization of the mean, and other models for polymer segmental motion.
F. D. Blum and R. B. Durairaj, "Dynamics of Polyacrylates in Concentrated Chloroform Solutions," Polymer Preprints, American Chemical Society (ACS), Jan 2001.
National Science Foundation (U.S.)
Article - Journal
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