TRANSLATIONAL DYNAMICS IN BINARY HOMOPOLYMER MIXTURES

The influence of constraint release on the translational dynamics of deuteriated polystyrene (d-PS) chains of molecular weight, M, into two different binary mixtures was examined using forward recoil spectrometry. The first mixture was composed of two polystyrenes differing in molecular weight and the second was composed of polystyrene (PS) and poly(vinyl methyl ether) (PVME). The results are compared with a model developed to describe the effects of constraint release on the translational dynamics of a single chain diffusing into a melt whose behavior is characterized by chains that exhibit two different relaxation rates. A single fitting parameter, the ratio of the relaxation times of the fast to slow components, was used to describe the data. In the case of the PS/PS host, the ratio increased as the volume fraction of the slow component increased. For the PS/PVME system, a slight minimum was observed in the middle of the composition regime. Independent studies of the poly(ethylene oxide)/polymethylmethacrylate system, where relaxation times of the PEO and PMMA components were determined independently, reveal similar trends.