Molecular weight dependence of polystyrene segmental dynamics in dilute blends with poly(vinyl methyl ether)

The segmental dynamics of backbone-deuterated polystyrenes (d(3)PS) with varying molecular weights (1.7-67 kg/mol) have been measured in blends with poly(vinyl methyl ether) (PVME). H-2 NMR T-1 values at 15 and 77 MHz are reported for the pure d(3)PS and for the dilute d(3)PS component in PVME matrices. The temperature shift that is needed to superpose the NMR T-1 data for the pure d(3)PS and the d(3)PS as a dilute component in the blend ranges from 45 to 70 K. In the framework of Lodge/McLeish model, the self-concentration value for d(3)PS in these dilute blends with PVME is found to be independent of molecular weight. We thus establish for this system that the substantial influence of molecular weight on the blend segmental dynamics can be explained by homopolymer T-g differences. (c) 2007 Wiley Periodicals, Inc.