Polymer blends of poly(N-vinylpyrrolidone) (PVPr) and poly(styrene-co-4-vinylphenylmethylphenylsilanol) (ST-VPMPS) copolymers with varying amounts of VPMPS monomer units have been investigated. Glass transition temperature (Tg) measurements indicated that miscible blends of PVPr with ST-VPMPS copolymers were formed when the copolymers contained 9 mole% VPMPS or more. In addition, precipitated interpolymer complexes were formed from solution blending when the copolymer contained 31 mole% VPMPS or more. Enhanced Tgs were found for most miscible blends. Fourier transform infrared spectroscopy studies revealed that the hetero-associated hydrogen bond between the silanol and amide carbonyl groups was stronger than that of the silanol self-associated hydrogen bonds of the copolymers. Tg comparisons of the ST-VPMPS/PVPr miscible blends with the previously reported poly(styrene-co-4-vinylphenyldimethylsilanol) and PVPr (ST-VPMPS/PVPr) miscible blends were made. The enhanced Tgs of the miscible ST-VPMPS/PVPr blends were attributed to a close-packed hetero interpolymer chain segments associated with the “free volume” changes due to the formation of strong hetero-associated hydrogen bond.
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Lu et al. (1996) studied this question.