MOLECULAR-INTERACTIONS IN POLYSTYRENE COSOLVENT SYSTEMS

Studied are miscible binary cosolvents for polystyrene, for which polystyrene is insoluble in either of the individual solvents. Polymer-solvent interactions in solutions of atactic polystyrene in acetone/diethyl ether and in methylcyclopentane (MCP)/acetone binary cosolvents have been investigated using nuclear magnetic resonance (NMR) spectroscopy. Polystyrene **1**3C chemical shifts were measured as a function of miscible binary solvent compositions and temperature. The NMR data were used to calculate 'association constants' as a measure of specific interactions of the solvent components with all sites on the polymer. In mixtures of acetone and diethyl ether, **1**3C-NMR indicates a weak interaction between the polystyrene phenyl ring and the diethylether solvent component. In the polystyrene/MCP/acetone system, present NMR data reveal no preferential interactions. Additional NMR measurements were performed on polystyrene in mixtures of CCl//4/acetone. From these results, it is concluded that although preferential polymer-solvent interactions are present in some cosolvent systems, they are not a prerequisite for such behavior.