KINETICS OF COIL OVERLAP IN IONOMER BLENDS BY H-1-NMR IN DMSO-D6 .1. EFFECT OF ELECTROLYTES, WATER, MOLECULAR-WEIGHT, ION CONTENT, AND TEMPERATURE

H-1 nuclear magnetic resonance (NMR) studies were performed on solutio ns of mixtures of lightly sulfonated polystyrenes (PS-SSA), with poly( methyl methacrylate-co-4-vinylpyridine) (PMMA-4VP) copolymers. The PS- SSA (5-15 mol % sulfonation) had molecular weights (MW) ranging from 2 X 10(3) to 1 X 10(5), while the PMMA-4VP chains (5-11 mol %) had a MW of 1 x 10(5). The driving force for coil overlap was electrostatic at traction between the sulfonate anions and the pyridinium cations which were produced as a result of proton transfer from the sulfonic acid t o the 4VP moieties. The coil overlap process was monitored as a functi on of time by the acquisition of proton spectra, which showed the grad ual disappearance of the original (unshielded) methoxy signal and the appearance of a new signal originating from the shielded methoxy proto ns. In order to propose a complete model for the coil overlap process, it was first necessary to ascertain that the ionic species were, inde ed, responsible for the interchain attraction rather than some other u nsuspected mechanism. The electrostatic nature of the mechanism was co nfirmed by the addition of various electrolytes to the equilibrated bl end solutions. The addition of electrolytes does, indeed, result in th e disappearance of the shielded methoxy signal, confirming the electro static nature of the mechanism. In addition, the qualitative influence of other parameters on the electrostatic interaction was studied. The se parameters were the water content of the solution, the ion content of the copolymers, the MW of the PS-SSA chains, and the temperature. T he detailed kinetics and the mechanistic aspects of the coil overlap p rocess are described in a subsequent paper.