A series of poly(4-vinylpyridinium salts) was prepared by spontaneous polymerization of 4-vinylpyridine in the presence of various alkylating agents and at different temperatures in order to study by 1H-NMR the stereoregularity of the obtained polysalts. Contrarily to poly(4-vinylpyridine) which always gives an atactic structure, the polysalts were found to have an isotactic character. The observed isotactic triad content varies from 30%–50% and increase when the temperature of the polymerization decreases and with the hydrophobic character of the side chain. The preferential isotactic placement is explained in terms of the zwitterionic polymerization mechanism and the formation of a sandwich-like association between a quaternized monomer and the growing chain, an association stabilized by Coulombic interactions.
Посилання на статтю:
Stereoregularity of poly(4-vinyl-n-alkyl-pyridinium) salts prepared by spontaneous polymerization / Christian Chovino, Philippe Gramain // Polymer. – 1999. – N 40. – P. 4805–4810.