Polysoaps derived from poly-2-vinylpyridine

Abstract

A series of poly-2-vinylpyridine derivatives prepared by partial quaternization of their pyridine groups with alkyl bromide was studied. The ratios of the quaternized pyridine groups were 0, 12.1, 27.9 and 51.2% withre-butyl bromide; 6.4, 8.8, 14.2 and 23.6% withn-hexyl bromide; 6.2, 13.7 and 28.2% withn-octyl bromide; 4.5, 15.0, 24.4 and 30.5% with lauryl bromide. The transition of poly-2-vinylpyridine derivatives from polyelectrolyte to polysoap was examined in an aqueous KBr solution by measuring the light scattering, the viscosity, and the solubilization of Sudan III. The transition occurred when the quaternization degree or the chain length of alkyl groups was increased. The end-to-end distance per monomer unit determined by light scattering gradually decreases with an increase in the alkyl content or in the alkyl length. It contracts abruptly as the content of octyl bromide increases from 13.7% to 28.2%, and that of lauryl bromide from 4.5% to 15.0%, respectively. These properties suggest that the alkyl groups are brought into the intramolecular aggregation, and therefore the polysoap molecule contracts as a whole. The transition from typical polyelectrolyte to typical polysoap was also supported by the viscosity measurement and the solubilization of Sudan III. The conclusion on this transition is consistent qualitatively with our previous deductions obtained from a statistical treatment of the solution state of polysoaps.