Interaction of sols of polysilicic acid with quaternized poly-4-vinylpyridines

Abstract

A study was made of the interaction of sols of polysilicic acid (PSA) with poly-N-ethyl-4-vinylpyridinium bromide (Q-PVP) in dilute solutions. It was shown that in weak alkaline and neutral media (7 ⩽ pH ⩽ 9) all Q-PVP fractions studied form insoluble polycomplexes with PSA sol, while in acid media (pH 3) the solubility of polycomplexes depends on the molecular weight of the polycation. A study was made of the composition of polycomplexes formed and the type of variation of these compositions according to medium pH. It was established by potentiometric titration that the interaction between Q-PVP and PSA sol is electrostatic, the number of salt bonds formed by quaternary nitrogen atoms of Q-PVP and ionized silanol groups of PSA sol, increasing with an increase in pH. The dependence on medium pH of the degree of conversion in the intermacromolecular reaction of Q-PVP-PSA sol was calculated for various polycation fractions. Equilibrium systems were proposed and described for the association of the polycation and PSA sol particles, resulting in the formation of polycomplex particles.