Dissolution behaviour of model alkali-soluble emulsion polymers: effects of molecular weights and ionic strength

Abstract

The dissolution behaviour of model alkali-soluble polymer emulsions with different molecular weights was studied using conductometric and potentiometric titration and laser light scattering techniques. The behaviour of the copolymer was studied as a function of the degree of neutralisation, α = [NaOH]/[COOH]. The polymer latex swells with increasing α values up to α = 0.5–0.7, after which the dissociation of polymer chains commences. At α = 1.0, all the polymer latexes dissociate into individual polymer chains. By combining the results of static and dynamic laser light scattering, we observed that the polymers have a compact conformation at α = 0. This compact conformation changes to a random coil at around α = 0.5, which then becomes a fully extended coiled conformation at α = 1.0, when all the COOH polymer groups are hydrolysed. The dissolution of low-molecular-weight polymers is faster than that of high-molecular-weight polymers.