Preparation of sulphonate-containing core/shell latex particles via seeded emulsion copolymerization

In this study, P(St–MAA) seed latex particles were first prepared via soap-free emulsion polymerization of styrene (St) and methacrylic acid (MAA), then the seed particles were allowed to swell with St at room temperature, and the P(St–MAA)/P(St–NaSS) core/shell latex particles were then synthesized via seeded emulsion copolymerization of St and sodium styrene sulphonate (NaSS) using AIBN as initiator in the presence of N,N′-methylenebisacrylamide (BAA, water-soluble crosslinker). Results showed that the polymerization could be carried out smoothly when the ratio of BAA to total monomers was less than 3 mol%, the narrow dispersed P(St–MAA) seed particles with the diameter of 150 nm and the P(St–MAA)/P(St–NaSS) core/shell latexes with the particle size of about 200 nm were synthesized. When the 25/75 mole ratio of NaSS/(St + MAA) and 2 mol% of BAA were used in the seeded emulsion polymerization, the resulted P(St–MAA)/P(St–NaSS) latex product showed a low weight loss after water extraction, and the NaSS unit content in the whole particle and in the shell reached 11.7 mol% and 34.6 mol%, respectively.