The properties of functional polymer latex is closely related to its functional group amount. Crosslinked poly(methyl methacrylate-ethyl acrylate-methacrylic acid) [P(MMA-EA-MAA)] latex particles with different amount of carboxyl groups and with narrow size distribution were synthesized by seeded emulsion polymerization in the absence of surfactant materials, and soap-free porous latex particles with high amount of carboxyl groups were obtained after alkali post-treatment. Influences of MAA on polymerization, latex properties and porous morphology were investigated. The results showed that when 0.3 g of divinyl benzene was used as crosslinking agent, the crosslinking degree increased significantly from 28.26% to 90.95% with the increase of MAA amount from 4.0 mol% to 10.0 mol%, and this increase became slowly as MAA amount was more than 10.0 mol%; the particle volume expansion (ΔV) was increased gradually as MAA amount increased, and reached a maximum of 42.1% when 12.0 mol% of MAA was used, and perfect porous morphology inside particles was observed even when the crosslinking degree reached 95.4% at 14.0 mol% of MAA.

Key words: soap-free seeded emulsion polymerization, crosslinking agent, porous morphology, carboxylic acid amount