Preparation of Hollow Latex Particles——Preparation of Seed and Core Particles

For preparing the hollow polymer particles, seed latex particles with carboxylic group were synthesized via emulsion polymerization by using methyl methacrylate (MMA), butyl acrylate (BA) and methacrylic acid (MAA) as comonomers. The sodium dodecyl benzene sulfonate (SDBS) was used as emulsifier and its dosage used was lower than its critical micelle concentration (CMC). The seeded emulsion copolymerization of MMA, MAA and divinyl benzene was carried out by using the prepared carboxylated latex particles as seeds, so that the lightly crosslinked core particles with more carboxylic groups were prepared. Hollow polymer particles can be obtained by core-shell emulsion polymerization on the base of the core particles and then by alkalization treatment of the core-shell latex particles. The diameters and their distributions of latex and hollow particles were determined by nanosizer. The particle morphology was also characterized by TEM. The effects of the ways of monomer feeding, emulsifier dosage used and kinds of carboxylated monomer used on the polymerization stability, seed and core diameters and their distributions were studied. The optimal conditions for preparing seed and core latex particles were obtained as follows. During seed forming stage, the SDBS dosage used is 0.5%(wt) of total monomer and the monomer mixture is fed in one batch. During the core forming stage, MAA is used as carboxylic comonomer, and the monomer mixture is fed in a starved feeding fashion, the supplementary emulsifier is fed in a semi-continuous fashion and its dosage used is 0.15%(wt) of the total monomers to ensure the polymerization stability and monodispersity of the obtained seed and core particles.