Synthesis of branched poly(butyl methacrylate) via semicontinuous emulsion polymerization

Latex particles comprised of branched poly(butyl methacrylate) (PBMA) were prepared via semicontinuous emulsion polymerization. The extent of branching was controlled by adding various amounts of bisphenol A dimethacrylate (BPDM) as a branching agent, and 1-dodecanethiol (C12SH) was used as a chain transfer agent to prevent cross-linking and to control molecular weight. All PBMA samples have relatively high molecular weights with molecular weight distributions similar to that of the polymers synthesized by regular free radical polymerization in the presence of a chain transfer agent. The degrees of branching were determined using H-1 NMR. G' and G '' measurements indicated no significant entanglement contributions to the theological properties. The latex particles containing branched PBMAs are monodisperse, and the particle sizes are well controlled.