Block Copolymer Dispersions

L. Rosengarten, K. Tauer

Block Copolymers via Emulsion Polymerization
Azo-initiators with polymeric side groups

Redox Initiator systems

The formation of primary block copolymer dispersions is possible if the heterophase polymerization is started with polymeric radicals which are soluble in the dispersion medium. The polymer chains of those radicals simultaneously impart stability to the particles. The polymeric radicals can be formed either by thermal decomposition of a symmetrical azo initiator with polymeric side groups or by a redox reaction taking part with a proper polymer.

Morphology of Block Copolymer Latices

The morphology of block copolymer dispersions is governed by the compatibility of both polymeric blocks as well by the solubility of the stabilizing blocks in the monomer swollen particles during the polymerization. For instance, aqueous block copolymer dispersions consisting of poly(ethylene glycol) as stabilizing block and poly(methyl methacrylate) as water-insoluble block lead during the polymerization at high conversions to the formation of hollow particles due to a segregation caused by the mutual incompatibility of both blocks in the solid polymer particles.