Grafting of dodecyl methacrylate onto hydroxylated polybutadiene by miniemulsion polymerization

Homogeneous copolymer latex particles of dodecyl methacrylate (DMA) and low-molecular-weight hydroxy-terminated polybutadiene (HTPB) oligomers were prepared by free-radical polymerization using miniemulsion methods. Rate data and latex characteristics were consistent with the classical miniemulsion mechanism where nucleation of monomer droplets is the predominant pathway of particle formation. There is essentially no particle formation by secondary nucleation in the water phase. Characterization of the copolymer latex particles using transmission electron microscopy and modulated differential scanning calorimetry suggested that there is a significant amount of grafted poly(DMA)/HTPB polymer contributing to the miscibility of the HTPB and poly(DMA) phases. Particles were more homogeneous at increased HTPB composition, of relatively narrow polydispersity, and could be prepared reproducibly using a number of different initiation systems. The observed trends can all be rationalized in terms of conventional understanding of miniemulsion polymerization systems.