Emulsifier-Free Emulsion Polymerization of Acrylonitrile in the Presence of Poly(methyl methacrylate) Seed Particles: Influence of the Addition Mode on the Surface Morphology

Acrylonitrile (AN) was polymerized in the presence of poly(methyl methacrylate) (PMMA) seed latex by both the batch and dropwise addition modes. The two addition modes both led to PMMA/polyacrylonitrile (PAN) composite particles with a core/shell structure with PMMA as the core and PAN as the shell. The shell thickness could be adjusted by a change in the amount of the second-stage AN monomer relative to the PMMA seed polymer. However, the surface morphologies of the composite polymers were quite different, which showed a rambutan-like batch mode and an urchinlike dropwise mode. The reason was considered as the different precipitation mechanisms of PAN small-particle precipitation for the batch mode and linear PAN segment growth for the dropwise mode. 0 2008 Wiley Periodicals, Inc. J Appl Polym Sci 112: 410-415, 2009