In-Situ Synthesis of PBA-graft-PMMA Copolymers to Be Used as Compatibilizing Agents in PBA/PMMA Composite Latex Particles via the Macromonomer Method

Abstract

The concept of using block or graft copolymers as compatibilizing agents for immiscible polymer phases was applied to the preparation of composite latex particles with a controlled core/shell morphology. Graft copolymers of poly(n-butyl acrylate) (PBA) and poly(methyl methacrylate) (PMMA) were prepared in-situ during the PBA seed particles synthesis via miniemulsion polymerization of n-butyl acrylate (n-BA) in the presence of different PMMA macromonomers. The copolymers are to be used as compatibilizing agents to improve the coverage between phases in PBA/PMMA core/shell-type composite latex particles. By varying the amount and the molecular weight of the macromonomer, the macromonomer method allows control over the structure of the graft copolymers. Changes in particle size averages and size distributions, effective surface area of surfactant coverage on the particle surface, and oil/water phase interfacial tensions were measured as a function of the ratio between added macromonomer and n-BA. Copolymer latexes of n-BA and methyl methacrylate (MMA) monomers, synthesized under similar conditions, were compared with PBA particles prepared in the presence of PMMA macromonomers in all of the above experiments. Experimental results suggest that the PBA particle's surface was modified by the presence of graft copolymer of n-BA and PMMA macromonomer at the interface.