IN-SITU SYNTHESIS OF PBA-GRAFT-PMMA COPOLYMERS TO BE USED AS COMPATIBILIZING AGENTS IN PBA PMMA COMPOSITE LATEX-PARTICLES VIA THE MACROMONOMER METHOD/

The concept of using block or graft copolymers as compatibilizing agen ts for immiscible polymer phases was applied to the preparation of com posite latex particles with a controlled core/shell morphology. Graft copolymers of poly(n-butyl acrylate) (PEA) and poly(methyl methacrylat e) (PMMA) were prepared in-situ during the PEA seed particles synthesi s via miniemulsion polymerization of n-butyl acrylate (n-BA) in the pr esence of different PMMA macromonomers. The copolymers are to be used as compatibilizing agents to improve the coverage between phases in PB A/PMMA core/shell-type composite latex particles. By varying the amoun t and the molecular weight of the macromonomer, the macromonomer metho d allows control over the structure of the graft copolymers. Changes i n particle size averages and size distributions, effective surface are a 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 meth acrylate (MMA) monomers, synthesized under similar conditions, were co mpared with PEA particles prepared in the presence of PMMA macromonome rs in all of the above experiments. Experimental results suggest that the PEA particle's surface was modified by the presence of graft copol ymer of n-BA and PMMA macromonomer at the interface.