Synthesis and property behavior of dioctyl phthalate plasticized styrene-acrylate particles by Shirasu porous glass emulsification and subsequent suspension copolymerization

摘要

Two-phase model styrene-acrylate copolymers were synthesized with a soft phase consisting of methyl acrylate, butyl acrylate, and butyl methacrylate. Besides the styrenic copolymers, copolymers containing a hard phase of methyl methacylate and methyl acrylate were also synthesized. Comonomer droplets with a narrow size distribution and fair uniformity were prepared using an SPG (Shirasu porous glass) membrane having pore size of 0.90 mum. After the single-step SPG emulsion, the emulsion droplets were composed mainly of monomers, hydrophobic additives, and an oil-soluble initiator, suspended in the aqueous phase containing a stabilizer and inhibitor. These were then transferred to a reactor, and subsequent suspension polymerization was carried out. Uniform copolymer particles with a mean diameter ranging from 3 to 7 mum, depending on the recipe, with a narrow particle size distribution and a coefficient of variation of about 10% were achieved. Based on the glass-transition temperatures, as measured by differential scanning calorimetry, the resulting copolymer particles containing a soft phase of acrylate were better compatibilized with a hard phase of methyl methacrylate than with styrene with dioctyl phthalate (DOP) addition. Glass-transition temperatures of poly(MMA-co-MA) particles were strongly affected by the composition drift in the copolymer caused by their substantial difference in reactivity ratios. Incorporation of DOP in the copolymer particles does not significantly affect the glass-transition temperature of MMA- or MA-containing copolymer particles, but it does affect the St-containing copolymer and particle morphology of the copolymers. (C) 2003 Wiley Periodicals, Inc. [References: 20]