화학공학소재연구정보센터
Journal of Applied Polymer Science, Vol.110, No.3, 1469-1476, 2008
Preparation of core-shell particles by dispersion polymerization with a poly(ethylene oxide) macroazoinitiator
A macroazoinitiator (MAI) containing a poly(ethylene oxide) (PEO) block was used with a methyl methacrylate monomer to prepare polymer particles in ethanol/H2O solutions. The effects of the monomer/MAI ratio (RMI) and H2O content in the solutions on the molecular weight, particle diameters, and chemical structure of the resulting polymer particles were investigated. The reaction mixtures showed three kinds of states, which were milky colloid solutions, macrogels and/or precipitations, and clear solutions. The colloid solutions were obtained in the solutions with an H2O content of about 50-90 vol % and a RMI of 20-400. In the colloid solutions, core-shell nanospheres consisting of PEO shells and poly(methyl methacrylate) (PMMA) cores were predominantly obtained. In the specific conditions close to the area of gel and/or precipitation formation, particles connected about 0.5-5 mu m in length were obtained. Multiblock copolymers nanospheres tended to be obtained with lower RMIs, and PMMA-PEO-PMMA tri-bloc and/or PMMA-PEO di-block copolymer nanospheres were obtained with higher RMIs. The solubility of the monomer and the generated polymer in solutions may have affected the polymerization development and the state of the products. (C) 2008 Wiley Periodicals, Inc.