Preparation and Characterization of Polymeric Microspheres Having Isotactic Poly(methacrylic acid) o

A poly(tert-butyl methacrylate)(PBMA) macromonomer was synthesized by anionic polymerization with bis(2,6-di-t-butyl phenoxy) methyl aluminum [MeAl(ODBP)2] as the initiator and trimethylsilylmethacrylate(TMSMA) as the end capping agent in dry THF. Then, a poly(methacrylic acid)(PMAA) macromonomer was obtained by means of hydrolysis reaction from the PBMA macromonomer in the presence of hydrochloric acid. The structures of the PBMA macromonomer were characterized by using 1H NMR. It was found that the resulted PBMA macromonomer has highly isotactic properties and the PMAA macromonomer has an end vinyl group on per polymer chain. The monodisperse polymeric microspheres, which consisted of polystyrene cores and PMAA branches on their surfaces, were prepared by the dispersion copolymerization of styrene with the PMAA macromonomer in an ethanol/water mixed solvent. It was found that the concentration of the PMAA macromonomer would affect the microsphere formation, the morphology and its size in the copolymerization system.