Micron-size monodisperse polymer microspheres having chloromethyl groups thereon were prepared by two-step polymerization process as follows. First, micron-size monodisperse polystyrene particles were prepared by dispersion polymerization with 2,2'-azobisisobutyronitrile as initiator in ethanol-water medium in the presence of poly(acrylic acid) as stabilizer under various conditions. Secondly, in the presence of the 1.9-Fm monodisperse polystyrene particles produced under the optimum conditions, seeded copolymerization for styrene and chloromethyl styrene was carried out. The seeded copolymerization proceeded smoothly without producing new particles, and it was confirmed by x-ray photoelectron spectroscopy that the chloromethyl group existed more at the surface of the produced microsphere than at that of film cast from the benzene solution in which the microspheres were dissolved.
Polymer microspheres composed of various compositions of styrene and 2hydroxyethyl methacrylate (HEMA) were produced by batch emulsifier-free emulsion polymerization. The HEMA content at the surface, [I-IEMA] s , of the microspheres powdered by freeze-drying was determined by both quantitative Cl,/Ois analysis and Cls peak shape analysis of the x-ray photoelectron spectroscopic spectra. When the HEMA content in the microsphere, [HEMA]p, was less than about 5 mole 0/0, the [HEMA]s values determined by the two different methods showed good agreement. At [HEMA]p above 5 mole %, [HEMA] ~ values determined by the first method were about 15 mole % greater than those determined by the second. They both showed a similar tendency with the [HEMA], being higher than the [HEMA]p, e.g., when [HEMA]p was 1 mole0/0, [HEMA], was 11 mole %. The intensity of the satellite peak due to the z ~ ~* transition of the benzene ring of the styrene component decreased with an increase in [HEMA]p, to zero at 5 mole 0/0 of [HEMA]p. These results indicate that the HEMA component is localized at the surface.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.