Narrowly dispersed micrometer-sized composite spheres based on diazonium-polystyrene

Diazonium group-substituted polystyrene (PS-N-2(+)) micrometer-sized spheres with narrow distribution were prepared from highly crosslinked polystyrene particles. Then a composite sphere was prepared with the micro-PS-N-2(+) sphere as core and submicrometer-sized poly(styrene-methyl methacrylate-acrylic acid) [P(S-MMA-AA)] colloids or nanometer-sized SiO2 particles as shell via columbic interaction. The ionic linkages between the core and shell convert to covalent bonds in the thermal treatment process. As a result, the composite sphere becomes very stable toward polar solvents as well as toward ultrasonic treatment. A hollow SiO2, micrometer-sized sphere then was achieved by removing the core under sintering conditions (700 degreesC). (C) 2004 Wiley Periodicals, Inc.