Multihollow structured poly(methyl methacrylate)/silver nanocomposite microspheres prepared by suspension polymerization in the presence of dual dispersion agents

Poly(methyl methacrylate) (PMMA)/silver nanocomposite microspheres with unique multihollow structures were prepared by suspension polymerization in the presence of dual dispersion agents. The addition of a lipophilic emulsifier, polyethylene glycol (30EO) dipolyhydroxystearate (Arlacel P135), not only stabilized water-in-oil (W/O) emulsion, but also converted silver nanoparticles from hydrophilic to lipophilic. When a suspension polymerization dispersion agent, poly(vinyl alcohol), was added to the above W/O emulsion system, a water-in-oil-in-water suspension was formed with silver nanoparticles dispersed in the oil phase. The suspension polymerization was carried out at low temperature with 2,2′-azobis(2,4-dimethylvaleronitrile) as the initiator. When modified silver nanoparticles were added, the rate of polymerization increased slightly. High monomer conversion (about 85%) was obtained in spite of low polymerization temperature of 30 °C. Under controlled conditions, PMMA/silver microspheres with various hollow structures were synthesized. The PMMA/silver microspheres with multihollow structure showed high antibacterial ability.