Monodisperse Superparamagnetic pH-Sensitive Single-Layer Chitosan Hollow Microspheres with Controllable Structure

Facile strategy was developed for the fabrication of the monodisperse superparamagnetic pH-sensitive single-layer chitosan (CS) hollow microspheres with controllable structure. The carboxyl group-functionalized polystyrene microspheres prepared by soap-free emulsion polymerization were used as the templates. After the Fe3O4 nanoparticles were in situ formed onto the surface of the templates, the single-layer CS was self-assembled and cross-linked with glutaraldehyde subsequently. Then, the magnetic single-layer CS hollow microspheres were obtained after the templates were removed. It was found that the feeding ratio of the monomer acrylic acid in the soap-free emulsion polymerization had played an important role on the particle size and surface carboxyl group content of the templates, which determined the particle size and shell thickness of the magnetic single-layer CS hollow microspheres in the proposed strategy. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4981-4988, 2010