SPECTRAL CHARACTERIZATION AND THERMAL-BEHAVIOR OF CROSS-LINKED POLY(HYDROXYETHYLMETHACRYLATE) BEADS PREPARED BY SUSPENSION POLYMERIZATION

Crosslinked poly(hydroxyethylmethacrylate) [poly(HEMA)] beads were prepared by the suspension copolymerization of 2-hydroxyethylmethacrylate monomer with ethyleneglycol dimethacrylate (EGDMA) in aqueous media which contained only magnesium oxide (MgO) as a suspension stabilizer and also salting-out agent. The procedure gives spherical particles with narrow size distribution. The reaction mechanism, composition and structure of poly(HEMA) beads were studied by solid-state C-13 CP/MAS NMR, FTIR, ESCA, and elemental analysis. C-13 NMR implies the existence of unreacted pendant groups in the HEMA-EGDMA copolymer. The surface composition obtained by ESCA is almost the same as the bulk composition determined by elemental analysis. FTIR spectra provide compelling evidence for the presence of carboxyl and hydroxyl groups. The glass-transition temperature and the thermal stability of beads were determined by DSC.