Polyacrylamide with a bromine atom end group (PAM-Br) was synthesized by atom transfer radical polymerization (ATRP) of acrylamide (AM) in water at 70 ℃. The molecular weight and molecular weight distribution of the PAM-Br were characterized by aqueous gel permeation chromatography (GPC). It was found that the molecular weight and molecular weight distribution of PAM-Br were affected by changing concentration of AM, ratio of AM monomer to initiator and reaction time. The reaction process contributed to the basic rule of ATRP under a low molar ratio of [AM]∶[EPN-Br]＝25∶1. Furthermore, the polyacrylamide macromonomers (MAA-PAM) with vinyl double end groups were successful prepared by the nucleophilic substitution reaction of bromine atom to methacrylic acid (MAA). Then polyvinylamine macromonomers (MAA-PVAm) were obtained by Hofmann degradation reaction of MAA-PAM at 0 ℃. The structure of MAA-PVAm was characterized by using FTIR and NMR spectra. The polymeric microspheres were also prepared by dispersion copolymerization of MAA-PVAm macromonomers with styrene using 2,2’-azobisisobutyronitrile as an initiator in ethanol/water mixed solvent. The polymeric microspheres have sphere morphology and uniformity of diameters based on the observation of scanning electron microscopy.

Key words: ATRP, nucleophilic substitution, Hofmann degradation, polyvinylamine macromonomer, microsphere