A novel phosphate monomer, O-p-(methacryloyloxymethyl)benzyl O,O-diethyl phosphate (MDP) was synthesized by the reaction of diethyl phosphorochloridate with 1,4-benzenedimethanol, followed by the reaction with methacryloyl chloride in the presence of triethylamine. The radical polymerization of MDP and copolymerization with methyl methacrylate were carried out in the presence of 2,2 ' -azobisisobutyronitrile (3 mol %) in dimethylacetamide at 60 degreesC for 20 h to afford phosphate-pendant polymers. The polymerization of glycidyl phenyl ether (GPE) was carried out with the phosphate-pendant polymer as an initiator in the presence of ZnCl2. The polymerization did not proceed below 90 degreesC but rapidly proceeded above 90 degreesC to afford polyGPE. The phosphate-pendant polymer served as a good thermally latent polymeric initiator.