| Abstract: | Phenyl glycidyl ether was found to react with potassium starch alkoxide in dimethyl sulfoxide (DMSO) to give graft polymers in almost quantitative yields, both the monomer and the starch being incorporated completely into the graft polymer. No transfer reactions to monomer or solvent leading to homopolymerization was found. For this reason this system was used as a model for the study of the rate of the graft polymerization of alkylene oxides on starch and other carbohydrates. Comparison of the rates of the graft polymerization of phenyl glycidyl ether on starch alkoxide with that of the homopolymerization by potassium naphthalene in DMSO under comparable conditions showed that the former reaction was much slower. Rates of the graft polymerizations on dextrin and sucrose under comparable conditions, were similar to those obtained with starch. On the other hand, the rates of polymerization on poly(ethylene oxide) alkoxides of different molecular weights were similar to those obtained in the corresponding homopolymerization by potassium naphthalene, showing that neither the molecular weight of the initiator nor the viscosity of the reaction medium were the governing factors. This suggested that the lower rates obtained by using the carbohydrate alkoxides as initiators were connected with the heterogeneity of these reaction systems, the polymeric alkoxide being insoluble in DMSO. The systematic study carried out on the homopolymerization by potassium naphthalene in DMSO showed that the effective initiator was dimsyl anion obtained by interaction of potassium naphthalene with DMSO. The reaction was bimolecular, being first order to monomer and to initiator. The molecular weights increased with increasing monomer concentration and decreasing catalyst concentration, in accordance with a “living” polymerization system. |
