PHOTO-INDUCED GRAFT POLYMERIZATION OF METHYL METHACRYLATE ONTO 2, 3-DICARBOXY CELLULOSE

The photo-induced graft polymerization of methyl methacrylate onto 2, 3-dicarboxy cellulose was carried out in aqueous systems using a quartz and a pyrex tube. The total conversion and the degree of grafting increase with an increase of the carboxyl group content in the cellulose, and reached a levelling-off value at approximately 10 mmol carboxyl group. Grafting efficiency was 90-95%. When the cellulose was treated with sodium borohydride, the degree of grafting and the apparent numbers of grafted chains decreased. The degree of grafting and the molecular weight of grafted chains increased with increasing monomer concentration. The apparent activation energy of graft polymerization onto the celluloses with the carboxyl group contents of 6.8, 18.1 and 55.0 mmol/100g sample were 11.4, 7.3 and 1.1 kcal/mol, respectively.From these results, it is considered that the graft polymerization proceeds mainly via the photolysis of carboxyl groups in the cellulose by the light with the wavelength above 300 nm. On irradiation with the light with the wave length above 253 nm, however, grafting onto the end group, due to the chain scission of the cellulose molecules, concurrently occurred. Termination proceeded by the coupling between the growing polymer radical and cellulose radical, and was accelerated by raising the temperature of the reaction and by irradiation with the light of 253 nm.