Endgroups in poly (methyl methacrylate) initiated by photosensitized ferric salts in aqueous media

Abstract

Photosensitized ferric salts (ferric chloride, as well as bromide and perchlorate) have been used as initiators of aqueous polymerization of methyl methacrylate under varied conditions. Analysis of endgroups in the resulting polymers have been made by the application of dye techniques. Both hydroxyl and halogen endgroups have been traced in the polymers in varying proportions except in case of perchlorate where only hydroxyl endgroups have been detected. Some of the results are in sharp contrast with those reported by Evans et al. While increasing concentration of both ferric chloride and bromide was associated with a sharp fall in the total endgroup content of the polymers, ferric perchlorate did not show such effect. Specific action of some anions derived from additives such as salts and acids on the total endgroup content of the polymer was also investigated. Total endgroup content of the polymer decreased appreciably when a halide or a halogen acid was used in the polymerization medium, the effect of bromide being more predominant than the chloride. No such effect was observed in the case of potassium perchlorate, perchloric acid, and potassium sulfate as the additive. An explanation has been suggested for such specific action of anions.