Methyl ketone‐photosensitized polymerization of N‐methylolacrylamide with cotton

Photoinitiated, free‐radical reactions of cotton cellulose with N‐methylolacrylamide (NMA) from aqueous solution through direct excitation of cellulose are reported. Also reactions initiated by energy transfer from excited methyl ketone compounds to cellulose are reported. Dimethyl ketone, dimethyl ketoneformaldehyde, dimethyl diketone, dimethyl diketoneformaldehyde, methyl ethyl ketoneformaldehyde, and methyl phenyl ketoneformaldehyde were used in the sensitized reactions. When methyl ketone products were in solution during photoirradiation, they acted as sensitizers to increase the rate and extent of the reaction of NMA with cotton cellulose. When products that contained formaldehyde were covalently reacted with cotton before photoirradiation, the rate and extent of the reaction of NMA with cellulose were generally decreased. These effects can be at least partially explained by intramolecular energy transfer, as determined by chemiluminescence, electron spin resonance, and excitation fluorescence measurements. When methyl phenyl ketoneformaldehyde was covalently linked to cellulose before photoirradiation, energy localization that initiated free‐radical polymerization of NMA was minimized. When cellulose that was padded with a monomer solution was dried before photoirradiation, the extent of the reaction of NMA with cellulose was decreased.