Design, synthesis, and photodegradation of silicon-containing polyureas

Novel N-phenyl aromatic polyureas containing bis(N,N'-diphenylureylene)methyl]silane units in the skeleton were designed as a new type of photodegradable polymer. These materials were successfully prepared in 88-93 % yields by copolymerization of bis(anilinomethyl)dimethylsilane and dianilino-p-xylene with 4,4'-methylenebis(phenylisocyanate). Their photodegradability was found to be 10.1 times higher than that of polymers of similar structure, but lacking the silyl unit. Furthermore, the photodegradation mechanism of polyureas was elucidated, and involves single-electron transfer between silyl and carbonyl groups, silyl group migration, and solvolysis. These novel polymers are potential materials of high economic value for use in photolithography and microelectronics.