Controllable Photo-degradability on Polyurethane from AB-Type Monomers

A new photodegradable AB-type monomer (3-nitro,4-hydroxylmethyl benzoylazide) was developed for the synthesis of polyurethanes featuring a photodegradability, which could be finely controlled through copolymerization. Because of the o-nitrobenzyl alcohol framework on the monomer, the resulting polymer was decomposed by UV irradiation at 365 nm. Moreover, since the introduction of a nitro group on the AB-type monomer framework reduced the reactivity of the alcohol group and increased that of the isocyanate group, copolymerization with other monomers induced a certain preference of diad patterns, which would affect the photodegradability of polyurethanes. The results suggested the AB-type monomer protocol enables the synthesis of more precisely designed polyurethane structures than the conventional synthesis, i.e., by a polyaddition between diol and di-isocyanate.