One-pot strategy for preparation of photo- and chemo-cleavable polystyrene containing o-nitrobenzyl ester moieties

A new strategy have been developed for preparation of photo- and chemo-cleavable polystyrene by incorporating o-nitrobenzyl ester moiety as a photosensitive linking unit into the main chain of the polymer. The strategy is based on the highly efficient esterification reaction of dicarboxylic acid, 4,4′-azobis(4-cyanovaleric acid), with organic dihalide, 2-nitro-1,3-phenylene bis(methylene-2-chloroacetate) and free radical polymerization of styrene. Multiblock polystyrenes were successfully synthesized by a combination of the esterification reaction and the radical polymerization of styrene by one-pot approach. Moreover, the photocleavage behavior of the multiblock PS in THF solution and in solid state was examined under UV irradiation at room temperature in air atmosphere. The results demonstrated that the multiblock polystyrenes could be cleaved into separate PS blocks not only by UV light, but also by hydrolysis of the ester groups. In addition, the incorporation of o-nitrobenzyl units into the backbone of PS has no obvious influence on the thermal stability.