Energy transfer and photoactivity of photozymes included in polyacrylate hydrogels

Two photozymes poly(vinylnaphthalene/sodium styrenesulfonate) (PZ1) and poly(vinylnaphthalene/sodium styrenesulfonate/N,N'-dimethyl methacryloyloxyethyl propanesulfonate) (PZ2) were synthesized and used for the modification of hydrogels. The hydrogels were composed of acrylamide and 2-acrylamido-2- methylpropanesulfonic acid monomers, and modified with sodium bentonite (NB). The fluorescence properties and photoactivity of the photozymes were examined. Both photozymes demonstrated high self-assembly in both aqueous solutions and hydrogel matrices, which is of great importance for the antenna effect. For the NB-reinforced hydrogel, strong energy transfer from the excited chromophores to the NB was observed and assigned to the high surface conductivity of clay. PZ2 exhibited higher photocatalytic activity for the methylene blue (MB) photodegradation than PZ1. This is most likely due to the better self-assembly and thus enhanced antenna effect of the zwitterionic PZ2. MB a bsorbed by the hydrogel from aqueous solution was efficiently decomposed in a photozyme-catalyzed photochemical process.