Synthesis and bacterial degradation of an azopolymer

Azopolymers were synthesised with differing degrees of hydrophobicity, from 2-hydroxyethylmethacrylate (HEMA), styrene and 2,2'-dimethylacryloyloxyazobenzene as azo crosslinker. Bacterial degradation of the series of polymers was assessed using a pure culture of the colonic organism Enterococcus faecalis and rat caecal contents. Polymer degradation was determined in terms of weight loss on polymer coated glass beads and using scanning electron microscopy after incubation. Similar weight loss occurred on incubation of polymers in both bacterial cultures and non-bacterial control. The presence of styrene was found to decrease the amount of weight loss. The polymer surfaces showed microscopic cracks and holes after incubation, again, this phenomenon was less pronounced with increasing styrene content. As there was no increase in polymer degradation in the presence of azo reducing microorganisms, the results of this study suggest that these polymers are degraded by mechanisms other than azo reduction.