Brisbane, Australia – A group of chemists led by Christopher Barner-Kowollik at Queensland University of Technology has developed a way of making polyurethanes that degrade under UV light. This was achieved by using a polyol derived from nitrobenzene.
Degradation of polyurethanes is usually difficult to achieve in an environmentally friendly way because of the strength of the urethane bond, allied to the high level of crosslinking.
Including a o-nitrobenzyl moiety in the polyol gives a PU that includes many photosensitive groups. When irradiated with UV light, the C–O bond joining it to the diisocyanate moiety undergoes heterolytic fission, breaking the polymeric structure.
The photolysis reaction was successfully performed both in solution and in thin films. The scientists suggest that polyurethanes with these properties may prove useful in adhesives and packaging.