Enzymatic degradation of polyurethane-based coatings

In order to develop a potentially environmentally safe alternative to conventional paint removal methods we are investigating the enzymatic degradation of liquid polyurethane-based coatings and their films. A simple protocol for degradation has been developed using aqueous buffer solutions at 37°C and an optimum pH. Two enzymes were selected, namely am esterase from Bacillus sp. and a protease (papain) that could potentially attack ester and urethane linkages. The extent of degradation was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and weight loss. Results indicate higher activity for the papain enzyme depending on the type of paint, enzyme concentration and conditions of application.