Preliminary study on the biodegradation of adipate/phthalate polyester polyurethanes of commercial-type by Alicycliphilus sp BQ8

Accumulation of polyurethane (PU) waste has increased considerably due to its extensive use. Even though many efforts are being carried out to develop more biodegradable PU, the use of these new materials is far from being commercially available. Here, we analyzed the susceptibility of solid polyester polyurethanes (PS-PU) of commercial-type, to biodegradation by Alicycliphilus sp. BQ8, a polyurethanolytic bacterial strain. Four polyester polyols were synthesized from dipropylene glycol (DPG) or diethylene glycol (DEG), and adipic acid (ADA) or phthalic anhydride (PHA), and were combined with either 4,4- and 4,2-methylene diphenyldiisocyanate (MDI) or 2,4- and 2,6-toluene diisocyanate (TDI). Synthesized polyols and PUs were characterized. PU biodegradation was assessed by the capacity of the polymers to support bacterial growth, and by scanning electron microscopy (SEM), Fourier transformed infrared (FTIR) spectroscopy, and gas chromatography/mass spectrometry (GC-MS) analyses. Although all the synthesized PUs supported BQ8 growth, SEM analysis showed that PHA-based PU foams were the most affected by bacterial growth. FTIR spectroscopy and GC-MS analyses of bacterial treated PS-PUs showed that they were attacked at ester and urethane groups, suggesting that esterase and amidase activities are involved. Extra-cellular and membrane bound esterase activities were detected during the five days of analysis. Our results suggest that solid PHA-based PUs might be more susceptible than ADA-based PUs to microbial biodegradation in the environment. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42992.