Solving the plastic dilemma: the fungal and bacterial biodegradability of polyurethanes

Polyurethane (PU) is a plastic polymer which, due to its various desirable characteristics, has been applied extensively in domestic, industrial and medical fields for the past 50 years. Subsequently, an increasing amount of PU waste is generated annually. PU, like many other plastics, is highly resistant to degradation and is a substantial threat to our environment. Currently PU wastes are handled through conventional disposal techniques such as landfill, incineration and recycling. Due to the many drawbacks of these techniques, a 'greener' alternative is necessary, and biodegradation appears to be the most promising option. Biodegradation has the potential to completely mineralise plastic waste or recover the input materials and better enable recycling. There are hurdles to overcome however, primarily the efficiency of the process and the presence of waste plastics with inherently different chemical structures. This review will focus on polyurethanes and their biodegradation, outlining the difficulty of degrading different versions of the same material and strategies for achieving more efficient biodegradation.