Editing Polyurethane (section)

===Hydrolysis and biodegradation===
Polyurethanes may degrade due to [[hydrolysis]]. This is a common problem with shoes left in a closet, and reacting with moisture in the air.<ref>{{cite web |title=Hydrolysis, The Crumbling of Shoe Soles explained {{!}} Safety Shoes and Gloves |url=https://www.safetyjogger.com/en/academy/hydrolysis-crumbling-shoe-soles-explained |website=www.safetyjogger.com}}</ref>

Microbial degradation of polyurethane is believed to be due to the action of [[esterase]], [[urethanase]], [[hydrolase]] and [[protease]] enzymes.<ref>{{cite journal |last1=Toward 
|first1=Gary T. |title=Biodegradation of polyurethane: a review |journal=International Biodeterioration & Biodegradation |date=June 2002 |volume=49 |issue=4 |pages=245–252 |doi=10.1016/S0964-8305(02)00051-3|bibcode=2002IBiBi..49..245H }}</ref> The process is slow as most microbes have difficulty moving beyond the surface of the polymer. Susceptibility to fungi is higher due to their release of [[fungal extracellular enzyme activity|extracellular enzymes]], which are better able to permeate the polymer matrix. Two species of the Ecuadorian fungus ''[[Pestalotiopsis]]'' are capable of biodegrading polyurethane in aerobic and anaerobic conditions such as found at the bottom of [[landfill]]s.<ref>{{cite journal |doi=10.1128/AEM.00521-11 |pmid=21764951 |pmc=3165411 |title=Biodegradation of Polyester Polyurethane by Endophytic Fungi |journal=Applied and Environmental Microbiology |volume=77 |issue=17 |pages=6076–84 |year=2011 |last1=Russell |first1=J. R. |last2=Huang |first2=J. |last3=Anand |first3=P. |last4=Kucera |first4=K. |last5=Sandoval |first5=A. G. |last6=Dantzler |first6=K. W. |last7=Hickman |first7=D. |last8=Jee |first8=J. |last9=Kimovec |first9=F. M. |last10=Koppstein |first10=D. |last11=Marks |first11=D. H. |last12=Mittermiller |first12=P. A. |last13=Nunez |first13=S. J. |last14=Santiago |first14=M. |last15=Townes |first15=M. A. |last16=Vishnevetsky |first16=M. |last17=Williams |first17=N. E. |last18=Vargas |first18=M. P. N. |last19=Boulanger |first19=L.-A. |last20=Bascom-Slack |first20=C. |last21=Strobel |first21=S. A. |bibcode=2011ApEnM..77.6076R }}</ref><ref>{{Cite web|last=|first=|date=2021-04-14|title=Could Plastic-Eating Mushrooms Solve mankind's Plastic Problem?|url=https://sciencemint.com/could-plastic-eating-mushrooms-solve-mankinds-plastic-problem/|access-date=2021-07-02|website=Sciencemint|language=en-US|archive-date=2021-07-09|archive-url=https://web.archive.org/web/20210709182652/https://sciencemint.com/could-plastic-eating-mushrooms-solve-mankinds-plastic-problem/|url-status=dead}}</ref> Degradation of polyurethane items at museums has been reported.<ref>{{cite journal |doi=10.1128/AEM.01768-07 |pmid=18065627 |pmc=2227722 |title=Microorganisms Attack Synthetic Polymers in Items Representing Our Cultural Heritage |journal=Applied and Environmental Microbiology |volume=74 |issue=3 |pages=564–9 |year=2007 |last1=Cappitelli |first1=F. |last2=Sorlini |first2=C. |bibcode=2008ApEnM..74..564C }}</ref> Polyester-type polyurethanes are more easily biodegraded by fungus than polyether-type.<ref>{{cite journal |doi=10.3390/ijms10093722 |pmid=19865515 |pmc=2769161 |title=Biodegradability of Plastics |journal=International Journal of Molecular Sciences |volume=10 |issue=9 |pages=3722–42 |year=2009 |last1=Tokiwa |first1=Yutaka |last2=Calabia |first2=Buenaventurada P. |last3=Ugwu |first3=Charles U. |last4=Aiba |first4=Seiichi |doi-access=free }}</ref>