Editing Polyurethane (section)

{{short description|Polymer composed of a chain of organic units joined by carbamate (urethane) links}}
[[File:Polyurethane synthesis.svg|class=skin-invert-image|thumb|right|Polyurethane synthesis, wherein the urethane groups −NH−(C=O)−O− link the molecular units]]
[[File:Urethane sponge1.jpg|thumb|A kitchen sponge made of polyurethane foam]]

'''Polyurethane''' ({{IPAc-en|ˌ|p|ɒ|l|i|ˈ|jʊər|ə|ˌ|θ|eɪ|n|,_|-|j|ʊəˈr|ɛ|θ|eɪ|n}};<ref>{{cite Dictionary.com|polyurethane}}</ref> often abbreviated '''PUR''' and '''PU''') is a class of [[polymer]]s composed of [[organic chemistry|organic]] units joined by [[carbamate]] (urethane) links. In contrast to other common polymers such as [[polyethylene]] and [[polystyrene]], polyurethane term does not refer to the single type of polymer but a group of polymers. Unlike [[polyethylene]] and [[polystyrene]], polyurethanes can be produced from a wide range of starting materials resulting in various polymers within the same group. This chemical variety produces polyurethanes with different chemical structures leading to many [[List of polyurethane applications|different applications]]. These include rigid and flexible [[foam]]s, and coatings, adhesives, [[Potting (electronics)|electrical potting]] compounds, and fibers such as [[spandex]] and [[polyurethane laminate]] (PUL). Foams are the largest application accounting for 67% of all polyurethane produced in 2016.<ref>{{cite journal |last1=Gama |first1=Nuno |last2=Ferreira |first2=Artur |last3=Barros-Timmons |first3=Ana |title=Polyurethane Foams: Past, Present, and Future |journal=Materials |date=27 September 2018 |volume=11 |issue=10 |pages=1841 |doi=10.3390/ma11101841|pmid=30262722 |pmc=6213201 |bibcode=2018Mate...11.1841G |doi-access=free }}</ref>

A polyurethane is typically produced by reacting a polymeric [[isocyanate]] with a [[polyol]].<ref>{{Cite web |title=Polyurethane |url=https://www.americanchemistry.com/chemistry-in-america/chemistries/polyurethane |access-date=2022-09-19 |website=American Chemistry Council |language=en}}</ref> Since a polyurethane contains two types of monomers, which polymerize one after the other, they are classed as [[Copolymer#Alternating copolymers|alternating copolymers]]. Both the isocyanates and polyols used to make a polyurethane contain two or more [[functional group]]s per molecule.

Global production in 2019 was 25 million metric tonnes,<ref>{{cite web |title=Polyurethane global market volume 2015-2026 |url=https://www.statista.com/statistics/720341/global-polyurethane-market-size-forecast/ |website=Statista |access-date=23 July 2021 |language=en}}</ref> accounting for about 6% of all polymers produced in that year.