Depolymerizable polymers

{{short description|Polymeric materials that can be reverted to monomers}}

Depolymerizable polymers or Low-Ceiling Temperature Polymers refer to polymeric materials that can undergo depolymerization to revert the materials to their monomers at relatively low temperatures, such as room temperature. For example, the ceiling temperature T_c for formaldehyde is 119 °C, and that for acetaldehyde is -39 °C.{{Cite journal|title = Depolymerizable polymers: preparation, applications, and future outlook|journal = MRS Communications|date = 2015-01-01|issn = 2159-6867|pages = 191–204|volume = 5|issue = 2|doi = 10.1557/mrc.2015.28|first1 = Joshua A.|last1 = Kaitz|first2 = Olivia P.|last2 = Lee|first3 = Jeffrey S.|last3 = Moore}}

Unlike stable polymers such as PVCs that have high thermal stability, depolymerizable polymers and closely related self-immolative polymers can be triggered by stimuli to break fast under moderate to low temperatures.{{Cite journal|last1=Peterson|first1=Gregory I.|last2=Larsen|first2=Michael B.|last3=Boydston|first3=Andrew J.|date=2012-09-25|title=Controlled Depolymerization: Stimuli-Responsive Self-Immolative Polymers|url=https://pubs.acs.org/doi/10.1021/ma300817v|journal=Macromolecules|language=en|volume=45|issue=18|pages=7317–7328|doi=10.1021/ma300817v|issn=0024-9297}} The first type of polymers, poly (olefin sulfone), was reported by Snow and Frey in 1943.{{Cite journal|title = The Reaction of Sulfur Dioxide with Olefins: the Ceiling Temperature Phenomenon|journal = Journal of the American Chemical Society|date = 1943-12-01|issn = 0002-7863|pages = 2417–2418|volume = 65|issue = 12|doi = 10.1021/ja01252a052|first1 = R. D.|last1 = Snow|first2 = F. E.|last2 = Frey}} It was further confirmed and explained in terms of the thermodynamics of a reversible propagation step by Dainton and Ivin.{{Cite journal|title = Reversibility of the Propagation Reaction in Polymerization Processes and its Manifestation in the Phenomenon of a 'Ceiling Temperature'|journal = Nature|date = 1948-10-30|issn = 1476-4687|pages = 705–707|volume = 162|issue = 4122|first1 = F. S.|last1 = Dainton|first2 = K. J.|last2 = Ivin|doi = 10.1038/162705a0| s2cid=4105548 }} Closely related to depolymerizable polymers, self-immolative polymers can also irreversibly disassemble into their constituent parts in response to stimuli such as temperature, biological inputs or pH.{{Cite journal |last1=Roberts |first1=Derrick A. |last2=Pilgrim |first2=Ben S. |last3=Dell |first3=Tristan N. |last4=Stevens |first4=Molly M. |date=2020-04-08 |title=Dynamic pH responsivity of triazole-based self-immolative linkers |journal=Chemical Science |language=en |volume=11 |issue=14 |pages=3713–3718 |doi=10.1039/D0SC00532K |pmid=34094059 |pmc=8152797 |issn=2041-6539}}