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This study employed alkaline hydrolysis to recover the degradation products of clear aligners. The aligners were subjected to hydrolysis under various reaction conditions, including different concentrations of sodium hydroxide (NaOH), temperature, reaction time, ethanol\u2010to\u2010water mass ratio, and stirring rate. After the reaction, the organic components were isolated using thin\u2010layer chromatography (TLC) plates, and their structure was characterized by <jats:sup>1<\/jats:sup>H\u2010NMR spectroscopy and mass spectrometry. The degradation product was identified as 4,4\u2032\u2010methylenedianiline (MDA). The optimal reaction conditions for achieving the maximum degradation yield of MDA were determined to be stirring at 300\u00a0rpm at 130\u00b0C in a solution containing 5\u00a0wt% NaOH and a 1:1 mass ratio of ethanol to water for 24\u00a0h. This method demonstrates that clear aligners can be effectively recycled through alkaline hydrolysis, supporting global efforts to reduce environmental emissions.<\/jats:p>","DOI":"10.1111\/eos.70010","type":"journal-article","created":{"date-parts":[[2025,4,17]],"date-time":"2025-04-17T01:07:17Z","timestamp":1744852037000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Application and optimization of alkaline hydrolysis in recycling clear aligners"],"prefix":"10.1111","volume":"133","author":[{"ORCID":"https:\/\/orcid.org\/0009-0004-3867-1210","authenticated-orcid":false,"given":"Chenkai","family":"Lan","sequence":"first","affiliation":[{"name":"Center of Stomatology The Affiliated Hospital of Hangzhou Normal University  Hangzhou China"},{"name":"Center of Stomatology Hangzhou Normal University  Hangzhou China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0003-3599-7672","authenticated-orcid":false,"given":"Wubin","family":"Ouyang","sequence":"additional","affiliation":[{"name":"Center of Stomatology The Affiliated Hospital of Hangzhou Normal University  Hangzhou China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0001-3687-5007","authenticated-orcid":false,"given":"Heqian","family":"Wang","sequence":"additional","affiliation":[{"name":"Xinhua Hospital of Tongzhou District  Beijing China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7911-8268","authenticated-orcid":false,"given":"Jingjing","family":"Yan","sequence":"additional","affiliation":[{"name":"Center of Stomatology The Affiliated Hospital of Hangzhou Normal University  Hangzhou China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0004-2844-1841","authenticated-orcid":false,"given":"Shu","family":"Ouyang","sequence":"additional","affiliation":[{"name":"Center of Stomatology The Affiliated Hospital of Hangzhou Normal University  Hangzhou China"},{"name":"Center of Stomatology Hangzhou Normal University  Hangzhou China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-9746-6221","authenticated-orcid":false,"given":"Xiaoxuan","family":"Xu","sequence":"additional","affiliation":[{"name":"Center of Stomatology The Affiliated Hospital of Hangzhou Normal University  Hangzhou China"},{"name":"Center of Stomatology Hangzhou Normal University  Hangzhou China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-2305-4718","authenticated-orcid":false,"given":"Frank","family":"Keko","sequence":"additional","affiliation":[{"name":"Guangzhou Fan Yu Medical Technology Company Limited  Guangzhou China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8734-3003","authenticated-orcid":false,"given":"Jian","family":"Zhang","sequence":"additional","affiliation":[{"name":"College of Material Chemistry and Chemical Engineering of Hangzhou Normal University  Hangzhou China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4280-4042","authenticated-orcid":false,"given":"Dalei","family":"Sun","sequence":"additional","affiliation":[{"name":"Center of Stomatology The Affiliated Hospital of Hangzhou Normal University  Hangzhou China"},{"name":"Center of Stomatology Hangzhou Normal University  Hangzhou China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2025,4,16]]},"reference":[{"key":"e_1_2_8_2_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.bioactmat.2022.10.006"},{"key":"e_1_2_8_3_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.scitotenv.2022.161356"},{"key":"e_1_2_8_4_1","doi-asserted-by":"publisher","DOI":"10.3233\/BME-191065"},{"key":"e_1_2_8_5_1","unstructured":"ALIGNERCO.What's the environmental impact of clear aligner manufacture use & disposal?ALIGNERCO. 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