biostudies-literatureDavis MDow Chemical CompanyNational Science Foundation2685-2693https://www.ebi.ac.uk/biostudies/studies/S-EPMC12690813biostudies-literatureUnknown17(5)Polyurethane (PU), the sixth most produced plastic globally, is widely used as flexible foam synthesized from polyol, isocyanate, and water to form a thermoset polymer containing urethane and urea bonds. Chemical recycling of PU foams (PUFs), such as acidolysis by carboxylic acids, offers a sustainable route to recover polyol, the predominant mass component. Although PUFs contain both urea and urethane linkages, previous studies have not distinguished their relative acidolysis rates. Here, we use benzoic acid and its electronic analogues to distinguish urea and urethane acidolysis rates by tracking depolymerization <i>via</i> gas evolution, GPC, and NMR. Results reveal biphasic kinetic behavior characterized by rapid urethane bond cleavage and slower urea acidolysis. We find that urethane Chemical scienceDifferentiating urethane and urea bond activation in polyurethane foam acidolysis.PMC12690813DMR 1720256Westman ZLetko CChristopher PStottlemyer ALHooshyar NAbu-Omar MMRichardson KVlcek VDavis MfalseDifferentiating urethane and urea bond activation in polyurethane foam acidolysis.Polyurethane (PU), the sixth most produced plastic globally, is widely used as flexible foam synthesized from polyol, isocyanate, and water to form a thermoset polymer containing urethane and urea bonds. Chemical recycling of PU foams (PUFs), such as acidolysis by carboxylic acids, offers a sustainable route to recover polyol, the predominant mass component. Although PUFs contain both urea and urethane linkages, previous studies have not distinguished their relative acidolysis rates. Here, we use benzoic acid and its electronic analogues to distinguish urea and urethane acidolysis rates by tracking depolymerization <i>via</i> gas evolution, GPC, and NMR. Results reveal biphasic kinetic behavior characterized by rapid urethane bond cleavage and slower urea acidolysis. We find that urethane 2026-01-01T00:00:00Z2026 Feb2026-06-12T10:15:07.708Z2026-06-12T03:12:19.852ZS-EPMC126908134138345510.1039/d5sc05599g