O'Dea Robert M, Nandi Mridula, Kroll Genevieve, Arnold Jackie R, Korley LaShanda T J, Epps Thomas H
Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, United States.
Center for Plastics Innovation, University of Delaware, Newark, Delaware 19716, United States.
JACS Au. 2024 Apr 11;4(4):1471-1479. doi: 10.1021/jacsau.4c00013. eCollection 2024 Apr 22.
We report a depolymerization strategy to nearly quantitatively regenerate isocyanates from thermoplastic and thermoset polyurethanes (PUs) and then resynthesize PUs using the recovered isocyanates. To date, chemical/advanced recycling of PUs has focused primarily on the recovery of polyols and diamines under comparatively harsh conditions ( high pressure and temperature), and the recovery of isocyanates has been difficult. Our approach leverages an organoboron Lewis acid to depolymerize PUs directly to isocyanates under mild conditions ( ∼80 °C in toluene) without the need for phosgene or other harsh reagents, and we show that both laboratory-synthesized and commercially sourced PUs can be depolymerized. Furthermore, we demonstrate the utility of the recovered isocyanate in the production of second-generation PUs with thermal properties and molecular weights similar to those of the virgin PUs. Overall, this route uniquely provides an opportunity for circularity in PU materials and can add significant value to end-of-life PU products.
我们报道了一种解聚策略，可从热塑性和热固性聚氨酯（PU）中近乎定量地再生异氰酸酯，然后使用回收的异氰酸酯重新合成PU。迄今为止，PU的化学/高级回收主要集中在相对苛刻的条件下（高压和高温）回收多元醇和二胺，而异氰酸酯的回收一直很困难。我们的方法利用有机硼路易斯酸在温和条件下（甲苯中约80°C）将PU直接解聚为异氰酸酯，无需光气或其他苛刻试剂，并且我们表明实验室合成的和商业来源的PU均可解聚。此外，我们证明了回收的异氰酸酯在生产具有与原始PU相似的热性能和分子量的第二代PU中的实用性。总体而言，此路线独特地为PU材料的循环利用提供了机会，并可为报废PU产品增加显著价值。
