Beyond the polyo l: valorization of the derivatized isocyanate fraction after chemical recycling of polyurethane

Abstract

This review is the first to address the fate of the isocyanate-derived fraction resulting from polyurethane (PU) chemical recycling. While most literature focuses on polyol recovery, this work highlights valorization strategies for the underexplored isocyanate-derived fraction obtained via glycolysis, aminolysis, phospholorysis, alcoholysis, etc. While many valorization routes face technical or economic barriers, several show industrial promise. Pathways such as poly(urethane-urea) synthesis via hindered urea bonds, alkoxylation to rigid polyols, and thermolysis of carbamates offer circularity and energy efficiency, though safety and regulatory constraints, limit scalability. Other routes, including epoxy curing and polyamide synthesis, balance recyclability, cost, and complexity. A case-specific evaluation remains essential to identify viable strategies for sustainable PU valorization.