Endowing Polyurethane with Degradability via a Cleavable Bis(cyclohexanone) Oxalyldihydrazone Structure for Adhesive Detachment

Abstract

Detachable and degradable polymeric adhesives have demonstrated considerable value and significance, accompanying the increasing demands for waste recycling and the ongoing concern for green and sustainable development. Herein, a chain extender containing the bis(cyclohexanone) oxalyldihydrazone structure was introduced into polyurethanes, which achieved efficient degradation in an alkaline environment with the M w decreasing from 41.9 to 4.9 kDa. The shear strength of the linear polyurethane between polycarbonate specimens reduced by 98.5%, and on a wide range of substrates, the shear strength of both linear and cross-linked polyurethanes reduced by more than 65.0% as a joint result of the base and cosolvent. These degradable polyurethanes with adhesion properties have exhibited great potential to be used in the separation of multilayer flexible packaging, electronics assembly, and battery pack recycling.