Mismatched Supramolecular Interactions Facilitate the Reprocessing of Super-Strong and Ultra-Tough Thermoset Elastomers.

Thermoset elastomers have been extensively applied in many fields because of their excellent mechanical strengths and durable characteristics, such as an excellent chemical resistance. However, in the context of environmental issues, the non-recyclability of thermosets has become a major barrier to the further development of these materials. Here, we report a well-tailored strategy to solve this problem by introducing mismatched supramolecular interactions (MMSIs) into a covalently cross-linked poly(urethane-urea) network with dynamic acylsemicarbazide moieties. The MMSIs significantly strengthen and toughen the thermoset elastomer by effectively dissipating energy and resisting external stress. In addition, the elastomer recycling efficiency is improved 2.7-fold due to the superior reversibility of the MMSIs. The optimized thermoset elastomer, i.e., SPUUN-IE, features outstanding characteristics, including an ultra-high tensile strength (110.8 MPa), an unprecedented tensile toughness (1245.2 MJ m -3 ), as well as remarkable resistance to chemical media, creep, and damage. Most importantly, SPUUN-IE exhibits an extraordinary multi-recyclability, and the 4 th recycling efficiency remains close to 100%. This scalable method promotes the development of thermosets with both high performance and excellent recyclability, thereby providing valuable guidance for addressing the issue of non-recyclability from a molecular design standpoint. This article is protected by copyright. All rights reserved.