Weldable and closed-loop recyclable monolithic dynamic covalent polymer aerogels

Owing to their low density, high porosity and unique micro-nanostructures, aerogels are attractive for application in various fields; however, they suffer from shrinkage and/or cracking during preparation, mechanical brittleness, low production efficiency and non-degradation. Herein, we introduce the concept of dynamic covalent polymer chemistry to produce a new class of aerogels-referred to as DCPAs. The resulting lightweight DCPAs have the potential to be prepared on a large scale and feature high porosity (90.7%-91.3%), large degrees of compression (80% strain) and bending (diametral deflection of 30 mm) without any cracks, as well as considerable tensile properties (an elongation with a break at 32.7%). In addition, the DCPAs showcase the emergent characteristics of weldability, repairability, degradability and closed-loop recyclability that are highly desirable for providing versatile material platforms, though hardly achieved by traditional aerogels. Taking advantage of their robust porous structures, we demonstrate the potential of DCPAs for applications in thermal insulation and emulsion separation. These findings reveal that the dynamic covalent bond strategy would be generalized for the production of a new generation of aerogels with customized features for functioning in the field of intelligent and sustainable materials.