Thermally Processable Adhesive Aerogel Capsules

Aerogels are renowned for their ultralow density and superior thermal insulation. However, the poor adhesion of traditional aerogels, arising from their porous surfaces and rigid frameworks, presents a significant challenge for integration into functional systems. Inspired by the core-shell architecture of expanded thermoplastic polyurethane (ETPU) beads, which feature a thermoplastic shell enabling thermally activated adhesion and a resilient core ensuring mechanical recovery, we developed self-assembled adhesive aerogel capsules (SAACs). SAACs emulate this decoupling strategy with a porous chitosan/silica aerogel (CTS/SA) core preserving the thermal insulation, while an adhesive chitosan/carboxylated nitrile rubber (CTS/XNBR) shell enables adhesion. Through electrostatically-based self-assembly and freeze-drying, negatively charged XNBR encapsulates a positively charged CTS/SA scaffold, forming a core-shell structure. SAACs can be thermally processed at mild temperatures (≤ 80°C) to adhere into 3D assemblies, conform to irregular shapes, and adhere to diverse substrates. Despite their adhesive capability, SAACs retain low density, low thermal conductivity (30-39 mW·m^-1·K^-1), and inherent flame retardancy. Unlike conventional aerogels or ETPU, SAACs combine the thermal processability of elastomers with the insulation and fire resistance of aerogels, offering a promising platform for applications in on-site thermal management, energy conservation, and fire protection.