Tunable Waterborne Aspartic Acid-Based Covalent Adaptable Networks with Internal Catalysis and Incorporation in Bioinspired Nanocomposites

Waterborne resins are important for coatings and adhesives, yet the field of reprocessable covalent adaptable networks (CANs) is dominated by hydrophobic materials. Here, we introduce waterborne CANs that feature dual internal catalysis, dissociative bond exchange, and customizable properties through specific selection of different cross-linkers. The system uses random copolymers based on aspartic acid, which can catalyze formation and exchange of dynamic covalent ester bonds. Cross-linker variation enables vast differences in thermoresponsive properties: diols with a tertiary amine feature the fastest bond exchange and stress relaxation and enable ductile mechanical behavior in ambient conditions. Amine-containing triols instead lead to high nonelastic deformation resistance, linked to, e.g., creep, by slowing stress relaxation until high temperatures. Aliphatic diols exhibit low exchange kinetics while affording glassy mechanical behavior. Our CAN-prepolymer/cross-linker systems offer great potential for aqueous applications due to their good recyclability and excellent tunability, as further demonstrated by their incorporation in waterborne bioinspired nanocomposites.