Covalent Adaptable Networks with Mobile Cross‐linking Points

Abstract

Abstract Covalent adaptable networks (CANs) have garnered increasing attention for their potential in sustainable materials. However, their material properties remain limited by interrelated challenges, particularly the need to ensure ease of processing while maintaining excellent mechanical performance. Herein, we report a class of polyrotaxane‐based CANs ( PR CANs) in which an axle containing dynamic boronic ester bonds is mechanically interlocked with two polymer chains, forming mobile dynamic cross‐linking points. The mobile dynamic covalent bond cross‐linking points simultaneously improve the mechanical performance of CANs while reducing the processing temperature. Under applied force, sliding occurs at both ends of the cross‐linking points, creating an efficient pathway for energy dissipation. The representative PR CAN exhibits enhanced mechanical performance, showing twice the elongation at break (1160 % versus 570 %) and tensile strength (11.0 versus 4.6 MPa), and over four times the toughness (43.7 versus 10.1 MJ m −3 ) relative to the control with fixed dynamic covalent bond cross‐linking points. At high temperatures, the mobility of the cross‐linking points enhances the reaction probability for dynamic covalent bonds, thereby effectively reducing the processing temperature of CANs. The representative PR CAN can be processed at 110 °C for 10 min, whereas the control sample requires 140 °C for 30 min to reach a comparable reprocessing level.