Dynamic β-Amino Sulfonamides for the Synthesis of Covalent Adaptable Networks

Thermosets are indispensable for their lightweight and excellent thermomechanical properties but suffer from nonrecyclability, exacerbating plastic pollution. Covalent Adaptable Networks (CANs), leveraging dynamic covalent bonds, address this challenge. This study explores β-amino sulfonamides (BASA) as novel dynamic and thermoreversible linkers for CANs. Compared to previously investigated β-amino amides (BAAs), small molecule BASA studies show a faster amine exchange reaction via (retro)aza-Michael reactions in a temperature window from 140 to 180 °C. More importantly, in contrast to the acrylamide monomers released from BAAs, the vinyl sulfonamide monomers released from BASAs are more robust and can resist homopolymerization at elevated temperatures. We showed that bisfunctional vinyl sulfonamide cross-linkers enable the synthesis of CANs with tunable properties, as verified through thermomechanical and rheological analysis. The anticipated increased thermal stability of BASA-based CANs was shown by the retention of mechanical and rheological performance over at least five recycling cycles.