Vitrimer-like Polyampholyte Networks: Toward Elevated Creep Resistance and Fast Dynamic Exchanges

Vitrimers represent dynamic polymer networks with unique viscoelastic behavior, combining the best attributes of thermosets and thermoplastics. In this work, we report the concept of polyampholyte physical networks that go far beyond the merits of vitrimer-like materials by combining elevated creep resistance and fast dynamic exchanges. By contrast with most vitrimeric systems requiring out-of-stoichiometric approaches or external catalysts, we simply design polyampholyte physical networks of charge-balanced ionic methacrylates via free radical copolymerization combining poly(ethylene glycol) methyl ether methacrylate (PEGMA). The high ion concentration (i.e., from 33 to 67 mol %) enabled the formation of a physical network containing ionic cross-links acting as both sacrificial and permanent bonds mitigated by the presence of neutral PEGMA. In addition to their vitrimer-like behavior demonstrated using thermomechanical and rheological tools, these physical networks show exceptionally short relaxation times and high creep resistance. Conceptually, these polyampholyte physical networks due to extensive dynamic ion exchange open the door to more circular vitrimer-like systems toward more sustainable plastic materials.