Recyclable Polyurea-Urethane Thermosets with De-Crosslinking Capability in Acetic Acid

Covalent crosslinking points within thermosets generally result in excellent mechanical properties and solvent resistance yet lead to limited degradability and recyclability. Those thermosets become degradable or recyclable if crosslinking points are cleavable or reversible. Following this principle, we report a kind of polyurea-urethane thermoset with borate ester as its crosslinking point to enable a controllable de-crosslinking in response to acetate acid. Such a thermoset presents remarkable mechanical properties as well as outstanding solvent resistance capability, due to the high crosslinking density and intermolecular hydrogen bonding. Furthermore, the de-crosslinked product can be reporcessed to generate a brand new thermoplastic material.