Solvent-free thermo-reversible and self-healable crosslinked polyurethane with dynamic covalent networks based on phenol-carbamate bonds

Abstract

Polyurethanes with dynamic covalent networks have the potential of self-healing, reprocessing and recycling, however, how to improve the efficiency of self-healing and reprocessing, and reduce the use of solvent and costs, are still problems to solve. In this work, we synthesized a cross-linked polyurethane containing dynamic phenol-carbamate bonds from low-cost raw materials without use of solvent. The dynamic polyurethane possesses excellent self-healing and reprocessing properties, which exhibits low relaxation activation energy (92.7 kJ/mol) and can be almost completely healed at 80 °C for 2 h. After remolded for 4 times, the material shows almost little change in mechanical properties. Further studies on the phenol-carbamate bonds give the quantitative reaction equilibrium constants, thermodynamic parameters and dissociation activation energy. In viewpoint of the dynamic properties and easy synthesis of phenol-carbamates, various types of cross-linked polymers containing such dynamic bonds can be further tailor designed.