Concise and Efficient Self-Healing Cross-Linked Polyurethanes via the Blocking/Deblocking Reaction of Oxime Urethanes

Abstract

The development of self-healing polymers can extend the service life of polymer materials. However, it is still a challenge to prepare a polyurethane with high healing efficiency and maximum retention of the properties of polyurethane itself. In this research, we proposed a new scheme for the industrial production of self-healing polyurethane and successfully synthesized a self-healing polyurethane using diacetyl oxime as the chain extender and triethanolamine as the cross-linking agent. Oxime-blocked isocyanates deblock at a higher temperature and regenerate oxime urethanes at a lower temperature, thereby achieving thermal reversibility and self-healing due to the concise and efficient thermal reversible reaction of oxime urethanes. Fourier transform infrared and differential scanning calorimetry experiments confirmed that the oxime urethanes in the polyurethane deblock efficiently at around 90 degrees C and re-block after the temperature is lowered. The process can be cycled at least three times. Microscopic observation confirmed that the cracks disappeared within 60-90 min at 90 degrees C. The tensile test shows that the synthetic DiO-c-PU has a self-healing efficiency of over 94% at 90 degrees C for 1.5 h, which is more efficient. From the results, it appears that DiO-c-PU has good self-healing properties.