Highly Self-Healable Polymeric Blend Synthesized Using Polymeric Glue with Outstanding Mechanical Properties

Abstract

A highly self-healable polymeric system with enhanced mechanical properties is prepared by blending conventional polyurethane (PU) with functional polyimide (PI). PU and PI synthesized in this study are miscible with each other and the thermal stability of the self-healable blend (PUPI) is improved by incorporation of PI into PU. Interestingly, on adding only a small amount of PI to PU, PUPI exhibits higher self-healing efficiency and faster self-healing kinetics. Furthermore, unlike conventional self-healing materials, PUPI also has superior surface and bulk mechanical properties. A model for the mechanism for the improvement of self-healing and mechanical properties is derived by analyzing FT-IR spectra. The outstanding self-healing and mechanical properties are attributed to the unique intermolecular networks resulting from the strong supramolecular interactions between urethane groups in PU and imide groups in PI. As a result, the PI chain acts as a polymeric glue inside the PU matrix of PUPI, which results in significant enhancements in both properties mentioned previously.