Figure 48 Proposed Photochromic Mechanism of E-FBOXEs.
The fast development of self-healing materials based on supramolecular interactions has attracted considerable attention in recent years,[173-179] among the supramolecular interactions, ionic interactions are very interesting because of their high aggregation strength that results in low healing agent content for self-healing materials.[180] However, most of self-healing materials based on ionic interactions are all thermocured materials.
Based on the above background, Sun et al.[181]designed and synthesized a novel imidazolium-containing photocurable monomer, 6-(3-(3(2-hydroxyethyl)-1H-imidazol-3-ium bromide) propanoyloxy) hexyl acrylate (IM-A), based on 1,6-hexanediol diacrylate (HDDA) and 1H-imidazole and 2-bromoethanol, the synthesis route of IM-A is displayed in Figure 49. Then, the self-healing flexible materials was prepared by fast photocuring with IM-A, isobornyl acrylate (IBOA), 2-(2-ethoxyethoxy) ethyl acrylate (EOEOEA), and 2-hydroxyethyl acrylate (HEA). Herein, IM-A-containing imidazolium plays a self-healing role in the materials. The self-healing process of the photocured polymer contained IM-A is exhibited in Figure 50. The as-prepared self-healing polymer IB7-IM5 exhibited a tensile strength of 3.1 MPa, elongation at break of 205%, healing efficiency of 93%, and a wide healing temperature range from room temperature to 120 °C. The self-healing polymer was also employed as a flexible substrate to fabricate a flexible electronic device, which could be healed and completely restore its conductivity after the device was damaged.