Mechanically strong, soft yet tough, tear-resistant and room-temperature healable elastomers via dynamic biphasic hard segment strategy for flame retardant application

Due to the inherent weak molecular chain migration ability of hard polymer materials, leads to their inability to recover after damage. Hence, a novel approach as the “dynamic biphasic hard segment” strategy is proposed. This strategy involves introducing hard segments with both hard and soft phase structures into the molecular chain to balance high mechanical strength with self-healing properties. The essential features of dynamic biphasic hard segments include: (Ⅰ) asymmetric continuous loose structure, (Ⅱ) controllable binding energy strength, (III) sequential dissociation and recombination of multiple hydrogen bonds. To synthesize supramolecular polyurethane elastomers (PUMI-A3D7) based on this dynamic biphasic hard segment strategy. PUMI-A3D7 exhibits high mechanical strength, toughness, notch insensitivity and room temperature self-healing ability. Specifically, the mechanical tensile strength of PUMI-A3D7 is 26.59 MPa, and 96.54% of its original mechanical properties can be restored within 24 h after a fracture. Using the superior properties of PUMI-A3D7 as the matrix, a flexible room temperature repairable flame-retardant composite (PUMI-A3D7/Al(OH)3/GP) is developed. PUMI-A3D7/Al(OH)3/GP possesses both room temperature self-healing function and flame-retardant properties. Notably, few studies have been conducted on repairable flexible flame-retardant materials. The combination of self-healing and flame-retardant properties provides valuable guidance for the development of multi-functional materials in the future.