Waterborne dispersion-processed self-healing elastomers with hydrogen-bond locked hydrophobic microdomains for multifunctional applications†

Abstract

The integration of self-healing properties into waterborne polyurethane (WPU) represents a significant advancement in materials chemistry. However, the practical application of self-healing WPU is often hindered by its compromised toughness, flexibility, and water resistance, as well as the challenges accompanied by complex production processes and high manufacturing costs. In this study, we propose a novel network optimization strategy that leverages the synergistic effects of multiple lateral hydrogen bonds from amide (A)–urea (U) motifs, hydrophobic aggregation of non-crystalline flexible alkyl segments, branched topology, and intrinsic intermolecular interactions within WPU. This strategy is implemented through a straightforward, stepwise chain extension synthesis of WPU, incorporating a biomass-derived chain extender (CA) designed from the condensation of cost-effective dimer acid and pentylenediamine. Remarkably, the optimized WPU exhibited bio-elastic tissue-like properties, including self-healing capability, high strength, toughness, ductility, low modulus and minimal water absorption. The self-healed material, derived from recycled film fragments, achieves an ultimate tensile strength of 41.4 MPa and an elongation at break of 1040%, with no significant stiffening or loss of elasticity. Additionally, the material demonstrated excellent interfacial adhesion, conductivity and strain sensitivity, making it suitable for use as a conductive elastomer. Furthermore, when plasticized with electrolytes, the material exhibited room-temperature self-healing within the conductive network, providing broad potential for applications in flexible electronics and related fields.