Mussel-inspired, self-healing polymer blends

Abstract

Reversible dynamic covalent and noncovalent interactions are widely used to generate intrinsically self-healing polymers. However, nearly all approaches require sophisticated design and multi-stepped, tedious synthesis limited to weak hydrogels and rubbers, and pre-assume that high-modulus materials are more difficult to heal than low-modulus ones. Inspired by mussel foot proteins with the special amino acid unit of 3, 4-dihydroxy-l-phenylalanine, we develop a paradigm for achieving self-mendable polymer blends, composed of polyurethane (PU) as the matrix and poly(dopamine methacrylamide) (PDMA) as the dispersed phase. Healing efficiency increases from 24 to 32% for neat PU to 80–90% for the blends with increased moduli. This paradigm provides new insights into the role of mechanical properties in determining self-healing: high mechanical properties do not necessarily weaken self-repairability. The proof-of-concept enables easy modification of soft materials by solution mixing them with a polymer containing catechol groups, and thus opens up new applications in coatings, adhesives, antifouling, and biological engineering.