Mussel-inspired, self-healing polymer blends

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. Multiple adhesive proteins of mussels inspire to form polymer blends via solution polymerization. These blends are self-healable though the matrix of polyurethane contains no catechols, implying the essential roles of catechols in the dispersed phase (i.e., polydopamine methacrylamide) in rendering mendability. [Display omitted] •Poly(dopamine methacrylamide)/polyurethane blends were formed via solution polymerization.•These PDMA/PU blends achieve superior self-healability even though the matrix contains no catechol groups.•Self-healing is dominantly determined by the availability of PDMA rather than by mechanical properties.