Simultaneously achieving high strength, thermal resistance and high self-healing efficiency for polyacrylate coating by constructing a Diels–Alder reversible covalent structure with multi-maleimide terminated hyperbranched polysiloxane

It is difficult for the self-healing polyacrylate coatings reported so far to simultaneously achieve high mechanical strength and high self-healing efficiency within a short healing time. Herein, derived from multi-maleimide terminated hyperbranched polysiloxane, linear polyacrylate with furan-containing side chain and polydopamine particles (photothermal conversion agent), a new kind of polyacrylate coating (HPA) with a strong and flexible crosslinking network was developed, which simultaneously shows high mechanical strength and high self-healing efficiency within a short time. With 0.3 wt% polydopamine particles in HPA, the resulting coating (HPA3) has the highest toughness (2.63 ± 0.10 MPa) with 12.9 ± 0.7 MPa tensile strength and 23.9% ± 1.6% elongation at break; in addition, the self-healing efficiency of HPA3 is over 87.6% after only 2.5 min of near-infrared laser irradiation, overcoming intractable problems in developing self-healing polyacrylate coatings. A study of the mechanism behind these outstanding performances of the HPA system reveals that the reversible covalent crosslinking formed by multi-maleimide terminated hyperbranched polysiloxane is the necessary and crucial factor for simultaneously achieving high mechanical strength and high self-healing efficiency in a short time. © 2019 Society of Chemical Industry