Supramolecular polymer-based, ultra-robust, and nonfluorinated, sub-zero temperature self-healing superhydrophobic coatings for energy harvesting

In this study, ultra-robust, nonfluorinated, and sub-zero temperature self-healing superhydrophobic coatings are fabricated by spray-coating imine-bond crosslinked polydimethylsiloxane-based supramolecular polymers (I-PDMS) and SiO2 nanoparticles (NPs). Due to the synergy between I-PDMS binding and SiO2 NPs reinforcement, the resulting I-PDMS/SiO2 coatings can maintain their superhydrophobicity after sandpaper abrasion, sand impacting, hand tapping, and foot trampling and showed the best mechanical robustness among reported superhydrophobic coatings. Furthermore, due to the low glass-transition temperature of I-PDMS monomers and the dynamic nature of the imine bonds, the I-PDMS/SiO2 coatings can spontaneously restore their damaged superhydrophobicity at -30 °C through the free energy-driven diffusion of I-PDMS monomers. The I-PDMS/SiO2 coatings can be used as friction layers for triboelectric nanogenerators (TENGs), which provide them with long-lasting waterproofing and self-cleaning capabilities, thus preventing their output performance from being degraded due to water infiltration and dust accumulation. Due to the excellent mechanical strength of the I-PDMS/SiO2 coatings, the resulting self-healing superhydrophobic TENGs can generate electrical energy from repetitive motions such as hand tapping or foot trampling, which has not been possible in other reported superhydrophobic TENGs.