Durable and self-healing superhydrophobic polyvinylidene fluoride (PVDF) composite coating with in-situ gas compensation function

A durable and self-healing superhydrophobic polyvinylidene fluoride (PVDF)/polyester-modified silicone resin (PMSR)/microspheric Na2CO3@SiO2 coating with WCA of 158 ± 1.5° and low SA of 4 ± 0.5° has been successfully prepared via sol-gel and spraying technique. After 24 h hydrolysis of tetraethylorthosilicate (TEOS), microspheric Na2CO3@SiO2 particles with extremely large storage spaces were obtained as reservoirs for the healing agent of POTS. The superhydrophobicity of the prepared coating can be recovered after 10 rubbing/healing test cycles, indicating the excellent self-healing ability. Simultaneously, the prepared coating also possesses gas compensation capability in acidic condition, which can extend superhydrophobic duration by 400%. The gas compensation capability can be mainly attributed to the bubbles generated from the reaction between acid and porous Na2CO3, hindering water wetting the surface. Moreover, the prepared coating can withstand 4217 friction cycles without obvious surface damage, which is approximately 6 times higher than that of pure PVDF coating. This is mainly due to the combined action of the high adhesion of PMSR, the self-lubrication of PVDF and the surface hierarchical nano/micro wrinkles. The prepared coating also shows prominent superhydrophobic stability under the conditions of acid/alkaline solution (pH = 1-14) or strong UV exposure (14 days). It is believed that this durable and self-healing superhydrophobic coating is anticipated to open a new avenue to enlarge the application range of superhydrophobic coatings.