Facile fabrication of superhydrophobic coatings based on two silica sols

Superhydrophobic coatings were successfully fabricated by using two silica sols and fluorinated acrylate copolymers through the organic-inorganic hybrid method. The two silica sols contained different nanoparticles, namely, silica nanoparticles with many hydroxyl groups on their surfaces and silica nanoparticles with many long-chain alkyls on their surfaces. The integration of these two silica sols and fluorinated acrylate copolymers satisfied two necessary conditions of multi-scale nano/microstructures and low surface energy for fabricating superhydrophobic coatings. The superhydrophobic surfaces were constructed by using appropriate weight ratios of silica/copolymers and silica sol (methanol) contents. The superhydrophobic coatings displayed a water contact angle as high as 156.2° and contact angle hysteresis of 2.4°, which indicated their good self-cleaning capability. In particular, these coatings showed good mechanical properties and excellent thermal stabilities. The method is not only a facile and inexpensive way to achieve the lotus effect but could also create coatings with high values in practical application.