Superhydrophobic SiO2 micro-particle coatings by spray method

In nature, numerous biological surfaces depict hierarchical micro- and nano-structures with low energy surfaces that offer the superhydrophobic properties with low water adhesion. The superhydrophobic coatings were prepared using sol–gel derived SiO2 micro-particles by spray method. A methyltrimethoxysilane (MTMS) was used as a sol–gel precursor to prepare a coating sol. The entire spray coating process is a single-step and takes place at 70 °C temperatures. The surface morphological studies showed that the size of SiO2 particles were between 8 and 14 μm in diameter. These different diameter SiO2 micro-particles form hierarchical micro-structure which facilitates to reduce solid/water interface. The prepared superhydrophobic coatings showed static water contact angle (θ) of 162° ± 2° and roll-off angle of 6° ± 1°. The wetting properties and surface morphology of the coatings were investigated by static and dynamic water contact angle measurements and scanning electron microscopy, respectively. The characterization of the coatings by Atomic Force Microscopy and Fourier transformation infrared spectroscopy was also made. The resulting hierarchical surface morphology can be easily tuned over large areas by simple spray method.