Sol-gel-processed porous water-repellent silica microbowls

Surface wettability, as one of the most crucial properties of solid surface, is a very common interface phenomenon in our daily life and nature. The authors obtained water-repellent porous silica microbowl-like structure by controlled sol-gel method with tetraethaoxysilane (TEOS) as a precursor and 3,3,3-trifluropropyltrimethoxysilane (TFPTMOS) as a coprecursor. The water-repellent properties of the coatings were raised with increasing molar ratio (M) of TFPTMOS/TEOS. The prepared silica coatings showed water-repellent behavior with water contact angle of 136 +/- 3 degrees and sliding angle of 18 +/- 1 degrees without any posthydrophobization. In conclusion, the wetting properties were dependent on the micro-/nano-structure and the chemical composition of the coatings.