Fabrication of superhydrophobic glass capillary

Abstract

This thesis presents the fabrication of superhydrophobic glass capillaries with water contact angles >168 ͦ, contact angle hysteresis <1 ͦ and water droplet sliding angle <10 ͦ through a three-step fabrication approach: ALD deposition of Al2O3 film, hydrothermal treatment to produce Al2O3 nanograss and silane coating of the nanograss.

The fabricated superhydrophobic glass capillaries retained their transparency and provided drag reduction when compared to the as received capillaries which served as controls. They provided reduced droplet sliding angles and improved water flow rates in hydraulic drag resistance testing. It was demonstrated through hydraulic testing that, the lowered drag resistance was higher at low Reynolds numbers, where reductions of over 40% were achieved.

The superhydrophobic capillaries also exhibited bio-repellency, as they provided lower droplet sliding angles of protein solution bovine serum albumin (BSA).

The characterization of the fabricated glass capillaries indicated that the adopted fabrication method was successful in creating superhydrophobic surface on the inner walls of glass capillaries with aspect ratio (length to inner diameter) of up to 25.