Hydrophobic Aerogel Films

Hydrophobicity is a measure of a surface’s lack of affinity to a fluid, and this surface property has a wide array of applications. Some of these include being suitable for self-cleaning surfaces, corrosion resistant surfaces, or as a means to keep clothing dry. Extensive research has also gone into making hydrophobic surfaces as a means of drag reduction on water vehicles. This research aims to create a hydrophobic aerogel-based film for drag reduction applications using a  polymer binder (polyvinyl butyral, PVB), with crushed hydrophobic aerogel. Aerogels are nanoporous materials that are comprised of 95 - 99% air. They have unique properties, one of which is the ability to be hydrophobic. Experimental trials were run to manipulate parameters, such as temperature, PVB to aerogel ratio, and solvent addition. The goal was to produce a hydrophobic film with uniform hydrophobicity, uniform thickness and flexibility. Contact angle measurements were used to quantify the level of hydrophobicity. The films were also tested for their drag reduction properties through use of a rotational viscometer. Results showed successful hydrophobicity levels were achieved with contact angles of approximately 150^o. However, drag reduction was not seen for the films in the range for which they were tested. This presentation will focus on the methods of making the films, as well as results obtained from the contact angle and drag measurements.