Surface Wettability Using Contact Angle Goniometry

This study measured surface wettability on a variety of coatings at various temperatures to assess the capacity of the coatings to facilitate water condensation for water collection from vapor. Both commercial polymeric coatings and oxide coatings made in house were selected based on their published hydrophobicity, and aluminum and copper coupons were used as substrates. Dynamic contact angle measurements were performed over the temperature range 5 deg C-50 deg C with an automated, tilting-stage, contact angle goniometer equipped with a Peltier environmental chamber for temperature control. While the commercial polymeric coatings exhibited consistent super hydrophobic wettability across all substrates, the roll-off angles were greater than 20 degrees. The most promising candidate was the wet-oxide coating formed on copper substrates. The high contact angles, low hysteresis, and negligible roll-off angles imply that droplets formed on these surfaces would have very low adhesion and high collection efficiency.