Formation of Superhydrophobic Surfaces by Spray-Coating Using Supercritical Carbon Dioxide

CENGİZ U., Erbil H. Y.

13th European Conference on Applications of Surface and Interface Analysis (ECASIA’09), Turkey, 1 - 04 October 2009, pp.252

  • Publication Type: Conference Paper / Summary Text
  • Country: Turkey
  • Page Numbers: pp.252
  • Çanakkale Onsekiz Mart University Affiliated: Yes


Superhydrophobic surfaces are characterized by high values of water contact angles (larger than 150°) and with low contact angle hysteresis. Recently, a variety of methods have been proposed to fabricate superhydrophobic surfaces using cheap polymers such as phase seperated porous polypropylene. The use of supercritical or liquid carbon dioxide as an environmentally friendly medium for delivering coating systems has been applied. However, relatively little research has been reported for controlling the microscopic morphology of coated surfaces for targeted applications. A suitable polymer is dissolved in sc-CO2 and this solution is rapidly expanded through a nozzle to ambient conditions in the rapid expansion of supercritical solutions (RESS) method. RESS application has been limited low polymer solubility so that whether the polymer is CO2-philic or not, and CO2-soluble amorphous fluoropolymers and silicon polymers can be used in this process. RESS method can be modified if a non-solvent is added to the solution (RESS-N) and co-solvents such as ethanol, propanol and acetone are used in RESS-N process to increase the dissolution of the polymers in scCO2. In the first part of this study, we synthesized fluoroacrylate homopolymer and copolymers from methylmethacrylate (MMA), buthylacrylate (BA) and vinylacetate (VA) monomers in scCO2 system at 80 oC, 125-160 bar for 16 hours. BA and VA were added to improve the adherence of the spray-coating to the substrate. In the second part, we prepared superhydrophobic surfaces by applying the RESS and RESS-N methods using copolymers previously synthesized, and their wax blends and obtained a water drop contact angle between 130-160o on these surfaces.