Transformation of a hydrophilic membrane into semi-super-hydrophobic based on self-assembly of stearic acid monolayer over induced nanostructures on the membrane surface

Both the chemical and structural properties of a surface determine the contact angle. For the formation of super-hydrophobic surfaces, modification of surface chemistry must be always combined with surface roughness enhancement. The used methods to make a super-hydrophobic surface are expensive and need very complicated equipments and cannot be scale up easily. In this study a simple and less expensive method was developed to transform a hydrophilic membrane into a semi-super-hydrophobic. In order to modify the membrane surface geometrically, the required needle-like rugosities were created by boiling the membrane in the water. The chemical modification of the roughened surface was created by the chemical adsorption and controlling the reaction time of stearic acid (STA) on the polymer of the membrane surface. Finally, by controlling the surface roughness, the concentration of the STA solution and duration of reaction time, a semi-super-hydrophobic membrane with the contact angle of 120° was prepared.