Importance of gelation and crystallization for producing superhydrophobic surfaces from mixtures of hydrogenated castor oil and fatty acids
Year: 2016
Journal: Colloid Polym. Sci.
Authors: Nakano, K; Ito, T; Onouchi, Y; Yamanaka, M; Akita, S
Superhydrophobic surfaces were obtained easily from a mixed solution of hydrogenated castor oil (HCO) as an organogelator and a fatty acid as a crystalline compound by a casting method: a contact angle of 160A degrees A +/- 2A degrees and a sliding angle of 5A degrees A +/- 1A degrees were achieved on a surface prepared from the mixed solution of HCO and stearic acid (SA) at 6:4 weight ratios at 30 A degrees C. The superhydrophobicity of the surface was attributable to a hierarchical structure which consisted of self-assembled nano-fibers of HCO and nano/micrometer-scale crystals of SA on hemispherical sub-structures having a diameter of several tens of micrometers. The hierarchical structure was formed under controlled conditions involving mixing ratios of HCO and a fatty acid, preparation temperatures, and fatty acid species. These results indicated that balance between gelation of HCO and crystallization of a fatty acid in the casting process was of importance in producing superhydrophobic surfaces.
