Gel coating films comprising nanodiamonds organo-modified with 12-hydroxystearic (12-OHC18 ) and stearic acids were prepared and characterized. Because molecules with 12-OHC18 groups can convert solvents into thixotropic gels, Gemini-type diamide derivatives with two 12-OHC18 chains were also introduced as thixotropic additives into the gel coating films. Although the 12-OHC18 -modified nanodiamonds did not lead to solvent gelation on their own, they displayed an affinity for the thixotropic additive molecules. The 12-OHC18 -modified nanodiamonds were localized near the surface of the nanofibers formed by the Gemini-type diamide derivative in the solvent, and the thixotropic properties of the supramolecular gel were confirmed. Nanoparticle aggregation and nanofiber crystallinity were found to be suppressed by the effect of 12-OHC18 modification in the gel coating films, making them suitable for cosmetic coating applications.
Keywords: 12-hydroxystearic acid; gel coating films; lipophilization; nanodiamond; thixotropy.