Formation of organized films with fluorocarbon-modified inorganic nanoparticles and their nanodispersion behavior in solvent

Abstract

Nanodispersion behavior in organic solvents of nanodiamonds with surfaces modified by amphiphiles containing fluorocarbon chains of different lengths was investigated for future lubricant applications. Fluorocarbon-modified nanodiamonds exhibit excellent dispersion behavior, specifically in nonpolar solvents. This is a phenomenon that is not seen in hydrocarbon-modified nanoparticles. The reduction in the aggregated particle size in organic solvents is more dependent on the modified chain length than on the modification rate. In addition, the behaviors of these organo-modified nanodiamonds on a water surface were systematically compared. These single-particle layers on the water surface were confirmed to depend on the compression rate. The slower the compression speed, the more homogeneous the single-particle layer formed is. Further, proper lattice spacing and high regularity in this system were achieved by low-speed compression. Good dispersibility in organic solvents was related to a long relaxation time to achieve a stable conformation on the water surface. In other words, it was suggested that nanoparticles with better dispersibility in organic solvent require a longer relaxation time for rearrangement in the air/water interface field.