Effect of Partially Fluorinated Alkyl Chain on Friction and Surface Energy

Partially fluorinated carboxylic acid derivatives were synthesized and their macroscopic frictions and wetting properties were examined. The carboxylic acid adsorbs on a Co-15 wt % Ni metal surface with high orientation, but the ester has a weak interaction and its film is isotropic, which are suggested by the surface energy and the FTIR measurements of the film The outermost part of the acid is occupied by fluorinated alkyl groups and the surface energy is 10 mJm(-2), which agrees with values for the fluorinated self-assembled monolayers. The friction coefficient does not depend on the fluorine content in the lubricant molecules, not only for the highly oriented layer, but also for the isotropic film This seems to be caused by the anchoring effect. Macroscopic friction is largely dependent on the polar group. The alkyl chains in the monolayer of the semifluorinated materials contain gauche conformers, and the odd-even effect was insignificant in the film The molecules of the odd CH2 units in the monolayer are more inclined on average and the friction and surface energy are slightly greater than the even ones.