Friction of brushlike self-assembled monomolecular coatings

Friction modes of self-assembled monomolecular coatings (SAM) based on dodecyclophosphoric acid ester and its derivatives on a silicon substrate are investigated. The antifriction properties of the films are shown to be due to their ability to decrease the interfacial energy of friction contact. Models are suggested for friction force computation for single and multiple molecularly smooth contacts. They are based on consideration of the thermodynamic cycle of formation and break-off of the friction junction. On the example of composite coatings having different surface energy, a possible means of regulation of the tribological parameters of the silicon-SAM-silicon system is discussed.