AbstractA smooth, ultrathin film of a polydimethylsiloxane (PDMS) on a silicon substrate has been prepared by spin‐coating. This film gives a 0.06 dynamic coefficient of friction against paper, the lowest value ever reported for polymer–paper sliding pairs. The value is only about one‐third of the coefficient of friction (0.21) between polytetrafluoroethylene and paper. The coating is not scratchable by sliding a stainless steel stylus over the surface with a pressure greater than 3.6 × 1010dyn/cm2. The film displays a surface tension of 20.5 dyn/cm. It is stable in water and propylene glycol. The film is an effective and durable solid lubricant. The surface characteristics of a spray‐coated PDMS and a plasma‐copolymerized thin film of perfluoropropane and 3,3,3‐trifluoropropylmethyldimethoxysilane have also been investigated. Both films show much lower scratch resistance, weaker adhesion to the silicon substrate, and higher friction. The plasma film yields the same surface tension as the spin‐coated PDMS. Its surface energy, however, increases after soaking in water or propylene glycol. The exceptionally low friction and the unusually high scratch resistance of the ultrathin film of PDMS are attributed to the absence of deformation and tearing components and a low adhesion components in the sliding fric
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