Exploiting poly(dimethylsiloxane)-modified tips to evaluate frictional behavior by friction force microscopy

With the aim of investigating the effect of the surface properties on the friction behavior of self-assembled monolayers, we have modified tipless atomic force microscopy (AFM) cantilevers with a poly(dimethylsiloxane) (PDMS) lens. The friction coefficient using the silicon tip is strongly influenced by the mechanical properties of the substrate monolayer because hard, sharp silicon tips penetrate the surface of organic monolayers. However, the friction coefficient obtained for the PDMS-modified AFM cantilever is mostly due to the surface properties of the monolayer functional end group, rather than the viscoelastic deformation of the monolayer. The use of the PDMS tip was demonstrated as a novel means to investigate the effect of surface properties on the frictional behavior of self-assembled monolayers with various functional groups with less mechanical deformation.