Probing of micromechanical properties of compliant polymeric materials

Scanning force microscopy (SFM) was used for probing nanomechanical properties of compliant polymeric materials with lateral resolution from 20 to 140 nm and indentation depths from 2 to 200 nm. Sneddon's, Hertzian, and Johnson-Kendall-Roberts theories of elastic contacts were tested for a variety of polymeric materials with Young's modulus ranging from 1 MPa to 5 GPa. Results of these calculations were compared with a Sneddon's slope analysis widely used for hard materials. It was demonstrated that the Sneddon's slope analysis was ambiguous for polymeric materials. On the other hand, all models of elastic contact allowed probing depth profile of elastic properties with nanometre scale resolutions. The models gave consistent values of elastic moduli for indentation depth up to 200 nm with lateral resolution better 100 nm for most polymeric materials. (C) 1998 Kluwer Academic Publishers.