Visualizing polymeric liquid/solid interfaces by atomic force microscopy utilizing quartz tuning fork sensors

We investigated a polymeric liquid/solid interface by frequency modulation atomic force microscopy (FM-AFM) using a quartz tuning fork sensor, so-called qPlus sensor. We carried out topographic imaging on a muscovite mica surface in poly(dimethylsiloxane) (PDMS) which has 1000 times higher viscosity than that of water and the crystal structure of the mica surface was successfully imaged. Two-dimensional frequency shift mapping was also demonstrated at the interface and the layered structure of density distribution of the PDMS was imaged. The monotonic energy dissipation curve indicated the fluid-like behavior of the PDMS near the mica surface. In addition, lateral variation of density distribution was also imaged. The results in this work indicated usefulness of FM-AFM using qPlus sensors for lubrication study.