Nanoindentation measurements of teflon-AF nanosheets

We report the formation of cohesive, mechanically robust thin films of Teflon-AF formed via self-assembly of nanoparticles at both air/water and oil/water interfaces of micro-emulsion droplets. We also present results of morphological and mechanical investigations of thin films formed at these oil/water interfaces. Scanning electron microscope and low angle X-ray diffraction characterization of drop cast thin films from the micro-emulsions showed the presence of stacks of nanosheets with an average thickness of 6 nm. Atomic force microscopy (AFM) characterization put the thickness at a much lower value of around 2 nm implying that these sheets are comprised of molecular sheets of Teflon-AF. AFM characterization also indicated that these sheets are stretched molecular films comprising inter-diffused molecular chains, arranged in a regular fashion. Nanoindentation studies of these films unambiguously demonstrated the "tablet sliding" mechanism, similar to nacre, for dissipating applied stress.