MOLECULAR-STRUCTURE AND THICKNESS OF HIGHLY ORIENTED POLY(TETRAFLUOROETHYLENE) FILMS MEASURED BY ATOMIC FORCE MICROSCOPY

Atomic force microscopy (AFM) was used to image thin single-crystal-like layers of poly(tetrafluoroethylene) (PTFE) deposited mechanically on glass. Not only can AFM reveal details of the molecular structure, but it can also provide direct measurement of the absolute thickness and continuity of these films. High-magnification images show individual rod-like molecules with an intermolecular spacing of 0.58 nm. The helix of individual molecules is clearly resolved and fine structures along the polymer chains may indicate individual fluorine atoms. The thickness of the films varies from 7-32 nm depending on deposition temperature and mechanical pressure. The continuity of the films strongly decreases at lower temperatures. The remaining single fibres are not stable and can be modified by the imaging tip.