Pulsed-laser deposition of crystalline Teflon (PTFE) films

Pulsed plasma enhanced chemical vapor deposition (pulsed PECVD) and pyrolytic chemical vapor deposition (pyrolyric CVD) of fluorocarbon films from hexafluoropropylene oxide (HFPO) have demonstrated the ability to molecularly design film architecture. Film structures ranging from highly amorphous crosslinked matrices to linear perfluoroalkyl chain crystallites can be established by reducing the modulation frequency of plasma discharge in plasma activated deposition and by eventually shifting mechanistically from an electrically activated to a thermally activated process. X-ray photoelectron spectroscopy (XPS) showed CF2 content increasing from 39–65 mol%. Fourier transform infrared spectroscopy (FTIR) showed an increasing resolution between the symmetric and asymmetric CF2 stretches, and a reduction in the intensity of the amorphous PTFE and CF3 bands. High-resolution solid-state 19F nuclear magnetic resonance spectroscopy (NMR) revealed an increasing CF2CF2CF2 character, with the pyrolytic CVD film much like bulk poly(tetrafluoroethylene) (PTFE). X-ray diffraction (XRD) patterns evidenced an increase in crystallinity, with the pyrolytic CVD film showing a characteristic peak at 2θ = 18° representing the (100) plane of the hexagonal structure of crystalline PTFE above 19°C.

Molecular Design of Fluorocarbon Film Architecture by Pulsed Plasma Enhanced and Pyrolytic Chemical Vapor Deposition

Thin-film deposition of polymers by vacuum degradation.

Thermal degradation of poly(ethylene oxide) (PEO) was studied under vacuum conditions. PEO macromolecules degrade predominantly by random chain scission of a backbone with elimination of oligomer fragments. The reactions include the mechanism of radical termination by disproportionation. The eliminated fragments form thin film deposits which have chemical composition close to the original PEO. Activation of the evaporated flux with a glow discharge leads to further fragmentation and recombination of the released species and can be used to tune the properties of the resulting thin films.

Vacuum thermal degradation of poly(ethylene oxide).

Polymeric film deposition by ionization-assisted method for optical and optoelectronic applications

Thin films were deposited from low molecular weight polytetrafluoroethylene source materials by an ionization‐assisted evaporation method, and their crystallinity and molecular orientation were studied by x‐ray diffraction and infrared spectroscopy. The film properties were largely influenced by the substrate temperature and the molecular weight of the source material. At lower substrate temperatures, the molecules were oriented with the chain axis parallel to the substrate surface, and the film had preferential crystal orientation with the (100) plane of the hexagonal structure parallel to the substrate. With increasing substrate temperature, the molecules lost parallel orientation and the film crystallinity decreased. Such changes took place upon increasing the substrate temperature from 180 to 240 °C when deposited from a source material with a molecular weight of 8500, and from room temperature to 130 °C when the source molecular weight was 1500.

H. Koshikawa

Papers

Effect of substrate temperature on the deposition of polytetrafluoroethylene by an ionization‐assisted evaporation method