Pulsed-laser-deposited and plasma-polymerized polytetrafluoroethylene (PTFE)-like thin films: A comparative study on PTFE-specific properties

Glass-like and structural first-order phase transitions are investigated in polytetrafluoroethylene (PTFE) foils and PTFE-like films prepared by pulse d-laser deposition (PLD) and plasma polymerization (PP). A structural compa rison of the investigated polymers is performed by infrared spectroscopy an d dielectric dilatometry. It is shown that dielectric dilatometry (the meas urement of the susceptance vs. temperature) provides a simple and elegant m eans for detecting volumetric transitions in thin nonpolar polymer films. I n conventional PTFE foils, the known glass-like and structural first-order phase transitions are identified. The structure of pulsed-laser deposited P TFE strongly depends on the target material, ranging from highly crystallin e films showing only structural phase transitions to films strongly deviati ng from PTFE foils, with structural characteristics comparable to plasma-po lymerized fluorocarbons. The dielectric loss of the highly crystalline PLD films compares favorably with conventional PTFE foils, making the films att ractive for new applications in miniature electret devices. (C) 1999 John W iley & Sons, Inc.