Estimation of the linear thermal expansion coefficient in friction-deposited, oriented poly(tetrafluoroethylene) films by temperature-dependent lateral force microscopy

Preliminary lateral force microscopy (LFM) results are presented which were obtained at different temperatures on thin films of poly(tetrafluoroethylene) prepared by friction deposition. Chain-chain distances of rodlike poly(tetrafluoroethylene) macromolecules were determined as a function of temperature from LFM images which exhibit molecular resolution. The value of the linear thermal expansion coefficient in the chain-perpendicular direction was estimated to be 3.5x10-3 [1/°C] in the temperature range between+10°C and+40°C. This value is higher than the literature data quoted for the temperature range between 0 °C and 25 °C. Possible reasons for this deviation are discussed.