Measuring Tg in Ultra-Thin Polymer Films With an Excimer Fluorescence Technique.
Measuring Tg in Ultra-Thin Polymer Films With an Excimer
White, C. C.; Migler, K. B.; Wu, W. L.
Polymer Engineering and Science, Vol. 41, No. 9,
1497-1505, September 2001.
polymer films; fluorescence; temperature
An excimer fluorescence technique has been applied to
the measurement of Tg of ultra-thin polystyrene films.
This technique utilizes an excimer-forming molecule with
fluorescent emission in two wavelength bands. The
intensity ratio of these bands is a sensitive measure of
local viscosity. This technique has been applied to five
polystyrene films in the thickness range of 25 nm to 200
nm supported on quartz substrates. The observed Tg for
the five ultra-thin polymer films was similar to the
bulk Tg with no observed dependence upon thickness.
Additionally, the Tg determined for each film did not
show any dependence upon thermal history.