POSITRON-ANNIHILATION LIFETIME AND DOPPLER BROADENING STUDIES OF AMORPHOUS FLUOROPOLYMER-POLY(2,2-BIS-TRIFLUORO-4,5-DIFLUORO-1,3-DIOXOLE)

Positron annihilation lifetime spectroscopy (PALS) and Doppler broadening spectroscopy (DBS) measurements are reported on poly (2,2-bis trifluoro 4,5 difluoro 1,3-dioxole) over the temperature range 303-423 K. The PALS data are best described by four components; the two longest lifetime components corresponding to ortho-positronium (o-Ps) annihilations with different characteristic lifetimes associated with different structural elements of the polymer. The total intensity attributed to o-Ps annihilations is small relative to that found in most common polymers. This suggests that in this material the free volume distribution is composed of a small number of large holes. The temperature dependence of the PALS data parallels that found in the DBS measurements. This type of free volume distribution is consistent with the high gas permeability found in these materials.