Study of high permeability polymers by means of the spin probe technique

The spin probe technique was systematically applied to study a family of hi gh permeability and high free volume glassy polymers. Rotation correlation times tau(c) Or frequencies nu = 1/tau(c) of 2,2,6,6-tetramethylpyperidine- 1-oxyl (TEMPO) were measured in amorphous teflons - random copolymers of te trafluoroethylene and 2,2-bistrifluoromethyle-4,5-difluoro-1,3-dioxole, pol yacetylenes and polynorbornenes. Polymers distinguished by unusually high, for the glassy state, permeability and free volume exhibit large rotational mobility of TEMPO. The correlation times correspond to fast rotation of th e spin probe previously observed only in rubbery polymers, Correlations bet ween the frequency nu and gas permeability and diffusion coefficients were observed. However, in some polymers, the spin probe's rotation rate is also sensitive to side-chain local mobility, which does not affect translationa l diffusion coefficients of gas molecules in polymers. (C) 1999 Elsevier Sc ience Ltd. All rights reserved.