Correlation of Activation Energies of Gas Diffusivity and Local Matrix Mobility in Polycarbonate/POSS Nanocomposites

Abstract

ABSTRACT According to basic phenomenological models describing the solution‐diffusion based mechanism of penetrant diffusion in dense polymers, a connection between the diffusive transport of gas molecules in a polymeric matrix and the molecular mobility of that matrix on a certain length scale is, in principle, established for a long time. However, experimental data directly showing this correlation are rare. The investigation of a series of nanocomposites based on a polyhedral oligomeric silsesquioxane (POSS) and a polycarbonate matrix allows a systematic change of the molecular mobility on a local length scale (β‐relaxation) and of the corresponding activation energy E A , both determined by broadband dielectric spectroscopy. Independently, activation energies of penetrant diffusion ( E D ) of these nanocomposites were determined for N 2 , O 2 , CO 2 , and CH 4 and a clear linear correlation between the two activation energies was established for the first time. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51 , 1593–1597