The impact of nanofillers on the swelling characteristics of hydrogenated nitrile butadiene rubber (HNBR)clay nanocomposites was thoroughly investigated. The nanocomposites exhibited a dramatic decrease in the solvent uptake compared to the unfilled HNBR even at very low filler loadings because of the molecular dispersion of the organically modified montmorillonite and sepiolite and strong interaction between the HNBR and clays. The dispersion of the clay layers was verified by transmission electron microscopy. In addition, the clay content was found to influence the solvent uptake properties of the HNBRclay nanocomposites. The diffusion and sorption behavior of chloroform in the HNBRclay nanocomposites at different loadings was studied by a conventional weight gain method. The diffusion results were analyzed in terms of the simple Fickian model. Finally, Arrhenius and thermodynamic parameters were evaluated from these diffusion data. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013