Permeation and sorption of various organic liquids (chlorinated hydrocarbons, lower alcohols, hydrocarbons, etc.) in amorphous copolymers of 2,2-bis-trifluoromethyl-4,5-difluoro-1,3-dioxole and tetrafluoroethylene (amorphous Teflons AF) were studied in the temperature range 5-95 degreesC. Based on permeation rate and solubility coefficients, the diffusion coefficients of organic penetrants in AF copolymers AF were estimated. It was shown that the copolymer with a higher content (87%) of the dioxole component (AF2400), as distinguished by a larger free volume, is much more permeable to liquids than the copolymer AF1600 containing 65% of the dioxole comonomer. In contrast, solubility of organic compounds in both copolymers is hardly affected by their composition. The effects of penetrant parameters, such as critical volume (V-c) and critical temperature (T-c) were analyzed. The variation in permeation rates of liquids and gases through these materials are consistent with a mobility (diffusion) controlled mechanism for mass transfer. A trade-off between the Arrhenius parameters for permeability and the van't Hoff parameters for solubility is demonstrated for pervaporation. On this basis, novel correlations are obtained that enable a determination of the activation energy for permeation E-p and the enthalpy of sorption H-S from the permeability (P) and solubility (S) coefficients. Long term tests (up to 12 months) showed excellent time stability of the transport parameters, a property unexpected and quite important for a high flux, high free volume pervaporation material. (C) 2003 Elsevier Science B.V. All rights reserved.