Gas and Vapor Transport in Mixed Matrix Membranes Based on Amorphous Teflon AF1600 and AF2400 and Fumed Silica

Abstract

The enhancement of gas and vapor transport rates induced by the addition of fumed silica nanoparticles to fluorinated glassy polymers is interpreted and quantitatively modeled considering the additional free volume created by incorporation of filler. That effect can be evaluated accurately from gas solubility data, using the NELF model. The solubility of CH 4 and CO 2 in matrices of Teflon AF1600 and AF2400, filled with variable amounts of fumed silica nanoparticles, was measured at 35 °C; the solubility of n-C 4 and n-C 5 vapors, as well as their diffusivity and the dilation induced in the same polymer matrices, was also measured at 25 °C. The fractional free volume (FFV) values, estimated on the basis of CH 4 solubility data, were used to predict the solubility of the other penetrants inspected, with excellent agreement with experimental data. In addition, a single empirical correlation can be drawn, for both AF1600 and AF2400-based mixed matrices, between the infinite dilution diffusivity of vapors and the FFV value calculated from solubility data. Similarly, a simple correlation valid for both matrices is obtained as well for the dependence of diffusivity on penetrant concentration. Finally, use of the NELF model also allows an estimate of the swelling induced by the sorption process on the basis of virtually one simple data point of gas solubility.

Polymeric mixed matrix membranes containing zeolites as a filler for gas separation applications: A review

“…Due to the non-permeability of the nonporous silica particles, the addition of this filler into the polymer matrix does not directly contribute to the change of transport property, but it alters the molecular packing of the polymer chains, resulting in an improvement of the permeation as well as the selectivity [42,53].…”

“…Metal organic frameworks (MOF) [20][21][22][23][24][25][26][27][28], zeolitic imidazolate frameworks (ZIFs) [29][30][31][32][33], activated carbon [15,34], carbon nano tubes [35][36][37][38][39], titanosilicates [40,41], and ordered mesoporous silica [11,[42][43][44][45][46][47] are other types of porous materials that have been applied as the dispersed phase in mixed matrix membrane fabrication. Silica [42,[48][49][50][51][52][53], TiO 2 [42,[54][55][56][57], and fullerene (C60) [58] are the most conventional impermeable inorganic particles used for the MMMs fabrication.…”

Nonequilibrium Lattice Fluid Modeling of Gas Solubility in HAB-6FDA Polyimide and Its Thermally Rearranged Analogues

“…Compared to other models for gas sorption in glassy polymers 15,16 , the NELF model exhibits remarkable predictive power 12,14,17,18,19,20 . This model requires, for the penetrant and the polymer, the same characteristic parameters as the corresponding equilibrium model, and it uses the same mixing rules to estimate properties of polymer-penetrant mixture 14 .…”

“…When considering strongly sorbing penetrants, such as CO2 at high pressure or condensable vapors, changes in polymer density (i.e., swelling) due to sorption must be considered 12,18,22 .…”

Calculation of the solubility of liquid solutes in glassy polymers

“…[23][24][25] The NELF model was later successfully applied to the prediction of gas solubility in many different situations: (i) mixed gases in glassy polymers, 26 (ii) single gases in glassy polymeric blends, 27 and (iii) single gases in composite (mixed matrix) membranes. 28,29 Moreover, the NELF model was applied to represent the effect of ageing on the sorption process in glassy polymers, 30 to establish correlations between the infinite dilution solubility in glassy polymers and the penetrant parameters, 31,32 to estimate the swelling of a glassy polymer on the basis of sorption data, 33 and to elucidate the interactions between alkane penetrants and fluorinated glassy polymers. [34][35][36] The solubility calculations based on nonequilibrium models use expression mathematically not as easy as the DMS model.…”