Gas-transport properties of new mixed matrix membranes based on addition poly(3-trimethylsilyltricyclononene-7) and substituted calixarenes

Herein we report the results of the preparation and investigation of gas permeation parameters of novel membrane composite materials based on highly permeable addition poly(3-trimethylsilyltricyclononene-7) (PTCNSi1) and different substituted calixarenes (CA). Calix[4]arene and calix[8]arene with substituents R-1 (R-1 = Me, Et, SiMe3) in the lower rim and R-2 (R-2 = tert-Bu, PI) in the upper rim were used as the additives. We explored the correlations between the structure of fillers (calixarenes) and gas permeation parameters of the composites. It is shown that the introduction of calixarenes results in increases in the separation factors, though a decrease in the observed permeability coefficients is observed. Thus, the addition of calix[4]arene with R-1 = Et and R-2 = tiert-Bu increases the separation factors for H-2/N-2 gas pair more than twice, from 5.2 to 11.4, while the permeability coefficient P(H-2) decreases from 2060 to 1000 Barrer. The increase of calixarene content Lends to further enhance the separation factors. The application of positron annihilation lifetime spectroscopy indicated that these changes can be explained by certain reduction of mean size of free volume elements in the compositions containing calixarenes. The data of BET, TEM. WAXD, and mechanical properties of the composites are also reported and discussed. (C) 2014 Elsevier B.V. All rights reserved,