Mesoporous KIT-6 silica-polydimethylsiloxane (PDMS) mixed matrix membranes for gas separation

In this study, we have explored for the first time the use of the mesoporous KIT-6 silica as an additive to enhance the gas permeability and separation characteristics of PVDF supported polydimethylsiloxane (PDMS) with filler loadings varying between 0 and 25 wt%. The KIT-6 silica was synthesized by a templating method and functionalized through silanization confirmed via Fourier transform infrared spectroscopy. The SEM images of the MMMs suggested that p-KIT-6 silica particles could embed well into the PDMS matrix and the MMMs could be defect free. With an optimum loading of 2 wt%, the C4H10 permeability and C4H10/N-2 ideal selectivity of the MMM were shown to increase by 464% and 248% compared with the neat polymer membrane, respectively. In addition, the optimum membrane was also evaluated for CO2/N-2 separation, which proved that the permeability and selectivity increased simultaneously. An interface morphology has also been proposed to explain the separation phenomenon of the MMM reasonably. Taken all together, it is expected that the mesoporous KIT-6 silica would be an attractive additive to enhance the gas separation performances of polymer membranes.