Influence of Blend Composition and Silica Nanoparticles on the Morphology and Gas Separation Performance of PU/PVA Blend Membranes

Polymer blending and mixed-matrix membranes are well-known modification techniques for tuning the gas separation properties of polymer membranes. Here, we studied the gas separation performance of mixed-matrix membranes (MMMs) based on the polyurethane/poly(vinyl alcohol) (PU/PVA) blend containing silica nanoparticles. Pure (CO2, CH4, N2, O2) and mixed-gas (CO2/N2 and CO2/CH4) permeability experiments were carried out at 10 bar and 35 °C. Poly(vinyl alcohol) (PVA) with a molecular weight of 200 kDa (PVA200) was blended with polyurethane (PU) to increase the CO2 solubility, while the addition of silica particles to the PU/PVA blend membranes augmented the CO2 separation performance. The SEM images of the membranes showed that the miscibility of the blend improved by increasing the PVA contents. The membrane containing 10 wt % of PVA200 (PU/PVA200–10) exhibited the highest CO2/N2~32.6 and CO2/CH4~9.5 selectivities among other blend compositions, which increased to 45.1 and 15.2 by incorporating 20 wt % nano-silica particles.