PEBAX® with PEG functionalized POSS as nanocomposite membranes for CO2 separation

Nanocomposite membranes were prepared by incorporation of commercial poly(ethylene glycol) functionalized polyoctahedral oligomeric silsesquioxanes (PEG-POSS) in two grades of poly(ether-block-amide) namely PEBAX® MH 1657 and PEBAX® 2533. Single gas permeabilities of N2, O2, CH4, H2, and CO2 were measured using the time-lag method. CO2 permeability increased two fold after incorporation of 30 wt% PEG-POSS in PEBAX® MH 1657, while the selectivity was not significantly affected at 30 °C. Simultaneous enhancement in permeability and selectivity was observed up to 30 wt% loading of PEG-POSS in PEBAX® 2533 at 30 °C. The effect of temperature upon CO2 permeability and CO2 selectivity over N2, O2, CH4 and H2 was studied between 30 °C to 70 °C. Substantial influence upon the thermal transition of the polyether domain of both polymers was observed due to incorporation of PEG-POSS by differential scanning calorimetry (DSC). Atomic force microscopy was used to evaluate the impact of 30 wt% PEG-POSS loading upon the surface topography of both investigated grades of PEBAX®. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were used to study the membrane morphology and the distribution of the nanofillers (PEG-POSS) in PEBAX® membranes.