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Aminosilane-modified poly(ethylene glycol) (PEG), PEG-block-poly(propylene glycol) (PPG)-block-PEG (PEPEG), and PPG-block-PEG-block-PPG (PPEPG) diacrylate prepolymers are synthesized as new membrane materials for gas separation. By combining the in situ sol−gel process and cross-linking process together, the silane-modified prepolymers form flexible nanocomposite membranes with a maximum CO2permeability of 274 barrer and CO2/N2selectivity of about 30. The CO2permeabilities of silane cross-linked PEPEG and PPEPG membranes are higher than those of silane cross-linked PEG membranes, whereas the CO2/N2and CO2/H2selectivities increase as the PEG content increases in the membrane. A proper aminosilane/prepolymer reaction ratio benefits the gas separation performance of the membrane due to the formation of different cross-linking structures and composites. [ABSTRACT FROM AUTHOR]

Brominated poly(2,6-diphenyl-1,4-phenylene oxide) (BPPOdp) is synthesized as a new membrane material for gas separation. BPPOdpforms flexible membranes with higher CO2permeability (PCO278 Barrer) and selectivity (CO2/N230) than poly(2,6-dimethyl-1,4-phenylene oxide) (PPOdm) membranes. BPPOdpalso forms nanocomposite membranes with silica nanoparticles. The nanocomposite membranes have a greatly enhanced CO2permeability while maintaining the CO2/N2and CO2/CH4selectivities of the pure BPPOdpmembranes. The CO2permeability increases as the silica content increases in the membrane. The 10-nm silica nanoparticles are more effective at increasing the CO2permeability than the 30-nm silica nanoparticles. Mechanism studies show that the enhanced permeability results from the nanogaps between the silica nanoparticles and the polymer chains due to their incompatibility. [ABSTRACT FROM AUTHOR]

Silica-impregnated, brominated PPO poly(phenylene oxide) (BPPO) membranes exhibit enhanced CO2permeability relative to pure BPPO membranes due to higher gas solubility and especially higher gas diffusivity. Among the three silica sizes (2, 10, and 30 nm) characterized in this work, the 10 nm silica is found to result in the highest gas permeability, about 5 times higher than that of the pure BPPO membranes. These permeability enhancements do not cause an appreciable loss of selectivity, which remains essentially unchanged, for example, about 21 for the CO2/N2separation and about 15 for the CO2/CH4separation. The permeability increases with increasing silica content, which, however, cannot exceed about 0.35 silica/BPPO weight ratio due to a substantial increase in brittleness. [ABSTRACT FROM AUTHOR]