Preparation and characterization of POSS-PEG high performance membranes for gas separation

Abstract

The efficient CO2 separation process depends on the trade-off among permeability and selectivity requirements. In this work, copolymers of polyhedral oligomeric silsesquioxanes (POSS) with cage-like rigid structure and polyethylene glycol (PEG) with good CO2 affinity were synthesized by introducing allyl-POSS and allyl-EO into the side chain of polymethylhydrosiloxane (PMHS) in different proportions. The POSS80PEG20 copolymer fashioned into membrane showed good CO2 separation performance (permeability of 679 barrer and CO2/N2 selectivity of 38.1). The effect of POSS content on morphology, thermal stability and mechanical properties was also investigated. Multilayered composite membranes using POSS80PEG20 copolymer of different concentration as a selective layer, polyacrylonitrile (PAN) support layer and polydimethylsiloxane (PDMS) middle layer were also fabricated to achieve improved mechanical stability. The composite membrane with selective layer concentration of 0.25 wt% (POSS-PEG-0.25) offered optimum CO2/N2 and CO2/O2 selectivity performances. Moreover, the effect of feed pressure on mixed gas permeance was also reported. © 2020 Elsevier B.V.