303430 Improving CO2 Permeation Performance of Poly(ethylene oxide)- Polyamide Block Copolymer Membrane

Monday, June 10, 2013
Ballroom (Grove Hotel)
Yuanyuan Wang1, Hongyu Li1, Guangxi Dong2 and Vicki Chen1, (1)UNESCO Centre for Membrane Science and Technology, The University of New South Wales, Sydney, Australia, (2)UNESCO Centre for Membrane Science and Technology, School of Chemical Engineering, The University of New South Wales, Sydney, Australia

Development of a gas separation membrane with high permeability, desired selectivity for specific gas separation process as well as cost-effectiveness is the research focus to drive wider application in industry.

Our approach was to employ the commercially available poly(ethylene oxide)(PEO) block polyamide (PA) copolymers (Pebax® grade MH1657 and MV1074, with similar PEO soft phase content but different hard phase PA6 and PA12 respectively) to develop CO2 separation membranes and enhance their permeability by physical blending. A new method to prepare Pebax®1074 polymer solution was found to prevent the occurrence of gelation at room temperature for the preparation of defect free dense film membranes. Pebax®1074 membrane yielded higher CO2 permeability than Pebax®1657 and similar CO2/N2 selectivity. The Langmuir sorption effect on the equilibrium of CO2 permeation was observed at relatively low pressure. Membranes with CO2 exposure history showed less permeability to non-polar gases, however non-polar gas permeability appeared to recover with extensive purging or relaxation at ambient environment.

Blending with a linear PEO-polydimethylsiloxane (PDMS)-PEO triblock copolymer (under the tradename IM22) enhanced CO2 permeability of Pebax®1657 significantly. CO2 permeability was increased over three fold at 20wt% loading while maintaining similar CO2/N2 selectivity. Differential scanning calorimetry (DSC) analysis suggested that the glass transition temperature (Tg) and melting temperature(Tm) of the soft phase were reduced, but  the Tm of hard phase in the blended membranes remained intact. Excessive loading (over 20wt%) led to aggregation of the additive in the blended membrane matrix that distorted the lamellar nanostructure of the virgin polymer as observed  from phase images obtained from Scanning Probe Microscopy (SPM).

The study established the basis to further develop composite membranes with enhanced CO2 permeation property by using additives.


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