Effects of Supercritical CO₂ Conditioning on Cross-Linked Polyimide Membranes

Abstract

The effects of supercritical CO 2 (scCO 2 ) conditioning on high-performance cross-linked polyimide membranes is examined through gas permeation and sorption experiments. Under supercritical conditions, the cross-linked polymers do not exhibit a structural reorganization of the polymer matrix that was observed in the non-cross-linkable, free acid polymer. Pure gas permeation isotherms and mixed gas permeabilities and selectivities show the cross-linked polymers to be much more stable to scCO 2 conditioning than the free acid polymer. In fact, following scCO 2 conditioning, the mixed gas CO 2 permeabilities of the cross-linked polymers increased while the CO 2 /CH 4 separation factors remained relatively unchanged. This response highlights the stability and high performance of these cross-linked membranes in aggressive environments. In addition, this response reveals the potential for the preconditioning of cross-linked polymer membranes to enhance productivity without sacrificing efficiency in practical applications which, in effect, provides another tool to "tune" membrane properties for a given separation. Finally, the dual mode model accurately describes the sorption and dilation characteristics of the cross-linked polymers. The changes in the dual mode sorption model parameters before and after the scCO 2 exposure also provide insights into the alterations in the different glassy samples due to the cross-linking and scCO 2 exposure.

Effects of supercritical carbon dioxide treatment conditions on the gas separation properties of polydimethylsiloxane hybrid membrane materials for air purification

“…9,30 Crosslinking can provide enhanced plasticization ARTICLE resistance and can also provide intrinsic selectivity increases in some cases. 23,31,32 In addition, the mechanical properties of scCO 2 are highly dependent on the pressure and temperature;…”

“…10 In addition, scCO 2 has attracted a great deal of interest in both the academic and industrial fields for polymeric applications, such as polymer modification, 11 polymer blending, 12 the formation of polymer composites, 13 microcellular foaming, 14 particle production, 15 and polymerization, 16 where CO 2 plays the role of a plasticizer, solvent, or antisolvent. 23,24 The objective of this study was to improve the air-purification performance of PDMS membrane materials by means of scCO 2 . [18][19][20][21] Only fluoropolymers and silicon-containing polymers can be dissolved in scCO 2 ; carbon-chain polymers and heterochain polymers are indissoluble, but they can be swelled and plasticized.…”

“…Nevertheless, few studies have explored the application of scCO 2 conditions in the field of high-performance rubber polymer membranes for gas separation. 23,24 The objective of this study was to improve the air-purification performance of PDMS membrane materials by means of scCO 2 . In this study, a PDMS hybrid membrane containing fluorinated side chains was first prepared, and the effects of the scCO 2 conditions on the permeation properties of the PDMS hybrid membrane were investigated.…”

Ionic liquid modified poly(2,6-dimethyl-1,4-phenylene oxide) for CO2 separation

“…Global warming resulting from the increased CO 2 concentration in the atmosphere due to the emission of CO 2 from fossil fuel combustion has been becoming one of the most important environmental issues [1,2]. Thus, CO 2 capture and sequestration are receiving significant attention [3][4][5].…”

Carbon Dioxide Capture by Dendrimer-Modified Silica Nanoparticles

“…Improvements in the adsorption performance of solid adsorbents, such as zeolites, pillared clays, activated carbons and metal-organic frameworks (MOFs), have been reported (Krishna and van Baten 2010;Alcaniz-Monge et al 2011;Chen and Ahn 2011). Significant advancements towards the fundamental understanding of the relationship between the adsorption and structure, solubility and selectivity of the solid adsorbent have been achieved (Dennis and Pacciani 2009;Arenillas et al 2005;Zou and Rodrigues 2001).…”