The effect of crosslinking temperature on the permeability of PDMS membranes: Evidence of extraordinary CO₂ and CH₄ gas permeation

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• 作者：Kyle Berean ; Jian Zhen Ou ; Majid Nour ; Kay Latham ; Chris McSweeney ; David Paull ; Andri Halim ; S ; ra Kentish ; Cara M. Doherty ; Anita J. Hill ; Kourosh Kalantar-zadeh
• 关键词：Polydimethylsiloxane (PDMS) ; Carbon Dioxide (CO2) ; Methane (CH4) ; Gas permeation ; Crosslinking
• 刊名：Separation and Purification Technology
• 出版年：10 February, 2014
• 年：2014
• 卷：122
• 期：Complete
• 页码：96-104
• 全文大小：1766 K

文摘

It is important for gas permeable membranes, employed in many industrial applications, to have a high permeability as the cost of many processes such as gas separation and sensing directly depend on it. Polydimethylsiloxane (PDMS) has been a widely utilized polymer within permeable membranes as it possesses high intrinsic flux. However, little attention has been placed on the effect of crosslinking temperatures during synthesis. In this work, PDMS membranes were prepared using a range of crosslinking temperatures and evaluated for their gas permeation towards CO₂, N₂ and CH_4. The investigation of the effect of the crosslinking temperature on gas permeation of PDMS membranes revealed an optimum temperature of 75 掳C at which the permeability increased (for N₂ from 360 to 590 Barrer, for CO₂ from 3190 to 3970 Barrer, and for CH₄ from 850 to 1000 Barrer). The vibrational and electron beam spectroscopy studies show that at this optimum temperature the structure of polymer chains is relaxed due to the reduction of the crosslinking density and an enhancement in the fractional free volume (FFV) within the polymer matrix, allowing more efficient diffusion of the gas molecules. Eventually, we demonstrate the extraordinary capability of the membranes crosslinked at 75 掳C by incorporating them in sensing systems. Remarkably the sensors鈥?response with and without the presence of the improved membrane are nearly the same for CO₂ and only show a 30% decrease for CH₄. This experiment depicts the strong potential of the developed membrane for efficient, passive and low cost gas phase separation of selected gas species.