PEG Containing Thiol鈥揈ne Network Membranes for CO2 Separation: Effect of Cross-Linking on Thermal, Mechanical, and Gas Transport Properties

详细信息    查看全文

• 作者：Luke Kwisnek ; James Goetz ; Kevin P. Meyers ; Stephen R. Heinz ; Jeffrey S. Wiggins ; Sergei Nazarenko
• 刊名：Macromolecules
• 出版年：2014
• 出版时间：May 27, 2014
• 年：2014
• 卷：47
• 期：10
• 页码：3243-3253
• 全文大小：615K
• 年卷期：v.47,no.10(May 27, 2014)
• ISSN：1520-5835

文摘

A new family of poly(ethylene glycol) (PEG) based membranes for CO₂ separation was developed using thiol鈥揺ne photopolymerization. Compared to photopolymerized PEG-containing acrylate membranes, these new thiol鈥揺ne based membranes offer improved mechanical properties and processing advantages. The starting material, a combination of a trithiol cross-linker and a PEG diene, was gradually modified with a PEG dithiol while maintaining 1:1 thiol:ene stoichiometry. This approach made it possible to decrease the network cross-link density, resulting in simultaneous increases in free volume and PEG content. Materials with high concentrations of dithiol were very stretchable, with largely, up to 500%, improved elongation at break, yet they exhibited commendable CO₂/N₂, O₂, H₂, and CH₄ permeability-selectivity performance. The average molecular weight of polymer chains between cross-links, M_c, was determined experimentally by fitting the classic network affine model to stress鈥搒train data obtained via tensile testing. M_c was also calculated assuming an ideal, lattice-like, network structure based on monomer stoichiometry. The effect of M_c on glass transition temperature and gas permeation behavior was studied. A free volume based model was employed to describe experimental gas permeability (diffusivity) trends as a function of M_c.