High Ionic Liquid Content Polymeric Gel Membranes: Preparation and Performance
High Ionic Liquid Content Polymeric Gel Membranes: Preparation and Performance
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DOI：
10.1021/ma102438k
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发表时间：
2011-01-11
期刊：
影响因子：
5.5
通讯作者：
Izak, Pavel
中科院分区：
文献类型：
--
作者：
Jansen, Johannes Carolus;Friess, Karel;Izak, Pavel
通过从丙酮中的溶液中溶剂浇铸来制备含有20重量%至80重量%的在聚（偏二氟乙烯-共-六氟丙烯）（p（VDF-HFP））中的离子液体1-乙基-3-甲基咪唑鎓双（三氟甲基磺酰基）酰亚胺（[EMM][TFSI]）的离子液体聚合物凝胶膜。讨论了离子液体对膜性能的影响，并与纯聚合物进行了比较。在过量离子液体的存在下，p（VDF-HFP）膜以显著的方式溶胀，特别是在70 ℃以上，在90 ℃以上变得完全可溶。DSC分析表明，随着IL含量的增加，凝胶的熔点逐渐降低，总熔融焓降低，而聚合物级分的熔融焓归一化显示出初始下降，然后逐渐增加。在离子液体的存在下，弹性模量和断裂强度急剧降低，而最大变形首先由于增塑聚合物的更高柔性而增加，然后由于缠结数量的逐渐减少而在IL的40重量%以上迅速降低。X-射线研究表明，总的晶体含量减少。最强衍射峰的位置在所有样品中保持不变，表明只有聚合物链结晶，而没有离子液体和聚合物的共结晶发生。初步的气体渗透测量表明，在[EMIM][TFSI]的存在下，渗透性显著增加，尤其是对于二氧化碳。这表明在气体分离膜中的潜在应用，例如用于天然气处理或用于从烟道气中封存CO（2）。
Ionic liquid polymeric gel membranes containing from 20 wt % to 80 wt % of the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI] in poly(vinylidene fluoride-co-hexafluoropropylene) (p(VDF-HFP)) were prepared by solvent casting from a solution in acetone. The effect of the ionic liquid on the performance and properties of the membranes was discussed and compared with the neat polymer. In the presence of an excess of ionic liquid, p(VDF-HFP) membranes swell in a significant way, especially above 70 degrees C, becoming completely soluble above 90 degrees C. DSC analysis shows a gradual decrease of the melting point of the gel and a decrease in the overall melting enthalpy with increasing IL content, whereas the melting enthalpy normalized for the polymer fraction shows an initial drop and then a gradual increase. In the presence of the ionic liquid, the elastic modulus and break strength decrease dramatically, while the maximum deformation first increases due to higher flexibility of the plasticized polymer and then rapidly decreases above 40 wt % of IL as a consequence of the progressive decrease of the number of entanglements. X-ray studies demonstrate a reduction in the overall crystal content. The position of the strongest diffraction peak remains unaltered in all samples, suggesting that only the polymer chains crystallize and that no cocrystallization of ionic liquid and polymer takes place. Preliminary gas permeation measurements show a significant increase of the permeability in the presence of [EMIM][TFSI], especially for carbon dioxide. This suggests a potential application in gas separation membranes, for instance for natural gas treatment or for CO(2) sequestration from flue gas.