Gelation Properties of Polymer Solutions

Hiltner, A.

doi:10.1002/0471532053.bra065

Cited by 2 publications

(1 citation statement)

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“…Numerous polymers may form thermoreversible gels from dilute or concentrated solution in the proper solvent. 10 A continuous physical network structure extending throughout the volume of the system is formed when at a certain reduced solvent power of the medium the polymeric chains form association complexes at widely separated points. In the majority of the cases these gels derive from the existence of a crystalline network structure, formed upon cooling from the homogeneous solution.…”

Section: Introductionmentioning

confidence: 99%

High Ionic Liquid Content Polymeric Gel Membranes: Preparation and Performance

et al. 2010

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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 fluorideco-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°C, becoming completely soluble above 90°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.

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Section: Introductionmentioning

confidence: 99%