Surface-Functionalized Ionic Liquid Crystal-Supported Ionic Liquid Phase Materials: Ionic Liquid Crystals in Mesopores

• Published in: Chemphyschem 2011-12, Vol.12 (18), p.3539-3546
• Main Authors: Kohler, Florian T. U., Morain, Bruno, Weiß, Alexander, Laurin, Mathias, Libuda, Jörg, Wagner, Valentin, Melcher, Berthold U., Wang, Xinjiao, Meyer, Karsten, Wasserscheid, Peter
• Format: Article
• Language: English
• Subjects: Calorimetry, Differential Scanning; Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; ionic liquids; Ionic Liquids - chemistry; IR spectroscopy; liquid crystals; Liquid Crystals - chemistry; materials science; Phase Transition; phase transitions; Porosity; Porous materials; Silicon Dioxide - chemistry; Spectroscopy, Fourier Transform Infrared; Transition Temperature
• ISSN: 1439-4235; 1439-7641
• DOI: 10.1002/cphc.201100379

The influence of confinement on the ionic liquid crystal (ILC) [C18C1Im][OTf] is studied using differential scanning calorimetry (DSC), polarized optical microscopy (POM), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The ILC studied is supported on Si‐based powders and glasses with pore sizes ranging from 11 to 50 nm. The temperature of the solid‐to‐liquid‐crystalline phase transition seems mostly unaffected by the confinement, whereas the temperature of the liquid‐crystalline‐to‐liquid phase transition is depressed for smaller pore sizes. A contact layer with a thickness in the order of 2 nm is identified. The contact layer exhibits a phase transition at a temperature 30 K lower than the solid‐to‐liquid‐crystalline phase transition observed for the neat ILC. For applications within the “supported ionic liquid phase (SILP)” concept, the experiments show that in pores of diameter 50 nm a pore filling of α>0.4 is sufficient to reproduce the phase transitions of the neat ILC. The influence of confinement on the ionic liquid crystal (ILC) [C18C1Im][OTf] (Im=imidazolium, OTf=trifluoromethanesulfonate) is studied. The ILC is supported on Si‐based powders and glasses with pore sizes ranging from 11 to 50 nm. The ILC–supported ionic liquid phase (SILP) materials (see picture) are characterized in terms of their phase‐transition temperatures. A contact layer with a thickness of about 2 nm is identified.