The T′ phase and its ‘sandwich-like layer’ structure as shown by ionic liquid crystals containing a biphenyl ester-based rigid-core modified by 3-alkylimidazolium salts

摘要

Eight ionic liquid crystals containing a biphenyl ester-based rigid core modified by a 3-alkyl-imidazolium cation were synthesised and characterised. The length of the alkyl chain varied between n = 4-18 carbon atoms. Their thermotropic phase behaviour was investigated using X-ray diffraction (XRD) measurements, variable temperature small-angle X-ray scattering (SAXS), polarising optical microscopy (POM) and differential scanning calorimetry (DSC). The compounds show rich mesomorphism, such as SmA₂ phase (for compound C18) and SmC₂ phases (for compounds C12-C16). For the molecules containing long alkyl chains (n ≥ 12), a novel mesophase, the T′ phase, was seen which has a unique ‘sandwich-like layer’ structure. The T′ phase is different from the known T phase and is formed at room temperature. Based on XRD, SAXS, DSC and POM data, models for the formation of the T′ phase are proposed.View full textDownload full textKeywordsionic liquid-crystals, imidazolium salts, biphenyl ester, T′ phaseRelated var addthis_config = { ui_cobrand: "Taylor & Francis Online", services_compact: "citeulike,netvibes,twitter,technorati,delicious,linkedin,facebook,stumbleupon,digg,google,more", pubid: "ra-4dff56cd6bb1830b" }; Add to shortlist Link Permalink http://dx.doi.org/10.1080/02678292.2012.668566