Influence of semiperfluorinated chains on the liquid crystalline properties of amphiphilic polyols: Novel materials with thermotropic lamellar, columnar, bicontinuous cubic, and micellar cubic mesophases

被引:77
作者
Cheng, XH
Das, MK
Diele, S
Tschierske, C
机构
[1] Univ Halle, Inst Organ Chem, D-06120 Halle An Der Saale, Germany
[2] Univ Halle, Inst Chem Phys, D-06108 Halle An Der Saale, Germany
关键词
D O I
10.1021/la015770i
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
Novel amphiphilic diols with semifluorinated alkyl chains have been synthesized. These are 1-benzoylaminopropane-2,3-diols carrying one, two, or three semiperfluorinated chains at the aromatic core, as well as a 2-benzoylaminopropane-1,3-diol and a 2-benzoylaminoethanol with two semiperfluorinated chains. Their thermotropic liquid crystalline properties were investigated by means of polarizing microscopy, differential scanning calorimetry, and X-ray diffraction. In comparison with the related hydrocarbon compounds, the semifluorinated analogues have significantly more stable mesophases. Because of the larger cross-sectional area of the perfluorinated segments, not only the three-chain compounds but also most two-chain compounds have reverse discontinuous (micellar) cubic mesophases (Cub(I2)). Additionally, phase diagrams of binary systems of a single-chain amphiphile with the two- and three-chain amphiphiles have been investigated. Hexagonal columnar (Col(h2)) and bicontinuous cubic phases (Cub(V2)) were induced in such systems. Remarkably, the Cub(V2) phases occur only above a distinct temperature, whereas at lower temperature a direct transition between the lamellar phase and the columnar phase takes place. This leads to a reentrant, behavior of the smectic A phases and columnar phases in certain concentration ranges.
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页码:6521 / 6529
页数:9
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