کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
610067 | 880639 | 2009 | 7 صفحه PDF | دانلود رایگان |

A homologous series of novel zwitterionic gemini surfactants, N,N-dimethyl-N-[3-(alkyloxy)-2-sulfate-propyl]-alkylammonium (referred to as CmEOSACn), were synthesized. One of the hydrophilic groups is a sulfate anion, and the other is an ammonium cation. Their thermotropic liquid crystalline properties were investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and variable-temperature X-ray diffraction (XRD). The results were compared with those for bis(quaternary ammonium) gemini amphiphiles with counterions and catanionic surfactants without a spacer. The CmEOSACns were shown to display improved thermal stability and to form a stable smectic A liquid-crystalline phase over a wide temperature region (63 ± 0.5 °C), which can be attributed to weakening the interactions between the surfactant headgroups. The XRD data confirmed that the two chains of molecules were arranged in a cis configuration with respect to the extended N–CH2–CH–SO4 skeleton in both the solid lattice and the mesophases. In addition, the DSC results showed that the dissymmetry of the hydrophobic chains had a slight effect on the melting point and the clearing point of the CmEOSACn compounds. The present investigation points the way to developing stable liquid crystalline materials using gemini-type surfactants.
Zwitterionic gemini surfactants consisting of a quaternary ammonium and a sulfate group (referred to as CmEOSACn) formed stable thermotropic smectic A liquid-crystalline phases.Figure optionsDownload high-quality image (73 K)Download as PowerPoint slide
Journal: Journal of Colloid and Interface Science - Volume 338, Issue 1, 1 October 2009, Pages 156–162