Lyotropic Liquid Crystalline Mesophases of Lithium Dihydrogen Phosphate and 10-Lauryl Ether Stabilized with Water or Phosphoric Acid.

Abstract

The molten phase of transition metal and lithium salts self-assemble with non-ionic surfactants to form lyotropic liquid crystalline (LLC) mesophases, which are important in the development of gel-electrolytes and mesoporous materials. Here, we show that LiH2 PO4 forms a semi-stable LLC mesophase with 10-lauryl ether (C12 H25 (OCH2 CH2 )10 OH, C12 E10 ), decoded as Li-EO-X (X is LiH2 PO4 /C12 E10 mole ratio and between 2 and 200). The stability of the Li-EO-X phase is improved by increasing salt concentration (X>20) in the media. The semi-stable Li-EO-X mesophase is further stabilized by adding either water by controlling the humidity or H3 PO4 (PA) to the media. The phase behaviour of the above samples was investigated using POM, XRD, conductivity, and ATR-FTIR measurements. The addition of PA not only brings stability and higher conductivity (increase from 0.1 to 8.9 mS/cm) to the mesophase but also produce an LLC gel-electrolyte with a high buffer capacity that may be useful and important in various applications.