Lyotropic liquid crystal phases of lithium perfluorinated fatty acid salts in aqueous solutions and molecular dynamics study of the lamellar phase

Anisotropic lyotropic liquid crystal (LLC) of lithium perfluorinated fatty acid salts with long fluorocarbon chains (PFL-Li and PFM-Li, denotes lithium perfluorolaurate and perfluoromyristate, respectively) were prepared in aqueous solutions, and characterized by a variety of techniques in detail. Results of small-angle X-ray scattering (SAXS) study indicate that PFL/M-Li molecules are arranged to form lamellar liquid crystal in water, which were determined by freeze-fracture transmission electron microscopy (FF-TEM) images. Differential scanning calorimetry (DSC) measurements showed that, with the increase of the concentration of lithium perfluorolauric (PFL-Li), the temperature-dependent transition of LLC phases to micelle phases increases. However, LLC phases of lithium perfluoromyristate (PFM-Li), which is not temperature-sensitive, can not be transferred to micelle solution below 100 °C. Based on the SAXS measurements, constant volume and temperature (NVT) molecular dynamics (MD) simulation have been carried out to investigate the mechanism for the formation of lamellar LLC phases and their properties.