Lyotropic liquid crystals formed in 3-dodecyloxy-2-hydroxypropyl trimethyl ammonium bromide—<i>n</i>-butanol—<i>n</i>-decane—water system

Abstract

Lyotropic liquid crystals formed in 3-dodecyloxy-2-hydroxypropyl trimethyl ammonium bromide (a new surfactant) —<i>n</i>-butanol—<i>n</i>-decane —water system have been studied. Pseudo-ternary phase diagrams have been drawn based on experimental data at 298.2 K, and the specific regions in which a single type of liquid crystal existing or different types of liquid

crystals coexisting have been determined in the diagrams. Some typical photographs clearly showing texture structure of liquid crystal have been obtained using polarizing-light microscope and the symmetry structure of the liquid crystals has been determined with ²H nuclear magnetic resonance (²H NMR) method. The formation of crystal liquid has been proved to be an exothermal process by differential scanning calorimetry (DSC). The experimental results of the exploited methods show that the regions or microemulsion and liquid crystal contract with increase in percentage of the oil (<i>n</i>-decane) in the system. The phase structure varies from the single lamella liquid crystals to mixed lamella, hexagonal and cubic crystals, and finally to microemulsion with the addition of water into mixture containing only lamella crystal region.