Incorporation of graphene oxide into C12E4/C12mimBr hybrid lyotropic liquid crystal and its thermo-sensitive properties

Abstract

Graphene oxide (GO) was successfully incorporated into a hybrid lyotropic liquid crystal (LLC) matrix formed by two kinds of surfactants n-dodecyl tetraethylene monoether (C₁₂E₄) and 1-dodecyl-3-methylimidazolium bromide ionic liquid (C₁₂mimBr). By changing the ratios of C₁₂E₄ and C₁₂mimBr, two types of C₁₂E₄/C₁₂mimBr LLC matrixes (lamellar and hexagonal phase) were formed and the effects of the concentration of GO and temperature on the properties of GO/C₁₂E₄/C₁₂mimBr LLC composites were systematically investigated by polarized optical microscopy (POM) observations, small-angle X-ray scattering (SAXS) and rheological measurement. Both POM observations and SAXS results indicated that GO can be well-dispersed in the hybrid LLC matrixes at room temperature. Moreover, after the incorporation of GO, the temperature tolerance of GO/C₁₂E₄/C₁₂mimBr LLC composites were enhanced compared with pure C₁₂E₄/C₁₂mimBr hybrid LLC and aggregated GO was not observed in the C₁₂E₄/C₁₂mimBr LLC hybrid hexagonal matrix with the increase of temperature while it can be observed in the C₁₂E₄/C₁₂mimBr LLC hybrid lamellar matrix. The results of rheological measurements showed that the addition of GO were helpful for enhancing the mechanical properties of C₁₂E₄/C₁₂mimBr LLC. Thus, the success preparation of GO/hybrid LLC composites can highly improve the thermal stability of these materials and widen the applications of GO/LC materials in nanotechnology, electrochemical, drug delivery systems and bioengineering areas.