Construction And Characterization Of Novel Lyotropic Liquid Crystals

Traditional lyotropic liquid crystal (LLC) are always composed of surfactants and water or organic solvents, and they might be limited in application when water is underdesirable or high temperature. Ionic liquids have received vigorous attention recently as potential environmentally benign solvents and neoteric materials, due to their unique properties such as high mostability, negligible vapour pressure et al. In this work, the main purpose is to construct new LLCs with ionic liquids as surfactants and solvents. The effects of third component on the phase behaviors are also discussed. Three main experimental researches are included as followed:In the first part, [C12mim]Cl/H2O and [C12mim]Cl/alcohols binary systems. Phase behaviors of dierent binary systems involving 1-dodecyl-3-methylimidazolium chloride ([C12mim]Cl) and H2O, [C12mim]Cl and different alcohols (1-butanol, 1-pentanol, 1- hexanol and 1-octanol) are investigated by using polarized optical microscopy (POM) and small-angle X-ray scattering techniques (SAXS). In addition, with the help of differential scanning calorimetry (DSC) measurements and fourier transform infrared spectra (FTIR), the thermal stability and formation mechanism of [C12mim]Cl/1-octanol system are discussed in details. Hexagonal liquid crystal phase (H1) is identified in [C12mim]Cl/H2O system, and lamellar liquid-crystalline (Lα) phase is found in [C12mim]Cl/alcohols systems. In [C12mim]Cl/1-octanol system, the lattice spacings of lamellar phase increase with increased [C12mim]Cl concentration, due to stronger static repulsion between hydrophilic headgroups and hydrophobic force between alkyl chains of imidazolium salts. From 1-butanol to 1-octanol, the LLC structure is easier to be formed when the increasing of carbon chain length. The formation of such phases is considered as a synergetic result of the hydrophobic force and the H-bond network.In the second part, P123/[Bmim]PF6/glycerol ternary system. Phase behaviors involving PEO-PPO-PEO block copolymer Pluronic P123 (EO20PO70EO20), 1-butyl-3-methylimidazolium hexa?uorophosphate [Bmim]PF6, and glycerol are investigated by using SAXS techniques. A phase diagram is given, and the effects of glycerol concentration on the phase structure are discussed. At lower P123/[Bmim]PF6 ratio, the H1 phase can be formed easily. At higher P123/[Bmim]PF6 ratio, the Lαphase changes to H1 with increasing the glycerol content. Moreover, a phase separation takes place at a higher glycerol content.In the third part, [C12mim]Cl/H2O/L64(EO13PO30EO13) ternary system. Phase behaviors of [C12mim]Cl/H2O/L64 system are investigated by using POM, SAXS techniques and deuterium nuclear magnetic resonance (2H NMR) spectra. A simple phase diagram is mapped, and the effects of L64 concentrations on the phase structure are discussed. With constant [C12mim]Cl/H2O ratio and increasing L64 concentration, phase transitions will occur from H1 to multiphases of H1 and cubic phases (C), then to Lα+C phases. Disruption of H-bond network, as well as hydrophobic force between alkyl chains of imidazolium [C12mim]Cl and PO block of L64 are helpful to the occurrence of phase transitions. Moreover, at given L64 (5 %, 20 %) concentration, the lattice parameter of H1 or Lαphase decreases with increasing [C12mim]Cl/H2O ratio. Fourier transform infrared (FTIR) spectra indicate that the H-bond network comprising an imidazolium ring, chloride ion and water formed in [C12mim]Cl/H2O binary system is disrupted upon addition of L64.This work extend aggregation behaviors of long chain imidazolium salts from water and ionic liquids to alcohols, and are helpful in improving our knowledge of solvent effect on phase structures of such imidazolium salts. The aggregation behaviors of the mixed surfactants are further investigated based on the realization of interaction between [C12mim]Cl and L64. The results about the effect of glycerol on the self-assembly of P123 in [Bmim]PF6 are helpful in further understanding the aggregation behaviors of both the P123 and imidazolium ILs.