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      Liquid crystalline mesophases of pluronics (L64, P65, and P123) and transition metal nitrate salts ([M(H2O)6](NO 3)2)

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      Author(s)
      Demirörs, A. F.
      Eser, B. E.
      Dag, Ö.
      Date
      2005
      Source Title
      Langmuir
      Print ISSN
      0743-7463
      Publisher
      American Chemical Society
      Volume
      21
      Issue
      9
      Pages
      4156 - 4162
      Language
      English
      Type
      Article
      Item Usage Stats
      204
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      260
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      Abstract
      The triblock poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) copolymers, Pluronics (L64, P65, and P123), form liquid crystalline (LC) mesophases with transition metal nitrate salts (TMS), [M(H2O) n] (NO3)2, in the presence and absence of free water in the media. In this assembly process, M-OH2 plays an important role as observed in a TMS:CnEOm (C nEOm is oligo(ethylene oxide) nonionic surfactants) system. The structure of the LC mesophases and interactions of the metal ion-nitrate ion and metal ion-Pluronic were investigated using microscopy (POM), diffraction (XRD), and spectroscopy (FTIR and micro-Raman) techniques. The TMS:L64 system requires a shear force for mesophase ordering to be observed using X-ray diffraction. However, TMS:P65 and TMS:P123 form well structured LC mesophases. Depending on the salt/Pluronic mole ratio, hexagonal LC mesophases are observed in the TMS:P65 systems and cubic and tetragonal LC mesophases in the TMS:P123 systems. The LC mesophase in the water/salt/Pluronic system is sensitive to the concentration of free (H2O) and coordinated water (M-OH2) molecules and demonstrates structural changes. As the free water is evaporated from the H2O:TMS:Pluronic LC mesophase (ternary mixture), the nitrate ion remains free in the media. However, complete evaporation of the free water molecules enforces the coordination of the nitrate ion to the metal ion in all TMS:Pluronic systems. © 2005 American Chemical Society.
      Keywords
      Concentration (process)
      Copolymers
      Liquid crystals
      Nitrates
      Polyethylenes
      Salts
      Surface active agents
      X ray diffraction analysis
      Ion density
      Nitrate salts
      Pluronics
      Solid materials
      Transition metals
      Permalink
      http://hdl.handle.net/11693/24074
      Published Version (Please cite this version)
      http://dx.doi.org/10.1021/la047136l
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      • Department of Chemistry 707
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