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Cubic Liquid Crystals of Polyoxometalate-Based Ionic Liquids
journal contribution
posted on 2020-03-24, 14:11 authored by Zhaohui Huang, Geping Zhang, Ling Wang, Aixin Song, Jingcheng HaoThermotropic ionic
liquid crystals of polyoxometalate (POM)-based
ionic liquids (POM-based ILs), which are formed by a POM, K7PW11O39, and cationic surfactants, tetra-n-alkylammonium bromide ((CnH2n+1)4N+Br–, n = 6 and 7), are first proposed.
As a model system, the cubic phase structure of a POM-based IL, {(C7H15)4N+}7PW11O39, was determined to form in a wide range of
temperatures, exhibiting good thermostability, excellent mechanical
strength, and high viscosity. Furthermore, the lyotropic ionic liquid
crystals formed by {(C7H15)4N+}7PW11O39 in solvents such
as chloroform or toluene still maintained a cubic structure. These
cubic ionic liquid crystals (CILCs) were used as anticorrosion coatings
both in acidic and neutral environments. The electrochemical measurements
of Cu and Fe surfaces coated by CILCs showed an excellent ability
of anticorrosion, indicating that the metals can be perfectly protected
by the CILC coatings with high resistance and low capacitance. We
assume that the CILCs may serve as barriers to stop oxygen diffusing
to metals and interrupt the electron tunnels between the metal surfaces
and the electrolyte solutions. Such environmentally friendly CILCs
of POMs-based ILs are convenient for coating and removal, being vital
to versatile industrial and academic applications.