Lyotropic Metal-Containing Liquid Crystals

It is now certain that metal carboxylates were the first metal-containing liquid crystals, and were first reported in 1855 with Heinz s work on magnesium tetradecanoate [4]. Then, many other mesomorphic metal carboxylates, with the general formula M(02C—C H2 +i) , were prepared [150]. They showed thermotropic lamellar and columnar mesophases, but also, when dissolved in water or alkanes, lyotropic mesophases. 

Metal-containing poly-yne polymers with molecular weight (Mw) of ca 1.2 xlO were soluble in usual organic solvents such as benzene, methylene chloride, tetrahydrofuran etc. The thermal stability of the polymers was increased with the metals, in the order of Pt > Pd >Ni. Films with a thickness of several microns and with a tensile strength as large as 9.0 X 10 g/mm were fabricated from the Pt-containing polymer. One of the characteristics of these polymers is their lyotropic liquid crystal behavior in solution. Some representative polymers prepared are listed in Table 15. 

The chapter starts with a discussion of the basics of liquid crystal phase behavior, the types of mesophase that are formed and methods for their characterization those requiring more detail and/or breadth are directed to the volumes of reference. This chapter does not cover all liquid crystals which might be considered as being somehow inorganic in origin, and so, for example, systems containing boron clusters, and the lyotropic mesophases of metal oxides, etc., are omitted. Similarly, polymeric systems are not covered in any detail as since some earlier reviews, there has been relatively little development in the field. 

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