Hexagonal mesophase structure

Figures 9a-c represent transmission electron micrographs of different lyotropic liquid crystals after freeze fracture without etching. The layer structure of the lamellar mesophase including confocal domains, hexagonal arrangement of rodlike micelles within the hexagonal mesophase, as well as close-packed spherical micelles within the cubic liquid crystal can be clearly seen.

Figure 6 also displays the connection between the stable hexagonal phase in short n-alkanes and the hexagonal mesophase in polyethylene as a function of chain length in the p-T diagram. A full discussion is given by one of us elsewhere (6). At this place our emphasis is on the continuity, despite the fact that the pressure coefficient of the width of the temperature interval is of opposite sign in these two families of material. This continuity is apparent also by a structural feature, namely the concentration of conforma-... 

In fact, since the mesophase synthesis or reaction is a kinetically control process and the solid formed is not a thermally stable phase, the phase transformation is very common during the synthesis of mesoporous materials. The phase transformations include the transition from one structure or symmetry into another structure or symmetry, or the transition from a disordered phase to an ordered phase, or from an ordered phase to a disordered phase. The intermediate phase can be isolated as a product or be observed by analysis techniques. The phase transformation can occur during the synthesis process or in a post-synthesis treatment. The early famous example is the transition of lamellar mesophase of silicate into hexagonal mesophase in basic or near neutral media.[5]... 

Ga203-based dodecyl sulfate mesophase[184] with a hexagonal structure was synthesized by the homogeneous precipitation method using urea. On removal of the incorporated surfactants by chemical or thermal treatment the mesophase structure collapsed. 

Lattermann et al. reported the first metallomesogenic dendrimer when they described results on trigonal bipyramidal metal complexes of ethylene-imine dendrimers of the first and second generation, based on derivatives of tris(2-aminoethyl)amine. Complexes of cobalt, nickel, copper, and zinc were prepared and found to exhibit relatively low temperature mesophases, which generally possessed hexagonal columnar structures. These materials therefore provided the first examples of metallomesogenic dendrimers [72,73]. 

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