Polymerizable lyotropic liquid crystals containing transition-metal ions as building blocks for nanostructured polymers and composites

Transition-metal-containing analogues of a polymerizable lyotropic liquid crystal were prepared from sodium p-styryloctadecanoate by ion exchange with water-soluble metal chlorides, nitrates, and acetates. The mesophases of these amphiphilic monomers were investigated by polarized light microscopy, low-angle X-ray diffraction, and infrared spectroscopy. It was found that cadmium(II), manganese(II), and cobalt(II) p-styryloctadecanoate form an inverted hexagonal lyotropic phase at ambient temperature (22 degrees C), while the copper(II) salt forms a columnar hexagonal thermotropic phase. The monomers can be cross-linked photolytically in their respective liquid crystal phases with retention of phase architecture to yield polymer networks containing ordered microdomains of transition-metal ions. The relationship between the dimensions of the hexagonal mesophase formed and the identity of the counterion present in each salt is discussed. The polymerized inverted hexagonal phase of the cadmium salt was also used as a template for the formation of CdS nanoparticles, affording a novel, nanostructured composite.