Polymerizable liquid crystals as a template for synthesizing ordered composite materials

Structural ordering and organization on the nanometer or micrometer scale has been shown to translate into notable effects on the intrinsic physical properties of materials at the bulk level. Naturally-occurring organic-inorganic composites prepared through biomineralization, such as bone and tendon, have often been used as model systems for the production of comparable synthetic materials. For example, turkey tendon is comprised of roughly plate-like hydroxyapatite crystals stacked in regular parallel arrays that extend throughout the length of individual collagen fibrils. This arrangement acts both to reinforce the tendon and to provide natural break planes when the material is pushed beyond its mechanical tolerances.; In an attempt to replicate the degree of order found in such biological systems, a novel, versatile strategy has been developed for constructing tunable, ordered organic-inorganic nanocomposites with well-defined architectures. This approach takes advantage of the self-assembling properties of lyotropic liquid crystals (LLCs). In this method, an amphiphilic, polymerizable LLC that forms the inverse hexagonal phase first spontaneously organizes around a reactive, around reactive, strongly hydrophilic solution, producing an ordered template with periodic dimensions on the order of 25–60 Å. Photopolymerization of the mixture subsequently yields a heavily cross-linked network around the precursor solution, locking the structure of the matrix into place. This organic matrix then directs the formation of “fillet” material within the hydrophilic channels while preserving the architectural sophistication of the template, allowing for the facile production of customized, ordered, integrated polymer-inorganic composite materials under comparatively mild conditions.; Since the mesophase geometry and the dimensions that a LLC mixture will adopt depends heavily on the shape of the mesogen and the sample composition used, extensive modification of the amphipihlic template is possible. Several series of main-group and transition-metal salts of the parent mesogen were prepared and shown to exhibit a wide range of mesomorphic behavior. Alteration of the amphipihle structure itself also enabled selective control over the template dimensions. Several of these compounds were subsequently used as the basis for the formation of silicate oligomers and semiconductor nanoparticles of controlled size within an ordered polymer matrix.