One of the most important frontiers in materials chemistry is the architectural control of synthetic materials on the nanometer-scale. Nanometer-scale architecture is primarily responsible for the impressive properties of many biological structural materials (e.g., bone) and the unique reactivity of many inorganic supercage catalysts (e.g., zeolites). Unfortunately, very few techniques for constructing man-made materials offer compositional or architectural control on this size regime. One of the principal questions that we are addressing is whether materials with unique or superior bulk properties can be generated if nanometer-scale architectural control could be achieved with modern engineering components.
My research group and I has developed a successful research program directed at constructing functional materials with controlled nanostructures by designing self-organizing monomers based on thermotropic (i.e., temperature-dependent) and lyotropic (i.e., amphiphilic; solvent-dependent) liquid crystals (LCs) (Figure 1). Through molecular design, we have been able to incorporate functional properties into the LC assemblies and subsequently polymerize them into robust polymer networks with preservation of their nanostructure. These ordered matrices serve as the basis for our new materials synthesis, as well as a platform for investigating structure–property relationships on this size regime. These new LC monomers and assemblies also serve as novel platforms for examining the effect of nanostructure on polymerization kinetics, connectivity, etc., in addition to functional properties.
The goals of our research program are fundamental in concept and applied in their long-range perspective. We are interested not only in the design of organic monomers with self-assembly properties but also intensely interested in the effects of engineered order on their useful bulk properties. We endeavor to tailor our chemistry to provide control over nanoarchitecture, chemical composition, and processing in our new materials. These factors are crucial if these strategies are to evolve into viable technologies. In order to accomplish these goals, we have taken the approach of initially designing relatively simple molecules to test fundamental concepts such as (1) the viability of polymerizing certain LC assemblies, and (2) whether these assemblies are capable of enhancing or modifying particular properties. Once these proofs of concept have been demonstrated, our subsequent goal is the design of more elaborate building blocks to more thoroughly probe chemical behavior on this size regime.
Our research program in LC-based, nanostructured polymers is divided into three main areas. The first area is the development of polymerizable lyotropic LCs for the construction of functional, nanostructured polymeric materials. The second area involves the design of monomers based on functional thermotropic LCs to control order, symmetry, and symmetry-based bulk properties in the final polymer assembly. The third area is the development of new strategies for the synthesis of LCs that exhibit functional properties and new supramolecular architectures to serve as building blocks for new materials.