(583c) The New Liquid Crystals: Self-Assembly and Processing of Nanocylinder Dispersions
Nanoscience has enabled the controllable production of materials with an unprecedented range of chemistries, sizes, and shapes including cylindrical nanomaterials. Nanocylinder dispersions undergo self-assembly and rheological behaviors that can be generally be explained in terms of the known behavior of lyotropic liquid crystalline polymer solutions. However, there are several key distinctions. Nanocylinders can have significantly larger aspect ratios, persistence lengths, polydispersities, attractive interactions, and densities than their polymeric cousins. Comparison of various nanocylinder dispersions to each other, and to lyotropic liquid crystalline polymers, highlights opportunities for new insights into the fundamental behavior of colloidal rods. In addition, understanding the interplay between dispersion microstructure and applied shear can enable producing bulk nanocylinder films with controlled morphologies.
Over the last ten years, we have investigated nanocylinder dispersions with a broad range of chemical and physical properties. This talk highlights our work on cellulose nanocrystals in water, carbon nanotubes in aqueous dsDNA, mixtures of silver nanowires and spheres in ethylene glycol, and silica nanorods in dimethyl sulfoxide. We have shown that nanocylinders can assemble into cholesteric, nematic, and smectic phases. We have also shown that these structures can be maintained, enhanced, or erased during processing into solid coatings. Finally, we have raised new questions about what determines biphasic microstructure and rheological behavior at low shear. Answering these questions promises to enhance our fundamental understanding and ability to control the microstructure of bulk materials produced from nanoscale building blocks.