(338o) Harnessing Liquid Crystallinity to Prepare Macroscopically Organized Organic Solids: An Alternative to Traditional Crystallography

The growth of single crystals is the traditional route to control molecular structure over macroscopic distances (~ 1 cm). However, single crystals cannot be grown for all molecules. Moreover, crystals usually exhibit poor mechanical properties and limited compositional flexibility. Organizing and solidifying liquid crystals provides an alternative to traditional crystallography. We discuss here the use of lithographically defined patterns to direct the self-assembly of blue-phase and discotic liquid crystals. Blue-phases are cubic liquid crystalline phases with lattice sizes of ~100 nm that are observed in systems with a high degree of chirality. We demonstrate how aligned blue-phases, prepared using chemical patterns, can be used to prepare single crystalline, polymeric photonic crystals. The design of the templating substrates for blue-phase self-assembly is based on predictions from Landau de-Gennes based continuum simulations. We also discuss the directed self-assembly of discotic liquid crystals, which are mesophases observed in systems with an aromatic “disk-like” core and alkyl side chains. We demonstrate the alignment of discotic liquid crystals in microchannels, and the growth of biaxial crystals from the aligned mesophases. Finally, future directions are discussed for harnessing liquid crystallinity to prepare novel organic materials, such as anisotropic glasses. The proposed work aims to create solids that combine the most desirable properties of crystalline and amorphous solids and could have broad implications for applications such as organic electronics, photonics, and sensing.