Fabrication of oriented thin films using lyotropic chromonic liquid crystals and its templating applications

Abstract

Soft materials have inherent properties that show an excellent self-assembly phenomenon and can react sensitively to external stimuli such as electric field. Thus, they can be applied not only to display field but also to various fields like new electronic materials, organic devices, and biosensors. Among the various soft materials, lyotropic chromonic liquid crystal (LCLC) phase appears in biocompatible materials such as various food coloring dyes and DNA. Recently, biotechnological applications have become important, thus studies for applying LCLCs in material science have been conducted. In particular, the LCLCs are inexpensive and abundant on the earth, it can be easily used without risk of depletion compared with other industrial materials, and thus it has received considerable attention in the material science. In addition, the LCLCs are well known for its interesting structural characteristics exhibiting self-organization by non-covalent interactions to form column structure, and have electrical and optical anisotropy along the column axis. In order to give new functions to LCLC materials and to apply them in various research fields, control of ordering of the LCLC molecules is very important. For this, various methods using external force such as magnetic field or confined geometry have been introduced. However, there was a limit for controlling the LCLC alignment in large areas. This Ph D. thesis will discuss the structural control of LCLCs including DNA in a large area. In this study, a system to orient LCLC by applying simple mechanical force, here shear force, have been developed in which the competitive interaction between elasticity of the molecules and shear forces induces various configurations of LCLCs. The fabricated thin films can be applied as templates due to the structural features of LCLCs, and furthermore, a thin film having high performance such as surface plasmonic properties can be produced by mixing with other metal nanoparticles.