Title : Liquid Crystals and Nanotechnology: From Display Materials to Graphene Applications
Speaker : Prof. Hee-Tae Jung (Chair Professor, Dept. of Chemical & Biomolecular Engineering, KAIST)
Date & Time : 2012. 3. 14. 수요일 17:00
Where : 융대원 D-123
Abstract
Recently, smectic liquid crystal (LC) structures have been suggested as a new class of soft self-assembly building blocks that form an ordered, periodic array of LC defects array. Unlike previously reported self-assembling materials such as blockcopolymer, colloid particle, surfactant etc., the defect ordering of the LC self-assemblies takes advantage of the ability to achieve fast stabilization of molecular ordering and structure due to the reversible and noncovalent interactions of the LC molecules. In this presentation, fabrication and fundamental studies of the periodic smectic LC defect structures based on focal conic domains (FCDs), including toric FCD (TFCD), parabolic FCD (PFCD) and oily streak (OS), are briefly reviewed. Then, in particular, the controlling of regular domain size as well as arrangement and the large area patterning methods of TFCDs are discussed.
In addition, a simple method has been developed to macroscopically visualize graphene domains and their boundaries by using nematic liquid crystals (LCs) on the graphene surface. The results show that nematic LC molecules, containing aromatic and alkyl chains, orient with respect to the domain orientation of graphenes. Thus, the sizes of graphene domains and their boundaries can be simply observed by changes in the birefringences that arise from variations of the director field of the LC molecules. This method should significantly aid the control of domain, boundary structure and properties of graphene.
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