Holographic Polymer Dispersed Liquid Crystals and Polymeric Photonic Crystals formed by Holographic PhotolithographyMacromolecular Research
AbstractThe present article describes the experimental and theoretical observations on the formation of holographic, polymer-dispersed, liquid crystals and electrically switchable, photonic crystals. A phase diagram of the starting mixture of nematic liquid crystal and photo-reactive triacrylate monomer was established by means of differential scanning calorimetry (DSC) and cloud point measurement. Photolithographic patterns were imprinted on the starting mixture of LC/triacrylate via multi-beam interference. A similar study was extended to a dendrimer/ photocurative mixture as well as to a single component system (tetra-acrylate). Theoretical modeling and numerical simulation were carried out based on the combination of Flory-Huggins free energy of mixing and Maier-Saupe free energy of nematic ordering. The combined free energy densities were incorporated into the time-dependent Ginzburg-Landau (Model C) equations coupled with the photopolymerization rate equation to elucidate the spatio-temporal structure growth. The 2-D photonic structures thus simulated were consistent with the experimental observations. Furthermore, 3-D simulation was performed to guide the fabrication of assorted photonic crystals under various beam-geometries. Electro-optical performance such as diffraction efficiency was evaluated during the pattern photopolymerization process and also as a function of driving voltage.
Citation InformationThein Kyu, Scott Meng, Hatice Duran, Kumar Nanjundiah, et al.. "Holographic Polymer Dispersed Liquid Crystals and Polymeric Photonic Crystals formed by Holographic Photolithography" Macromolecular Research Vol. 14 Iss. 2 (2006) p. 155 - 165
Available at: http://works.bepress.com/thein_kyu/49/