(273d) Synthesis and Optical Characterization of Polymeric Nanofibers Templated into Topological Defects in Ultrathin Liquid Crystalline Film

Topological defects are ubiquitous in nature. Point defects, disclination lines and grain boundaries are also observed in the liquid crystalline (LC) materials under specific anchoring conditions or external stimuli. Recently, LC defect architecture has been utilized to provide an orientational order towards growth of human fibroblast cell monolayer. However, application of these charged topological defects to synthesize materials has been rarely explored. In this work, we intend to polymerize into liquid crystalline defects using chemical vapor deposition (CVD) technique of [2.2] Paracyclophane based monomers and guide nanofiber synthesis along the LC defect lines. Finally, our aim is to synthesize polymeric nanostructures from LC defects over a large area and explore their optical applications. To achieve high density of LC defects, spin coating has been used to fabricate large area ultra-thin coatings of LC materials. The growth mechanism of nanofibers under the ultrathin film confinement have been explored using spectroscopic ellipsometry. Polarizing optical microscopy (POM) shows naturally occurring topological defects in the nematic LC film on silicon substrate. We predict that the polymerization would proceed exactly along the defect lines and to avoid changes in the nanofiber orientation after templating, critical point drying (CPD) has been used for removal of the LC phase. We have observed that these distinctly identifiable nanofibers can map 3-dimensional space of defect lines which shows presence LC defects including s = ±1 type that appear to align with mathematically predicted defect patterns. To control defect orientation, order, and size, we fabricated inducible defects from smectic LC phase coated on rubbed PVA surfaces. Depending on the rubbing method we have achieved self-assembled array of 1-dimensional line defects or 2-dimensional focal conic defects. Nanostructures resulting from these defects shows wavefront guiding properties in the visible region of the spectrum and have been characterized by Circular Dichroism and Mueller Matrix Polarimetry. We believe, leveraging the promising optical properties of these ordered array of nanostructures may lead to their application as chiral meta surfaces.