Fluorophore Self-Assembly in Liquid Crystals*

Liquid crystals (LCs) are a state of matter, characterized by an order called the nematic phase. While past work has investigated how 5CB LC drop configuration transforms under an electric field, 5CB behavior in magnetic (B) fields is yet to be studied. This project uses the fluorophore BODIPY-C5 to visualize the transition of radial 5CB drops in response to B fields. With zero B field, radial drops with 5CB molecules arrange from the center to the edges. As the B field increases, the 5CB molecules rearrange to be aligned with the direction of the field. Similarly, drop defects (regions in which 5CB molecules do not have uniform direction) change configuration, starting as a point defect in the zero B field configuration and converts to a ring defect with an increasing B field. Fluorophores are added to topological defects formed by planar rubbing of PVA-coated substrates to stretch polymers and induce 5CB alignment. Fluorescence microscopy is used to take images of drops and quantify the intensity distribution. Preliminary results show that at zero B field, the intensity is lowest at the center of the radial drops containing the point defect. Future work will use confocal microscopy to analyze layers of drops and quantify intensity change over an increasing B field.