Magnetically Aligned Helical Liquid Crystal Field Allows the Production of Polymer with Laser Diffraction and Prism Function

A fluorene-based π-conjugated polymer, poly[2,7-di(2-furyl)fluorene], with a one-directionally aligned convex–concave structure was electrochemically synthesized using a magnetically aligned cholesteric liquid crystal (CLC) as the template. The CLC was used as a soft template for the construction of a periodic convex–concave structure on the surface of the π-conjugated polymer film. Here, an external magnetic field was applied to a CLC electrolyte solution containing the monomer before the electrochemical polymerization process was performed to determine the orientation of the CLC helical axis. Polarizing optical microscopy and atomic force microscopy revealed that the periodic convex–concave structure derived from the CLC fingerprint texture was one-directionally aligned. Linear polarized UV–vis absorption spectroscopy indicated that the main chain of the π-conjugated polymer was parallel to the magnetic field’s direction. Reflection spectroscopy showed the one-dimensional diffraction grating function of the film, which was due to the one-directionally aligned periodic convex–concave structure. Finally, the one-directionally aligned polymer film was silver-coated to enhance the diffraction light intensity. The magnetically ordered helical CLC can be used to prepare π-conjugated polymers with a highly aligned morphology that exhibited light diffraction and prism functions.