Cooperative Liquid Crystal Photo-Polymerization and -Alignment with In Situ Monitoring for Substrate Independent Patterning of Optical Anisotropy

Spatial control over molecular order in polymeric systems will enable advancements in healthcare and photonics, from soft actuators to data storage and encryption. Liquid crystalline (LC) materials are attractive for their intrinsic combination of long-range anisotropy and fluidity that enables alignment. Photoalignment represents an attractive noncontact ordering mechanism. However, contemporary hurdles preventing widespread implementation of photoalignment include the use of high-intensity light sources, restrictions to thin films (<1 & mu;m) and specific substrates, multistep LC syntheses, and costly processing. Herein, an interplay between photo-polymerization and -alignment with commercially relevant LCs is reported. Systematic, in situ monitoring of optical anisotropy using a custom microscopy setup provides unique mechanistic insight and facilitates optimization. The optimized process occurs rapidly (<10 min) from an isotropic state with a one-step exposure to low-intensity blue linearly polarized light. As a result, substrate-independent photoalignment of thick (& AP;6-38 & mu;m), optically transparent LC networks is demonstrated, along with a wide LC-matrix scope that includes thiol-containing elastomers. Furthermore, photopatterning provides excellent fidelity (<5 & mu;m) and access to complex images with multiangle optical anisotropy. This user-friendly process will facilitate production of "smart" (stimuli-responsive) plastics for improved human health and information security.