A new strategy based on ionic self-assembly technology was provided for design of photosensitive material as liquid crystals (LC) alignment layer. The complex material was constructed by the coupling of poly-(ionic liquid) and photosensitive unit azobenzene dye methyl orange. The structure, phase behavior and photoresponse were examined by a variety of techniques including FTIR, NMR, thermal analysis, polarized optical microscopy, X-ray diffraction, small-angle X-ray scattering, and birefringence measurements. Highly ordered lamellar nanostructure and photosensitive character were confirmed. Under the irradiation of pulsed UV laser with certain fluences, a pronounced optical anisotropic surface with the preferred direction perpendicular to the pulsed polarization or regular periodic grooves microstructure surface parallel to the pulsed polarization was obtained. The anisotropic surface of oriented molecular chain or topography was demonstrated to result in the alignment of LC by the optical transmittance plot and polarizing microscopy images of LC cells with different rotation angles.
A new type of thermotropic liquid-crystalline photosensitive supramolecule was fabricated by ionic self-assembly of polyelectrolyte and functional unit azobenzene ionic liquid crystal (azo-ILC). It was found that the thermal and phase behaviors can be modulated by changing of the spacer length (4, 6, or 12 methylene units designated PAZO 4 , PAZO 6 , and PAZO 12 , respectively). Highly ordered liquid-crystalline structure with a lamellar morphology of different d-spacing was observed. The photoinduced orientation of azobenzene groups in thin films of the obtained ionic-bonding supramolecules was studied by polarized UV-vis and FTIR. Under the irradiation of pulsed laser, very effective induction of optical anisotropy with the preferred direction perpendicular to the pulsed polarization was observed. Typically, the maximum in-plane orientation order (S) of -0.93 for PAZO 12 at maximum absorbance was achieved after irradiation and subsequent anneal at its liquid-crystalline temperature. It was found that the maximum S can be increased by increasing the clearing temperature of the photosensitive material. These results may provide guidelines for the design of effective photoinduced anisotropic materials. Furthermore, uniform alignment control of low-molecular-weight liquid crystals on the oriented supramolecular films was achieved.
Through an ionic self-assembly approach, a photosensitive complex was prepared by attaching two different matching anions, photoresponsive units of methyl orange (MO) and perfluorinated dodecanoic acid (FDA), to a poly(ionic liquid) backbone (PIL). The FTIR spectrum proved that the two anions were competitively attached to the PIL backbone. The complexes show typical liquid crystalline behavior and have a single layer lamellar mesostructure for PMOF 0 . The incorporation of FDA leads to different lamellar structures in casting film depending on the FDA content: when the FDA content increases to 10%, MO and FDA side chains organized into a different lamellar structure independently: MO lamellar structure favors single layer packing order and FDA favors bi-layer packing order according to XRD investigation. These complexes are effective in controlling the inplane and out-of-plane alignment of liquid crystal molecules.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.