Optical Behaviors of Cholesteric Liquid-Crystalline Polyester Composites with Various Chiral Photochromic Dopants

New developments in the field of chiral nematic liquid crystals, such as color displays, are now being widely proposed. This article describes the tunable incident reflection band based on composite materials of low-molecular-weight chiroptical dopants and polymeric networks. These materials have advantages including easily manageable color according to a change in the helical pitch of the cholesteric liquid crystal upon exposure to light. A series of novel chiral dopants of isosorbide derivatives containing photochromic groups and three new main-chain liquid crystalline polyesters were synthesized and identified using nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), and elemental analyses. The phase-transition temperatures and the liquid-crystal phase determination of the synthesized polymers were estimated using DSC, WAXD, and POM analyses. The influence of the dopant concentrations and the solubility in a liquid crystalline polymer blend were also studied. The reflection band of the cholesteric liquid crystalline composites could be adjusted and tuned with a wide range of color variation across the entire visible region. A real image recording of the chiral photochromic liquid crystalline polymer blend was achieved by exposing it to UV light through a mask

Fabrication and Characterization of a Novel Inclusion Complex of Chiral Monomer Derived from (+)-Camphor with β-Cyclodextrins

In order to develop a highly ordered polymer dopant to improve the physical properties of polymer materials for microsystems, a novel supramolecular inclusion complex (IC) of chiral bornyl 4-(6-acryloyloxyhexyloxy) phenyl-4′-benzoate (BAPB) threaded with β-cyclodextrins (β-CDs) was synthesized. The inclusion complex was identified using Fourier transform infrared (FTIR), UV, 13C cross-polarization/magic-angle spinning (CP/MAS) NMR, 1H NMR, and X-ray diffraction (XRD). The construction of the fibrous self-assembled inclusion complex was confirmed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The highly ordered polymerized inclusion complex β-CD-BAPB revealed significant birefringence and was confirmed using polarized optical microscopy (POM). Polymerization of self-assembled nanofibrous monomers with methyl methacrylate was carried out, and the distribution of the nanofibers in the polymer matrix was confirmed using POM. This investigation demonstrates a novel method for the fabrication of polymeric nanofibers with highly ordered, self-assembled functional monomers. The polymeric nanofibers are expected to improve the physical properties of polymer films in the field of microelectric and micromachine systems (MEMS)

Fabrication and Characterization of Self-Assembled β-Cyclodextrin Threaded Monomers and Induced Helical Polymers

A novel chiral monomer end-capped with a cholesteryl group and threaded with β-cyclodextrin was synthesized in order to induce the formation of a helical polymer. 1H NMR studies revealed that one or two cyclodextrin molecules were threaded onto the synthesized chiral monomer, leading to the formation of a helical construction of self-assembled inclusion complexes. The formation of a self-assembled inclusion complex was identified using SEM and TEM. The monomeric self-assembled inclusion complex was further polymerized using benzoyl peroxide as a photoinitiator. Both the highly ordered alignment and the helical structure of self-assembled supramolecules were confirmed using polarized optical microscopy and circular dichroism spectroscopy, respectively. We have first demonstrated an easy process for the fabrication of helical polymers via self-assembled monomers threaded with a β-cyclodextrin end and capped with a chiral moiety