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By interaction between light and structural periodicity, structural coloration is caused. The artificially periodic materials are called photonic crystals and it has attracted great attention for optical applications. Recently, we prepared one-dimensional photonic crystal with multibilayered films consisting of azobenzene-containing polymers and polyvinyl alcohol and reported the on–off switching controlled by refractive index change depended on the molecular orientation states. In addition, we studied the birefringence properties of azobenzene-containing polymers based on their molecular design for the improvement of the switching speed and reflection intensity of photonic crystals.
Zwitterions are organic salts whose cation and anion are covalently bridged. In the Focus Review, I describe the potential utility of these zwitterions as building blocks for self-organizing materials, such as liquid crystals and block copolymers. Owing to the unique characteristics of zwitterions to form homogeneous mixtures with certain acids and lithium salts, their self-organization behavior can be tuned by addition of these compounds. In particular, these zwitterion derivatives are useful for constructing bicontinuous cubic liquid-crystalline assemblies with three-dimensionally continuous periodic minimal surface.
The Michael addition of N-heterocyclic carbenes (NHCs) to the unsaturated polyesters, polymaleates and a polyfumarate, produced the polymers bearing the NHCs as side chains in good-to-high yields. The glass transition temperatures of the obtained polymers were widely tunable and increased linearly with the increasing NHC content. The stiff and bulky structures of the NHCs can reduce the mobility of the polymer main chain. The simultaneous Michael addition and transfer hydrogenation of the unsaturated polyesters have also been performed by the reaction with an NHC in the presence of water.
The polythiophene nanoparticles exhibit multichromic responses to solvent, temperature and acid/base, which can be detected by the naked eye in tetrahydrofuran/water mixtures. As the concentration of water increases, the nanoparticles turn from yellow to violet by solvatochromism. The nanoparticles display a reversible thermochromic response between 20 and 90 °C, which originates from the morphological changes between an amorphous solid and isotropic liquid. Halochromic behavior of the nanoparticles is achieved by adding hydrobromic acid and bubbling with ammonia gas owing to p-doping and dedoping of the polythiophene nanoparticles, respectively.
The 1,1,3,3,5,5,7,7-octamethyltetrasiloxane-containing gelator, (R, R)-g/Si, was synthesized by a hydrosilylation with a gelation-driving segment based on trans-(1R, 2R)- 1,2-diaminocyclohexane. Gelation abilities were investigated in the mixed solvents of HDEH, liquid paraffin, and D5. (R, R)-g/Si could form stable and transparent gels due to the flexible octamethyltetrasiloxane segment.
The influence of polymer formation in liquid crystals (LCs) was investigated using several analytical techniques. The monomers 4,4′-dimethacryloyloxy-biphenyl (4,4′-DMOB) and 3,3′-dimethacryloyloxy-biphenyl (3,3′-DMOB) were used. The results indicated that the orientation of the LC affects the rate constant of polymerization. Moreover, the structures of the monomers affected the orientation of the LC.
