In order to obtain an important azobenzene liquid crystal with high birefrience, click chemistry reaction was used to preparation the compound. In this paper, the novle azobenzene liquid crystal was ...synthesized by (4-Ethynyl-phenyl)-(4-trifluoromethyl-phenyl)-diazene and C8H17Br as raw materials. In addition, the synthesized compound was characterized by FT-IR and 1H-NMR to confirm the consistent structure, and the liquid crystal phase behaviors of phase sequences were investigated by polarizingmicroscope (POM).
An novel intermediate of (4-Iodo-phenyl)-(4-trifluoromethyl-phenyl)-diazene for azobenzene liquid crystal was synthesized. 4-Trifluoromethyl-phenylamine as raw material was oxidized by Oxone ...(Potassium peroxymonosulfate) in CH2Cl2/H2O solvent to synthesize 1-Nitro-4-trifluoromethyl-benzene (m1). The effect of Oxone amount on the conversion degree of raw material was discussed in ditail. Then m1 was coupled with 4-Iodo-phenylamine to obtain the important intermediate, yellow solid, the yield was 52%. The chemical structures of synthetic intermediate was confirmed by FT-IR and 1H-NMR.
Mesoporous silica fibers were prepared by varying primary variables of the synthesis conditions in the static two-phase acidic system such as the hexane/Si(OR)4 and HCl/Si(OR)4 ratios as well as the ...alkyl chain length of silicon alkoxide. The morphological and structural features of the mesoporous silica materials were strongly dependent upon the hydrolysis rate of silica source used. Namely, the high fraction of well-ordered mesoporous silica fibers was achieved by a delicate balance of the hydrolysis rate of silicon alkoxide and the condensation rate of silicate species. The obtained mesoporous silica fibers consisted of hexagonally organized channels running circularly around the fiber axis. The fibers prepared with Si(OC4H9)4 showed the high thermal stability because of the lower content of structural defects within the framework.
メソポーラスシリカファイバーの合成とそのキャラクタリーゼーション 菅野, 英明; 近江, 靖則; 小平, 哲也 ...
Journal of the Ceramic Society of Japan (日本セラミックス協会学術論文誌),
2003, Letnik:
111, Številka:
1295
Journal Article
In recent years, supramolecular complexes comprising a poly(4-vinylpyridine) backbone and azobenzene-based halogen bond donors have emerged as a promising class of materials for the inscription of ...light-induced surface-relief gratings (SRGs). The studies up to date have focused on building supramolecular hierarchies, i.e., optimizing the polymer-azobenzene noncovalent interaction for efficient surface patterning. They have been conducted using systems with relatively low azobenzene content, and little is known about the concentration dependence of SRG formation in halogen-bonded polymer-azobenzene complexes. Herein, we bridge this gap, and study the concentration dependence of SRG formation using two halogen-bond-donating azobenzene derivatives, one functionalized with a tetrafluoroiodophenyl and the other with an iodoethynylphenyl group. Both have been previously identified as efficient molecules in driving the SRG formation. We cover a broad concentration range, starting from 10 mol % azobenzene content and going all the way up to equimolar degree of complexation. The complexes are studied as spin-coated thin films, and analyzed by optical microscopy, atomic force microscopy, and optical diffraction arising during the SRG formation. We obtained diffraction efficiencies as high as 35%, and modulation depths close to 400 nm, which are significantly higher than the values previously reported for halogen-bonded polymer-azobenzene complexes.
Overcoming multidrug resistance is achieved by developing a novel drugdelivery-system paradigm based on azobenzene liposome and phosphatidylcholine-modified upconversion nanoparticle (UCNP) hybrid ...vesicles for controlled drug release using a nearinfrared (NIR) laser. Upon 980 nm light irradiation, the reversible photoisomerization of the azobenzene derivatives by simultaneous UV and visible light emitted from the UCNPs makes it possible to realize NIR-triggered release of the chemotherapeutic drug doxorubicin.
A novel low molecular weight organogelator (LMOG) containing an azobenzene group has been designed and synthesized. Stable gels could be formed in various organic solvents. UV–Vis spectroscopy ...indicated that the sol-gel transition of the organogels could be reversibly tuned by UV/visible light irradiations. Importantly, scanning electron microscopy (SEM) revealed that the characteristic gelation morphologies would vary from solvents of different polarities. FT-IR, XRD and rheological measurements demonstrated that the different nanostructures in polar and non-polar solvents might result from the differences in the intermolecular hydrogen bonding, π-π stacking driving forces as well as the different stacking models for the formation of the gels. Moreover, as an efficient phase-selective gelator, this photo-switchable gel could perform as an efficient absorbent and water cleaner to remove pollutants (e.g. rhodamine B).
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This paper describes a strategy for preparing photosensitive polymeric grafts on flat solid surfaces by loading diblock-copolymer or homopolymer brushes with cationic azobenzene-containing ...surfactants. In contrast to previous work, we utilize photosensitive surfactants that bear positively-charged polyamine head groups whose charge varies between 1+ and 3+. Poly(methylmethacrylate-b-methacrylic acid) (PMMA-b-PMAA) brushes were prepared by employing atom transfer radical polymerization, where the bottom poly(methyl methacrylate) block was grown first followed by the synthesis of t-butyl methacrylate block that after de-protection yielded poly(methacrylic acid). We used PMMA-b-PMAA brushes with constant grafting density and length of the PMMA block, and three different lengths of the PMAA block. The azobenzene-based surfactants attached only to the PMAA block. The degree of binding (i.e., the number of surfactant molecules per binding site on the brush backbone) of the surfactants to the brush depends strongly on the valence of the surfactant head-group; within the brushes the concentration of the surfactant carrying unit charge is larger than that of multivalent surfactants. We detect pronounced response of the brush topography on irradiation with UV interference pattern even at very low degree of binding (as small as 0.08) of multi-valence surfactant. Areas on the sample that receive the highest UV dose exhibit chain scission. By removing the ruptured chains from the substrate via good solvent, one uncovers a surface topographical relief grating, whose spatial arrangement follows the intensity distribution of the UV light on the sample during irradiation. Due to strong coupling of the multi-valence surfactants to the polymer brush, it was possible in some cases to completely remove the polyelectrolyte block from the PMMA layer. The application of multi-valence azobenzene surfactants for triggering brush photosensitive has important advantage over usage of surfactant with unit charge because relative to single-valence surfactants much lower concentrations of the multivalent surfactant are needed to achieve comparable response upon UV irradiation.
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•Polymer brushes are triggered photosensitive by loading them with azobenzene containing surfactants.•Nanostructuring of photosensitive polymer brushes under irradiation.•Rupturing of polymer chains during SRG formation.
Dendrimers with azo moieties in their peripherals (azodendrimers), which we developed, are useful as a photoactive interface for liquid crystal (LC) systems. The azodendrimer spontaneously adsorbs on ...a variety of interfaces, so that we can obtain photoactive surfaces without pretreatment only by introducing a small amount of the azodendrimers in LCs. We first describe our previous studies applied for a variety of LC systems such as sandwich cells, LC droplets and shells in a solvent and microparticles in LCs. Some unpublished results on nematic droplets of bent-shaped molecules demonstrate current developments in the research of the interactions between the photoswitchable dendrimer and complex liquid crystalline structures.
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