Pyrrole in a cholesteric liquid crystal was discharged using a Tesla coil to generate pyrrole radicals, affording linear-shaped nano-ordered pyrrole oligomers. Subsequently, the electrochemical polymerisation of a pre-oriented pyrrole oligomer having good affinity for liquid crystals was performed to achieve polypyrrole-imprinted asymmetry from the cholesteric liquid crystal structure. The resultant polymers were analysed using polarising optical microscopy observations, scanning electron microscopy, electrochemistry, optical spectroscopy, and electron spin resonance.
View Article and Find Full Text PDFA new method for fabricating conjugated polymer films was developed using electrochemical polymerization in liquid crystals and magnetic orientation. A uniaxial main chain orientation and a crosslinked network structure were achieved with this method. By employing eight types of monomers, the influence of the crosslinking for the film was investigated.
View Article and Find Full Text PDFNew molecular design of conjugated polymer that possess high sensitivity to vapour and self-recovering property against pressure is proposed. We synthesised a rod-rod diblock copolymer, poly(3-((3S)-3,7-dimethyl-octyl)-thiophene)-block-poly(4-octyl phenylisocyanide) (PTh- b -PPI), composed of a π-conjugated polymer and a rod-type helical coiled polymer. Introduction of PPI block in the block copolymer architecture enabled PTh- b -PPI film to exhibit solid-to-liquid crystal phase transition by exposure to chloroform vapour, accompanied with colour change (purple-to-yellow), which is the first report on a new phenomenon of "vapour-induced liquid crystallinity".
View Article and Find Full Text PDFWe synthesize PbMn7O12 perovskite under high-pressure (6 GPa) and high-temperature (1373 K) conditions and investigate its structural, magnetic, dielectric, and ferroelectric properties. We find that PbMn7O12 exhibits rich physical properties from interplay among charge, orbital, and spin degrees of freedom and rich structural properties. PbMn7O12 crystallizes in space group R3̅ near room temperature and shows a structural phase transition at TCO = 397 K to a cubic structure in space group Im3̅; the Im3̅-to-R3̅ transition is associated with charge ordering.
View Article and Find Full Text PDFTlMO(3) perovskites (M(3+) = transition metals) are exceptional members of trivalent perovskite families because of the strong covalency of Tl(3+)-O bonds. Here we report on the synthesis, crystal structure and properties of TlCrO(3) investigated by Mössbauer spectroscopy, specific heat, dc/ac magnetization and dielectric measurements. TlCrO(3) perovskite is prepared under high pressure (6 GPa) and high temperature (1500 K) conditions.
View Article and Find Full Text PDFMacroscopically highly oriented polythiophene derivative films are synthesized by electrochemical polymerization in a smectic liquid crystal reaction medium. Control of orientation direction of conjugated main chains is performed by use of magnetic field which is applied parallel, obliquely, and perpendicularly to the substrate electrodes to align the liquid crystal reaction medium.
View Article and Find Full Text PDFWe report on aging, rejuvenation and memory effects in the ferromagnetic phase of pure terbium. We have applied an experimental method specifically for investigating slow dynamics of spin glasses, because these effects cannot be interpreted as conventional diffusion after-effects. Results show that relaxation times of the magnetic response are widely distributed, and isothermal aging shifted the distribution towards longer durations.
View Article and Find Full Text PDFJ Phys Condens Matter
January 2009
We present the results of the temperature dependences of ac and dc susceptibilities, high-field magnetization, magnetic relaxation, specific heat, and electrical resistivity of Pr(2)CuSi(3) and Nd(2)CuSi(3), compounds previously shown in the literature to exhibit interesting properties. It is observed that the investigated compounds undergo a ferromagnetic phase transition at a characteristic temperature T(C) (= 9.8 K for Pr(2)CuSi(3) and 5.
View Article and Find Full Text PDFDNA films showing highly homogeneous orientation of molecular chains were successfully prepared by drying a semidiluted solution in a horizontal magnetic field. Most of the molecular chain elements in the obtained film were found to be one-dimensionally oriented, as shown by X-ray diffraction, polarization microscopy, and linear dichroism spectroscopy. Because a DNA chain is theoretically expected to orientate only in divergent directions perpendicular to a magnetic field, this result suggests that the DNA chains were aligned not only by a magnetic field but also by the interfacial effect that induced the chains to fit along the air-liquid interface.
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