Toshikazu Narahara

Highly conductive polyacetylene film prepared by the liquid crystal polymerization method under magnetic field

Abstract Advanced synthetic method of highly oriented polyacetylene film has been developed by applying magnetic force into a polymerization system consisting of nematic liquid crystals. Polymerizations were carried out at 10 – 13°C in order to keep the nematic phase under magnetic field of 2 – 14 kGauss. Polyacetylene films prepared showed high alignment of fibrils, providing not only crucial infrared dichroism in polarized infrared absorption spectra, but also the highest value of electrical conductivity with 10 4 S/cm order upon iodine doping.

Synthesis of highly-oriented polyacetylene film in a liquid crystal solvent

Abstract The synthesis of oriented polyacetylene films is investigated by using a nematic liquid crystal as polymerization solvent. Highly-oriented thin films are obtained under a flow of catalyst solution in which a nematic liquid crystal is used instead of common solvents such as hexane and toluene. Nematic liquid crystals that could be used as solvents for the Ziegler-Natta catalysts are limited due to their reactive substituents with the active species and/or the components of the catalyst. Among the available nematic liquid crystals, phenylcyclohexane type is stable in the presence of Ziegler-Natta catalysts. Since fibril alignment in the oriented films is found to be along the flow direction of the catalyst solution, it appears that the direction of fibril growth coincides with that of the liquid crystal orientation, which is caused by an alignment effect of the liquid crystal molecules under a flow of the solution. This new and simple method allows quite large highly-oriented films to be synthesized, which makes it possible to investigate various kinds of anisotropic properties of polyacetylene.

Synthesis, characterization, and properties of aligned polyacetylene films

Abstract Highly aligned polyacetylene films are synthesized by three different methods in which nematic liquid crystals are used as an ordered matrix solvent: Method 1, polymerization of acetylene is carried out in a quiescent nematic solution in which a Ti(OBu)4-AlEt3 Ziegler-Natta catalyst is dissolved homogeneously; Method 2, macroscopic alignment is attained by gravity flow of the nematic liquid crystal-catalyst system; and Method 3, the nematic liquid crystal-catalyst solution is aligned under a magnetic field. Characterization of these films is carried out through SEM observation and measurements of polarized visible and infrared absorption spectra. Results indicate that as-prepared films have highly aligned fibrils. Upon doping by I2 and AsF5, these films exhibit high electrical condactivity of the order of 104 S/cm.

Memory effect of chromophore orientation in merocyanine Langmuir-Blodgett films☆

Abstract The changes in the in-plane spectral anisotropy caused by heat, acidic vapour and basic vapour treatments after deposition are studied for Langmuir-Blodgett (LB) films of merocyanine dye containing a benzoselenazole nuclei mixed with arachidic acid. The as-deposited films exhibit a J-like aggregate band at 597 nm which is strongly polarized along the dipping direction of the substrate. After heat treatment or HCl vapour treatment, the J-like band disappears and the in-plane spectral anisotropy is reduced. NH3 vapour treatment causes the J-like band to be restored in the wavelength region 620–627 nm. The restored J-like band is polarized along the same direction as the original J-like band. This memory effect of chromophore orientation suggests that there is a highly anisotropic structure of J-like aggregates in LB films.

Morphology and characterization of polyacetylene films synthesized in a liquid crystal solvent

Abstract The synthesis of oriented polyacetylene films was investigated by using a nematic liquid crystal as a polymerization solvent. As a result, when polymerization was carried out on a quiesent surface of the nematic catalyst solution, partially oriented polyacetylene films were obtained. On the other hand, in the polymerization under a flow of the nematic catalyst solution, highly oriented films were obtained. The order parameter of the oriented sample, estimated from polarized absorption spectra, was about 0.57. The maximum value of parallel electrical conductivity of the films doped with iodine was 4600 S/cm, while that of the films doped with arsenic pentafluoride was 11000 S/cm.

Thermally stimulated current in aluminium phthalocyanine chloride film

Analyse des courbes de courant thermostimule, induit par irradiation par laser a 600 nm: les sites des pieges peuvent etre exprimes par le modele de Poole-Frenkel. Evaluation des parametres de piegeage dans les limites de repiegeage rapide ou lent

Bending strength of thermosetting resins containing isocyanurate and oxazolidone rings and analysis of their chemical structures.

ジフェニルメタンジイソシアナートを含む化合物とビスフェノールAのジグリシジルエーテルとをN-メチルモルホリンの存在下, 加熱して得られる樹脂硬化物の曲げ特性を25℃で測定した, 曲げ強さはイソシアナート化合物とエポキシ化合物のモル比 (0.63～51) 及び加熱処理温度 (180, 200, 及び225℃) などに強く依存することを見いだした. 硬化物の赤外線吸収スペクトルを測定し, イソシアヌラート環とオキサゾリドン環の形成割合を解析し, 曲げ強さとの関係について考察を加えた. 硬化物中の未反応のイソシアナート基量をスベクトルの吸光度比から定量化し, 硬化反応がほぼ終了するまで, 更に加熱し, 曲げ強さを追跡して樹脂組成物の硬化性を検討した.

New heat resistant solventless varnish “10 resin” (part II)

The research and development of organic heat resistant materials has made a great progress especially in the field of solvent type varnishes. For example, polyimide, polybenzimidazole, polydiphenylether, and silicone have been developed so far. However, solventless varnishes that can resist high temperatures have not been developed yet, because it is very difficult to give high temperature heat resistant properties to cured resins which have a low viscosity before curing. Epoxy resins are now widely used as solventless varnishes, however, they cannot be used at temperatures above 180°C.

New rubberlike resins for casting and impregnation

Typical properties were evaluated on a newly developed rubber-like resins. The properties illustrated are: 1. viscosity and cure schedules adjustable to meet specific requirement, 2. good tensile and electrical properties, 3. good retention of tensile properties on long-term exposure at 130°C, 4. high resistance to severe thermal shock, 5. excellent resistance to water.