Phase separation of poly(γ-benzyl L-glutamate) to liquid crystal and isotropic solution in various helicogenic solvents

Solvent effects on the phase separation of poly(-benzyl L-glutamate) to liquid crystal and isotropic solution have been observed in various helicogenic solvents. The temperature-composition phase diagrams have been determined for each solution. The critical concentrations, ₂ ^* , at which the phase separation occours have been compared in various solvents. In dimethylformamide in which the polymer is molecularly dispersed, the observed ₂ ^* value has agreed with that calculated by Flory's theory. In some solvents in which the polymer aggregates in a head-to-tail mode such as chloroform, the observed ₂ ^* values have been considerably small. It is assumed that the polymer aggregates behave as longer particles than the original particles. In dioxane in which the polymer aggregates highly both in a head-to-tail and a side-by-side modes, the ₂ ^* value has been a little larger than that in chloroform. In this case the relationship between the aggregation and the liquid crystal formation is so complicated that further investigation is necessary. In aromatic solvents such asm-cresol that dissolves the polymer almost molecularly, the ₂ ^* is smaller than that in dimethylformamide. Therefore, the intermolecular interactions between the phenyl groups in the side groups of the polymer and those in solvent molecules must be considered.The author is grateful to Mr. K. Sano and Mr. M. Watanabe for their observation of the liquid crystal formation.     

Identification of radicals spin-trapped in autoxidized linoleic acids: A high performance liquid chromatography and electron spin resonance study

Radicals generated in linoleic acid and deuterated linoleic acid have been trapped by the spin trap 2-methyl-2-nitroso-propane (MNP) and identified by electron spin resonance (ESR) and ENDOR spectroscopy. The formation of two distinct secondary alkyl radical adducts (one conjugated, the other non-conjugated, as shown by their UV absorption spectra) was demonstrated by 11, 11-dideuterio-9-cis-12-cis-linoleic acid using HPLC and ESR spectroscopy.     

三元无规芳—脂族聚酯酰胺的热致液晶行为

采用低湿溶液缩聚的方法合成了对苯二甲酰氯，二甲基联苯胺和己二醇为单体的芳酯族液晶聚酯酰胺。用ＤＳＣ，Ｘ光衍射分析和偏光显微镜等手段研究了该系列聚酯酰胺的热致液晶行为，确认了二甲基联苯胺单体用量在２０％（ｍｏｌ）的情况下，所得聚酯酰胺仍为向列型液晶聚合物。由于聚酯酰胺分子间聚酰胺链段之间的氢键作用，随着二甲基联苯胺用量增加至６０ｍｏｌ％时，所得的聚酯酰胺己无液晶转变温度，其液晶区间即从熔融温度直至分     

Fluorescence study of the solubilization of benzo[a]pyrene: application to its detection in coal washing waters

The solubilization of benzo[a]pyrene by organic solvents (dioxane, toluene and dichloromethane) and a surfactant (Triton X-100) was investigated. These media were successfully used for the determination of benzo[a]pyrene using fluorescence detection, with excellent limits of detection and large linear analytical ranges. Benzo[a]pyrene was detected in coal washing waters using liquid chromatography with fluorescence detection. The stability of this compound in dioxane was also examined.     

Synthesis of novel tri-podal mesogenic alkenes and side-chain polysiloxanes

Low molecular weight tri-podal biphenyl- and benzoate-type mesogens [C₆H₅C₆H₄O(CH₂)₅SiMe₂CH₂CH₂SiMe₂]₃CH (4), [C₁₁H₂₃O(C₆H₄)₂O(CH₂)₅SiMe₂]₃CH (5) and [MeOC₆H₄OC(O)C₆H₄O(CH₂)₅SiMe₂]₃CH (6) (C₆H₄ = 1,4-phenylene) were obtained, from branched silyl substituted methane precursors [CH₂CH(Me)₂Si]₃CH (1) and (HMe₂Si)₃CH (2). The biphenyl-containing ones (4) and (5) were converted into terminal alkenes, which were subsequently hydrosilylated with poly(methylsiloxanes). The polymer derived from (5) exhibited mesomorphic properties. Such systems have the potential to significantly increase the density of liquid crystal rod-like structures in side chains of linear polymers (or dendritic liquid crystal polymers).     

Dielectric studies under high pressure on strongly polar liquid crystals exhibiting monolayer smectic A phase

Dielectric studies have been performed at elevated pressures on two compounds of a homologous series possessing a strongly polar terminal group and three phenyl rings in their molecular structure. This is the first high pressure dielectric study on such systems that exhibit a monolayer smectic A phase. Also notable is the fact that these compounds show a dual frequency response, a promising feature for fast liquid crystal display devices. The low frequency relaxation recorded in the nematic and smectic A phases is attributed to the reorientation of the molecules about the short axis. The temperature and pressure dependence of the relaxation frequency of this mode as well as the involved activation parameters are discussed. At a given relative temperature the relaxation frequency decreases as the pressure is increased. However, the parameter that characterizes the temperature dependences of the relaxation frequency, viz., the activation enthalpy, has a very weak dependence on pressure. In contrast, the activation volume shows a linear decrease with temperature.     

PREPARATION AND CHARACTERIZATION OF SHISH-KEBAB TYPE LIQUID CRYSTALLINE POLY（p-PHENYLENEVINYLENE）

Novel shish-kebab type liquid crystalline poly（p-phenylenevinylene） derivatives were synthesized by Stille coupling reaction from 2,5-bis[（4-n-alkoxyl）benzoyloxy]1,4-dibromobenzene （monomer l） and 1,2-bis（tributylstannyl） ethylene （monomer 2）. The polymers with alkoxy groups are soluble in common organic solvents and exhibit blue fluorescence. Both the cast film and the annealed film have large red-shifts in fluorescence spectra and show yellow fluorescence. The polymers with CN and NO2 groups show poor solubility and green fluorescence. All the polymers possess liquid crystalline smectic phases. The melting point （Tm） of the polymers decreases when the length of the alkoxy tails of the mesogenic units increases. The polymers are easily aligned under a magnetic field of 10 Tesla. It is found that the conjugated backbone and LC side chain are aligned perpendicular and parallel to the magnetic field, respectively. The polymers show optical dichroism in fluorescence spectra, suggesting that they are available for advance materials with linear optical polarization.     

W／O／W乳液的渗透溶胀与夹带溶胀

研究了W/O/W乳液的溶胀,实验结果表明,渗透溶胀随内外相溶液间的渗透压差、表面活性剂及载体浓度的增大而增加,但随膜粘度的增加而降低,渗透压差较高时,水渗透的影响大于夹带的影响;膜相中含氧化合物对溶胀的影响大于含氮化合物,采用Span 80作乳化剂时,比采用E 644渗透溶胀约高6倍,夹带溶胀也较高;重复聚结再分散使夹带溶胀急剧增加,因而多级混合澄清槽对液膜操作似不适用。     

Liquid chromatography of benzene derivatives on a porous methacrylate copolymer containing epoxy groups

Summary The retention of benzene derivatives with nonpolar and polar substituents on a porous methacrylate copolymer containing epoxy groups using both nonpolar and polar eluents was investigated. When n-hexane is used as the eluent, the retention of n-alkylbenzenes and polymethylbenzenes is weaker than that of benzene. In the case of benzene derivatives containing polar functional groups their capacity ratios (k) on this porous polymer increases approximately linearly with the increase of the adsorbate molecules dipole moment. The retention characteristics of the methacrylate copolymer were compared with that of a styrene-divinylbenzene copolymer and silica gels with a hydroxylated surface and with a surface modified by chemically bonded alkylsilyl groups.     

Volume and compressibility changes of complex formation between 18-Crown-6 and NaCl,KCl, and CsCl in water

The apparent molal volumes and compressibilities of NaCl, KCl, and CsCl in mixtures of 18-Crown-6 and water have been calculated from density and speed-of-sound measurements at 25°C. The partial molal volumes and compressibilities of the salts when all cations have formed complexes with 18-Crown-6 molecules have been evaluated. The sign and magnitude of the volume and compressibility changes of complex formation strongly suggest that the charge of the cation becomes very effectively screened by the crown ether.