A study of chromatographic properties of liquid crystalline polyacrylates using WCOT columns in gas chromatography

Liquid crystalline polyacrylates (LCPAs) are evaluated as stationary phases for capillary gas chromatography (CGC). Aromatic hydrocarbons as well as polar isomeric compounds are used as test solutes to compare the polarity of the LCPAs with a conventional polysiloxane column and a Carbowax 20M column. The relative polarity of the columns with respect to change in the lateral and terminal substituents is also discussed. Lateral substitution, polarity of the terminal group, together with the solute size, affect the LCPA selectivity.     

表面附聚薄壳型单分散高效阳离子柱填料的研制及其性能

 报道了一种新的表面附聚薄壳型阳离子柱填料的简易制备方法。首次合成了单分散高效阳离子柱填料。以10μm的单分散聚苯乙烯 二乙烯基苯(PSTDVB)微球为基球,对其表面季铵化,然后均匀附聚一层磺化的阳离子乳胶(0 2μm),即得到阳离子固定相。分别用碱金属及碱土金属离子对用该填料制成的柱的性能进行了测试,结果表明该柱填料对常见阳离子具有很好的分离效果、良好的重现性和低的检测限。     

三(对溴苯甲酰基)纤维素的合成及其分离性能的考察

采用超声方法合成了三(对溴苯甲酰基)纤维素[CTBB]，并用红外光谱、元素分析对此衍生物的结构进行了表征。将等量微品纤维素(MC)与三(对溴苯甲酰基)纤维素混合制成一种新型的手性薄层板。结合展开剂系统的优化，6种手性药物对映体获得了良好的分离，分离因子α≥1．30。此固定相适用于正相和反相液相色谱。     

Stationary states for a mechanical system with stochastic boundary conditions

We consider a system of Newtonian particles, with a long-range repulsive pair potential, moving in a cavity whose surface temperature is spatially varying. When a particle hits the surface, it is thermalized at the temperature of the collision point. We prove that this system has a unique stationary ensemble, to which any initial distribution converges for large times. We show that this stationary ensemble depends continuously on the surface temperature profile.     

Thermal analysis of macromolecules

This review traces the development of thermal analysis over the last 50 years as it was experienced and contributed to by the author. The article touches upon the beginning of calorimetry and thermal analysis of polymers, the development of differential scanning calorimetry (DSC), single-run DSC, and other special instrumentations, up to the recent addition of modulation to calorimetry and superfast calorimetry. Many new words and phrases have been introduced to the field by the author and his students, leaving a trail of the varied interests over 50 years. It began with cold crystallization and more recently the terms oriented, intermediate phase, glass transitions of crystals, and decoupled chain segments were coined. In-between the following phenomena were named and studied: extended-chain crystals, irreversible thermodynamics of melting of polymer crystals, zero-entropy-production melting, dynamic differential thermal analysis (DDTA), the rule of constant increase of C _p per mobile bead within a molecule at the glass transition temperature, superheating of polymer crystals, melting kinetics, crystallization during polymerization, chin-folding principle, molecular nucleation, rigid amorphous phase, system of classifying molecules, macroconformations, amorphous defects, rules for the entropy of fusion based on molecular shape and flexibility, single-molecule single-crystals, systems for classifying phases and mesophases including condis phases, and the globally metastable semicrystalline polymers with reversible, local subsystems. This review is update of a publication written in 1995 and published under the same title in the J. Thermal Anal., 46 (1996) 643. Parts F and G are fully new, and Part G is the basis for my lecture: ‘The development of the idea of thermodynamic decoupling in macromolecules’.     

Structure-Bonding Relationships in the Laves Phases

The Laves phase structures (MgCu₂ MgZn₂ and MgNi₂ types) are adopted by a large number of binary intermetallic compounds of composition AB₂. These phases belong to the class of tetrahedrally closepacked alloys. Two of the structural features of the Laves phases which have aroused interest are, firstly the dependence of the structure adopted (especially the choice between the cubic MgCu₂ and hexagonal MgZn₂ types) on the number of valence electrons of the constituent metal atoms and, secondly the structural distortions observed in a number of the hexagonal MgZn₂ type phases. By performing extended Hückel band calculations on model AB₂ compounds with both the cubic and hexagonal structures and on the B sub-nets alone, structure electron-count and deformation-electron count correlations are derived. These correlations depend on the highly peaked nature of the density of states of the Laves phases, primarily due to the B network.     

涂敷三苯基氨基甲酸纤维素酯高效液相色谱手性固定相的制备和对映异构体分离

微晶纤维素与异氰酸苯酯在４－Ｎ，Ｎ－二甲基氨基吡啶催化下反应合成三苯基氨基甲酸纤维素酯，反应温度低，反应时间短；以平均粒径６μｍ、平均孔径１５ｎｍ、比表面积６７ｍ２／ｇ的堆积硅珠做担体，涂敷１５％（质量分数）三苯基氨基甲酸纤维素酯在上述担体上制备手性固定相；以此手性固定相高效液相色谱法直接分离（±）－２，２，２－三氟－１－（９－蒽基）乙醇对映异构体，确定了对映异构体的出峰顺序．     

Photoelectrochemical solar cells: Stabilization of small band GAP semiconductor in aqueous solution by surface-attached organic conducting polymer

Surface-attached polypyrrole films have been shown to produce a marked improvement in the stability of n-type single-crystal and polycrystalline Si against oxidation in an aqueous electrolyte. The current production of n-type polycrystalline Si coated with polypyrrole deteriorates less than 30% during 122 hr of irradiation whereas the unprotected bare electrode stops producing photocurrent within 30 s. The polymer protection of the n-type single-crystal Si is significantly less than that of the polycrystalline material because of differences in the adhesion of the polymer film to the electrode surfaces. The adhesion strength is shown to depend on various surface properties of Si and other electrode materials. Moreover, the surface morphology of the electrode affects the topography of the growing surface of the polypyrrole film. Requirements are discussed for the applications of organic conducting polymers to photoelectrochemical devices utilized for solar energy conversion.     

Polypyrrole - Semiconductor photovoltaic devices

Abstract

A new approach is given for obtaining fast electro-optical response and good angular-viewing characteristics in a liquid-crystal variable-retardation device. The improved characteristics make the new device well suited for use in field-sequential color systems.     

Thiol‐ene click derived structurally well‐defined per(3,5‐dimethyl)phenylcarbamoylated cationic cyclodextrin separation material for achiral and chiral chromatography

In this work, a novel single sulfoether‐bridged cationic per(3,5‐dimethyl)phenylcarbamoylated‐β‐cyclodextrin separation material was prepared by thiol‐ene click chemistry and characterized by using FTIR spectroscopy, solid‐state ¹³C NMR spectroscopy and elemental analysis, which confirmed the correct structure. The separation material exhibited a good achiral separation performance for benzene homologues and phenylamine analogs, especially o‐xylene and m‐xylene, and m‐phenylenediamine and o‐phenylenediamine can be discriminated by the (3,5‐dimethyl)phenylcarbamoyl cyclodextrins. The chiral resolving ability of the separation material was evaluated by discriminating various isoxazolines, flavonoids, and β‐blockers in reversed‐phase high‐performance liquid chromatography. For isoxazolines, the material showed the best chiral discrimination toward 3‐aryl‐5‐(2‐oxopyrrolidin‐1‐yl)‐isoxazolines, where the resolution for 3ClPh‐OPr  reached 6.03. For flavonoids, it exhibited more efficient separation to the ones with more hydrophobic substituents, with a resolution of 5.93 for 6‐hydroxyflavanone. β‐Blockers were also enantioseparated satisfactorily on the material. The as‐prepared separation material is a good member of the thiol‐ene click derived cyclodextrin stationary phase family.