The reciprocal CuInS2+2CdSe⇔CuInSe2+2CdS system. Part I. The quasi-binary CuInSe2-CdSe system: Phase diagram and crystal structure of solid solutions

The type of interaction in quasi-binary system CuInSe₂ (CIS)-CdSe was investigated using differential thermal and X-ray phase analysis methods. The limits of existence of solid solutions based on low-temperature (α) and high-temperature (γ) CIS modifications and CdSe (β) with chalcopyrite, sphalerite and wurtzite structures, respectively, were established in sub-solidus region at 620 K and 870 K. For certain compositions of solid solutions, the structure was refined using powder X-ray diffraction. A phase diagram of the CIS-CdSe system was constructed. A peritectic process L+β⇔γ takes place in the system at 1260 K.     

Structure formation and dynamics of water in strong external electric fields

We have performed molecular dynamics computer simulations of water in homogeneous external electric fields which were varied in a wide range of field strengths. The dielectric response is found to be linear up to fields E₀≈0.01 V/Å from where dielectric saturation effects become important. At fields of E₀≈3 V/Å a phase transition into an ordered, ice-like structure is observed, which is stabilized through hydrogen-bonds. With an increasing external electric field, the frequency spectrum of the water dynamics shows a remarkable red shift of the intramolecular modes and a blue shift of the librational motions, where the frequency varies quadratically with the field strength. A simple analytical model is discussed which reproduces the observed behavior.     

Controlled phase separations in solutions of soluble polyelectrolyte complex of DIVEMA (copolymer of divinyl ether and maleic anhydride)

Copolymer of divinyl ether and maleic anhydride (DIVEMA) is known to possess some anti-tumor and immune-stimulating activity and use as a drug carrier in anti-tumor drug delivery systems. Samples of DIVEMA of different degrees of polymerization were synthesized and characterized. Interaction of the hydrolyzed water-soluble DIVEMA polyanions with poly(N-ethyl-4-vinylpyridinium) cations (PEVP) has been studied. According to the potentiometry data, almost all carboxylic groups of the polyanions were able to form ion pairs with PEVP. In aqueous and water-salt solutions, formation of either soluble or insoluble polyelectrolyte complexes occurred depending on pH, ratio of the oppositely charged groups, and degree of polymerization of PEVP and/or DIVEMA. The phase separations followed general rules revealed by studying mixtures of PEVP and polycarboxylic acids. However in the case of DIVEMA, a significant broadening of the region for insoluble complexes at the expense of the region of soluble complexes was established. The data obtained demonstrate plausible advantages of the complex formation as the non-covalent modification of the polymeric carrier that endow DIVEMA with the ability for reversible soluble-insoluble transformation, in particular at physiological pH and ionic strength.     

The ordered phase of methylammonium lead chloride CH3ND3PbCl3

The perovskite-structured compound methylammonium lead chloride orders into a low-temperature phase of space group Pnma, in which at 80 K each of the orthorhombic axes , and is doubled with respect to the room temperature disordered cubic phase (). The structure was solved by ab initio methods using the programs EXPO and FOX. This unusual cell basis for space group Pnma is not that of a standard tilt system. This phase, in which the methylammonium ions, are ordered shows distorted octahedra. The octahedra possess a bond angle variance of 60.663°² and a quadratic elongation of 1.018, and are more distorted than those in the ordered phase of methylammonium lead bromide. There is also an alternating long and short Pb-Cl bond along a, due to an off-center displacement of Pb within the octahedron. This suggests that the most rigid unit is actually the methylammonium cation, rather than the PbCl₆ octahedra, in agreement with existing spectroscopic data.     

Volume and heat capacity of model non-aqueous self-assembly systems

Blends of immiscible polymers are often stabilized by block copolymers which can form non-aqueous micelles and microemulsions in the liquid polymers. The phase diagrans, apparent volumes and apparent heat capacities of model non-aqueous binary and ternary systems were studied in order to investigate the conditions under which such self-assembly systems could form. 1,2-Hexanediol, which can cosolubilize hexane and ethyleneglycol, forms inverse micelles in hexane and weak microaggregates in ethyleneglycol. Genapol X-060, a commercial alcoholic surfactant containing on the average an aliphatic chain of 13 carbons and 6 oxyethylenes (C₁₃E₆), forms microaggregates in poly(ethyleneglycol) 400. These self-assembly systems are strengthen in the presence of a third component which has an affinity for the inner phase.Presented at the Symposium, 76^th CSC Congress, Sherbrooke, Quebec, May 30–June 3, 1993, honoring Professor Donald Patterson on the occasion of his 65^th birthday.     

Phase separation behavior of epoxy resin modified with crosslinked rubber

Low molecular weight liquid rubber (ATBN = amine terminated butadiene acrylonitrile copolymer or CTBN = carboxyl terminated butadiene acrylonitrile copolymer)–DGEBA (diglycidyl ether of bisphenol A) blends indicated upper critical solution temperature (UCST) behavior. The phase separation behavior of the neat and crosslinked rubber (ATBN, CTBN)–epoxy blends was analyzed by a laser light scattering experiment. Lauryl peroxide (LPO) was employed to crosslink the rubber during the initial annealing stage. The onset point of the phase separation in the crosslinked ATBN–epoxy system occurred later than in the case of the neat ATBN–epoxy system. However, the onset point of the phase separation process started earlier in the case of the crosslinked CTBN–epoxy system. The domain correlation length of the crosslinked rubber-added system was smaller than that of the neat rubber-added system.     

高折光指数光学树脂的合成——相转移法合成不饱和硫醇酯单体的条件控制

采用正常的低温相转移催化（ＰＴＣ）和反滴碱溶液ＰＴＣ法分别合成了含硫双烯ＭＥＳＤＭＡ和单烯ＭＥＰＳＭＡ．１Ｈ ＮＭＲ分析证明ＭＥＳ中的杂质主要是由原料ＴＤＧ引入的．对含单个巯基的ＭＥＰＳ的正常ＰＴＣ酯化接枝双键，因存在巯基和不饱和双键的加成反应而导致失败．作者最终得到了折光指数在１６２５以上的ＭＥＳＤＭＡ／ＭＥＰＳＭＡ共聚物．     

Curing reaction characteristics and phase behaviors of biphenol type epoxy resins with phenol novolac resins

Diglycidyl ether of 4,4′-dihydroxybiphenol (BPDGE) is a liquid crystalline epoxy. The biphenyl epoxy (diglycidyl ether of 3,3′,5,5′-tetramethyl-4,4′-biphenyl, TMBPDGE) has found great applications in plastic encapsulated semiconductor packaging. Phenol novolac (PN) was used as curing agent. The reaction kinetics of BPDGE/PN and TMBPDGE/PN systems in the presence of triphenylphosphine (TPP) were characterized by an isoconversional method under dynamic conditions using differential scanning calorimetry (DSC) measurements. The results showed that the curing of epoxy resins involves different reaction stages and the values of activation energy are dependent on the degree of conversion. The effects of curing temperature on their phase structure have been investigated with polarized optical microscopy and Wide-angle X-ray diffraction. With proper curing process, BPDGE showed a nematic phase when cured with PN.     

Formulation–composition map of a lecithin-based emulsion

Formulation–composition map is an interesting tool to predict the nature of an emulsion, stability, viscosity and nevertheless to decide the mixing protocol of its ingredients. Information based on optimum formulation (environmental conditions at which the affinity of an emulsifier for oil and for aqueous phase is same), which is depicted through hydrophilic–lipophilic deviation (HLD) concept, is necessary to make a formulation–composition map of an emulsion. In order to apply this concept in food emulsions, it is necessary to determine characteristic constants of each component of the system, i.e. the aqueous phase, the oil phase and the emulsifier at equilibrium. In this work formulation–composition map of a sunflower oil–water–lecithin system, based on the knowledge of phase behavior of lecithin at equilibrium and emulsification, was made. The shape of inversion line on formulation–composition map was not the classical stair type rather an almost vertical inversion line at water-fraction (f_w) near 0.20 was observed. It was supposed to be linked to the viscosity of oil phase which was 50 times the viscosity of aqueous phase. Additionally, emulsions were of oil-in-water (O/W) type for f_w higher than 0.20, but their viscosity and the drop size behavior with respect to salt concentration as formulation variable did not show the existence of transitional inversion line on formulation–composition map. Such map in advance can certainly facilitate the guidelines for dynamic emulsification.     

乳状液法制备憎液溶胶Ⅰ.BaCO_3均匀粒子的制备

均匀胶体粒子的形成，除与反应条件（反应物浓度、陈化时间和温度、介质种类等）有关外，反应体系的环境也影响最终产物的形态，《至结晶结构．气溶胶法和微乳液法正是利用微环境中的‘水池效应”；分别制备出球形亚微米和纳米级的均匀粒子［‘－‘］、这些方法与水解法和相转化法等方法比较，反应物浓度要大几个数量级，而反应时间却短很多，因而受到研究人员的关注．乳状液也能提供亚微米、微米及以上级的微环境，因此，可以应用O／W乳状液乳液中的聚合反应制备亲液的分散体系．然而，极少有关利用w／O乳状液制备僧液溶胶的报导问；最近…