酸、碱性条件下茜素红紫外-可见光谱的量子化学研究

茜素红(ARS)是葸醌类化合物中茜草素型的一种,被广泛应用于电化学、光谱学等领域的研究。在酸性溶液中,茜素红主要在260 nm和422 nm处出现明显的吸收峰,而在碱性溶液中吸收峰移动到272 nm和556 nm。为了分析不同溶液环境对茜素红吸收峰波长的影响,本研究在杂化密度泛函方法B3LYP/6-311+(d)水平上优化了ARS分子在酸、碱性情况时的稳定基态构型,并采用含时密度泛函(time-dependent density functional theory,TD-DFT)方法模拟了ARS分子的电子吸收光谱。计算结果与实验得到的紫外可见吸收光谱相吻合,说明密度泛函理论用来研究茜素红的紫外可见光谱是有效可靠的。通过计算还确定了每个吸收峰对应的各个电子跃迁的贡献率以及Mulliken电荷分布。该理论与实验的结合研究为茜草素型化合物的进一步应用、分子设计、药物构效关系和化学反应规律的研究提供了重要的参考依据。     

Possible use of methylbenzenes as electrolyte additives for improving the overcharge tolerances of Li-ion batteries

Based on the voltammetric behaviour of a series of methyl-substituted benzenes in 1M LiPF₆/EC-DMC electrolyte, xylene was selected and tested as an electrolyte additive for overcharge protection of Li-ion batteries. From the overcharge curves, CV behaviour and SEM observations of the cells in the presence of xylene, it was found that the additive can polymerize at the overcharged voltage to form a dense layer of isolating polymer film at the cathode surface, which blocks off further oxidation of the electroactive material and electrolyte and, therefore, improves the overcharge tolerance of the Li-ion battery. In addition, the xylene additive has shown only a slight influence on the cycling behaviour.     

K_2O－CaO－Al_2O_3－SiO_2系统自释釉瓷化学组成的研究

本文从酸度系数着手，证实了Ｋ２Ｏ－ＣａＯ－Ａｌ４Ｏ久－ＳｉＯ２系统中存在自释釉组成，限定了其组成范围，０．６７％＜Ｋ２Ｏ＜１．２８％，１０．６４％＜ＣａＯ＜１３．６２％，１１．５３％＜Ａｌ４Ｏ３＜１５．３２％，７２．７３％＜ＳｉＯ２＜７４．０４％，并讨论了自释釉瓷的性能。     

Kinetics for benzoylation of sodium 4-acetylphenoxide via third-liquid phase in the phase-transfer catalysis

In this research, the kinetics for synthesizing 4-acetylphenyl benzoate (R^*COOR) from benzoylation of sodium 4-acetylphenoxide via third-liquid phase-transfer catalysis was investigated. The reaction rate was observed to be strongly dependent on agitation speeds in the third-phase catalytic reaction. By forming the third-liquid phase, the observed reaction can be greatly enhanced to give a product yield of 100% in a duration of 3 min at 20 °C and 200 rpm. If a third-liquid phase was not formed in the liquid–liquid system, the reaction rate is very slow and the product yield is only 2% in 3 min at 20 °C. The reaction conducted in third-liquid phase-transfer catalytic system is faster than that in LLPTC system by 25–28 times. The amount of catalytic intermediate (QOR) in the third-liquid phase was about 50% of the catalyst initially added and kept about 30% of it remained after 1 min, and only small amounts of a catalytic intermediate residing in the organic phase were observed during the reaction using methyl t-butyl ether as the solvent. The concentration of catalytic intermediate slightly decreased with increasing reaction time, while the molar ratio of QOR to benzyl tri-n-butylammonium cation in the third-liquid phase remained almost constant after 1 min and increased with increasing agitation speeds. The experimental results were well described by the pseudo-first-order kinetics. The present work shows an effective method to synthesize 4-acetylphenyl benzoate.     

Composition of mixed octadecadienoates via ozonolysis,chromatography and computer solution of linear equations

An approach to the analysis of 55 possible nonconjugated positional isomers of octadecadienoic acid is described and tested with mixtures of individual synthetic methyl esters. In the first example, by ozonolysis a sevencomponent mixture consisting ofcis,cis 5,12-, 6,10-, 6,11-, 6,12-, 7,12-, 8,12-, and 9,12-octadecadienoates was converted to aldehydes, aldehyde-esters and dialdehydes. These fragments were separated on a 50 m×0.2 mm free fatty acid phase (FFAP) vitreous silica capillary column. Equations for an arbitrarily restricted 12×15 matrix of linear simultaneous equations and a computer solution of the matrix provided the composition of the initial methyl octadecadienoate mixture. The power and significance of this method became apparent with the observation that only two of the seven isomers in the known mixture were resolved as single peaks by state-of-the-art capillary gas chromatography, but all seven were identified and estimated with acceptable error by the ozonolysis-capillary gas chromatography-computer procedure. In a generalized approach to the analysis of the 55 possible nonconjugated isomers, a computer program selects the appropriate matrix of linear simultaneous equations based on the aldehyde data supplied by the analyst. Twenty of 21 combinations of seven isomeric esters taken five at a time have been analyzed to assess the efficiency of the method. To illustrate applicability at this stage of development, the method has been used to analyze the diene products of the hydrazine reduction of γ-linolenic acid and the diene products from the biological desaturation of isomeric monoenes. The possibility of distinguishing geometric and positional isomers of 18∶2 has been opened by the observed separation ofcis-andtrans-unsaturated aldehydes and aldehyde-esters. Presented in part at the 16th World Congress of the International Society for Fat Research, October 4–7, 1983, in Budapest, Hungary, and at the American Oil Chemists' Society Meeting, May 15, 1986, in Honolulu, Hawaii.     

Soap‐free emulsion copolymerization of perfluoroalkyl acrylates in the presence of a reactive surfactant

Soap‐free emulsion copolymerization of perfluoroalkyl acrylate (FA)/methyl methacrylate (MMA)/n‐butyl acrylate (n‐BA) was carried out in the presence of sodium 2‐acrylamide‐2‐methyl propanesulfonate (AMPSNa) as a reactive surfactant and potassium persulfate (KPS) as an initiator. An analysis of the effects of concentration of AMPSNa, KPS, FA as well as polymerization temperature on the kinetic features (rate of polymerization) and colloidal characteristics (mean particle diameter, particle disperse index, particle numbers, and surface charge density) was followed. NMR, FTIR, AFM, and fluorine‐selective electrode analysis were used to characterize the composition and morphology of the FA copolymers. Both AFM analysis and contact angle measurements strongly implied that the fluorinated segments migrated to the outmost surface and created films with lower surface energy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2438–2444, 2007     

Raman spectroscopic study of conformational changes in the amorphous phase of poly(lactic acid) during deformation

The conformational distribution change of amorphous poly(lactic acid) (PLA) induced by deformation has been studied using Raman spectroscopy. Spectroscopic features associated with the rotational isomeric states (ttt, ttg′, tg′t, tg′g′) have been established experimentally and supported by normal coordinate analysis. Deformation induced a significant increase in the most favorable tg′t conformation. Based on the relative intensities of Raman-active skeletal modes, a quantitative method has been developed that can be used to elucidate structural changes in a variety of deformed polymer samples. For biaxially oriented PLA films, the overall tg′t conformation increased from the 76% in undeformed sample to a value as high as 92%. The change in conformational distribution in the amorphous phase follows a different trend (76-88%) as compared to the increase in sample crystallinity (0-43%). A large change in amorphous chain conformation occurred at relatively low draw ratios. In contrast, the large change in the degree of crystallinity occurred at higher draw ratios.     

Fabrication and amplification of Rhodamine B‐doped step‐index polymer optical fiber

A step‐index polymer optical fiber (SI POF) containing Rhodamine B in poly(methyl methacrylate) (PMMA) has been fabricated by a preform technique. Fluorescence of different fiber lengths were observed and discussed. A high gain (23 dB) for a SI POF with 60‐cm length, 400‐μm diameter was obtained. The Rhodamine B content of the doped SI POF is 5 ppm‐wt. The signal wavelength providing the highest gain for a 60 cm SI POF is around 630 nm, and the optimum fiber length is about 60 cm at 10 kW launched pump power. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 681–685, 2004     

农作物秸秆增强氟石膏复合材料的微观结构研究

将玉米秸秆加入改性后的氟石膏中，研究改性剂、玉米秸秆对氟石膏复合材料结构性能的影响；并用苯丙乳液对玉米秸秆纤维进行表面处理，用以改善基体材料和增强材料的界面结合状况，由此显著提高制品性能。     

竹材丙酮法木质素高效分离技术研究

在一定的温度、压力条件下,利用丙酮提取竹材中的木质素,丙酮通过蒸馏回收后,可以反复利用;而通过蒸馏,得到的高纯度的木质素是重要的化工原料,整个过程形成一个封闭循环系统,基本上无三废排放;研究结果表明:当丙酮浓度为80%,液固比为10∶1,在最高反应温度160℃下保温3h,降解木质素的效果最佳;为解决制浆造纸行业废水对环境的污染问题提出了一条新的途径。