疏水上转换纳米晶的均相体系聚合物包覆及在发光检测中的应用

选用水解的十八碳烯-马来酸酐共聚物(PMAO)为表面修饰分子,发展了一种以疏水纳米粒子吸附表面活性剂十二烷基磺酸钠(Na YF_4-SDS)为中间体的均一液相聚合物包覆纳米粒子方法.该方法解决了油溶性纳米晶与弱极性聚合物分子难以在单一体系下均匀分散的问题,实现了在均一液相体系下对疏水纳米晶的单分散包覆以及表面羧酸官能团修饰.红外光谱与表面Zeta电位测试结果表明纳米晶已被聚合物包覆,粒子表面为强电负性的羧酸基团.电镜结果表明聚合物包覆的上转换纳米晶粒径无明显的变化,具有良好的单分散性.发射光谱表明聚合物包覆前后粒子的发射谱带无显著变化,保持了原油相粒子的发光性能.进一步的特异性识别荧光显微成像实验证实聚合物包覆后的粒子(Na YF_4-PMAO)可用于生物学检测.     

核壳型Gd2O3:Eu3+@Y2O3纳米发光材料的制备与发光性能

采用均相沉淀法制备了均匀球形的Gd2O3:Eu3+@Y2O3核壳结构纳米发光材料.XRD结果表明经过800℃焙烧后样品为立方晶系的Gd2O3,并且晶体发育良好,包覆Y2O3之后Gd2O3的衍射峰位置无明显变化,但随着包覆厚度的增加,出现了立方晶系Y2O3的衍射峰.FTIR谱图观测到了Gd-O,Y-O伸缩振动吸收峰,随着包覆厚度的减少吸收峰增强,认为当包覆层的厚度适当时,颗粒表面的悬空键(断键)变少,Gd(Eu,Y)-O键增多所致.SEM表明包覆前后样品为均匀分散的球形结构.XPS分析进一步证明了表面包覆上了Y2O3.荧光光谱表明:纳米Gd2O3:Eu3+表面包覆不同厚度的基质Y2O3后,均观测到Eu3+离子的特征红光发射,当包覆厚度R=4:1时的发光强度比未包覆的Gd2O3:Eu3+增强,认为核-壳型样品降低了纳米Gd2O3:Eu3+的表面效应给发光强度带来的负面影响.     

溶剂热合成的Cu掺杂ZnCdS量子点的发光性质研究

以低毒、廉价的环己烷为溶剂,通过调控杂质离子和基质材料阳离子的相对反应活性,合成了发光颜色可调、近似球形的Cu∶Zn Cd S量子点。系统研究了油胺的用量、Cu掺杂量、Cd/Zn比以及不同的Zn前驱体对量子点发光性质的影响。通过在Cu∶Zn Cd S量子点晶核外层包覆宽带隙Zn S材料,进一步消除了粒子的表面缺陷,有效提高了量子点的发光效率。     

阴阳离子表面活性剂体系超低油水界面张力的应用

通过阴阳离子表面活性剂复配,在实际油水体系中获得了超低界面张力.通过在阴离子表面活性剂分子结构中加入乙氧基(EO)链段,以及采用阴阳离子加非离子型表面活性剂的三组分策略,有效解决了混合表面活性剂在水溶液中溶解度问题.进而研究了阳离子表面活性剂结构、非离子表面活性剂结构、三者组分配比、表面活性剂总浓度等因素对油水界面张力的影响,从而在胜利油田多个实际油水体系中获得了较大比例范围和较低浓度区域的油水超低界面张力,部分体系甚至达到了10-4 mN·m-1.由于阴阳离子表面活性剂间强烈的静电吸引作用,相关体系具有很好的抗吸附能力.经过石英砂48 h吸附后,体系仍然具有很好的超低界面张力.     

pH值对硅烷偶联剂表面改性稀土长余辉发光材料的影响

为提高稀土长余辉发光材料SrMgAl4 O8:Eu2+,Dy3+在非极性树脂中的分散性和相容性,用硅烷偶联剂YDH-570在强酸条件下对其进行了表面改性.通过质量变化、比表面积、ATR-FTIR、SEM(能谱分析)和发光性能分别研究了该条件下不同ptH值改性对材料表面组成、形貌和性能的影响.结果发现:强酸条件下改性效果十分显著;当pH值由0.6增加到0.72时,样品增重率达23.3％,33.3％,53.3％,比表面积净增75.6％,215.2％,265.4％;对于改性效果较明显的pH为0.72的样品,能谱分析证实是一种片状有机包覆层结构;余辉衰减曲线表明,表面改性对材料发光性能影响不大.     

阴/阳离子表面活性剂复配体系的中相微乳液研究

阴离子表面活性剂双-2-乙基己基磺化琥珀酸钠(简称AOT), 和阳离子表面活性剂十六烷基三甲基溴代铵(简称CTAB), 在有醇、正辛烷、盐水存在的情况下,能形成多相微乳液。本文系统地研究了阴/阳离子表面活性剂配比、醇的种类、醇的浓度对该体系的中相微乳液的形成及特性的影响, 得到了中相微乳液的特性参数(最佳含盐量S^*, 最佳中相微乳液体积V^*, 界面张力r~E、盐宽△S等)。这些性质对与阴/阳离子表面活性剂复配体系, 三次采油及日用化工上的应用开发具有重要意义。最后还开展单独阴离子表面活性剂体系和阴/阳离子表面活性剂复配体系进行了比较, 得到一些有价值规律, 并从理论上进行了探讨。     

阴、阳离子表面活性剂混合体系在硅胶/水及硅胶/矿化水界面上的吸附

研究阴、阳离子表面活性剂混合体系(十二烷基氯代吡啶,辛基磺酸钠,辛基三乙基溴化铵/十二烷基苯磺酸钠)在硅胶,纯水和硅胶,矿化水界面上的吸附作用,探讨阴(阳)离子表面活性剂的存在对阳(阴)离子表面活性剂吸附作用的影响．结果表明,阴离子表面活性剂的存在基本不影响阳离子表面活性剂在带负电固体表面的吸附;而阳离子表面活性剂的存在却使本来吸附量就不大的阴离子表面活性剂在带负电的固体表面上不再吸附．在矿化水中阳离子表面活性剂的吸附量比在纯水中明显降低．从硅胶表面吸附机制解释了所得结果．     

YVO4∶Eu3+有序纳米球及其表面包覆GdVO4的水热合成与性能研究

采用水热法制备出了均匀有序的球形YVO4∶Eu3+发光材料,并用该法在其表面包覆一层基质材料GdVO4。XRD分析表明包覆前后的样品均为四方晶系锆英石结构的YVO4,且晶体发育良好。FTIR谱图观测到了V-O、Y-O伸缩振动吸收峰。SEM照片表明包覆前后样品均为均匀分散的纳米片组装的有序球形结构。XPS分析进一步证明形成了核壳结构的YVO4∶Eu3+@GdVO4发光材料。荧光光谱表明,YVO4∶Eu3+表面包覆GdVO4之后,发射光强度比未包覆的YVO4:Eu3+有所增强。     

簇状纳米二氧化锰修饰玻碳电极电化学发光法测定己烯雌酚

基于簇状纳米二氧化锰可显著增强玻碳电极的导电性能,且己烯雌酚在该电极上能够增强鲁米诺体系的电化学发光,据此建立了电化学发光测定己烯雌酚的新方法。采用壳聚糖包覆的方法将簇状纳米二氧化锰固定在玻碳电极表面,考察了电极的稳定性以及影响电化学发光的因素。己烯雌酚浓度在3.5×10-11~6.5×10-9mol/L范围内,与电化学发光信号呈良好线性关系;检出限(3σ)为2.0×10-11mol/L。对4.0×10-10mol/L己烯雌酚进行11次平行测定,相对标准偏差(RSD)为1.1%。     

不同类型表面活性剂对纳米SiO2流体粘度的影响

系统地研究了不同类型的表面活性剂对低浓度纳米SiO2流体粘度的影响规律,并在此基础上深入探讨了不同碳链长度的阳离子和非离子表面活性剂对纳米SiO2流体粘度的影响。结果表明,阴离子表面活性剂十二烷基苯磺酸钠(SDBS)对纳米流体粘度的影响较小,其相对粘度值维持在1.23左右;而阳离子表面活性剂十四烷基三甲基溴化铵(TTAB)、十六烷基三甲基溴化铵(CTAB)、十八烷基三甲基溴化铵(OTAB)、十六烷基氯化吡啶(CPC)、非离子表面活性剂OP-8、OP-10和两性离子表面活性剂DXS14、DXS18对纳米流体粘度的变化影响较大,其最大相对粘度值分别能达到3.42、1.82和8.87。同时也发现,阳离子表面活性剂碳链越长,纳米流体最高粘度值越大,且纳米流体最高粘度所对应的表面活性剂浓度均在其临界胶束浓度值附近。     

季铵阳离子与无机阴离子对铁的缓蚀协同效应

在酸性介质中,季铵阳离子与无机阴离子对铁具有明显的缓蚀协同效应,阴离子的表面活性越强,对协同效应的贡献越大,阳离子的结构对协同效应同样有着明显的影响。本文采用电化学方法仔细地研究了硫酸溶液中四丁基铵阳离子(TBA~+)和十六烷基吡啶阳离子(HDP~+)与SCN~-及I~-对铁的缓蚀协同效应。     

Ermittlung des Vernetzungsgrades und Beladungszustandes von Ionenaustauschern auf Kunstharzbasis durch Pyrolyse-Gas-Chromatographie

A special introduction device with switching of carrier gas for improving the reproducibility of pyrolysate composition in pyrolysis gas-chromatography has been described. Its influence on the formation of pyrolysis products and on retention times has been studied on a model substance. The peak area ratios for determining the degree of cross-linking in ion exchangers on styrene-DVB basis can be estimated considerably more accurately with the help of carrier gas switching. Since anion exchangers yield lessα-methylstyrene on pyrolysis than do cation exchangers, their peak area ratios are appreciably larger. Increasing the degree of cross-linking lowers the ratios with the anion exchangers and raises them with the cation exchangers. At 400° C the thermal attack on anion exchangers with styrene-DVB matrix occurs mainly at the active group. The methyl esters or their decomposition products formed from the counter ions are characteristic pyrolysis products. A feature of Dowex 1 is the formation of trimethylamine; of Dowex 2, acetaldehyde. In this way, pyrolysis gas-chromatography enables information about the degree of cross linking and the nature of the anion of ion exchangers, as well as about the matrix, type and structure of the functional group and position of substitution of the anchor group in the matrix to be obtained.     

A theoretical comparison of cationic and anionic homoaromaticity: Reinforcement of cationic homoaromaticity by σ-nonclassical effects

A MINDO/3 study of homoaromaticity in the 3-cyclobutenyl cation and the Mobius 3-cyclobutenyl anion has been used to evaluate cationic and anionic homoaromaticity quantitatively. π Homodelocalization energies of the two are found equal in isostructural planar comparisons. In planar optimized structures, the homodelocalization energy of the cation is slightly (about 4 kcal) greater than that of the anion, a consequence of the greater 1,3 distance in the latter. Full optimization produces a highly puckered and further stabilized cation, but engenders no change in the Mobius anion. The total stabilization of the cation relative to the anion is 13 kcal, in accord with the generalization that cationic homoaromaticity is more potent than the anionic variety. The fully optimized cation is revealed to actually have a much smaller π homodelocalization energy than the optimized anion, in contrast to the order of overall stabilities. σ-Nonclassical effects, which are stabilizing in the cation but destabilizing in the Mobius anion, provide the rationale for the above.     

A new QM/MM method oriented to the study of ionic liquids

The interest on room temperature ionic liquids has grown in the last decades because of their use as all‐purpose solvent and their low environmental impact. In the present work, a new theoretical procedure is developed to study pure ionic liquids within the framework of the quantum mechanics/molecular mechanics method. Each type of ion (cation or anion) is considered as an independent entity quantum mechanically described that follows a differentiated path in the liquid. The method permits, through an iterative procedure, the full coupling between the polarized charge distribution of the ions and the liquid structure around them. The procedure has been tested with 1‐ethyl‐3‐methylimidazolium tetrafluoroborate. It was found that, similar to non‐polar liquids and as a consequence of the low value of the reaction field, the cation and anion charge distributions are hardly polarized by the rest of molecules in the liquid. Their structure is characterized by an alternance between anion and cation shells as evidenced by the coincidence of the first maximum of the anion–anion and cation–cation radial distribution functions with the first minimum of the anion‐cation. Some degree of stacking between the cations is also found. © 2015 Wiley Periodicals, Inc.     

A proton-driven amino acid pump: lipophilic primary ammonium cation—crown ether complex as a new type of anion-transport carrier

A lipophilic primary ammonium cation—crown ether complex was shown to mediate effectively active and passive transport of amino acid derivatives via proton/amino acid anion cotransport as well as anion/amino acid anion countertransport. It may offer a new chemical analog to amino group-containing carrier proteins and a prototype for an anion separation membrane.     

SILAR法制备化学计量CuInS_2薄膜

在室温下,以不同cCu/cIn的CuCl2和InCl3混合溶液作为阳离子前驱体,Na2S水溶液为硫源,利用连续离子层吸附反应法(SILAR)在玻璃基底上制备了CuInS2薄膜。XRD结果表明,当cCu2 /cIn3 在1￣1.5范围内均可形成具有黄铜矿结构的CuInS2薄膜。SEM观察到随cCu2 /cIn3 的升高,薄膜表面颗粒长大并出现团簇聚集。通过XPS测定薄膜表面的化学组成证明当cCu2 /cIn3 =1.25时,CuInS2薄膜接近其标准的化学计量组成。此时薄膜的吸收系数大于>104cm-1,禁带宽度Eg为1.45eV。     

INTERFACIAL ELECTRON TRANSFER INVOLVING RADICAL IONS OF CAROTENE AND DIPHENYLHEXATRIENE IN MICELLES AND VESICLES

Abstract— The radical cations and anions of diphenylhexatriene have been produced and characterized in homogenous and micellar solutions by pulse radiolysis and laser flash photolysis techniques. Both types of radical ions were formed in cyclohexane on pulse radiolysis. The radical cation was formed in dichloroethane on pulse radiolysis, and by two photon photoionization in ethanol, dichloroethane, and various micelles. Both radical ions have intense ( 10⁵ M ^-1 cm^-1) absorption peaks at600–650nm. The cation peak occurs at slightly shorter wavelengths than that of the anion.
In micelles and vesicles the radical anion of carotene was formed by electron transfer from e_a– on pulse radiolysis. The radical cation was formed on pulse radiolysis of micellar solutions containing Br^-₂ as counterion, presumably by electron transfer to Br₂^-. The spectra agree with those of the radical cation and anion of carotene that have previously been obtained in homogenous solutions (Dawe and Land, 1975).
Electron transfer in micelles and vesicles from the radical anion of biphenyl to carotene and diphenylhexatriene, and from the radical anions of these to inorganic acceptors has been studied.     

Unexpected interconnection of the 7-norbornenyl and 3-nortricyclcyl/5-norbornen-2-yl cations

Fragmentation of syn-7-norbornenyloxychlorocarbene provides products derived from both 7-norbornenyl cation-chloride anion pairs and from 3-nortricyclyl/2-norbornen-5-yl cation-chloride anion pairs. A 5,7-hydride shift within the 7-norbornenyl cation is proposed to interconnect the two cation systems.     

Variations of diffusion coefficients of redox active molecules in room temperature ionic liquids upon electron transfer

In ionic liquids, the diffusion coefficients of a redox couple vary considerably between the neutral and radical ion forms of the molecule. For a reduction, the inequality of the diffusion coefficients is characterized by the ratio gamma = D(red)/D(ox), where D(red) and D(ox) are the diffusion coefficients of the electrogenerated radical anion and of the corresponding neutral molecule, respectively. In this work, measurements of gamma have been performed by scanning electrochemical microscopy (SECM) in transient feedback mode, in three different room temperature ionic liquids (RTILs) sharing the same anion and with a series of nitro-derivative compounds taken as a test family. The smallest gamma ratios were determined in an imidazolium-based RTIL and with the charge of the radical anion localized on the nitro group. Conversely, gamma tends to unity when the radical anion is fully delocalized or when the nitro group is sterically protected by bulky substituents. The gamma ratios, standard potentials of the redox couple measured in RTILs, and those observed in a classical organic solvent were compared for the investigated family of compounds. The stabilization energies approximately follow the gamma ratios in a given RTIL but change considerably between ionic liquids with the nature of the cation.     

Quantification of amino acid ionic liquids using liquid chromatography-mass spectrometry

Amino acid ionic liquids (AAILs) containing imidazolium cations and amino acid (AA) anions, were synthesized and applied as task-specific ionic liquids. A sensitive and fast liquid chromatography-mass spectrometry (LC-MS) method was established for the quantitative analysis of 20 AAILs. Using ion pairing-reversed phase liquid chromatography technique, heptafluorobutyric acid was used as ion-pairing reagent to increase the retention of AAILs. Based on the zwitterionity of amino acid, this method was proposed to determine both the cation and the anion of AAILs simultaneously. The limit of detection of this method is down to 1-15ng/mL and the analysis time is less than 15min. According to the analytical data of seven selected AAILs, we found that the content of amino acid anion is always lower than that of butyl methyl imidazolium cation in AAILs. Moreover, the molar ratio of imidazolium cation to amino acid anion is dependent on the chemical property of the amino acid. These results supplied useful information on the interaction of imidazolium cation with acidic, basic, neutral and non-polar amino acids in AAILs.