粒径可控的纳米铁酸铋的制备及其光催化性能

采用改进的聚丙烯酰胺凝胶法制备了BiFeO3纳米颗粒,利用热重-差热、红外光谱及X射线衍射等手段研究了干凝胶的热分解及BiFeO3的成相过程.结果表明,在600℃煅烧可制备出高纯的BiFeO3纳米颗粒.同时发现,随着双丙烯酰胺含量的增加,所得样品晶粒尺寸逐渐减小,从而制备出平均粒径约52～110nm的系列BiFeO3颗...     

Preparation and characterization of poly(lactic acid)/poly(methyl methacrylate) blend tablets for application in quantitative analysis by micro Raman spectroscopy

Poly(lactic acid) (PLA) is a biodegradable polymer that has a variety of applications, one of which is as biomaterial in surgery or as functional layers on implants, due to its compatibility with living tissue. This paper reports the possibilities of quantification of poly(lactic acid) (PLA) in a polymer matrix such as poly(methyl methacrylate) (PMMA) by micro Raman spectroscopy (MRS). Blends of amorphous poly(DL‐lactic acid) with poly(methyl methacrylate) were prepared by the procedure of dissolution/precipitation. Thermal properties of the blends such as the glass transition temperature (Tg) were characterized by differential scanning calorimetry (DSC). The PLA/PMMA blends exhibited only a single glass transition region, indicating that this system is miscible. The PLA/PMMA system obeys the Gordon–Taylor equation (Tg versus PLA content). Various concentration ratios of PLA blends were prepared to use as a basis for quantitative analysis by MRS. Intensities of the characteristic bands at 813 cm⁻¹ (νCOC of PMMA) and 873 cm⁻¹ (νC―COO of PLA) were used for the calculation. The calibration graph showed a good linear correlation with an R² value of 0.9985. On the basis of the calibration curve obtained, the determined content of several PLA/PMMA blends was in good agreement when compared with nominal contents. The limit of detection (LOD) and quantification (LOQ) were calculated by the calibration data set as signal‐to‐noise method. The relative standard deviation of this method was lower than 10% and the accuracy better than 4%. This study demonstrated that Raman spectroscopy provides an alternative non destructive method for quantitative analysis of PLA in a PMMA matrix. Copyright © 2015 John Wiley & Sons, Ltd.     

Reactions of fullerene C60 with methyl methacrylate radicals: A density functional theory study

We have investigated the stepwise addition of four growing methyl methacrylate (MMA) radicals to C₆₀ fullerene, taking into account all possible types of the formed adducts. This reaction set is a reliable approximation for understanding the MMA polymerization process in the presence of C₆₀ fullerene. We have analyzed the structures of the fullerene-MMA adducts and energy parameters of their formation (heat effects and activation enthalpies). We found that up to three MMA growing radicals are favorably attached to C₆₀ as the fullerene-MMA trisadduct is a stable radical of the allyl type. It is inactive for further radical addition, and the elimination of the hydrogen atom from the growing MMA radical becomes preferable. The effects of steric factors and structures of the products of multiple growing MMA radical additions to C₆₀ on the radical polymerization of MMA in the presence of C₆₀ fullerene are considered.     

介孔L材料CMK-3对甲基紫的吸附性能

合成了高度有序的具有二维六方(P6mm)结构的介孔碳材料CMK-3;利用X射线衍射分析了CMK-3的晶体结构,利用氮气吸脱附(BET)试验测定了孔体积;测定了CMK-3对水溶液中甲基紫的吸附行为,考察了不同pH、温度及浓度下水溶液中甲基紫的静态吸附行为,并分析了酸性、中性、碱性条件下吸附剂对甲基紫和罗丹明B混合溶液的竞...     

原甲酸三甲(乙)酯在药物合成中的应用

简要介绍了原甲酸三甲酯和原甲酸三乙酯在药物合成中的应用.参考文献35篇.     

Co-MCM-41催化H2O2氧化4-甲基吡啶生成4-吡啶甲酸的反应条件及机理

研究了乙酸溶剂中无引发剂条件下,Co掺杂MCM-41催化过氧化氢（30%）氧化4-甲基吡啶的反应,催化剂表现出高底物转化率和产物吡啶甲酸选择性以及良好的再生性。 探讨了不同溶剂、反应时间、反应温度、催化剂用量等对H2O2氧化4-甲基吡啶反应的影响,确定较优反应条件为m（4-甲基吡啶)∶m（催化剂)=10∶1,V（4-甲基吡啶)∶V（冰醋酸)=1∶10,温度363 K,时间6 h。 该条件下4-甲基吡啶的转化率为96.5%,4-吡啶甲酸的选择性为91.4%。 探讨了可能的反应机理。     

静电自组装制备纳米TiO2/SiO2光催化材料

采用静电自组装方法制备了纳米TiO2/SiO2光催化材料。采用巯丙基三甲氧基硅烷偶联剂对SiO2进行干法改性,采用双氧水/冰醋酸将偶联剂巯基基团氧化为磺酸基基团。在正负电荷的吸引下,带负电荷的SiO2与带正电荷的钛聚合阳离子自发地组装在一起,经一定温度热处理得到纳米TiO2/SiO2光催化材料。采用XRD、FTIR、PL、UV-Vis DRS、SEM和ICP等对材料进行了分析和表征。采用甲基橙溶液评价材料的光催化性能。结果表明:SiO2促使锐钛矿的形成,抑制锐钛矿向金红石的转变,减小TiO2的晶粒尺寸,使得TiO2光吸收波长发生蓝移。TiO2与SiO2通过Si-O-Ti键发生结合。采用静电自组装方法制备的材料中TiO2的含量高于传统方法,导致材料的光催化性能有所提高。     

Enhanced Visible‐Light‐Induced Photoelectrocatalytic Degradation of Methyl Orange by CdS Sensitized TiO2 Nanotube Arrays Electrode

In this work, CdS sensitized TiO₂ nanotube arrays (CdS/TiO₂NTs) electrode was synthesized with the CdS deposition on the highly ordered titanium dioxide nanotube arrays (TiO₂NTs) by sequential chemical bath deposition method (S‐CBD). The as‐prepared CdS/TiO₂NTs was characterized by field‐emission scanning electron microscopy (FE‐SEM) and X‐ray diffraction (XRD). The results indicated that the CdS nanoparticles were effectively deposited on the surface of TiO₂NTs. The amperometric I‐t curve on the CdS/TiO₂NTs electrode was also presented. It was found that the photocurrent density was enhanced significantly from 0.5 to 1.85 mA/cm² upon illumination with applied potential of 0.5 V at the central wavelength of 253.7 nm. The photoelectrocatalytic (PEC) activity of the CdS/TiO₂NTs electrode was investigated by degradation of methyl orange (MO) in aqueous solution. Compared with TiO₂NTs electrode, the degradation efficiencies of CdS/TiO₂NTs electrode increased from 78% to 99.2% under UV light in 2 h, and from 14% to 99.2% under visible light in 3 h, which was caused by effective separation of the electrons and holes due to the effect of CdS, hence inhibiting the recombination of electron/hole pairs of TiO₂NTs.     

C02（CO）8催化苯乙烯氢酯基化制α-苯基丙酸酯研究

以Co2（CO）8为催化剂,对苯乙烯与CO及甲醇氢酯基化反应制α-苯基丙酸甲酯的反应进行了研究,并根据实验结果提出了可能的催化反应机理．考察了催化剂用量、配体、溶剂、CO压力及反应温度等因素对氢酯基化反应的影响．结果表明：以甲苯为溶剂,在n（Co2（CO）8）／n（苯乙烯）=0．06,吡啶为配体且n（吡啶）／n（Co）=2,CO压力6．0MPa、反应温度95℃的较佳条件下反应12h,苯乙烯的转化率接近100％,α-苯基丙酸甲酯的收率达到89．07％,异正比24．35．     

9-蒽醛衍生化-高效液相色谱法拆分α-氨基酸甲酯和几种脂肪胺对映体

采用高效液相色谱法,以9-蒽醛为衍生试剂,在5种多糖衍生物的手性固定相(CSPs)上对几种α-氨基酸甲酯对映体进行了手性分离。色谱条件如下: 流动相为含3%～10%(v/v)异丙醇的正己烷溶液,流速为1.0 mL/min,检测波长为254 nm。结果表明,α-氨基酸甲酯-9-蒽醛亚胺衍生物在Chiralcel OD柱或Chiralcel OD-H柱上的手性分离结果优于其他CSPs,而且在Chiralcel OD柱或Chiralcel OD-H柱上全部得到了基线拆分(α=1.24～5.47, Rs=2.56～13.90), L-对映体在这两种色谱柱上的保留强于D-对映体。同时还考察了几种脂肪胺在5种多糖衍生物手性固定相上的对映体拆分效果,结果表明脂肪胺的9-蒽醛亚胺衍生物在Chiralcel OD柱或Chiralcel OD-H柱上的分离效果良好。该法可用于其他α-氨基酸酯和胺类化合物对映体的分析。