原位插层聚合法制备聚苯乙烯/海泡石纳米复合材料

采用十八烷基三甲基氯化铵(OTAC)作为有机插层剂对海泡石进行了有机化处理,该有机化的海泡石粒子在苯乙烯单体中很容易地均匀分散并形成稳定的胶体溶液.通过对分散有海泡石的苯乙烯进行原位插层聚合制备了聚苯乙烯/海泡石纳米复合材料.并用X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、扫描电镜(SEM)和透射电镜(TEM)对聚苯乙烯/海泡石复合材料的结构进行了表征.研究表明聚苯乙烯的大分子链插入到海泡石片层间,形成了部分插层、部分剥离型纳米复合材料.     

聚醋酸乙烯酯/纳米ZnO颗粒复合材料的等离子聚合及其光学性能

采用等离子镀膜方法在纳米ZnO颗粒表面沉积一层有机薄膜,制备出聚合物/ZnO复合材料.用高分辨透射电子显微镜(HRTEM)、傅立叶变换红外光谱(FTIR)、光致发光光谱(PL)和紫外-可见吸收光谱(UV-Vi8)对其形貌、结构和性能进行表征,研究了聚合物/ZnO复合材料的光学性能以及聚合物与纳米ZnO颗粒的结合强度.结...     

烷基硫醇自组装铜镀层及其树脂基复合材料界面性能研究

为改善金属转移法制备的铜镀层与碳纤维增强氰酸酯树脂基复合材料的界面粘附性能,选用4种烷基硫醇偶联剂自组装膜(SAMs)改性铜镀层.通过表征改性前后镀层表面形貌、表面极性变化、烷基硫醇与铜镀层之间的化学键合情况,研究不同烷基硫醇对铜镀层与复合材料界面结合强度的影响.结果表明：4种烷基硫醇不同程度地提高了铜镀层与复合材料的界面结合强度,具有反应活性基团和长链结构的11巯基-十一烷酸(MUA)和11巯基-十一烷醇(MUOL)因与复合材料产生化学键连接和分子链缠结作用,形成铜镀层-SAM-复合材料的界面结构,使界面结合强度提高超过70%.     

剥分蛭石包覆聚酰亚胺复合材料及性能研究

采用四甲基溴化铵和十六烷基三甲基溴化铵对蛭石进行有机膨胀和机械剥分,研究剥分蛭石包覆聚酰亚胺(PI)复合材料的耐热性能。采用傅里叶变换红外光谱(FTIR)和热重分析(TG)证明有机插层剂成功插入蛭石层间,采用小角X射线衍射(XRD)和扫描电子显微镜(SEM)表征不同蛭石样品的微观结构及剥分情况。剥分蛭石包覆聚酰亚胺复合材料的热隔绝性能和耐形变性由温差测试实验测定。     

改性凹凸棒石-不饱和聚酯复合材料的热性能研究

为研究改性凹凸棒石的掺入对不饱和聚酯热性能的影响,采用十八烷基三甲基氯化铵(OTAC)对凹凸棒石进行有机改性,然后制备改性凹凸棒石-不饱和聚酯复合材料,并用红外光谱(IR)和X射线衍射(XRD)等分析手段对改性效果进行表征,利用差热(DTA)、热重(TG)同步热分析仪研究复合材料的热性能,探究改性前后凹凸棒石的掺量对复合材料热起始温度的影响。结果表明:改性凹凸棒石-不饱和聚酯复合材料的热稳定性明显优于凹凸棒石-不饱和聚酯复合材料和纯不饱和聚酯,掺入改性凹凸棒石的最佳质量分数8.4%左右。     

激光烧结尼龙12/ 累托石复合材料的结构与性能

将尼龙12 与有机累托石的混合粉末进行激光烧结成型, 利用X 射线衍射(XRD) 、差示扫描量热分析(DSC) 、扫描电镜(SEM) 等手段对烧结试样的材料结构进行了表征, 并对其力学性能及热性能进行了研究。结果表明: 尼龙12 在激光烧结过程中插入到累托石层间, 形成了尼龙12/ 累托石纳米复合材料。复合材料的力学性能及热稳定性能同尼龙12 烧结试样相比均有不同程度的提高, 有机累托石质量分数为10 %时, 复合材料的拉伸强度、弯曲强度和冲击强度分别提高了10.7 %、15.9 %和38.7 % , 热分解温度提高了27 ℃。      

有机蛭石/酚醛树脂熔融插层纳米复合材料的研究

用十六烷基三甲基溴化铵对膨胀蛭石进行了有机化处理,并用熔融法制备了有机蛭石/酚醛树脂插层纳米复合材料.通过XRD,AFM,TGA测试分析了所制备的复合材料的结构与热性能.结果表明:酚醛树脂能插层于蛭石片层中,制得的蛭石/酚醛树脂插层纳米复合材料的耐热性有了很大程度的提高.     

聚丙烯/尼龙6/纳米蒙脱石复合材料的制备及热性能研究

采用熔融插层法成功制备了聚丙烯(PP)/尼龙6(PA6)/有机化蒙脱石(OMMT)纳米复合材料.用X-衍射分析(XRD)和透射电镜(TEM)观察OMMT层间距的变化和材料的结构,用示差扫描量热法(DSC)和热重分析(TG)研究了其热性能,并考察了纳米复合材料的拉伸强度.研究结果表明,OMMT的层间距由2.200nm扩大到2.800nm,PP/PA6合金高分子链取代了有机化蒙脱石层间的十六烷基三甲基溴化铵而进入到蒙脱石的片层间,加入质量分数为4%的OMMT的复合材料不仅使材料的拉伸强度提高了约15%,还提高了材料的热稳定性,使剩炭率增加了8.1%.     

改性菜籽油/有机蒙脱土纳米复合材料的制备及性能

首先以菜籽油、乙二胺、丙烯酸为原料,合成改性菜籽油(KRF),然后将其与有机改性蒙脱土(OMMT)复合制备了改性菜籽油/有机蒙脱土纳米复合材料(KRF/OMMT)。红外光谱分析结果表明,已成功制得了KRF/OMMT复合材料;X射线衍射(XRD)分析结果表明,KRF能在蒙脱土中进行插层;热重分析(TGA)结果表明,蒙脱土的引入使纳米复合材料的起始热分解温度升高,最高可达257℃。将KRF/OMMT应用于皮革加脂工艺,对加脂后坯革的阻燃性能检测结果表明,采用纳米复合材料加脂的坯革的有焰燃烧时间从146s可降至74s,阴燃时间从958s可降至11s,极限氧指数从14.8%增至21%,表明纳米复合材料能赋予坯革良好的阻燃性能。     

改性菜籽油/有机蒙脱土纳米复合材料的制备及性能EI北大核心CSCD

首先以菜籽油、乙二胺、丙烯酸为原料,合成改性菜籽油(KRF),然后将其与有机改性蒙脱土(OMMT)复合制备了改性菜籽油/有机蒙脱土纳米复合材料(KRF/OMMT)。红外光谱分析结果表明,已成功制得了KRF/OMMT复合材料;X射线衍射(XRD)分析结果表明,KRF能在蒙脱土中进行插层;热重分析(TGA)结果表明,蒙脱土的引入使纳米复合材料的起始热分解温度升高,最高可达257℃。将KRF/OMMT应用于皮革加脂工艺,对加脂后坯革的阻燃性能检测结果表明,采用纳米复合材料加脂的坯革的有焰燃烧时间从146s可降至74s,阴燃时间从958s可降至11s,极限氧指数从14.8%增至21%,表明纳米复合材料能赋予坯革良好的阻燃性能。     

In-situ monitoring of the thermal desorption of alkanethiols with surface plasmon resonance spectroscopy (SPRS)

Thermal desorption investigations on self-assembled monolayers (SAMs) had previously been carried out using techniques such as thermal desorption spectroscopy (TDS), scanning tunneling microscopy (STM) and X-ray photo-electron spectroscopy (XPS). In this paper, the thermal dissociation of alkanethiols (CnH(2n + 1)SH) at various chain lengths (n= 6, 12, 18) on sputtered gold layers was monitored in-situ using the Kretschmann surface plasmon resonance configuration on a spectroscopic ellipsometer. We found that the longest alkanethiol (C18) exhibits the greatest thermal stability, manifested by the least amount of angular shift, during heating, in the resonant spectral features. Predictions of desorption temperatures from SPRS for the longer chain thiols are in good agreement with XPS measurements.     

Direct detection of biologically significant thiols and disulfides with manganese(IV) chemiluminescence

The quantification of low-molecular mass thiols and disulfides involved in cellular redox processes is hindered by oxidation or degradation of analytes during conventional sample preparation steps (including deproteinization and derivatization). Researchers therefore seek techniques that minimize sample handling and permit direct detection of thiols and disulfides within a single chromatographic separation. We demonstrate a new HPLC procedure for these biologically important analytes that incorporates direct chemiluminescence detection with a manganese(IV) reagent. A mixture of seven thiols and disulfides (cysteine, N-acetylcysteine, homocysteine, glutathione (GSH), glutathione disulfide (GSSG), cystine, and homocystine) in their native forms were separated using a C18 column within 20 min. Detection limits for these analytes ranged from 5 × 10(-8) to 1 × 10(-7) M, and the precision for retention times and peak areas was excellent, with relative standard deviations of less than 0.3% and 2%, respectively. This approach was employed to determine two key biomarkers of oxidative stress, GSH and GSSG, in whole blood taken from 12 healthy volunteers. Samples were deproteinized, centrifuged, and diluted prior to analysis using a simple procedure that was shown to avoid significant artificial oxidation of GSH.     

Co (II) phthalocyanine - amine functionalized graphene oxide as a solid base catalyst for the oxidation of thiols

A noncovalent attachment of propylamine (PA), butylamine (BA), ethylenediamine (EDA) and tetramethylenediamine (TMD) - functionalized Graphene oxide (GO) to cobalt (II) phthalocyanine (CoPc) as a novel solid base catalyst was synthesized by mixing method. The synthesized catalysts were characterized using UV-vis, XRD, FTIR, FESEM, EDAX, MAP and HRTEM analyses. The catalytic performances of the synthesized catalyst were evaluated for the oxidation of various thiols in n-heptane under alkali free condition, and were in the following order: EDAGO-CoPc > TMDGO-CoPc > PAGO-CoPc > BAGO-CoPc. For better investigation, the potential of EDAGO-CoPc catalyst was investigated for thiols oxidation in real gasoline. According to the results, 96.55% thiols were removed from real gasoline over the EDAGO-CoPc catalyst. After eight runs of experiment, no significant change was observed in the activity of EDAGO-CoPc catalyst for thiols oxidation in real gasoline.     

Simultaneous LC/MS/MS determination of thiols and disulfides in urine samples based on differential labeling with ferrocene-based maleimides

A method for the simultaneous determination of a series of thiols and disulfides in urine samples has been developed based on the sequential labeling of free and bound thiol functionalities with two ferrocene-based maleimide reagents. The sample is first exposed to N-(2-ferroceneethyl)maleimide, thus leading to the derivatization of free thiol groups in the sample. After quantitative reaction and subsequent reduction of the disulfide-bound thiols by tris(2-carboxyethyl)phosphine, the newly formed thiol functionalities are reacted with ferrocenecarboxylic acid-(2-maleimidoyl)ethylamide. The reaction products are determined by LC/MS/MS in the multiple reaction mode, and precursor ion scan as well as neutral loss scan is applied to detect unknown further thiols. The method was successfully applied to the analysis of free and disulfide-bound thiols in urine samples. Limits of detection are 30 to 110 nM, and the linear range comprises two decades of concentration, thus covering the relevant concentration range of thiols in urine samples. The thiol and disulfide concentrations were referred to the creatinine content to compensate for different sample volumes. As some calibration standards for the disulfides are not commercially available, they were synthesized in an electrochemical flow-through cell. This allowed the synthesis of hetero- and homodimeric disulfides.     

Surface modification of CdS quantum dots using thiols-structural and photophysical studies

This study is aimed at identifying a suitable organic thiol for CdS by studying its structural, thermal and photophysical characteristics. Quantum dots of the II-VI semiconductor CdS, in the size regime of 2.0-3.3?nm, were prepared in the cubic phase by a wet chemical method. Five organic thiols were used for capping: (i) 1,4-dithiothreitol (DTT), (ii) 2-mercaptoethanol (ME), (iii)?cysteine (Cys), (iv)?methionine (Meth), and (v)?glutathione (GSH). Structural studies were carried out by x-ray diffraction (XRD) and transmission electron microscopy (TEM), which revealed the cubic phase of CdS. Optical properties were studied by FT-IR, UV-visible and fluorescence spectroscopic techniques, and a comparison was made between uncapped and capped CdS. FT-IR studies suggested two different bonding mechanisms of the capping agents with the CdS. GSH and DTT capped CdS showed significant decrease in absorption wavelengths. An increase in band gap was observed in two cases: when (i)?capped and (ii)?decreased in size. The band gap was increased from 2.50?eV for the uncapped to 2.77?eV for the DTT capped CdS. DTT was found to be the best capping agent for CdS among these five organic thiols in two aspects: (i)?yielding lower grain size in cubic phase, and (ii)?good fluorescence properties with efficient quenching of the surface traps.     

Capillary zone electrophoretic detection of biological thiols and their S-nitrosated derivatives.

Reduced thiols (RSH) react with certain oxides of nitrogen to yield S-nitroso thiols (RSNO) possessing smooth muscle relaxant and platelet inhibitory properties. Nitrosated derivatives of the biological thiols--glutathione, cysteine, and homocysteine--have therefore been considered as bioactive intermediates in the metabolism of organic nitrates and the endothelium-derived relaxing factor with properties of nitric oxide. As yet, however, there is no established chemical method for identifying the biological S-nitroso thiols and, consequently, little is known of their distinguishing chemical characteristics or biochemistry. In this study, we demonstrate for the first time a simple, rapid, and reproducible method for separating these thiols from their S-nitrosated derivatives using capillary zone electrophoresis. Cysteine, homocysteine, and glutathione were separated from one another and from their corresponding disulfides in 0.01 M phosphate buffer, pH 2.5, by capillary zone electrophoresis and absorbance detection at 200 nm with measured elution times of 5.92-16.15 min; corresponding S-nitroso thiols were selectively detected at 320 nm and eluted at 2.50-18.20 min. These data support the specificity and reproducibility of this technique for separation and identification of thiols, disulfides, and S-nitroso thiol derivatives.     

Nile red-adsorbed gold nanoparticles for selective determination of thiols based on energy transfer and aggregation

For the first time, an aqueous solution of 32-nm gold nanoparticles (GNPs), to which Nile red (NR) has been noncovalently adsorbed, has been used for sensing thiols. The as-prepared NRGNPs fluoresce weakly as a result of fluorescence resonance energy transfer between NR and the GNPs. The fluorescence of a solution containing NRGNPs at pH 4.0 increases upon the addition of thiols, but not when amines, acids, alcohols, bovine serum albumin, or hemoglobin are added. This phenomenon allows for the selective determination of thiols such as cysteamine and homocysteine, which have limits of detection of 10.2 and 10.9 nM, respectively, at a signal-to-noise ratio of 3. Interestingly, we have found that the excitation (lambda(ex) = 480 nm), emission (lambda(em) = 610 nm), and mass spectra (m/z 282) of the substance that desorbs from the GNPs in the presence of thiols are different from those of NR (lambda(ex) = 580 nm; lambda(em) = 652 nm; m/z 318), which indicates that a new product forms. When simultaneously conducting fluorescence and colorimetric assays, the selectivity of this approach further improves because at pH 4.0, the color of the NRGNPs does not change in the presence of negatively charged thiols, (e.g., N-(2-mercaptopropionyl)glycine), but changes from maroon to purple and lavender in the presence of neutral thiols (e.g., 3-mercapto-1,2-propanediol) and positively charged thiols (e.g., cysteamine), respectively, as a result of aggregation. This feature allows the types of thiols to be determined at concentrations >1.0 and 0.1 microM by the naked eye and by UV-vis absorption, respectively. Depending on the rate at which the NRGNP color changes, reduced glutathione (slow) is readily distinguishable from oxidized glutathione (no aggregation and no displacement) and from cysteine and homocysteine (fast).     

粉末冶金法制备SiC_p/Al_2W_3O_(12)/Al复合材料及其热膨胀性能

通过添加适量的Al_2W_3O_(12)负热膨胀粉体来优化碳化硅颗粒增强铝基(SiC_p/Al)复合材料的热膨胀系数。实验采用固相法制备负热膨胀性能的Al_2W_3O_(12)粉体,并按10%,20%,30%的体积比添加至SiC_p/Al复合粉体中,利用粉末冶金工艺制备SiC_p/Al_2W_3O_(12)/Al复合材料。实验结果表明:制备的复合材料组织分布均匀,致密度良好。室温到200℃内,在Al基体质量分数不变的前提下,Al_2W_3O_(12)的加入有效降低了复合材料的热膨胀系数。     

Benzofurazan Sulfides for Thiol Imaging and Quantification in Live Cells through Fluorescence Microscopy

Thiol groups play a significant role in various cellular functions. Cellular thiol concentrations can be affected by various physiological or pathological factors. A fluorescence imaging agent that can effectively and specifically image thiols in live cells through fluorescence microscopy is desirable for live cell thiol monitoring. Benzofurazan sulfides 1a-1e were synthesized and found to be thiol specific fluorogenic agents except 1d. They are not fluorescent but form strong fluorescent thiol adducts after reacting with thiols through a sulfide-thiol exchange reaction. On the other hand, they exhibit no reaction with other biologically relevant nucleophilic functional groups such as -NH(2), -OH, or -COOH revealing the specificity for the detection of thiols. Sulfide 1a was selected to confirm its ability to image cellular thiols through fluorescence microscopy. The compound was demonstrated to effectively image and quantify thiol changes in live cells through fluorescence microscopy using 430 and 520 nm as the excitation and emission wavelengths, respectively. The quantification results of total thiol in live cells obtained from fluorescence microscopy were validated by an high-pressure liquid chromatography/ultraviolet (HPLC/UV) total thiol assay method. The reagents and method will be of a great value to thiol redox-related research.     

材料表面自由能对微接触印刷油墨转移过程的影响

为提高印刷转移效果,以硫醇为研究对象,从理论上分析了理想状况印刷和实际印刷中硫醇的比表面能对其转移率和铺展系数的影响;实验研究了印刷图案精细程度和达到稳定的时间随硫醇浓度的变化情况。结果表明:降低硫醇浓度可降低其比表面能,从而增大转移率和增强在基底表面的铺展效果。为实际应用中硫醇转移过程的控制和改进提供一些指导。