利用表面活性剂量改变孔洞率制备的纳米多孔SiO2膜

采用表面活性剂十六烷基三甲基溴化氨(CTAB)为模板剂,在酸性条件下产生多孔结构,再经热处理去除CTAB。实验中使用溶胶?凝胶技术,正硅酸乙酯(TEOS)为硅源,以及二次去离子水,盐酸为催化剂等原料,利用表面活性剂与硅源水解后形成的聚集体相互作用,在溶液中形成分子自组装体,制备前驱体溶胶。通过简单提拉迅速蒸发溶剂制备纳米多孔或纳米介孔SiO2薄膜,分析和研究了表面活性剂浓度对纳米多孔SiO2薄膜的结构和孔洞率的影响,通过操纵表面活性剂的含量,能控制薄膜的纳米结构、孔洞率、孔大小和孔的形态以及膜的形貌。小角度射线衍射、场发射透射电子显微镜、原子力显微镜显示可以制得具有六方、立方和由三维六方和简单立方组成的新相结构以及比介孔大的纳米多孔结构的薄膜。椭偏仪测量得到所制备薄膜的孔洞率为51.8%-65.6%,借助此孔洞率能计算薄膜的折射率和介电常数。     

更正启事

本刊发表论文"树枝状与球状PbS纳米结构的组装合成及其形成机理研究(2010,25(2):135-140)",应原作者季振国的要求,作者署名更正为"糜裕宏,张孝彬,倪华良,祝华云,周胜名".     

前驱物和表面活性剂对等离子体电化学法制备银纳米颗粒的影响

利用等离子体电化学法成功制备出银纳米颗粒,并通过局域表面等离子共振效应对颗粒的生长过程进行实时监测,研究了表面活性剂的浓度、种类和前驱物浓度对银纳米颗粒制备的影响。研究结果表明:增大前驱物或表面活性剂浓度对Ag;还原均有促进作用;与聚乙烯吡络烷酮(PVP)和十六烷基三甲基溴化铵(CTAB)相比较,十二烷基硫酸钠(SDS)作为表面活性剂,在相同时间内,生成的银纳米颗粒数量更多,尺寸和形状分布更均匀。     

表面活性剂对FePt纳米颗粒形貌的影响

分别以乙酰丙酮铁(Fe(acac)3)和氯铂酸(H2PtCl6.6H2O)作为Fe源和Pt源,乙二醇作为还原剂和溶剂,通过多元醇还原法制备出单分散的FePt纳米颗粒,并研究了表面活性剂油酸油胺和CTAB对FePt纳米颗粒形貌和磁性能的影响。通过X射线衍射仪(XRD)、透射电子显微镜(TEM)和振动样品磁强计(VSM)对纳米颗粒进行表征。结果表明,表面活性剂油酸油胺和CTAB修饰的FePt纳米颗粒均为面心立方(FCC)结构,分散性良好,粒径分布较未使用表面活性剂时变窄;油酸油胺修饰的FePt形貌主要是球形,但是有四方形纳米结构出现;而CTAB修饰的FePt形貌有蠕虫状产生。VSM结果显示其矫顽力都趋近于零,呈现超顺磁性。     

纳米/微米结构粒子合成技术进展

介绍了近年来纳米/微米结构粒子的合成技术进展,将纳米单元(纳米棒、纳米带、纳米片、纳米颗粒)自组装为各种尺度的有序结构会产生更优异的整体协同性质,这对纳米/微米结构粒子的性能研究有重要意义。主要介绍了表面活性剂法、水热法和模板诱导法等。表面活性剂由于具有多种特殊、优异的性能,包覆在纳米粒子表面可使其组装成具有新颖结构的聚集体,是目前研究热点。水热法所得粒子具有纯度高、分散性好、晶形可控,生产成本低等特点已被广泛采用。     

以汞为反应介质制备氧化锌纳米空心球

以汞为反应介质, 表面活性剂胶束为模板, 通过锌的氧化反应制备了氧化锌空心球. 采用SEM、EDX、TG、DTA、XRD、IR等测试手段对产物的形貌和结构进行了表征, 并考察了表面活性剂对产物生长的影响. 研究表明, 氧化锌空心球为无定型结构, 壁厚为纳米尺度, 由氧化锌纳米粒子组装而成, 煅烧后转变为六方纤锌矿结构. 加入适量PEG或CTAB, 能制备出氧化锌空心球; 不加入表面活性剂、加入过量PEG或SDBS, 则不能制备出氧化锌空心球.     

表面活性剂辅助室温液相合成BaCO3纳米棒

用阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)为形貌控制剂,通过室温液相反应成功制备出BaCO3纳米棒.纳米棒的直径为60～250nm、长度达几微米.用X射线粉末衍射和透射显微镜技术对所制备纳米晶的成分、形状和尺寸进行了表征分析.研究结果表明,表面活性剂对BaCO~纳米棒的形成起着关键的作用.对BaCO~纳米棒的形成机理作了深入的讨论,提出了BaCO3纳米棒的表面活性剂软模板诱导自组装生长机理.     

二元混合表面活性剂对纳米流体热物性影响

采用两步法制备了添加二元混合表面活性剂的氧化锌纳米流体，纳米颗粒的体积浓度为0.398%～2.292%。XRD、TEM对氧化锌纳米粒子进行表征，吸光度法和沉降法分析了纳米流体稳定性，之后研究15～55℃时，制备流体的导热与黏度，并与添加单一表面活性剂的纳米流体进行对比。实验结果显示，添加SDS/CTAB纳米流体稳定性更优。纳米流体导热系数随温度及纳米粒子体积浓度的增加而增大，55℃,2.292%的纳米流体热导率增强最大，提高了38%,且热导率增强作用明显优于单一表面活性剂的添加。纳米流体黏度随温度及纳米粒子体积浓度的增加而逐渐降低，在55℃,2.292%时拥有最小黏度0.645 mPa·s。与单一表面活性剂相比，SDS/CTAB的添加能有效降低纳米流体黏度，对减小纳米流体黏度有积极作用。     

水热合成法制备La0.7Sr0.3FeO3纳米线的合成机理研究

在表面活性剂CTAB水溶液中添加硝酸盐溶液,并滴加氨水,采用水热合成法在180℃的温度下反应9h,制备了La0.7Sr0.3FeO3前驱体,在700℃下煅烧6h后得到La0.7Sr0.3FeO3纳米颗粒组装的纳米线。利用SEM、TEM和XRD对其形貌、尺寸和结构等进行了表征。制备的La0.7Sr0.3FeO3纳米线是由约为20nm的纳米颗粒组装而成的,纳米线的最大长径比达100以上。通过改变水热合成时间和前驱体的煅烧温度等实验条件,对La0.7Sr0.3FeO3纳米线的物相转化和生长机理进行了分析。表面活性剂CTAB作为生长控制剂和颗粒凝聚载体,能够控制材料沿着轴向生长,形成纳米线。     

钴纳米棒的有机相化学还原法制备及其表征

在有机相中,表面活性剂聚乙烯吡咯烷酮(PVP)存在下,采用联氨还原氯化钴的化学方法制备得到钴纳米棒,并用XRD、TEM、XPS和TG-DTA对样品的组成和形貌进行表征和分析.结果表明,用该法制得的钴纳米棒直径约为50～80m,长度约为300～500 nm,具有hcp相.表面活性剂PVP在钴纳米棒的形成过程中起到软模板的作用,使钴纳米粒子沿着一定的方向生长成纳米棒.     

Synthesis of polyaniline nanostructures in different lamellar liquid crystals and application to lubrication

Polyaniline (PANI) nanostructures were synthesized in lamellar liquid crystal (LLC) formed by different surfactants. It was found that PANI presented lamellar nanostructures by using the template of LLC formed by ionic surfactant of sodium dodecyl sulfonate (SDS) or hexadecyltrimethylammonium bromide (CTAB), whereas PANI spheric nanostructures were obtained within the LLC template formed by the nonionic surfactant of Triton X-100. The formation mechanisms of PANI nanostructures were discussed. Besides, the lubricating effect of PANI in LLC template was also investigated, and the results showed that spheric PANI had better lubricative performance than lamellar PANI.     

Synthesis and characterization of different nanostructures of cobalt phosphate

In this research, different nanostructures of cobalt phosphate were successfully prepared. Flowerlike cobalt phosphate and platelike ammonium cobalt phosphate were made by coprecipitation method without any use of surfactant or capping agent as structure directors. Reverse micelle route in water/CTAB/n-hexanol microemulsion system was used to synthesize cobalt phosphate nanoparticles. The synthesized nanostructures were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), chemical analysis, and BET. The SEM images showed that the flowerlike nanostructure is an arrangement of cobalt phosphate plates. TEM images revealed that the nanoparticles are spherical with the diameter of 30-50 nm. The purity of cobalt phosphate nanoparticles was confirmed by chemical analysis. Finally, the possible mechanisms which can describe the formation of these nanostructures were discussed.     

表面活性剂对纳米氧化锌形貌和发光性能的影响

以二水合乙酸锌和氢氧化钠为原料,分别以表面活性剂十六烷基三甲基溴化铵(CTAB)和聚乙烯吡咯烷酮(PVP)为结构导向剂,采用简单的水热法制备了不同形貌的纳米氧化锌。研究了两种表面活性剂对纳米氧化锌形貌和光致发光性能的影响,并探讨了表面活性剂的作用机理。采用X射线衍射(XRD)、扫描电子显微镜(SEM)和室温光致发光光谱(PL)等测试方法对样品的结构、形貌和发光性能进行了表征。结果表明:添加了表面活性剂后,样品形貌和尺寸都更加均匀,紫外发射峰强度相对增加。     

Synthesis of cross-shaped PbS nanostructures by a surfactant-assisted reflux process

Cross-shaped PbS crystals composed of six pods were prepared by a reflux process using CTAB as the surfactant. Parameters affecting the morphology of PbS have been investigated systematically. Results reveal that various PbS structures including cubic, truncated octahedral, flower-shaped and dendritic crystals can be obtained by changing the sulfur and lead source, the solvent or the surfactant. The difference of the morphology was explained to be closely related to the change of the relative growth rate in the 〈100〉 direction to that in the 〈111〉 direction.     

Microwave-controlled facile synthesis of well-defined PbS hexapods

Controlled synthesis of well-defined PbS nanostructures in terms of size and shape has been strongly motivated by their potential applications ranging from solar photovoltaics to near-infrared optics. Hereby, we report a facile microwave-assistant method for ultrafast fabrication of PbS nanostructures, by which uniform PbS hexapods with six arms stretching along six (100) directions of the crystal seeds have been easily synthesized within minutes. Various morphologies including rectangle plates, uniform cubes as well as nanoparticles were obtained by tuning the parameters for the formation of PbS nanocrystals. The results reveal that both concentration and feed ratio of precursors determine the growth of PbS nanocrystals significantly. And higher initial precursor concentration favors the formation of the hexapod structures. The process of crystal growth is monitored through scanning electron microscopy of PbS from different durations of the reaction. This controlled ultrafast synthesis of PbS structures at nanometer and micrometer scale with various morphologies may be promising in large scale fabrication of nanostructures. Based on the systematically study of the growth process, a possible mechanism for the formation of the hexapod-like structure is discussed.     

超声诱导CTAB/SDS溶液中纳米Pd粒子的形貌控制及对甲醛的电催化氧化

在十六烷基三甲基溴化铵(CTAB)-十二烷基硫酸钠(SDS)混合乙醇水溶液中,超声辐射PdCl2,合成了纳米Pd粒子,用XRD、TEM、选区电子衍射(SAED)、HRTEM和低温氮吸附-脱附等技术进行了表征,考察了CTAB/SDS组成对纳米粒子形貌的影响,纳米Pd粒子修饰玻碳电极对甲醛的电催化活性也通过循环伏安法进行了研究。结果表明:通过改变CTAB/SDS组成可以调控纳米Pd粒子的粒径和形貌;当CTAB与SDS物质的量之比为1∶1、超声反应60min时,得到呈多边形的纳米Pd粒子,粒径范围在10～20nm之间,比未添加表面活性剂样品的比表面积增大了14m2.g-1,对甲醛有较高的电催化活性。     

Investigation of different factors towards synthesis of CuS spherical nanoparticles

Spherical CuS nanocrystals were synthesised via reflux (R) and hydrothermal (H) methods using copper acetate monohydrate (Cu (ac)₂·H₂O) and thioacetamide as precursors. This process was carried out in the absence and presence of cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulphate (SDS) surfactants. The products were characterised by using the methods of X-ray powder diffraction (XRD), scanning electron microscopy, energy-dispersive X-ray and transmission electron microscopy. According to XRD results, nanoparticles with the size of 16–23 nm were obtained. The effects of surfactant type, reaction time and reaction temperature on the morphology, yield, size and phase of the obtained products were investigated. According to this study, CTAB was more appropriate than SDS in obtaining uniform and spherical CuS nanoparticles.     

Carbon nano-onion composites: Physicochemical characteristics and biological activity

Carbon nano-onion/surfactant (CNO/surfactant) composites offer the possibility to easily produce the soluble nanostructures. That approach combines the hydrophilicity of surfactants with the robustness of carbon structures to produce composites with superior and unusual physicochemical properties. We used the following surfactants: hexadecyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (SDBS), 4-(1,1,3,3-tetramethylbutyl)phenyl-polyethylene glycol (Triton X-100), and polyethylene glycol sorbitan monolaurate (Tween 20) to non-covalently modify CNO surfaces. The existence of stable CNO composites are clearly evidenced by direct transmission electron microscopy observations, which are also supported by thermogravimetric analyses. Dynamic light scattering and zeta potential confirmed their dispersion and stability. Additionally, the biological activity of well-dispersed CNO/surfactant composites against a strain of Escherichia coli was assayed. In vitro antimicrobial assays for the composites revealed that only the CNO/CTAB composite decreased cell viability. This activity could be assigned to the simple composite dissociation in water solutions, however antimicrobial properties of the composite are slightly better when compared with pure CTAB. This indicate some synergic effect with respect to the properties of the pure surfactant.     

Intrinsic effect of anionic surfactant on the morphology of hydroxyapatite nanoparticles and its structural and biological properties

This paper describes the potential effect of anionic surfactant on the morphology of hydroxyapatite (HA) nanostructures during hydrothermal synthesis. Sodium dodecyl sulfate (SDS) was used as an anionic surfactant. Various concentrations of SDS were used to study morphological changes in HA due to the presence of the surfactant. The final morphology, after treatment by a hydrothermal method, revealed that the anionic surfactant induced growth in one direction (a-axis) and inhibited growth in the other (c-axis) based on the charge distribution on the crystal faces of HA. Further structural analysis (by X-ray diffraction) confirmed this growth along the a-axis. In-vitro cellular analysis revealed that the plate-like nanoparticles possess better bioactivity than their bulk counterparts. Therefore, HA nanoplates could be used for applications that include controlled drug delivery and bone mineralization.