【作者】 王海花；

【导师】 沈强；

【作者基本信息】 山东大学 ， 物理化学， 2009， 硕士

【摘要】 十二烷基硫酸盐是一种阴离子表面活性剂,具有双亲结构。在制备纳米材料过程中,其极性头吸附在纳米颗粒表面,悬浮在颗粒表面的烷基链间的疏水作用防止纳米粒子的团聚,起到稳定分散作用,从而控制了纳米粒子的尺寸、形貌等。此外,它还可以作为制备纳米材料的离子来源。本文在十二烷基硫酸盐体系中成功合成出了CuO,Cu₂O和ZnO半导体纳米材料,并且利用透射电子显微镜（TEM）、扫描电子显微镜（SEM）、X射线衍射（XRD）、热重分析（TGA）等多种表征手段表征了其结构和形貌,并提出了其形成机理,具体内容如下:（1）利用十二烷基硫酸钠（SDS）和氯化铜（CuCl₂·2H₂O）反应合成的十二烷基硫酸铜（Cu（DS）₂）作为特殊的铜离子源来调控CuO的结构及形貌。在60℃条件下,首次得到层状结构的带状中间产物Cu（OH）₂-DS。无论是否在反应体系中加入添加剂十二醇（DOH）,Cu（DS）₂与NaOH反应均可得到哑铃状结构CuO,只是十二醇分子的加入可以使得到的哑铃状结构尺寸变大,可能是由于DOH与SDS形成DOH-DS复合物导致的。结果证明:带状结构的中间产物和悬浮在颗粒表面上烷基链的疏水作用导致了哑铃状结构的形成。此外,氯化钠的加入可以诱导哑铃状结构转化成孪生锚结构然后再转化成中间带有两个孔的孪生球结构。利用表面活性剂烷基链间的疏水作用调控纳米材料的结构及形貌为材料形貌调控领域提供了一个重要方法。（2） Cu（DS）₂既作为铜离子源又作为晶体形貌的调节剂来调控Cu₂O形貌和结晶。随着铜盐Cu（DS）₂浓度从0.27增加到3.64 mmol·L^-1,得到Cu₂O晶体的形貌从正方体截去八个角的十四面体结构转化成正十四面体结构,然后再转化成将八面体截去截去六个顶角的十四面体结构和一些小的正方体结构。作为对比实验,利用无机盐CuCl₂代替Cu（DS）₂作为铜离子源,研究了CuCl₂溶液浓度对Cu₂O形貌和结晶的影响。结果表明:表面活性剂阴离子（如DS^-）在Cu₂O形貌调控上起了非常重要的作用,此外,还原剂葡萄糖浓度和陈化时间也对Cu₂O形貌调控和结晶有重要影响。表面活性剂离子与葡萄糖分子的竞争吸附和陈化时间共同作用影响Cu₂O晶体的生长。（3）在60℃条件下,硫酸锌（ZnSO₄·7H₂O）和氢氧化钠（NaOH）反应合成ZnO。表面活性剂十二烷基硫酸钠（SDS）作为添加剂,在较低浓度下,不能影响ZnO的形貌,仅能使ZnO尺寸变大,在较高浓度下,会使ZnO形貌从玉米粒状转化成由两个孪生小棒组成的纳米棒。十二烷基硫酸钠和十二醇（DOH）共同作添加剂时,SDS量固定,随着DOH加入量的增加,会得到束腰纺锤形、六棱柱状、孪生棒状结构的ZnO,同时,ZnO晶体的尺寸先增大后减小,在DOH量为1.5 mmol·L^-1时,得到的六棱柱状ZnO尺寸最大为1.2±0.3μm。更多还原

【Abstract】 Divalent metal dodecyl sulfate is a type of anionic surfactants with amphiphilic structures.The hydrophobic interaction of pendent hydrocarbon chains adsorbed onto the surface of nanoparticles can prohibit the aggregation of inorganic nanoparticles, which can control the size and/or morphology of nanoparticles in the fabrication processes.Moreover,it is also used as a special metal-ion source.In this thesis,CuO, Cu₂O and ZnO semiconductor nanoparticles were successfully obtained from the aqueous systems of these divalent metal dodecyl sulfates,respectively.Meanwhile, the structure and morphology of obtained nanoparticles were characterized by transition electron microscopy（TEM）,scanning electron microscopy（SEM）,X-ray diffraction（XRD）,thermogravimetric analysis（TGA）,and etc.The possible formation mechanisms were also postulated.The main results of this thesis were summarized,listed as following:（1） The synthesized surfactant of copper dodecyl sulfate（Cu（DS）₂） was used as special metal-ion source for the morphological control of copper oxide（CuO） architectures.During the fabrication processes,the ribbon-shaped intermediates of basic copper salt with lamellar structures were observed at 60.0℃for the first time. In the absence or presence of dodecanol（DOH）,Cu（DS）₂ could react with sodium hydroxide to form dumbbell-like architectures of CuO nanoparticles.The incorporation of DOH molecules into the adsorption monolayers of surfactant ions could greatly enlarge the dumbbell size in length,probably depending upon the formation of the DOH-DS complex.These indicated that the template effectiveness of the intermediate ribbons,together with the hydrophobic interactions of adsorbed hydrocarbon chains,should account for the formation process of CuO dumbbells. Interestingly,the addition of sodium chloride into the reaction systems could induce the morphological change of CuO dumbbells to the twinanchors and then to the twin-spheres with two holes in the center.This further suggests that the hydrophobic interaction of pendent hydrocarbon chains provides an important approach for material fabrication purposes.（2） The functionalized surfactant of copper dodecyl sulfate（Cu（DS）₂） was used both as the metal ion source and as the crystal modifier to investigate the crystallization habits of cuprous oxide（Cu₂O）.The increase of Cu（DS）₂ concentration from 0.27 to 6.82 mmol·L^-1 caused the morphological change of Cu₂O crystals from the truncated cubic to the cuboctahedral,then to the coexistence of the cubic and the truncated octahedral,and finally to the truncated octahedrons.As an experimental control,the inorganic salt of copper（Ⅱ） chloride system was also used as the metal ion source to conduct the crystallization of Cu₂O.These results indicate that the special adsorption of organic counterions（i.e.,dodecyl sulfate ions） exerted a great influence on the shape control of Cu₂O crystals,especially at a relatively low concentration.Meanwhile,the D-glucose concentration and the incubation time of crystals were also considered to discuss the crystallization habits of Cu₂O.In conclusion,the competitive adsorption of surfactant ions and D-glucose molecules onto crystalline faces,as well as the aging time,accounted jointly for the shape control of Cu₂O crystals.（3） ZnO crystals were synthesized by mixing zinc sulfate（ZnSO₄·7H₂O） and sodium hydroxide（NaOH） aqueous solutions at 60℃.In the presence of low concentration of sodium doedcyl sulfate（SDS）,the added surfactants could only modify the size of ZnO crystals.While at a high concentration of SDS,the morphology of ZnO changed from corn-like structures into the twin-nanorods.When both SDS and DOH were simultaneously as additives,the structure of ZnO crystals changed from the spindle-like structures,with thin middle,to the hexagonal prisms and then to the twin-rods.At a fixed concentration of SDS,the average size of ZnO crystal increased at first and then reduced with increase of DOH concentration.The largest ZnO prism, obtained in the presence of 1.5 mmol·L^-1,possessed the hexagonal section and was 1.2±0.3μm in length.更多还原