【作者】 王新；

【导师】 刘孝恒；

【作者基本信息】 南京理工大学 ， 材料科学与工程， 2011， 博士

【摘要】 自组装技术的研究和应用是近年来十分受关注的研究领域,在纳米材料研究中越来越引起人们的重视。本文以表面活性剂为模板,醇盐为原料,大分子的明胶为稳定剂,利用自组装的方法在室温下制备了具有有序介观结构的空气-水界面无机氧化物纳米薄膜。采用了X射线衍射(XRD)、红外光谱(FT-IR)、拉曼光谱(Raman)、热重-差热分析(TG-DTA)、比表面及孔径分析仪(BET)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、能谱(EDS)等一系列分析手段,对这类薄膜样品的组成、结构、性质、形成机理等诸多方面进行了研究。随后将薄膜改性,研究改性后自组装产物的催化性能(包括光催化、化学催化)、表面增强拉曼性质、抗菌性质。全文主要研究内容如下：首先使用阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)为模板,在明胶的稳定作用下,以正硅酸乙酯(Si(OC2H5)4)为前驱体,在强碱性环境下自组装制备出无定形介孔状SiO2纳米薄膜。利用XRD、SEM、TEM、BET、Raman的表征结果对介孔结构的形成机理进行验证分析。考察了该薄膜的热性能,分析在不同温度下煅烧后样品的形貌和结构,着重讨论一次粒子聚合成二次粒子时的受热情况。用AgNO3溶液对无定形的SiO2薄膜改性,目的是将Ag粒子负载于SiO2氧化物颗粒上。首先利用自组装Si02颗粒作为微型反应器,生成树枝状纳米Ag颗粒,采用XRD,SEM,TEM、UV-vis的表征结果来分析这种多级结构树枝状纳米Ag颗粒的形成过程,提出了反应机理；并将树枝Ag颗粒作为拉曼基底,考察样品的表面增强拉曼性质。另外将自组装的SiO2颗粒在AgNO3溶液中浸泡5min后随即取出,再用Na2S2O3溶液浸泡,生成球状Ag-SiO2复合纳米颗粒,研究其对大肠杆菌的抗菌效果,阐述Ag-SiO2复合纳米颗粒的抗菌机理。用CTAB为模板,以钛酸四丁酯(Ti(OC4H9)4)为前驱体,自组装制备出无定形的层状TiO2纳米薄膜,对其结构进行表征。将其浸泡于AgNO3溶液中得到Ag-TiO2复合纳米颗粒,考察此复合型氧化物颗粒的抗菌性能。将煅烧后的复合纳米颗粒作为基底,考察其表面增强拉曼活性。同时将该样品作为光催化剂,以甲基橙为模拟污染物,衡量此光催化剂的催化性能及稳定性。再将此催化剂用于苯乙烯的催化氧化反应中,选取H202为氧化剂,目的产物为环氧苯乙烷,证实400℃温度下的煅烧后样品具有极好的化学催化性能,分析反应的各种影响因素(时间、温度、原料的摩尔比、溶剂),并考察此催化剂的稳定性。以阴离子表面活性剂十二烷基硫酸钠(SDS)为模板,以钛酸四丁酯(Ti(OC4H9)4)为前驱体,在强酸性环境中自组装制备了TiO2纳米薄膜。将薄膜浸泡于BaCl2溶液中,生成BaSO4-TiO2复合型氧化物颗粒。根据上一章热处理样品的结果,选择合适的煅烧温度将薄膜中的无定形TiO2转化为锐钛矿型。以此复合型氧化物为光催化剂考察其的光催化活性,并分析该光催化剂的重复使用情况。根据前面的实验方法,采用CTAB为模板制备无定形层状TiO2-SiO2二元复合氧化物纳米薄膜。将制备得到的薄膜进行热处理,以煅烧后的产物为光催化剂,甲基橙为模拟污染物,考察并与Ag-TiO2复合颗粒对比光催化活性和催化剂稳定性,发现后者的光催化活性稍高,但前者在重复使用中的稳定性较好。更多还原

【Abstract】 The research and application of self-assembly technique are of great scientific and technological importance, the preparation of inorganic material-based films using self-assembly technique has attracted intense research interest over recent years. This paper presents a novel method based on self-assembly for the fabrication of a series of air-water interfacial oxide nanofilms with ordered structure, using surfactants as template and gelatin as stabilizers with organic metallic alkoxide precursors. X-ray diffraction (XRD), fourier-transform infrared spectra (FT-IR), N2 adsorption-desorption isotherms, Raman spectra, thermal gravity and differential thermal analysis (TG-DTA), scaning electron microscope (SEM), transmission electron microscope (TEM) and energy dispersive spectra (EDS) are use to characterize the morphologies, structures, compositions and self-assembly mechanisms of the self-assembled nanofilms. The catalytic properties, surface-enhanced Raman spectroscopy and antibacterial properties have been carefully investigated and discussed after modification of the nanofilms.The main contents are summarized as following:Mesoporous-like amorphous silicon oxide nanofilms are self-assembled with gelatin as stabilizer by using cetyltrimethylammonium bromide (CTAB) as template and TEOS as precursor. The interaction between surfactant headgroups (dimeric molecular bar) and mesoporous-like silicon oxide is approved to be the formation mechanism to form the nanostructure by XRD, SEM, BET, TEM and Raman. The thermal property of the silicon oxide nanofilms is also investigated. TEM is successfully applied to observe the microstructural changes of air-water interfacial SiO2 secondary particles and the transformation mechanism is investigated, which analyze the morphology and structure of the SiO2 nanoparticles after calcination at different temperatures. The SiO2 nanoparticles as a microreactor are soaked into silver nitrate (AgNO3) aqueous solution. Then the dendritic Ag nanoparticles can be prepared by a reaction of silver nitrate with template agent (CTAB) and AgBr decompose into elemental Ag nanoparticles under visible light irradiation in the SiO2 microreactor. The morphology and structure of as-prepared Ag nanodendrites are characterized by XRD, SEM, TEM and UV-vis, the correlated surface-enhanced Raman scattering (SERS) effect have been investigated when 2-Mercaptobenzothiazole (2-MBT) is used as a Raman probe. The results clearly show that the dendritic nanostructures can be obtained through oriented attachment of nanoparticles along a crystallographically special direction and the morphology of the dendrites is dependent on the reaction duration in the reaction process. After soaked in silver nitrate (AgNO3) aqueous solution for 5min, the SiO2 nanoparticles are soaked into sodium thiosulfate (NaS2O3) solution so that the sphereical Ag-SiO2 composite nanoparticles can be obtained by the same method. The composite nanoparticles are used to the antimicrobial experiments, the experiments indicate that the Ag-SiO2 composite nanoparticles have good anti-bacterial properties. The action mechanism has also been discussed.By CTAB as template, gelatin as stabilizer and Ti(OC4H9)4 as precursor, Titanium oxide nanofilms composed of lamellar structure have been self-assembled. The TiO2 nanofilms are soaked into silver nitrate (AgNO3) aqueous solution. Then the Ag-TiO2 composite nanoparticles can be prepared by a reaction of silver nitrate and sodium thiosulfate with template agent (CTAB), the Ag-TiO2 particles are used to the antimicrobial tests and the experiments indicate that the Ag-TiO2 nanoparticles have good anti-bacterial properties. The structure of composite nanoparticles may be strengthened after heated treatment. We investigate the SERS effect on the surfaces of the composite nanoparticles. Methyl orange is used as the degradable agent in photocatalytic experiment by using the Ag-TiO2 particles as a photocalalyst. The Ag-TiO2 nanoparticles can be applied to improve catalytic activity of the epoxidation of styrene oxides. Styrene oxide is the main product of catalytic reaction with H2O2 as the oxidant by using Ag-TiO2 nanoparticles as catalysts. High catalytic activitity of styrene oxide can be obtainable. The reaction temperature, reaction time, the molar ratio of H2O2/styrene and solvent affect greatly the catalytic epoxidation of styrene and the stability of the catalyst has been analysed.By anionic surfactant sodium dodecyl sulfate (SDS) as template, the self-assembled TiO2 nanofilms are prepared under acidic conditions. The TiO2 nanofilms are soaked into barium chloride (BaCl2) aqueous solution. Then the BaSO4-TiO2 nanocomposite particles can be prepared by a reaction of BaCl2 with template agent (SDS). According to the heat treatment conditions, the amorphous TiCl2 nanofilms transform into anatase TiO2 after calcination at 400℃. The photocatalytic activities are described, and the catalyst has been proved to the instability in repeated using.TiO2-SiO2 binary nanofilms are self-assembled with cetyltrimethylammonium bromide as template. The nanofilms are composed of lamellar particles. Contrasted by Ag-TiO2 catalysts, TiO2-SiO2 has a little lower activity, but has characteristics of higher stability.更多还原