【作者】 王纯荣；

【导师】 方云；

【作者基本信息】 江南大学 ， 应用化学， 2007， 博士

【摘要】 纳米技术是当前最前沿的研究领域。纳米材料的形貌和尺寸控制则是纳米技术的重要组成部分。纳米材料在尺寸、形态以及表面与体相原子数比和表面性质等方面均与普通同质材料有很大的不同,它们在光学、微电子学、磁学、催化和生物学等领域有着重要的应用。纳米材料的制备是胶体化学、材料科学和界面科学的新兴交叉领域,也是当今科学研究十分活跃的领域。本论文考察了表面活性剂十二烷基硫酸钠(SDS)与大分子聚乙二醇(PEG)或聚乙烯吡咯烷酮(PVP)形成的软物质团簇与氯金酸(HAuCl4)之间的相互作用以及软物质团簇在溶液中的结构。在此研究基础上,以SDS-PEG软团簇为模板,利用超声还原和光还原方法制备了粒径可控的球形金纳米粒子;以SDS-PEG软团簇为模板,利用PEG自还原能力制备了片状、环状和弧形金纳米粒子;以SDS-PVP软团簇为模板,利用柠檬酸钠为还原剂,在微波辐射条件下制备了多脚状金纳米粒子。初步探讨了表面活性剂SDS与大分子PEG或PVP组成的软团簇在制备金纳米粒子过程中的模板作用。其主要包括以下四个部分:第一部分主要通过表面张力、稳态荧光猝灭、荧光分子探针和激光光散射等技术研究了HAuCl4对表面活性剂SDS与大分子PEG或PVP组成的水溶液体系的表面张力曲线的临界浓度、比饱和簇集量[Γ∞]、胶束聚集数N b、微环境极性(I1/I3)和水动力学半径Rh等的影响。实验发现HAuCl4促使SDS-PEG或SDS-PVP体系表面张力的第一临界浓度c1减小,而对于其第二临界浓度c2的影响不大。HAuCl4可促使SDS-PEG或SDS-PVP体系的束缚胶束聚集数和饱和簇集量增加,微环境极性减小,并且随着SDS浓度增加,水动力半径随之增大。第二部分着重研究了以SDS-PEG组成的软团簇作为模板,利用超声和光还原手段,分步诱导合成不同粒径的球形金纳米粒子。研究发现SDS和PEG含量对合成金纳米粒子的尺寸和形貌有明显影响,当SDS浓度较低时,随着SDS浓度增加,纳米粒子粒径逐渐变小;当SDS浓度高于一定值时,纳米粒子形貌发生变化,出现三角和截头三角形等不规则形状;在含较高浓度PEG的反应液生成的金纳米粒子的分布较窄。第三部分研究PEG自还原HAuCl4合成金纳米粒子时,SDS-PEG组成的软团簇作为模板对于金纳米粒子尺寸和形貌的影响。该制备过程中只有SDS-PEG模板中的PEG组分参与还原反应,而不添加外加任何还原剂。研究发现PEG自还原HAuCl4后首先形成金量子点;然后在软模板的作用下使金量子点自组装成金纳米片形貌的金量子阱,再通过控制不同的反应周期将此金纳米片母体经老化处理得到不同空洞尺寸的纳米环形貌的金量子阱;最终金纳米环裂解为金纳米弧。这里,SDS与PEG组成的软模板控制金纳米粒子的尺度和形貌,PEG既作为稳定剂保护金纳米结构,又作为自还原剂将水溶液中的金离子还原成金纳米粒子。第四部分采用SDS-PVP形成的软团簇为模板,在微波辐射条件下,以柠檬酸钠作为还原剂,快速还原HAuCl4并自组装成当量直径50 nm且粒径分布窄的多脚状金纳米粒子,并对微波辐射条件下合成多脚状金纳米粒子的模板作用进行了探讨。研究发现,通过改变SDS和PVP的含量,可以对金纳米粒子形貌实施调控,方便地实现金纳米粒子在球形-多脚状-球形形貌间的依次转变。更多还原

【Abstract】 At present, nanotechnology is the pioneering research fields and controllable synthesis of nanoparticles with special size and morphology is one of the most important components. It is well known that nanomaterials are different from the conventional materials due to the size, morphology, and the atom ratio of surface and bulk phase of particles, etc, and are widely and significantly used in such fields as photonics, microelectronics, magnetism, catalytic properties and biology. The formation of nanostructures is a new cross-field of colloid and interface chemistry and material science and also is one of the most active research fields.The characteristics of soft clusters composed of surfactant sodium dodecyl sulfate (SDS) and polyethyleneglycols (PEG) or polyvinylpyrrolidone (PVP) adding HAuCl4 were studied. Sphereial gold nanoparticles were synthesized in the soft template of SDS-PEG with the assistant of ultrasound and UV. Gold nanoplates, nanorings and nanoarcs were also synthesized in SDS-PEG soft template, but no metal hard template or extra reducer was needed and HAuCl4 was self-reduced by PEG component in the soft template. Multipod-like gold nanoparicles were then synthesized through reducing HAuCl4 by sodium citrate in the soft template composed of SDS-PVP clusters assisted by microwave irradiation. The effect of soft template for gold nanoparticles was studied. In a word, there are main four parts below:The first one includes in the critical concentration, specific saturation capacity of clusterization ([Γ∞]), aggregation number of bound micelle (Nb), polarity of microenvironment (I1/I3) and hydrodynamic radius distribution (Rh) of SDS-PEG or SDS-PVP system effected by HAuCl4, which were studied by means of surface tension, steady-state fluorescence quenching, fluorescent molecule probe and laser light scattering. It is found that HAuCl4 reduced the first critical concentration (c1), had no effect on the second critical concentration (c2), increased Nb, and decreased I1/I3 of SDS-PEG or SDS-PVP system. With the increase of SDS in solution, Rh increased when HAuCl4 in n SDS-PEG or SDS-PVP system.The second one is that gold nanoparticles of different diameters were synthesized in a soft template of SDS-PEG with the assistant of ultrasound and UV. The concentrations of PEG (cPEG) and SDS (cSDS) were found to have a dramatic influence on the formation of gold nanoparticles. At a certain concentration of PEG, when the concentration of SDS is low, the more the SDS was in solution, the smaller the diameter of gold nanoparticles was. When cSDS was too high there were anisotropic particles such as triangle or truncated triangle formed in solution. When cPEG was higher the distribution of gold nanoparticles was narrow.The third one studied the effect of SDS-PEG template on the size and morphology of gold nanostructures which were self-reduced by PEG component in the soft template and no extra reducer was needed. HAuCl4 formed gold quantum dots, and then these gold quantum dots self-assembled to construct quantum wells, for example, nanoplates. These gold nanoplates were aged in their mother solution in different reduction periods and turned into ring-like structures, and eventually were splited into nanoarcs. Here PEG played the roles of both the reducer for HAuCl4 and the stabilizer for fresh gold nanoparticles. SDS and PEG together controlled the size and morphology of gold nanoparticles.The last part is to synthesize multipod-like gold nanoparticles with equivalent diameter around 50 nm through reducing HAuCl4 by sodium citrate in the soft template composed of SDS-PVP clusters assisted by microwave irradiation. It is found that the concentration of SDS and PVP effected on the morphology of gold nanoparticles. The shape the gold nanoparticles changed from sphere to multipod, then to sphere again when the concentration of SDS increased.更多还原