【作者】 李恒恒；

【导师】 韩莹； 沈明；

【作者基本信息】 扬州大学 ， 有机化学， 2009， 硕士

【摘要】 近几十年来,金纳米颗粒由于具有小尺寸效应、表面效应、量子尺寸效应和宏观量子隧道效应等特性,被广泛应用于生物医学工程、非线性光学、电子学,和催化工业等领域。因此,其制备与应用一直是纳米材料领域研究的热点问题。本论文设计合成了烷氧基苄胺（SAOBA）类新型表面活性剂,它们能与正丁醇、正庚烷和HAuCl4·4H2O构成稳定的W/O型微乳液。利用该反相微乳液为模板,借助微波辐射加热手段,通过改变表面活性剂的种类、还原剂的种类、以及微乳液组成成分的比例等实验参数,很好的实现了不同尺寸和形貌的憎水性金纳米颗粒的控制合成。将制备的憎水性金纳米颗粒负载在γ-Al₂O₃上,可以很好的催化对硝基苯酚的还原。本文中所用的表征手段主要有FT-IR、1HNMR、MS、UV-vis、TEM、XRD、CA等。研究成果概括如下:1.分别用对羟基苯甲醛、香兰素和3,4-二羟基苯甲醛为原料,与不同链长的溴代烷烃发生O-烷基化反应生成系列烷氧基苯甲醛,然后与盐酸羟胺反应生成系列烷氧基苯甲醛肟,最后用锌粉还原生成烷氧基取代苄胺（SAOBA）。2.在CnOBA（n=8, 12或16）/正丁醇/正庚烷/HAuCl4/NaOH（aq.） W/O型微乳液体系中,通过微波辐射加热的碱促进条件下由正丁醇原位还原氯金酸分别制备了4-辛氧基苄胺（C8OBA）、4-十二烷氧基苄胺(C₁₂OBA)和4-十六烷氧基苄胺（C16OBA）稳定的纳米金粒子。选用C₁₂OBA为重点研究对象考察了利用正丁醇原位还原时,微乳液组成成分对形成金纳米粒子尺寸和形貌的影响。实验发现,增加C₁₂OBA/HAuCl4摩尔比或正庚烷/正丁醇的体积比,有利于获得球形、小粒径的憎水性金纳米粒子。所制备的高度单分散的憎水性金纳米粒子能够在空气/水界面形成大面积的短程有序单层膜。3.微波辐射下利用CnOBA（n=8, 12或16）/正丁醇/正庚烷/丙醛/HAuCl4（aq.） W/O型微乳液体系为模板,以丙醛作为还原剂合成了C8OBA、C₁₂OBA和C16OBA修饰的憎水性金纳米粒子。实验发现,在相同的反应条件下,金纳米粒子的粒径随着烷氧基链长的增加而减小,粒子形貌由不规则的多边形变为球形。同样以C₁₂OBA为研究对象,考察丙醛还原时粒子的形貌特点。实验结果显示:降低胺金摩尔比或正庚烷/正丁醇的体积比或增加还原剂丙醛的用量,有利于生成不规则形貌的憎水性金纳米颗粒;4.通过微波辐射加热的手段,在C₁₂OBA/正丁醇/正庚烷/甲酸/HAuCl4（aq.）反相微乳液体系中,利用甲酸作为还原剂制备了C₁₂OBA包裹的憎水性金纳米粒子。实验结果显示:金纳米粒子的尺寸随着C₁₂OBA/ HAuCl4摩尔比增大而减小、单分散性变好,粒子的形貌由不规则的多边形逐渐变为球形。用CnOBA（n=8, 16）、MDOBA、DDOBA代替C₁₂OBA分别制备了相应表面活性剂修饰的憎水性金纳米粒子。实验结果显示:烷氧基链长增加、取代烷氧基个数增加有利于生成小粒径、单分散好的憎水性金纳米粒子。5.利用胶体负载法将制备的憎水性金纳米粒子负载到γ-Al₂O₃载体上制得Au/γ-Al₂O₃负载型纳米金催化剂,探索了其在对硝基苯酚还原反应中的催化活性,并考察了金纳米粒子粒径、金的负载量、反应温度等因素对催化活性的影响。实验结果表明:当金纳米粒子粒径约为8nm,金负载量为0.1ωt%,反应温度为50℃时催化效果较好;该催化剂可被循环利用。更多还原

【Abstract】 In recent decades, preparation and application of gold nano-materials have been a hot research issue in nano-materials field. Gold nanoparticles with some characters such as small size effect, surface effect, quantum size effect and macroscopic quantum tunneling effect are widely used in the fields of biomedical engineering, non-linear optics, electronics and industrial catalysis.This thesis introduces a novel surfactant Alkoxybenzylamine （SAOBA）, which can be mixed with n-butanol, n-heptane and HAuCl4·4H2O to form W/O microemulsion. Using this reverse microemulsion as template and microwave radiation as heating means, hydrophobic gold nanoparticles with different sizes and morphologies have been prepared by changing the experimental parameters such as the type of the surfactant, the type of the reducing agent, as well as the microemulsion’s composition. When the prepared hydrophobic gold nanoparticles are surpported onγ-Al₂O₃, the Au/γ-Al₂O₃ catalyst plays a good catalytic activity in reduction of p-nitrophenol. All the products have been investigated by FT-IR, 1H NMR, MS, UV-vis, TEM, XRD, CA and so on.The main work completed in this thesis are summarized as follows:1. Alkoxybenzylamines （SAOBA） are carried out by zinc dust reduction of alkoyxybenzaloxime, which was obtained from alkoxybenzaldehyde （obtained from p-hydroxybenzaldehyde, vanillin or 3,4-dihydroxybenzaldehyde by O-alkylation） by reacting with hydroxylamine hydrochloride.2. Gold nanoparticles stablized by C8OBA, C₁₂OBA and C16OBA are obtained by n-butanol reduction in situ under microwave irradiation by using the CnOBA（n=8, 12, 16）/n-butanol/n-heptane/HAuCl4/NaOH（aq.） W/O microemulsion as a microreactor. We focus on C₁₂OBA in order to determine the influence of the microemulsion’s composition during the progress of formation the size and morphology of gold nanoparticles. The results show that CnOBA can be used not only as a surfactant which helps to form a stable microemulsion system, but also as a good protecting agent for gold nanoparticles. Gold nanoparticles with spherical morphology and small size can be easily obtained with the increasing of C₁₂OBA/ HAuCl4 molar ratio or the increasing of n-heptane/n-butanol volume ratio. The prepared hydrophobic gold nanoparticles with high monodispersity can spontaneously form large areas of the short-range ordered monolayer membrane at the air/water interface.3. Under the promotion of microwave irradiation, by the reduction of propionaldehyde, C8OBA, C₁₂OBA and C16OBA modified hydrophobic gold nanoparticles are prepared in CnOBA（n=8, 12, 16）/n-butanol/n-heptane/propion- aldehyde/HAuCl4 （aq） W/O microemulsion. The expermental results show that the size of the gold nanoparticles gradually decrease and the morphologies of gold nanoparticles gradually change from polygonal to spherical with the increasing length of the alkoxy chain of the CnOBA under the same reaction condition. We still focus on C₁₂OBA to study the morphology of C₁₂OBA-capped Au nanoparticles obtained by propionaldehyde as reductant. The results show that gold nanoparticles with polygonal morphology are obtained by decreasing the C₁₂OBA/HAuCl4 molar ratio or n-heptane/n-butanol volume ratio or increasing the amount of the reductant propionaldehyde. 4. C₁₂OBA-coated gold nanoparticles are synthesized under microwave irradiation in C₁₂OBA/n-butanol/n-heptane/formic acid/HAuCl4（aq.） reverse microemulsion system with formic acid as a reductant. The results illustrate that the size of the gold nanoparticles gradually decreasing with the molar ratio of aime/gold increasing, and the monodispersity of the gold nanoparticles increasing, the morphologies of the paricles gradually change from polygonal to spherical. C8OBA, C16OBA, MDOBA and DDOBA modified naoparticles are also sythesized by the same system. we find that increasing alkoxy chain length and alkoxy chain number are conducive to generate small particle size and good monodispersity gold nanoparticles.5. Au/γ-Al₂O₃ catalyst is prepared by loading the obtained gold sol onto the surface ofγ-Al₂O₃. Then, the catalytic activity in the reduction reaction of p-nitrophenol are tested. Meanwhile, we study the influence of the size of the gold, the amount of the supports and the temperature to the reaction. The optimum reaction conditions are described as follows: the size of the gold naoparticles should be smaller then 10nm, the load ratio of gold nanoparticles is 0.1ωt% and the reaction temperature is 50℃. This Au/γ-Al₂O₃ catalyst can be recycled .更多还原