【作者】 金磊；

【导师】 杨仕平；

【作者基本信息】 上海师范大学 ， 应用化学， 2008， 硕士

【摘要】 树枝形聚合物是近年来成功合成的一种新型的高分子材料,它在工业、农业、医学、生命科学、导电材料、纳米材料和催化等领域具有非常重要的应用前景。目前合成出来的树枝形聚合物的种类也很多,本文合成出了一类以苯环为中心的树枝形聚合物并对其进行了表征。本文初步研究了铜离子与以苯环为中心的树枝状化合物(下文简称为树枝状化合物)的相互作用。通过铜离子与树枝状化合物的浓度和溶液的pH值的改变对反应影响的研究,表明树枝状化合物内部三种不同的含氮原子基团,与铜离子作用的能力不同,作用的顺序依次为伯胺、叔胺和酰胺。采用液相法,利用树枝状化合物作为模板制备了纳米金属铜和银粒子。当铜离子和银离子与3代树枝状化合物(简称3 G)浓度比为2 : 1时,得到的铜和银粒子平均粒径分别为4.6和5.9 nm。讨论了铜离子和银离子与树枝状化合物浓度比以及树枝状化合物的代数对纳米铜和银粒子的粒径、分散性等的影响关系。发现随着铜和银离子浓度的增大,还原后的粒子较容易团聚,所得到的纳米铜与银粒子的尺寸变大,且分散性不好;在金属(铜和银)离子和树枝状化合物浓度比相同的情况下,随着树枝状化合物代数的增大,所得到的纳米金属(铜和银)粒子的粒径减小,且粒子更加分散。采用液相法,利用树枝状化合物为模板制备了钴纳米粒子。钴离子与3G浓度比为10 : 1时,得到的钴粒子平均粒径为7.5 nm。同时考察了钴离子与树枝状化合物浓度以及树枝状化合物的代数对钴粒子尺寸、分散性的影响,实验结果表明:增大钴离子的浓度,还原后所得到的钴粒子尺寸变大,且分散性变差;固定钴离子和树枝状化合物浓度比,随着树枝状化合物代数的增加,钴粒子的尺寸变小,分散性也较好。钴粒子的电子衍射表明,所制备的钴纳米粒子属于非晶态。利用超导量子干涉(Superconducting Quantum Interference)技术,通过对所制备的纳米钴粒子的磁滞回线、FC和ZFC的表征,考察了用不同代数的树枝状化合物制备的钴粒子的磁性强弱,得到的结果是利用低代数的树枝状化合物制备的钴粒子磁性大(钴离子与树枝状化合物的浓度比相同的条件);同时考察了温度对钴粒子磁性的影响:对同一钴粒子,在不同温度下(2K,150K,360K),它的磁性不同,随着温度的升高磁性变弱。钴粒子在低温下(如2K)表现出了较明显的磁滞现象,但温度升高磁滞现象减弱。当温度达到阻塞温度(Tb)以上时,磁滞现象表现的很弱,是由于此时钴粒子主要表现出超顺磁性的结果。更多还原

【Abstract】 Dendritic polymer （dendrimer） is a kind of macromolecular materials which have been applied on industry, agriculture, medicine, electric materials and nanomaterials so on. So far, a lot of new dendrimers have been synthesized. In this thesis we synthesize and characterize a kind of dendrimers with a trimesyl core.In my thesis first the complex reaction is completed between dendrimers with a trimesyl core and the copper ions. The results of the concentration of Cu²⁺ and dendrimers as well as pH values influence on the complex reaction show three kinds of amido groups of dendrimers behave different coordinate ability with Cu²⁺: -NH₂ > -NR₂ > -CONH-.Copper and silver nanoparticles are obtained through wet chemical method by dendrimers as templates. When the concentration ratio of copper ions and silver ions to G3 dendrimer （3G） are all 2:1, the average diameters of the copper and silver particles are 4.6 and 5.9 nm, respectively. It is also discussed that the relation between the concentration ratios of copper and silver ions to dendrimers as well as the generation of dendrimers and the copper and silver nanoparticles’size. When the concentration of metal （copper and silver） ions increase, the Cu and Ag nanoparticles obtained are easily aggregated, large in size and not well dispersed. When the concentration ratios of metal ions and dendrimers are the same, the generation of the dendrimers increasing, the metal （copper and silver） particles prepared are smaller and well dispersed.The cobalt nanoparticles are also prepared through the same method by dendrimers as templates. When the concentration ratio of cobalt ions to 3G is 10:1, the average diameter of the cobalt particles obtained is 7.5 nm. It is discussed that the relation between the concentration ratios of cobalt ions to dendrimers as well as the generation of dendrimers and the cobalt nanoparticles’size, too. When the concentration of cobalt ions increase, the particles we obtained are easily aggregated, large in size and not well dispersed. When fix the concentration ratios of cobalt ions and dendrimers, the generation of the dendrimers increasing, the cobalt particles prepared are smaller and well dispersed. They are smaller in size and well dispersed. The data from the Ed show that the cobalt particles prepared belong to amorphous. The magnetism of different cobalt particles prepared in different generation dendrimers is characterized through the hysteresis loop, FC, and ZFC by Superconducting Quantum Interference. The data of results show the magnetism of cobalt particles in which are prepared in lower generation dendrimers is stronger than that of higher generation dendrimers when concentration ratio of cobalt ions to dendrimers is equal. The data of different temperature （2K, 150K, 360K） suggests the cobalt particles show weaker magnetism in higher temperature. When in very lower temperature, the cobalt particles （for example 2K） show hysteresis obviously. Above blocking temperature （Tb）, cobalt particles’hysteresis becomes weak owing to superparamagnetism.更多还原