Study On Preperation And Properties Of Copper, Silver And Cobalt Nanometal/Dendrimers Composites

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.