Study On The Preparation Of Nano-copper By Thermal Decomposition In Liquid Phase

People pay more attention to the preparation of nano materials with the emergence and development of nano technology. Nano-copper shows many fancy physical and chemical properties because of its small size effect, surface effect, quantum effect and macro quantum tunnel effect. It has been widely used as lubricant additives, conductive materials, active component in catalyst, optics, heat, and so on.At present, nano-copper research is focus on how to obtain small particle size, morphology controllable, and can exist stably copper nanoparticles. The preparation of copper nanoparticles is liquid-phase reduction method, sol-gel method, chemical precipitation, hydrothermal method, etc. The liquid phase’reduction method is the most commonly used method, but for the adjunction of reducing agent in the reaction system, some reducing agent are more expensive, some one has a large toxicity, and some other introduce impurities, all of them limited its development.The essay is based on the early results of the group, polyethylene glycol or liquid paraffin is selected as liquid dispersion medium.nano copper is preparation by thermal decomposition in liquid phase, Polyethylene glycol and liquid paraffin is capable of reducing simple substance copper in nanoscale at a temperature.which is simple process, no additional reducing agent is added and controllable shape advantage.Polyethylene glycol (PEG) is a water-soluble polymer, it is often used as a surfactant in the preparation of the catalyst, it can be also used as solvent and structure-directing agent in the synthesis of organic compound materials.in this paper, PEG is used to be a solvent and a reducing agent,the influence of heat treatment temperature and time, average molecular weight of PEG, type of copper source on properties of nano-copper,while taking advantage of complexing agents and surfactants on the morphology of nano-copper. Liquid paraffin is most commonly used as a reaction medium in slurry-bed reaction system, the essay select liquid paraffin as the oil phase, while the aqueous solution of copper nitrate as a water phase to prepare prepare water-in-oil emulsions and the preparation of nano-copper by thermal decomposition.it is explored the emulsion system of the best preparation conditions, it is investigated the type and amount of the surfactant, copper concentration on the nano-copper properties.The experimental results come to the following conclusions:1. With the polyethylene glycol as a liquid medium and hydroxide of copper as copper source, cuprous oxide nanoparticles can be received by thermal decomposition at190℃, nano-copper can be obtained at210℃and2h reaction time.2. Complexing agent and surface active agent can be effectively modulating the morphology and size of nano-copper in the system of PEG, but also to avoid agglomeration of the particles themselves to a certain extent. By changing the kind and content of additives, we can get different morphology of nano-copper, which ethylenediamine as a complexing agent to get fibrous copper nano-copper, Diethanolamine as a complexing agent to get a cube copper nanoparticles, Sodium citrate as a complexing agent to get nearly spherical copper nanoparticles.3. The stable emulsion has been prepared when Copper nitrate solution as the aqueous phase, liquid paraffin as the oil phase, Span80and Tween80as emulsifier and HLB=6.5. Spherical nano-copper powder can be obtained at300℃and3h reaction time, the kind and amount of surfactant will have an impact on the size and morphology of the nanoparticles.