纳米球形二氧化硅的制备研究

【作者】 张明明；

【导师】 李凤生； 姜炜；

【作者基本信息】 南京理工大学 ， 材料学， 2008， 硕士

【摘要】 本文分别研究均相化学沉淀法、醇盐水解法以及微乳液法制备窄分布纳米球形SiO₂,对其制备条件进行研究,并用SEM、TEM、XRD、FTIR、TG等表征手段对粉体的性能进行分析。本文首先采用均相化学沉淀法制备纳米SiO₂,以聚乙二醇（PEG）为表面活性剂,丙三醇为分散剂,水玻璃为主要原料,乙酸乙酯为潜在酸试剂,进行沉淀反应,研究了硅源浓度、乙酸乙酯用量、分散剂用量、反应温度、焙烧温度等因素对SiO₂颗粒大小及形貌的影响。并采用现代检测手段对样品表征,制备出了无定形纳米SiO₂。结果表明该法所得SiO₂颗粒呈球形,平均粒径为80nm,比表面积为820m².g^-1,但分散性不好。醇盐水解法是在醇水混合溶剂中以浓氨水为催化剂,正硅酸乙酯为硅源,通过醇盐水解工艺制备出粒径为60～130nm SiO₂球形颗粒。研究氨水浓度、共溶剂的用量等对二氧化硅颗粒大小及形貌的影响。结果表明:氨水浓度是影响颗粒形态的主要因素,随着氨水浓度增大,SiO₂颗粒粒径有所增加;表面活性剂与产物的生成速度密切相关,需控制在合适的范围内;加入无水乙醇作为共溶剂,可促进水解反应的进行。但是此法所得样品的团聚问题依然存在,为解决这一问题,本论文又采用微乳液法。微乳液法是以环己烷/Span-80和Tween-80/水（质量比为12%氨水溶液）形成W/O反相微乳液法,采用正交试验制备出粒径为65～140nm,且分散性较好的SiO₂球形颗粒。正交试验分析表明:表面活性剂加入量是影响SiO₂粒径及形貌的主要因素。通过对以上三种方法的比较分析可知:前两种方法所得的样品存在粒径分布不均匀,团聚现象严重,且成球性不好的问题,而微乳液法能很好地解决这些问题。更多还原

【Abstract】 This article prepares nano-SiO₂ spherical particle with the homo-precipitation method, the alkoxide hydrolysis method and the micro-emulsion method.The basic performance of powder has been characterized by means of SEM, TEM, XRD, TG and FTIR.First, this paper prepares SiO₂ with homo-precipitation method, used the water glass as one major raw material, polyethylene glycol （PEG） as the surface active agent, Glycerol for dispersant, the ethyl acetate as hide reagent. It was studied that the influence of silicon source density, ethyl acetate amount ,dispersing agent amount , reaction temperature, roasting temperature on the size and appearance. Later we carry out symptom with modern detection means for it. The results indicated that these powder SiO₂ is spherical approximately, the average particle size is 80 run and the specific area is 820m².g^-1, but the dispersion is bad.The alkoxide hydrolysis method is that using the strong ammonia water as the catalyst in the mellow water component solvent and the tetraethoxy-silicane （TEOS） as the silicon source, prepares the particle size is between 60nm and 130nm . Effects of the solvent, the amount of surface active agent, the concentration of ammonia and etc. on the particle size and morphology SiO₂ were investigated by SEM. The result showed the ammonia water density was the primary factor to affect the particle shape, with the increasing of ammonia water density the SiO₂ particle size increases slightly. The production had the close relation with the water volume so it must be controlled in the appropriate scope. The absolute alcohol as the co-solvent could promote hydrolytic reaction. However, the reunion problem remains, this paper also used micro emulsion in order to solve this problem.The micro emulsion method is that forming the W/O opposition micro emulsion taking cyclohexane /Span-80 and the Tween-80/ water （mass ratio as 12% ammonia spirit）, uses the orthogonal test to prepare the monodispersed SiO₂ spherical particle with the size between 60 and 140 nm .The orthogonal test analysis indicated that the quantity of the surface active agent is primary factor which affects the SiO₂ pellet particle size and the appearance.Through the above three methods of analysis can be drawn: the first two methods exist samples from the uneven distribution of particle size, the reunion more serious, and product of a bad ball, but micro-emulsion can be a very good method to solve these problems.更多还原