SiO_2@Ag核壳粒子表面形貌及壳层厚度影响因素的研究

用溶胶-凝胶法制备单分散的亚微米二氧化硅,经表面巯基化改性后,采用自组装化学镀法在其表面包Ag,得到SiO2@Ag核壳复合粒子,研究还原剂的种类、浓度和反应温度对核壳结构SiO2@Ag亚微米颗粒形貌及表面Ag壳层厚度的影响规律。结果表明:还原剂的种类对SiO2@Ag核壳复合粒子表面形貌影响较大,还原性太弱很难在二氧化硅表面形成致密均匀的银层,还原性太强则容易形成散银;还原剂浓度增加使二氧化硅表面银颗粒的粒径增大,银壳层厚度增大,但是当还原剂浓度到达一定的值后,浓度对银粒径大小和银壳厚度的影响变弱;反应温度对SiO2@Ag核壳复合粒子表面形貌也有较大影响,0~30℃时,银粒子随温度升高尺寸变大,银壳厚度也相应增大,若温度继续增加到50℃后则开始出现散银,包覆效果变差。

Study on Factors Influencing Surface Morphology and Thickness of Silver Layer of SiO2@Ag Core-Shell Particles

The silicon dioxide spherical particles which had good monodispersion by sol-gel method were synthesized,then their surface were modified.Silver nano-particles was deposited on surface of the treated silicon dioxide spherical particles by self-assembly chemical plating method,so the submicron core-shell particles which not only had good electrical conductivity but also were light in weight was obtained.The effect of different reducer,concentration and react temperature on surface topography of the core-shell particles and thickness of silver was researched.The results showed that if the reducer was too weak,silver wasn't reduced from the liquid,so that it was hard to obtain dense and uniform silver-coated layer on the surface of silicon dioxide via silver heterogeneously nucleating.If the reducer was too strong,the speed of Ag separating out was so quick that silver scattered in the liquid.So the sort of reducer had significant effects on surface morphology of the core-shell submicron particles.With the increasing of reducer's concentration,the size of silver particles on the surface of silicon dioxide and the thickness of silver layer increased.The influence decreased when the concentration reached a certain value.Temperature also had an important influence on surface morphology of the core-shell submicron particles.From 0 ℃ to 30 ℃,the size of silver particles and the thickness of silver layer increased with increasing reaction temperature.When the temperature reached to 50 ℃,the silver particles began to disperse in the liquid and the coating result was not ideal.