单分散二氧化硅超细颗粒的制备

Preparation of Monodisperse Silica Ultramicrons

利用3种不同类型的表面活性剂反胶团体系制备SiO2超细颗粒，并与传统的Stober制备方法进行了对比. 在阴离子表面活性剂AOT和非离子表面活性剂TritonX-100两类体系中，得到了单分散的SiO2超细颗粒．在AOT体系中颗粒粒径随体系水含量w。的增大而增大；而TritonX-100体系中，颗粒粒径随w。的增大而减小；在阳离子表面活性剂(如CTAB，TOMAC)体系中无法得到SiO2超细颗粒．对不同体系所得颗粒的粒径标准偏差及粒度分布进行了对比，结果表明制备粒径小于100 nm的SiO2颗粒，反胶团法明显优于Stober方法，粒径相对标准偏差较低, 而对粒径大于100 nm的颗粒，Stober方法仍不失为一种很好的制备途径．

Preparation of silica ultramicrons was reported by using three different surfactants in reverse micellar systems and by using the conventional Stober method. It was found that in the anionic surfactant-based system (AOT/cyclohexane/NH3(H2O reverse micelles) the particle size increases as the water to surfactant molar ratio(wo) is increased. While in the non-ionic surfactant-based system (TritonX(100/hexano1/cyclohexane/NH3(H2O reverse micelles) the particle size decreases as wo is increased. It seems impossible to prepare SiO2 in cationic surfactant- based reverse micelles, such as CTAB and TOMAC systems. Effects of different system conditions on particle size and shape were studied. The particle size distribution and standard deviation were also compared among different methods. It indicates that the reverse micellar method is more suitable for synthesis of silica particles of diameter below 100 nm with lower standard deviation than the Stober method. But the latter is still a good method for preparing larger silica particles((100nm).