微流控制备单分散微米级SiO2微球

采用软模板法制备出了聚二甲基硅氧烷微流控装置。利用该装置讨论了正硅酸乙酯和氨水的用量分别对反应体系凝胶化时间的影响，确定了制备SiO2微球的优化反应体系，即二甲基乙酰胺、正硅酸乙酯和氨水的体积比为8∶4∶1，实验所需的反应温度为60 ℃。实验发现:在微流体通道中，分散相的流速越大，粒径越大；连续相流速越大，粒径越小。因此，通过控制微流控装置中分散相和连续相的流速制备了粒径40~220 m的单分散SiO2微球，并对其形貌进行表征。光学显微镜和粒径分析均表明所制备的SiO2微球球形度高，单分散性好。

Synthesis of monodispersed micron-level silica spheres in microfluidics

Polydimethylsiloxane microfluidic devices were fabricated by lithography. The effects of tetraethyl orthosilicate and ammonia amounts on gelation time were studied. The optimum formulation for preparing silica microspheres is the volume ratio of dimethylactamide, tetraethyl orthosilicate and ammonia is 8∶4∶1, and the reaction temperature is 60 ℃. In the microfluidic channels, the sphere size increases with increasing the volumetric flow rate of dispersed phase and decreasing the volumetric rate of continuous phase. Monodispersed silica microspheres with sizes ranging from 40 to 220 μm were prepared in the microfluidic devices by controlling the volumetric flow rates of dispersed phase and continuous phase. Optical microscopy and sphere size analysis show that the prepared silica microspheres have high sphericity and good monodispersity.