Preparation Of Porous Silica Microspheres By Self-made Silica Sol-PICA Method

Ultra-pure silica microspheres are the ideal HPLC packing matrix, and the preparation technology has been monopolized by a few foreign companies. Exploring the preparation method of high-purity silica microspheres and achieving industrial production have great social significance and economic value.Silica sol was prepared by using tetraethoxysilane (TEOS) as raw material, its gel time and content of SiO2 were examined. The influence on silica sol of reaction conditions was also studied through transmission electron microscopy (TEM). The results showed that:the linear silica sol was obtained by using hydrochloric acid as catalyst. Its gel time was 14h, and the SiO2 content was 5.5%. The silica sol like particle was obtained by using ammonia as catalyst. Its gel time was 25d, and the SiO2 content was 17.5%. The particle size increased as the ammonia concentration increasing, decreased as the reaction temperature increasing. When the H2O/TEOS molar ratio (R) exceeded a range, the colloidal particle size would increase significantly.Using self-made silica sol as raw material, silica microspheres were synthesized by polymerization-induced colloid aggregation method; The microspheres were characterized by scanning electron microscopy (SEM), inductively-coupled plasma spectrometer (ICP), Zetasizer and BET measurements. The impact of experimental conditions was studied. The results showed that:the silica microspheres prepared by particle silica sol were well monodisperse, had a very high purity, exhibited regular spherical morphology. The silica microspheres size increased as the reaction temperature, pH, colloid particle size increasing, decreased as the molar ratio of formaldehyde and urea decreasing; the pore size of silica microspheres could be controlled between 5nm and 65nm.High purity monodisperse silica microspheres were synthesized successfully by PICA method with self-made silica sol. This method was very stable. The morphology and pore structure of the silica microspheres had an excellent reproducibility laying a good foundation for the amplification experiment.