Spherical silica particles, with mean sizes about 1.2 gm, were prepared through TEOS sol-gel process catalyzed by ammonia. The silica particles have a smooth surface and a small specific surface area, 3.4 m 2/g. The sol-gel process was monitored by React IRTM using an in-situ technique. Based on the measurements, mechanism of TEOS hydrolyzation and succedent condensation polymerization was inferred. With the adding of ammonia, OH - anion attacks Si atomic nucleus directly and makes it showing negative electricity. Therefore the electron cloud shifts to the -OR group on the other side. This weakens the Si-O bond and results in the removal of the -OR group. Furthermore, silanol, generated from TEOS hydrolyzation, attracts Si-OR or other Si-OH around; thereby resulting rapid dehydration or dealcohol between molecular. So the condensation polymerization rate is elevated, and Si-O-Si bond comes into being. Lastly, cross-linking reaction among Si-O-Si bonds forms the particle.
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