Nucleation stage in the Ti(OPri)(4) sol-gel process

A spectroscopic study of the initial stage of the Ti(OPri)(4) sol-gel proce ss has been carried out. We have observed that the primary hydrolysis/conde nsation reaction is complete at low water concentration. At times shorter t hat the induction time, the reaction results in creation of nanosize nuclei . The most important finding is that the total nuclei mass, which appears a lmost instantaneously during the stage of mixing, is conserved throughout t he process: the particles grow by nucleus agglomeration. The hydrolysis rat io H less than or equal to 1 is sufficient for nucleus creation; H > 1 is n eeded for particle growth. The initial reagent mixing seems to be the key s tage of the process.