Probing the early-stage/rapid processes in hydrolysis and condensation of metal alkoxides

Understanding and control of the early-stage sol-gel reaction processes inv olving metal alkoxides are important to many advanced materials development and applications. In this work, Fourier transform infrared spectroscopy (F TIR) and small angle X-ray scattering (SAXS) were coupled with a specially designed, rapid flow-through mixing cell for monitoring such processes. The rapid, early-stage hydrolysis and condensation of zirconium n-butoxide in ethanol were chosen as the basis for a model system. FTIR was used to study soluble-species reaction kinetics, while the SAXS technique monitored in s itu the solid-phase particle formation/growth (i.e., the nucleation and agg regation kinetics of polymeric clusters/particles). Monitoring the reaction s and cluster/particle growth within a millisecond time regime was achieved . In addition, key parameters such as reaction time, concentration of base (i.e., quarternary tetramethyl ammonium hydroxide), temperature, water conc entration, and alkoxide concentration were fully investigated in a continuo us flow-through reactor. (C) 2000 Kluwer Academic Publishers.