Colomer, M. T. and Guzman, J and Moreno, R (2008) Determination of peptization time of particulate sols using optical techniques: Titania as a case study. CHEMISTRY OF MATERIALS, 20 (12). pp. 4161-4165.
Full text is not hosted in this archive but may be available via the Official URL, or by requesting a copy from the corresponding author.
Official URL: http://pubs.acs.org/doi/abs/10.1021/cm703560x
Colloidal sol-gel technology is widely used as a powerful synthesis route. It consists of two main stages, hydrolysis and peptization. The quantification of peptization time is necessary to improve the processing control and enhance product reliability. However, the peptization time is normally estimated by simple visual inspection. The aim of this work is to establish for the first time a procedure to quantify the peptization time. For such purposes, different optical techniques have been used, in particular the measurements of particle size distribution by laser diffraction and by dynamic light scattering. The experimental mismatch between both series of data allows determining the peptization time, and the results are in good agreement with turbidimetry measurements through the transmission of near-infrared light source. The synthesis of titania has been selected as a case study because anatase presents a large interest in many different applications. It has been demonstrated that peptization time significantly increases as the synthesis temperature decreases: Sots prepared at 25 degrees C present a peptization time of similar to 95 h, sots prepared at 30 degrees C need similar to 72 h for a complete peptization, sots synthesized at 35 degrees C present a peptization time of similar to 45 h, and those prepared at 50 degrees C show a peptization time of similar to 9 h. The peptization time for sots prepared above 80 degrees C is quite short; the synthesis is less reproducible and the risk of uncontrolled gelation increases. The average particle size changes from similar to 13 nm for sots prepared at 25 degrees C, 20 nm for sots prepared at 35 degrees C and, to similar to 30 nm for sots prepared at 50 degrees C. The resulting xerogel has been characterized in order to demonstrate the suitability of the synthesis procedure.
|Subjects:||Biomedical Science > Nanotechnology for human health|
|Deposited On:||21 Jan 2009 11:38|
|Last Modified:||26 Mar 2009 17:31|
Repository Staff Only: item control page