Physicochemical aspects of epoxide driven nano-ZrO sub(2) hydrogel formation: milder kinetics for better properties

• Published in: Dalton transactions : an international journal of inorganic chemistry Vol. 45; no. 24; pp. 9920 - 9924
• Main Authors: Oestreicher, V, Perullini, M, Jobbagy, M
• Format: Journal Article
• Language: English
• Published: 01.06.2016
• Subjects: Glycerols; Hydrogels; Nanostructure; Particle decay; Recrystallization; Ripening; Sol gel process; Trends
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c6dt00323k

Robust and highly transparent quasi amorphous ZrO sub(2)-water-glycerol hydrogels were obtained in a mild one pot procedure, based on the 2,3-epoxy-1-propanol driven alkalinization. SAXS-based characterization of the sol-gel transition revealed that an homogeneously nucleated sol composed of 2 nm primary particles continuously grows up to a critical size of 5-6 nm, when gelation takes place. These particles reach a size of 8-10 nm, depending on the Zr(iv) concentration. Conductivity measurements offer an overall in situ assessment of the reaction rate. The gelled samples share a common trend: once the conductivity decays to 40% of the starting value, the primary particles nucleate and when this decay reaches 20%, the sol-gel transition takes place. The mild conditions employed herein prevent massive ripening and recrystallization leaving hydrogels with extremely low undesired visible light scattering. This suitable nanostructure was achieved in a wide range of total Zr(iv) concentrations or water to glycerol ratios.