Physicochemical aspects of epoxide driven nano-ZrO2 hydrogel formation: milder kinetics for better properties

VICTOR OESTREICHER; MERCEDES PERULLINI; MATÍAS JOBBÁGY

DALTON TRANSACTIONS

ROYAL SOC CHEMISTRY

Lugar: CAMBRIDGE; Año: 2016

1477-9226

Robust and highly transparent quasi amorphous ZrO2-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 assesment of the reaction rate. The gelled samples share a common trend: once conductivity decays to 40% of the starting value, 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 under a wide range of total Zr(IV) concentration or water to glycerol ratios.