Sol-To-Gel Transition in Reversed Micelles Microemulsions I. A New Route to Produce Monolithic Metal-Organic Derived Gels

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Abstract
A new versatile method to prepare monolithic metal-organic derived gels is presented in which the sol-to-gel transition is achieved through hydrolysis and condensation reactions in a reversed micelles microemulsion. C7 to C10 alkanes were used as solvents for the reaction and water molecules were solubilized using a non ionic surfactant. The general rules governing the sol-to-gel transition for several alkoxides such as Ti (OPri)4, Ti(OBut)4 and Fe(OPri)3 have been laid down and the exchange of water between reversed micelles related to hydrolysis and condensation rates has been investigated. Hydrolysis and condensation kinetics were monitored for different water/surfactant ratio u-sing gas chromatography. At the sol state growing of colloidal particles is mainly affected by the structure of the water inside the reversed micelles. It has been demonstrated using light scattering measurements that gelation times depend on the particle size evolution into the sol.