Phase behavior and preparation of mesoporous silica in aqueous mixtures of fluorinated surfactant and hydrophobic fluorinated polymer

The phase behavior and formation of self-assemblies in the ternary water/fluorinated surfactant (C8F17EO10)/hydrophobic fluorinated polymer (C3F6O)nCOOH system and the application of those assemblies in the preparation of mesostructured silica have been investigated by means of phase study, small angle X-ray scattering, and rheology. Hexagonal (H1), bicontinuous cubic (V1) with Ia3d symmetry, and polymer rich lamellar (Lα′) are observed in the ternary diagram. C8F17EO10 molecules are dissolved in polymer rich aggregates, whereas (C3F6O)nCOOH molecules are practically insoluble in the surfactant lamellar phase due to packing restrictions. Hence, two types of lamellar phases exist: one with surfactant rich (LαLα) and the other with polymer rich (Lα′) in the water/C8F17EO10/(C3F6O)nCOOH system. As suggested by rheological measurements, worm-like micelles are present in C8F17EO10 aqueous solutions but a rod-sphere transition takes place by solubilization of (C3F6O)nCOOH. C8F17EO10 acts as a structure directing agent for the preparation of hexagonal mesoporous silica by the precipitation method. The addition of (C3F6O)nCOOH induces the formation of larger but disordered pores.

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