We report on the phase behavior and structural evolution during the early stages of silica templating using
surfactant liquid crystals in aminoalkoxysilane/lauric acid/water systems. Specific aminoalkoxysilanes are
used so that hydrolysis and condensation reactions are slow enough to follow the changes in the early stages
of mesoporous silica formation without the need for very sophisticated techniques. A lyotropic lamellar phase
that swells with water is present in the early stages of the system and develops into kinetically correlated
siliceous phases with preservation of morphology. Moreover, lyotropic and siliceous phases coexist at a certain
time. Hydrolysis and condensation of alkoxysilane groups cause microstructural changes in the lyotropic
lamellar phase, as monitored by in situ small-angle X-ray scattering and infrared spectroscopy measurements.
Although the changes in the initial lamellar phase depend on the nature of the alkoxysilane groups, the final
siliceous phases show similar correlation lengths, which are close to that of previously reported lamellar
mesoporous materials.The results indicate three stages during liquid crystal templating, controlled respectively
by self-assembly, hydrolysis, and condensation of alkoxysilane groups on the surface of aggregates. A
mechanism, based on phase separation, is proposed for the formation of these hybrid organic−inorganic
materials.
Cubic phases formed in surfactant or copolymer solutions are optically-isotropic and highly viscous liquid crystals. They are mainly categorized to four types; normal micellar discontinuous (I 1 ), reverse micellar discontinous (I 2 ), normal bicontinuous (V 1 ), reverse bicontinuous (V 2 ) cubic phases. We used both water-and oil-soluble dye solutions to specify the type of cubic phase by a simple dyeing method. Water-soluble dye (Tartrazine) colors I 1 phase, whereas it remains on the top of I 2 phase. Oil-soluble dye (Sudan III) shows the opposite phenomena. Both dyes do color the V 1 and V 2 phases in binary water-surfactant systems. In the presence of oil, the water-soluble dye colors the V 1 phase faster than the V 2 phase. The oilsoluble dye shows the opposite rate of dyeing to bicontinuous cubic phases.
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