Butanol solubilization in aqueous F127 solution: investigating the enhanced micellar solvation and consequent improvement in gelation characteristics.

Pluronics(®) are an important class of non-ionic surfactants because of their rich phase behavior and numerous industrial and biomedical applications. F127, an FDA approved Pluronic(®) is the most prominent member amongst them owing to its potential uses as vehicle for drug delivery and template for the fabrication of mesoporous materials. A cubic micellar gel formed by this copolymer above 15 wt% concentration is the commonly used form of self assembled structure for these applications. In this manuscript we report SANS, fluorescence and rheological studies on the effect of n-butanol on gelation characteristics of aqueous F127 solutions. The studies show that solubilization of n-butanol results in a large increase in viscosity of micellar solution at a fixed copolymer concentration, and leads to the formation of stiff gel at F127 concentration as low as 9 wt%. SANS and fluorescence studies attribute this to enhancement in micellar solvation due to solubilization of n-butanol. Quite interestingly, SANS studies show that n-butanol induced F127 gels form at significantly lower micellar volume fraction than the pure F127 gels. The observed improvement in gelation characteristics can have important bearing with the application in making mesoporous materials since n-butanol is used as co-surfactant to control pore size of such structures formed with F127 gels as template.