Effects of Alcohol Addition on Gelation in Aqueous Solution of Poly(ethylene oxide)-Poly(propylene oxide)-Poly(ethylene oxide) Triblock Copolymer

Abstract

The effects of alcohol addition on gelation and micellization in aqueous solution of EO100PO65EO100 (Pluronic F127) triblock copolymer were studied using tube inversion method (TIM), rheometry, dynamic light scattering (DLS), and high sensitive differential scanning calorimetry (DSC). Upon the addition of alcohol such as methanol or ethanol, the hard gel transition temperature is raised resulting in reduced hard gel region in the phase diagram and these alcohols were shown to increase the critical micelle temperature (cmt). Butanol, however, clearly lowers hard gel transition temperature and cmt. In the case of propanol up to 15 v% the onset temperature of the hard gel is slightly lowered while the hard gel transition temperature is raised for propanol content more than 20 v%. The experimental investigation shows that lower alcohols such as methanol and ethanol prevent the onset of gelation and micellization while higher alcohols such as butanol favor gelation as well as the formation of micelles in aqueous solution of EO100PO65EO100 triblock copolymer.