Molecular interactions between PEO–PPO–PEO and PPO–PEO–PPO triblock copolymers in aqueous solution

Abstract

Abstract The molecular interactions between Pluronic F127 (PEO100–PPO65–PEO100) and Pluronic-R 25R4 (PPO19–PEO33–PPO19) in aqueous solution have been studied using micro thermal analysis and rheology, where PEO and PPO stand for poly(ethylene oxide) and poly(propylene oxide) blocks respectively through a complete thermal cycle from heating to cooling. A completely thermoreversible micellization was observed for aqueous solutions of pure F127 and F127/25R4 mixtures even if an aqueous solution of pure 25R4 was not thermally reversible. The critical micelle temperature, CMT, decreased linearly with increasing the molar ratio of 25R4/F127. The sol–gel transition temperature during heating is higher than the gel–sol transition temperature during cooling over a range of 25R4/F127 ratio. F127 dominated the gelation of F127 at the molar ratio of 25R4/F127