Self-Assembly of Mixed Amphiphilic Triblock Copolymers in Aqueous Solution

Abstract

A 1:1 (weight ratio) mixture of two commercial amphiphilic triblock copolymers, F127 (E99P69E99) and B20-5000 (E45B14E45) in aqueous solution, was studied by using static light-scattering and dynamic light-scattering techniques. E, P, and B are oxyethylene, oxypropylene, and oxybutylene, respectively, with the subscript denoting the number of segment units in the block. Both triblock copolymers tend to self-assemble into starlike micellar structures in aqueous solution because of the poorer solubility of their middle blocks at room temperature. Due to the difference in their thermodynamic parameters of the micellization process and in their micellar sizes, the mixed block copolymer system provides a suitable model for studying the self-assembly behavior of mixed, miscible triblock copolymers in aqueous solution. At temperatures below 27 °C, the E45B14E45 block copolymer has a much lower cmc than that of E99P69E99. Therefore, the micelle formation of the mixed polymer solution was determined by the cmc of ...