Aggregation behavior of star-like PEO–PPO–PEO block copolymer in aqueous solution

The aggregation behavior of a star-like amphiphilic block copolymer (denoted as AP432, which was synthesized via anionic polymerization), in aqueous solutions was investigated by surface tension, steady-state fluorescence, dynamic light scattering (DLS) and transmission electron microscopy (TEM). For comparison, a commercially available linear amphiphilic PEO–PPO–PEO block copolymer, Pluronics L64, which has a similar PEO fraction to AP432, was also studied. It is found that the different molecular structure of AP432 and L64 leads to a significant difference on their behavior both at the air/water interface and in bulk aqueous solutions. The results of surface tension measurements indicate that the surface activity of AP432 is much more pronounced than that of L64. The formation of AP432 and L64 aggregates are identified by DLS, fluorescence and TEM measurement.