Association Behavior of Amphiphilic ABA Triblock Copolymer Composed of Poly(2-methoxyethyl acrylate) (A) and Poly(ethylene oxide) (B) in Aqueous Solution.

Poly(2-methoxyethyl acrylate) (PMEA) and poly(ethylene oxide) (PEO) have protein-antifouling properties and blood compatibility. ABA triblock copolymers (PMEA l -PEO 11340 -PMEA m (MEOM n ; n is average value of l and m )) were prepared using single-electron transfer-living radical polymerization (SET-LRP) using a bifunctional PEO macroinitiator. Two types of MEOM n composed of PMEA blocks with degrees of polymerization (DP = n ) of 85 and 777 were prepared using the same PEO macroinitiator. MEOM n formed flower micelles with a hydrophobic PMEA (A) core and hydrophilic PEO (B) loop shells in diluted water with a similar appearance to petals. The hydrodynamic radii of MEOM 85 and MEOM 777 were 151 and 108 nm, respectively. The PMEA block with a large DP formed a tightly packed core. The aggregation number ( N agg ) of the PMEA block in a single flower micelle for MEOM 85 and MEOM 777 was 156 and 164, respectively, which were estimated using a light scattering technique. The critical micelle concentrations (CMCs) for MEOM 85 and MEOM 777 were 0.01 and 0.002 g/L, respectively, as determined by the light scattering intensity and fluorescence probe techniques. The size, N agg , and CMC for MEOM 85 and MEOM 777 were almost the same independent of hydrophobic DP of the PMEA block.