Structural transition in block and gradient copolymer aqueous solutions

The structural transitions in block (Block) and gradient copolymer (Grad) aqueous solutions were investigated with small-angle neutron scattering and were compared to each other. The micelle formation was observed both in Grad and in Block systems. The micelle formation in Grad system was rather continuous, while that in Block underwent a stepwise transition. The size and its variation with temperature of the resulting micelles in Grad copolymer were also different from those in Block system. Possible transition mechanisms for these copolymer systems are described by taking account of the continuous variation in the composition along the polymer chain of Grad copolymer