Hierarchical structures in amphiphilic random copolymer solutions

Abstract

Surveying the theory of associating polymer solutions, we have applied the theory to aqueous solution systems of two amphiphilic random copolymers to reveal the hierarchical structure in the solutions. The two random copolymers form uni-core flower micelles comprising of 2 and 8 copolymer chains in dilute solution. However, a part of hydrophobic groups are outside the micellar core and act as binding sites for higher-order aggregation of micelles progressing with increasing the copolymer concentration. The aggregates of flower micelles are bimodal: the major fast relaxation mode component with mw (the weight average aggregation number) of the order of 10 and the minor slow relaxation mode component with mw of order of 103. The viscosity enhancement of the copolymer solutions with increasing the concentration mostly arises from the growth of the major fast mode aggregate.