Flower-like micelle association

Triblock copolymers of ABA-type have basically the same behavior in giving a star-like morphology (Fig. 6a) when dissolving into a selective solvent for the outer A blocks. However, the micellization of ABA-type triblock copolymers in selective solvent for the middle B blocks deals with a much more complex situation [42], A relatively low concentration of the copolymer in the selective solvent and/or a low molecular weight of the A blocks can lead to isolated flower-like micelles (Fig. 6b) with the middle B block being looped - referred to as petals - and with the two outer A blocks taking part of the same micellar core. However, if the copolymer concentration or the A block molecular weight is increased, a micelle association... 

The association of flower-like micelles through bridged conformations in an ABA triblock copolymer can be avoided by replacing the ABA triblock by a cyclic diblock copolymer. In this case, sunflower micelles have been observed for example by Borsali and coworkers from the assembly of cyclic and asymmetric polystyrene- >-polvisoprene diblock copolymer (PS-h-PI) and compared to the corresponding linear diblock [46, 47]. 

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