Supramolecular Assemblies of Starlike and V-Shaped PB-PEO AmphiphilesThe authors are grateful to the Donors of the American Chemical Society Petroleum Research Fund for partial support of this research (ACS-PRF No. 40727 G-10). PB[equals]polybutadiene, PEO[equals]poly(ethylene oxide).

Self-assembly of linear amphiphiles is a well-known phenomenon, and the number of different structures observed both in the solid-state and in selective solvents is exceedingly large. It is difficult to envision a diblock amphiphile that would not undergo self-assembly, and in this context, the terms “linear amphiphilic” and “self-assembling” are nearly synonymous. Branched amphiphiles such as dendrimers and stars also undergo self-organization in selective solvents. However, there are examples in which they do not aggregate, but rather behave as unimolecular micelles. Furthermore, the morphological diversity of aggregates formed by branched structures is significantly lower than that of linear counterparts. For example, most selfassembling star-shaped amphiphiles only form spherical micelles, whereas linear diblocks can organize into at least 30 different morphologies. This creates the impression that a branched architecture somewhat precludes morphological diversity and that star-shaped amphiphiles cannot compete with linear analogues. In contrast, we document here that the multiarm PB6–PEO6 (PB= polybutadiene, PEO= poly(ethylene oxide)) molecule 1 self-assembles into nonspherical structures in water and generates unique “cottonball” morphology in hexane. Such hierarchical structures have not been observed in PB–PEO diblocks or any other linear system. Starlike amphiphiles are generally difficult to synthesize owing to the limitations of many synthetic techniques,