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Science 1 October 2004:
Vol. 306. no. 5693, pp. 94 - 97
DOI: 10.1126/science.1102866
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Reports

Toroidal Triblock Copolymer Assemblies

Darrin J. Pochan,1* Zhiyun Chen,2{dagger} Honggang Cui,1{dagger} Kelly Hales,1{dagger} Kai Qi,2{dagger} Karen L. Wooley2*

A stable phase of toroidal, or ringlike, supramolecular assemblies was formed by combining dilute solution characteristics critical for both bundling of like-charged biopolymers and block copolymer micelle formation. The key to toroid versus classic cylinder micelle formation is the interaction of the negatively charged hydrophilic block of an amphiphilic triblock copolymer with a positively charged divalent organic counterion. This produces a self-attraction of cylindrical micelles that leads to toroid formation, a mechanism akin to the toroidal bundling of semiflexible charged biopolymers such as DNA. The toroids can be kinetically trapped or chemically cross-linked. Insight into the mechanism of toroid formation can be gained by observation of intermediate structures kinetically trapped during film casting.

1 Materials Science and Engineering and Delaware Biotechnology Institute, University of Delaware, Newark, DE 19716, USA.
2 Center for Materials Innovation and Department of Chemistry, Washington University in Saint Louis, One Brookings Drive, CB 1134, Saint Louis, MO 63130, USA.



{dagger} These authors contributed equally to this work.

* To whom correspondence should be addressed.

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Block Copolymer Assembly via Kinetic Control.
H. Cui, Z. Chen, S. Zhong, K. L. Wooley, and D. J. Pochan (2007)
Science 317, 647-650
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