PerspectiveMaterials Science

Approaching Asymmetry and Versatility in Polymer Assembly

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Science  03 Aug 2012:
Vol. 337, Issue 6094, pp. 530-531
DOI: 10.1126/science.1225524

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Summary

Modern integrated circuits are produced in a “top-down” approach with the aid of lithographic techniques to sequentially control the etching and deposition of materials. Arbitrary nanoscale shapes can be created in a desired hierarchical sequence to produce a functional device. If assembled with no control of size, shape, or sequence, the same materials produce no function and no technology. In contrast to lithography, “bottom-up” solution processing can assemble nanoscale polymeric materials in a simple manner, often through aggregation and phase separation processes driven by multiple weak interactions and the minimization of free energy (1). Unfortunately, bottom-up products are usually relatively simple and symmetrical (e.g., spherical and cylindrical micelles, bilayer membranes, and spherical colloids). On page 559 of this issue, Rupar et al. (2) present a beautiful example of complexity and arbitrary control of solution-grown nanomaterials. The authors combined aspects of sequential, top-down control with bottom-up simplicity by using molecular design, solution assembly, crystallization, and covalent cross-linking chemistry in a multistep fashion.