Chemistry

Powerful Twister

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Science  29 Jun 2007:
Vol. 316, Issue 5833, pp. 1815
DOI: 10.1126/science.316.5833.1815b

A solenoid consists of a conducting metal coil that can surround a metal core in which a magnetic field is induced when electrical current passes through the wire. One option to build a solenoid on the molecular scale would be to use a highly twisted conducting polymer such as polyacetylene to form the coil. Two problems arise, namely, making the polymer chain sufficiently coiled, and preventing the individual fibrils from forming bundles. Goh et al. investigated the synthesis of polyacetylene in nematic solvents doped with a series of substituted binaphthyl derivatives possessing different twisting powers. The best dopant gave a helical pitch to the solvent approximately one-fourth the size of that induced by the other dopants; for a range of concentrations, this pitch was smaller than the typical radius of a bundle of polyacetylene fibers (about 1 μm). Thus, when this dopant was used, the authors obtained single fibrils rather than bundles, a result they anticipate should lead to exceptional electromagnetic properties. — MSL

J. Am. Chem. Soc. 129, 10.1021/ ja070701x (2007).

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