Abstract
Block copolymers consisting of incompatible components self-assemble into microphase-separated domains yielding highly regular structures with characteristic length scales of the order of several tens of nanometres. Therefore, in the past decades, block copolymers have gained considerable potential for nanotechnological applications, such as in nanostructured networks and membranes, nanoparticle templates and high-density data storage media1,2,3,4. However, the characteristic size of the resulting structures is usually determined by molecular parameters of the constituent polymer molecules and cannot easily be adjusted on demand. Here, we show that electric d.c. fields can be used to tune the characteristic spacing of a block-copolymer nanostructure with high accuracy by as much as 6% in a fully reversible way on a timescale in the range of several milliseconds. We discuss the influence of various physical parameters on the tuning process and study the time response of the nanostructure to the applied field. A tentative explanation of the observed effect is given on the basis of anisotropic polarizabilities and permanent dipole moments of the monomeric constituents. This electric-field-induced effect further enhances the high technological potential of block-copolymer-based soft-lithography applications5,6.
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Acknowledgements
The authors thank H. Krejtschi and his team for assistance with building the capacitors, F. Schubert, F. Fischer, E. Di Cola, M. Sztucki, P. Bösecke and T. Narayanan for help at the ESRF and Y. Tsori and D. Andelman for fruitful discussions. We are grateful to the ESRF for provision of synchrotron beam time. V.U. acknowledges LDRD sponsorship through US-DOE ORNL/UT-Battelle Contract No. DE-AC05-00OR22725. This work was carried out in the framework of the Sonderforschungsbereich 481 (TP A2) funded by the German Science Foundation (DFG). A.B. acknowledges support by the Lichtenberg-Programm of the VolkswagenStiftung.
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Schmidt, K., Schoberth, H., Ruppel, M. et al. Reversible tuning of a block-copolymer nanostructure via electric fields. Nature Mater 7, 142–145 (2008). https://doi.org/10.1038/nmat2068
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DOI: https://doi.org/10.1038/nmat2068