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Ion Gels: A New Class of Responsive Polymer Composites Tim Lodge, University of Minnesota, DMR 0406656.
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Ion Gels: A New Class of Responsive Polymer Composites Tim Lodge, University of Minnesota, DMR 0406656 Ion gels consist of a polymer network swollen with an ionic liquid. These materials have many appealing features, with potential applications in sensors, actuators, membranes, batteries, supercapacitors, and fuel cells. We have demonstrated that well-defined ion gels can be made by direct self-assembly of ABA triblock copolymers, using as little as 5% polymer,while preserving the high ionic conductivity of the ionic liquid [1]. We have recently prepared thermo-reversible ion gels, which can be processed as liquids at high temperature but then solidify on cooling [2]. We have further shown that these gels are extremely promising gate dielectrics in organic thin film transistors, with switching speeds in excess of 10 kHz and very low turn-on voltages [3]. [1]. “Ion Gels by Self-Assembly of a Triblock Copolymer in an Ionic Liquid”, Y. He, P. G. Boswell, P. Bühlmann, and T. P. Lodge, J. Phys. Chem. B.,111, 4645-4652 (2007). [2]. “A Thermoreversible Ion Gel by Triblock Copolymer Self-assembly in an Ionic Liquid”, Y. He and T. P. Lodge, Chem. Commun. 2732-2734 (2007). Also featured in Chem. Technol., 4, T49, (2007). [3]. Ion Gel Gated Polymer Thin-film Transistors”, J. Lee, M. J. Panzer, Y. He, T. P. Lodge, C. D. Frisbie, J. Am. Chem. Soc., 129, 4532 (2007). A thermoreversible gel of poly(N-isopropyl acrylamide)-poly(ethylene oxide)-poly(N-isopropyl acrylamide) in ethyl methyl imidazolium trifluoromethyl sulfonimide. The dynamic moduli measured in a rheometer as a function of temperature show a melting point near 18 ºC. The inset photographs show the ion gel at 5 ºC and the processible liquid at 25 ºC [2].
Broader Impacts: Introducing K-12 Students to Self-Assembly Tim Lodge, University of Minnesota, DMR 0406656 October 20, 2006: 450 kids from “Lego League” visit the U of M for Nanotechnology Day; T. Lodge discusses self-assembly. July 18, 2007: 23 high schoolers learn to make polymers with T. Lodge and M. Hillmyer during “Polymer Day”, part of Exploring Careers in Engineering and Physical Sciences summer camp. June 23, 2007: 100 kids from the Davidson Institute for Talent Development spend a day with MRSEC faculty, organized by T. Lodge; the concluding event was a performance by the Physics Force.