Nanostructured Block Copolymer/Ionic Liquid Composite Materials

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TECHNICAL SUMMARY Ionic liquids exhibit many appealing properties, including chemical and thermal stability, vanishing vapor pressure, tunable solvation, high ionic conductivity, and high dielectric constant, that render them appealing as key ingredients in plastic electronics, batteries, fuel cells, gas separation membranes, and actuators. To realize these properties in applications, it is necessary to solidify the material, and/or to confine the ionic liquid within a desired nanostructure. Block copolymers offer unprecedented flexibility to direct self-assembly over lengthscales from 1100 nanometers, while simultaneously providing mechanical integrity. Five different sub-projects will be pursued, that collectively range from very dilute solutions to almost pure polymer, and that are aimed at a fundamental understanding of how polymer/ionic liquid interactions can be utilized to prepare functional materials. Specifically, this research will: (i) extend the concept of the micelle shuttle, whereby copolymer aggregates transfer reversibly and intact between aqueous and ionic liquid phases, to prepare systems that load, transfer, and release cargo at prescribed temperatures, and to prepare nanoemulsions for use in homogenous catalysis; (ii) prepare robust ion gels by tri- and multiblock copolymer self-assembly, whereby gelation and melting occur at tunable temperatures or under optical stimulation; (iii) optimize the use of ion gels as gate dielectric materials in organic transistors, for plastic electronic applications; (iv) create mechanically robust, ordered block copolymer membranes with ionic liquid channels for high ionic conductivity and transport, both isotropic and anisotropic; (v) create supramolecular polymers with relaxation times tunable over a remarkably wide range via hydrogen bonding in ionic liquids.NON-TECHNICAL SUMMARYThe goal of this project is to create a new class of functional nanostructured materials by combining ionic liquids with block copolymers. Materials containing polymers and ionic liquids are potentially useful across a wide spectrum of technology platforms, including plastic electronics, actuators, sensors, batteries, fuel cells, and separation membranes. For applications the simultaneous optimization of several properties, such as high ionic transport, mechanical integrity, and facile processing, is essential; this can be achieved through controlling the material structure at the nanoscale. Ionic liquids are already in commercial practice in Europe as green solvents for chemical transformations; block copolymer surfactants should greatly extend the range of reagents, products, and catalysts that can be employed. Graduate students working in this project will be broadly trained in polymer synthesis and advanced characterization techniques, and will have the opportunity to mentor talented undergraduates in research. High school students from the greater Twin Cities, particularly females and underrepresented minorities, will be exposed to polymer science as part of an "Exploring Careers" summer camp administered with the Institute of Technology Center for Educational Programs. Faculty and students from colleges and universities across the US will spend time in the PI's laboratories to utilize one or more of the experimental facilities, through the newly-forged Materials Research Facilities Network.