Nanostructured block copolymer gel electrolytes based on polyethers

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The goal of this project is to design nanostructured block copolymer gels for use as electrolytes in polymer-based batteries and electric double-layer capacitors. These materials also feature self-healing properties, whereby the designed nanostructure additionally enables the restoration of the functional properties after mechanical damage. For this purpose, amphiphilic polyether-based ABC triblock terpolymers will be utilized with a (covalently) crosslinkable block A (furfuryl moieties for Diels-Alder reactions or alkynes for copper-catalyzed azide-alkyne chemistry), a block B being soluble in both organic and aqueous electrolytes providing ion mobility (e.g., poly(methyl glycidyl ether)), and a block C carrying charged repeating units for reversible (non-covalent) crosslinks based on combinations of carboxyl and amino moieties or alternatively, zwitterionic comonomers. Self-assembly in aqueous media will then lead to core-shell-corona micelles, wherein the core-forming block A can be crosslinked to further enhance the nanostructured shape by covalent bonds whereas the C block allows for further crosslinks based on electrostatic attractions; here, an ABC triblock terpolymer micelle carrying, for example, anionic carboxyl moieties in the C block is intended to be combined with the antagonistic micelles, which analogously possess cationic amino groups in the C block. These ionic interactions might on the one hand lead to the formation of a defined network or gel, and on the other their dynamic nature will be the basis for the desired self-healing mechanism. Furthermore, the middle B block will enable the diffusion of ions through the gel, which should be ensured at a comparable level before damage and after healing.The synthesis will be accomplished using a combination of sequential living anionic polymerization of the respective glycidyl ether monomers (i.e. furfuryl or alkynyl glycidyl ether for block A, e.g., methyl glycidyl ether for block B, allyl glycidyl ether ether for block C) followed by side chain modification of the C block using thiol-ene click chemistry to realize the charged repeating units. The characterization will play an important role in this project starting from the comprehensive analysis of the ABC triblock terpolymers towards the preparation of the respective gels, including investigations of crosslinking efficiencies and probing the stability besides morphological studies. Furthermore, the functionality, i.e. the ionic conductivity, of the gels should be precisely understood with regard to the diffusion of ions, to evaluate the self-healing progress in the end. Finally, the gel electrolytes will be used in test batteries as proof-of-principle for new electrolyte materials.