Imidazolium ABA Triblock Copolymers as Ionic-Liquid Containing Electroactive Membranes

A series of ABA triblock copolymers, poly(Sty-b-(MVBIm-Tf2N)-b-Sty), were synthesized using nitroxide-mediated polymerization and found to exhibit good mechanical stability and microphase-separated morphology, as observed by dynamic mechanical analysis and small-angle X-ray scattering. Triblock copolymers containing 47 wt% and 60 wt% styrene outer blocks exhibited a Vogel-Fulcher-Tamman temperature dependence of ionic conductivity and mobility, indicating coupling between ionic conductivity and segmental motion. When cast with 32 wt% ionic liquid, poly(Sty35-b-(MVBIm-Tf2N)80-b-Sty35) (47 wt% styrene) showed actuation under an applied potential of 4 V. The membrane acts as a container of ionic liquid and provides channels for the migration of the ions of ionic liquid. The fast actuation speed indicates that the triblock copolymer has good ionic conductivity. These tailorable ABA block copolymers are promising candidates for ionic-polymer device applications.


C. Jangu, J.-H. H. Wang, D. Wang, S. Sharick, J. R. Heflin, K. I. Winey, R. H. Colby, T. E. Long*, Macromolecular Chemistry and Physics, 215, 1319-1331, 2014.
"Well-Defined Imidazolium ABA Triblock Copolymers as Ionic-Liquid-Containing Electroactive Membranes"