Effect of peptide nanotube filler on structural and ion-transport properties of solid polymer electrolytes

Casting, under an inhomogeneous magnetic field, of polymer electrolytes (PE) containing only 1% of aromatic diphenylalanine peptide nanotubes coated with ferrofluid (FF-PNT) increases the total PE conductivity at room temperature by two orders of magnitude, as compared to pristine PEs. The magnetically oriented FF-PNT-modified PE cast under MF is thermally stable. Even after 1 month of storage at 70°C it retains conductivity values that are very close to that of the freshly-cast film. As opposed to other fillers tested so far, the incorporation of FF-PNT to the pristine PE eliminates formation of large spherulites. A highly-homogeneous, fine-grained morphology with well-defined round-shaped crystallites develops in this composite PE under an applied MF. The XRD patterns make it clear that the applied magnetic field influences the crystallinity of the PE containing FF-PNTs more strongly than it does that of pristine films. Significant orientation effects are observed for LiTf:P(EO) ₃ + 1% (w/w) FF-PNTs by ⁷Li nuclear magnetic resonance measurements, as well.