Resolving Complex Multiscale Structure of Magneto- and Electroactive Polymer Composites With an Ionic Liquid.

Area of Science:

• Materials Science
• Polymer Science
• Nanotechnology

Background:

• Ionogels, nanoparticle-free polymer composites with ionic liquids, require multiscale structural understanding for advanced applications.
• Enhancing functional properties like energy storage and sensing depends on controlling ionogels' nanostructure.

Purpose of the Study:

• To elucidate the nano- and microstructuration of ionic liquids within a poly(vinylidenefluoride-co-trifluoroethylene) matrix.
• To correlate the ionic liquid's structural organization with the composite's functional properties.

Main Methods:

• Neutron scattering was employed to analyze the ionic liquid's structure.
• Cryogenic scanning electron tomography (FIB-assisted) and cryogenic transmission electron microscopy with elemental analysis provided detailed morphological and compositional insights.

Main Results:

• Ionic liquids form 10-12 nm nanostructures primarily within the polymer's amorphous phase.
• The ionic liquid does not infiltrate crystalline regions, preserving the polymer's crystallinity and its electroactive β-phase.
• Saturation of the amorphous phase with ionic liquid enhances ionic conductivity and maintains mechanical integrity.
• Excess ionic liquid microphase-separates into micrometer-sized pores at high concentrations, boosting conductivity and enabling magnetoelectric effects.

Conclusions:

• The spatial distribution and nanostructuration of ionic liquids in the amorphous polymer phase are critical for ionogel performance.
• Controlling ionic liquid concentration and phase separation is essential for optimizing ionic conductivity and achieving desired functional properties like magnetoelectric response.