"Tuning Ionic Interactions in PVA/IL Hybrid Electrolytes: Role of Imidazolium Anion Variations on Structure and Conductivity"

This study investigates the improvement of polyvinyl alcohol (PVA) films by utilizing imidazolium-based ionic liquids (ILs) to address limitations in ionic conductivity and thermal stability. This research aims to assess the effect of ion–polymer interactions on the dielectric, mechanical, and structural properties of composites formed by integrating 1-alkyl-3-methylimidazolium salts with diverse anions (Br⁻, BF₄⁻, PF₆⁻). Solution-cast films were systematically analyzed using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Thermogravimetric Analysis (TGA), as well as Dynamic Mechanical Analysis (DMA) and Dielectric Analysis, to evaluate the role of counter anions in tailoring chemical compatibility, morphology, and functional performance. The obtained results indicate that ionic liquids markedly enhance segmental mobility, charge transfer, and thermal characteristics. Such controlled variation of the ionic environment offers valuable insight into how anion type modulates both physical behavior and functional properties. By clarifying the relationship between ionic specificity and polymer motion. PVA/[CmMIM]Br exhibits the highest thermal stability, PVA/[CmMIM]BF₄ demonstrates moderate stability, and PVA/[CmMIM]PF₆ possesses the lowest thermal resistance among the three systems studied. The mechanical properties of PVA/IL composites were improved with the increasing content of IL. The tensile strength and the elongation at break were enhanced. In addition, the dielectric performance of IL-doped PVA composites is significantly influenced by the type and concentration of the ionic liquid. [CmMIM]Br-doped samples exhibit the highest ε′ and ε″ values at low frequencies, indicating pronounced interfacial polarization and high conduction losses. In contrast, the [CmMIM]BF₄ and [CmMIM]PF₆ systems exhibit enhanced dielectric stability with reduced losses, indicating more dielectric homogeneity. These findings highlight the potential of PVA/IL composites for flexible electronics, smart coatings, and other advanced functional applications.