This work reports on the development of ionic liquid (IL)/poly(vinylidene fluoride) (PVDF) actuator composites. ILs sharing the same anion (bis-(trifluoromethylsulfonyl)imide, [TFSI] − ), and different cations belonging to the families of pyridinium, imidazolium, and ammonium ions, comprising an alkyl side chains with variable length, were used. The physical−chemical properties, thermal behavior, mechanical, electrical, and bending responses of the PVDF/IL composites were evaluated. The incorporation of ILs into the PVDF matrix leads to an increase of the electroactive β phase content. Moreover, the β phase content increases with the increase of the IL alkyl chain length. The degree of crystallinity depends on the IL chain length as well as on the mechanical properties, revealing the plasticizing behavior exerted by the IL. The electrical conductivity decreased with the increase of the cation alkyl chain size. The highest bending response was observed for the [Pmim][TFSI]/PVDF and [Pmpip][TFSI] composites (where Pmim and Pmpip represent propylimidazolium and propylmethylpiperidinium), being 5.7 and 6.0 mm, respectively, at 5 V and 100 mHz.

This work represents an essential step towards the understanding of the dynamics and thermodynamic characteristics of a novel family of ionic liquids, namely fluorinated ionic liquids based on the combination of 1-alkyl-3-methylimidazolium cations with perfluoroalkylsulfonates or perfluoroalkylcarboxylates anions. The so far scarce information about these fluids constitutes a limiting factor for their potential applications. In this work, we provide detailed evidence on the influence of hydrogenated and fluorinated alkyl chain lengths in the final characteristics of the fluorinated ionic liquids. Different properties, namely, melting point, decomposition temperature, density, dynamic viscosity, ionic conductivity and refractive index, were determined and the experimental results were discussed taking into account the influence of the length of the hydrogenated and fluorinated alkyl chains. Molecular dynamic simulations were also performed to study the nanoscale structuration of these novel compounds. Electronic Supplementary Information (ESI) available: The ESI contains the synthesis and characterization of novel FILs and experimental data of thermal properties, density, viscosity, refractive index and ionic conductivity. Moreover, the fitting parameters of these properties and values of molar volume and molar refraction are also showed. See