# Effect of Cation Type on the Isothermal Crystallization of Poly(vinylidene fluoride) Blended in Ionic Liquids with [Eu(tta)4]− Anion

## TL;DR

This paper studies how different cations in ionic liquids affect the crystallization and properties of poly(vinylidene fluoride) (PVDF), promoting specific electroactive phases.

## Contribution

The study reveals that [Bmim][Eu(tta)4] strongly promotes electroactive PVDF phases and influences crystallization kinetics and electrical properties.

## Key findings

- Samples with [Bmim][Eu(tta)4] showed higher promotion of electroactive PVDF phases compared to Na[Eu(tta)4].
- Crystallization temperature and ionic interactions significantly influence PVDF phase development and dielectric behavior.
- Dielectric spectroscopy showed cation type strongly affects conductivity and functional properties of PVDF.

## Abstract

To develop smart
materials with tailored functional response, the
combination of poly­(vinylidene fluoride) (PVDF) and advanced ionic
additives such as ionic liquids (ILs) is increasingly being investigated.
Depending on the processing conditions, the incorporation of these
additives into PVDF, together with their functional response, promotes
the nucleation of specific electroactive phases. This work explores
the effect of incorporating sodium tetra­(2-thenoyltrifluoroacetonate)
europate­(III), Na­[Eu­(tta)4] and 1-butyl-3-methylimidazolium
tetra­(2-thenoyltrifluoroacetonate) europate­(III), [Bmim]­[Eu­(tta)4], into PVDF matrices through a comprehensive analysis of
isothermal crystallization behavior, morphological features, crystalline
phase development, and dielectric behavior. Field-emission scanning
electron microscopy (FESEM) was used to analyze the microstructure,
while Fourier transform infrared (FTIR) spectroscopy was used to assess
the development of PVDF crystalline phases during its isothermal crystallization
at various temperatures. All samples exhibited α, β, and
γ crystalline phases, although their relative proportions differed
significantly depending on the type of filler used. This suggests
that [Bmim]­[Eu­(tta)4] is a strong promoter of the electroactive
(EA) phases of PVDF. The results are attributed to the interaction
between the IL charges and the PVDF dipoles of the EA structures,
which are promoted by higher crystallization temperatures, as supported
by both FTIR and DSC data. Thus, the addition of Na­[Eu­(tta)4] and [Bmim]­[Eu­(tta)4] strongly influences the crystallization
kinetics of PVDF and allows nucleation of specific phases of PVDF.
Additionally, dielectric spectroscopy revealed that the nature of
the cation strongly influences conductivity behavior, as demonstrated
by the dielectric results. Overall, the incorporation of Na­[Eu­(tta)4] and [Bmim]­[Eu­(tta)4] not only influences the
crystallization kinetics of PVDF but also provides PVDF with intrinsic
functional properties such as luminescent behavior and improved electrical
performance, offering a simple and efficient strategy of nucleating
specific PVDF phases.