Colloidal Crystallization and Ionic Liquid Induced Partial β-Phase Transformation of Poly(vinylidene fluoride) Nanoparticles

Abstract

Colloidal crystallization of poly­(vinylidene fluoride) (PVDF) nanoparticles (NPs) and its β-phase transformation were studied. The pristine PVDF NPs with an average diameter of 230 nm consist of 46% α-phase and 54% amorphous PVDF. The PVDF NPs were assembled on a quartz substrate by means of vertical deposition method from a tetrahydrofuran dispersion of PVDF NPs with a few volume percentage of n-alkane. The resultant colloidal thin films displayed a pale-greenish structural color with the selective reflection at around 550 nm wavelength due to closely packed PVDF NPs. The colloidal thin films were immersed into an acetonitrile solution containing 2 wt % ionic liquid, subsequently air-dried, and thermally annealed at 140 °C, just below the melting point of the PVDF–IL blends. After annealing, the PVDF NPs partially transformed into its β-phase with the volume percentages of α-, β-, and amorphous phases of 22, 32, and 46%, respectively. The postannealed colloidal films still maintained the face-centered-cubic assembling structure of PVDF NPs, thus displaying the greenish structural color and selective reflection.

Poly(vinylidene fluoride-co-hexafluoropropylene)/polyaniline blends assisted by phosphonium – Based ionic liquid: Dielectric properties and β-phase formation

“…Figure The presence of IL also contributes for the formation of the β-phase, as also reported in the literature [36]. For example, the diffraction peak at 2 = 20.6° can be detected even for blend containing 10 wt% of PAni.DBSA and prepared in the presence of IL.…”

“…In this context, the modification of PVDF and PVDF -based copolymer matrices with imidazolium -based ionic liquids has been reported mainly with the aim of developing new polymeric gel electrolyte membranes for proton exchange fuel cell [32] and for energy storage applications [33][34][35]. Okada et al [36] have also reported the ability of ionic liquid in inducing the β-phase formation of PVDF. ILs have also been successfully employed to improve the dispersion of carbon nanotubes within the PVDF matrix [37].…”

Understanding of Versatile and Tunable Nanostructuration of Ionic Liquids on Fluorinated Copolymer

“…The latest case is that PVDF nanoparticles with α-phase were partly transformed into β-one by adding imidazolium nitrate IL and subsequent thermal annealing below the melting temperature. 27 Although the influence of IL on the structure of PVDF (mainly focusing on the formation of polar crystalline phase) has been observed above, the mechanism for the structuration is quite elusive. From current understanding, dipolar interactions between PVDF chain molecules and ILs contribute the formation of polar crystalline phase.…”

Local Grafting of Ionic Liquid in Poly(vinylidene fluoride) Amorphous Region and the Subsequent Microphase Separation Behavior in Melt

“…Recently, investigations on poly(vinylidene fluoride) (PVDF) modified by room temperature ionic liquids (ILs) have been widely reported in the literatures . The incorporation of ILs leads to the formation of electroactive phases ( β or γ phase) of PVDF . PVDF/IL blends have the potential applications as solid polymer electrolytes, actuators, biomedical devices, and smart materials .…”

“…[36][37][38][39][40][41][42][43][44][45] The incorporation of ILs leads to the formation of electroactive phases ( β or γ phase) of PVDF. [36][37][38][39][40][41][42] PVDF/IL blends have the potential applications as solid polymer electrolytes, [ 43 ] actuators, [ 44 ] biomedical devices, [ 45 ] and smart materials. [ 46 ] It has been demonstrated that PVDF is thermodynamically miscible with IL due to the specifi c interaction [ 37,38 ] between >CF 2 with cations of IL.…”