Poly(vinylidene fluoride) membrane with piezoelectric β‐form prepared by immersion precipitation from mixed solvents containing an ionic liquid

Abstract

Poly(vinylidene fluoride) (PVDF) membranes with exclusive b-form have been directly obtained by immersion precipitation from the mixed solvents containing an ionic liquid (IL). In contrast, without the IL only the a-form is generated. The ion-dipole interactions between the IL and PVDF chains should account for the formation of the b-form with TTTT conformation. In addition, the presence of the IL accelerates the crystallization and gelation of PVDF, responsible for the particulate morphology and high water flux in the membranes.

Ion Exchange Dependent Electroactive Phase Content and Electrical Properties of Poly(vinylidene fluoride)/Na(M)Y Composites

“…At the breaking voltage the electric field is strong enough to free the cations from their bonds. These becomes able to move through the zeolite cavities, and the resultant composite conductivity increases significantly . This phenomenon is also dependent on the exchanged ion type.…”

“…These becomes able to move through the zeolite cavities, and the resultant composite conductivity increases significantly. 23 This phenomenon is also dependent on the exchanged ion type. Figure 5 shows the dc conductivity for the different samples.…”

“…The presence of some fillers can induce the direct crystallization of PVDF in the electroactive phase, even when prepared from the melt, a method that usually results in the nonpolar α-phase . This fact is related to the size and electrical properties of the particles and has already been observed with clays, nanoparticles, , ferrites, and ionic liquids, among others. That is also the case of some zeolites, whose presence in the polymer matrix, depending on its shape and Si/Al ration, is able to crystallize PVDF in its piezoelectric γ-phase …”

Induced Formation of Dominating Polar Phases of Poly(vinylidene fluoride): Positive Ion–CF2 Dipole or Negative Ion–CH2 Dipole Interaction

“…Recently, it is revealed that polar phases (β, γ) can be induced directly from melt crystallization by incorporation of surface charged nanoparticles or ionic salts due to the “ion–dipole” interaction. The ion–dipole interaction was reported when both negatively charged magnesium lithium silicate, kaolinite, or ferrites − and positively surface charged onium salts, alkylammonium salts, , or room temperature ionic liquids − were incorporated into PVDF. The ion–dipole interaction in the former case was described as the interaction between the negatively charged surfaces and the CH 2 dipoles in PVDF chains, while in the latter case, it was described as the interaction between the positively charged surfaces and the CF 2 dipoles in PVDF chains.…”

Novel hybrid multifunctional magnetoelectric porous composite films

“…Compared to its PVDF homo-polymer, PVDFTrifuoroethylene P(VDF-TrFE) displays further advantages such as high dipole moment, high dielectric constant, and possibility of controlling porosity at room temperature 7 . Furthermore, P(VDF-TrFE), for TrFE contents between 50 and 80%, crystallizes in the piezoelectric phase independently of the processing method, allowing the preparation of piezoelectric porous films with improved flux and fouling in the case of filtration and separation membranes [8][9] , improved sensing properties for biomedical monitoring 10 and with the possibility of environmental energy storage and harvesting 11 .…”