Metal Salt‐Induced Ferroelectric Crystalline Phase in Poly(vinylidene fluoride) Films

Abstract

In this Communication, the effect of varying mass fractions (0–20 wt.‐%) of calcium chloride (CaCl2) salt on the α‐ and β‐phase content of poly(vinylidene fluoride) (PVDF) as‐cast films were investigated. Spectral and X‐ray studies revealed the maximum ferroelectric β‐phase for the addition of 15 wt.‐% of CaCl2 in PVDF compared to neat PVDF samples. The dense β‐phase dominant PVDF–CaCl2 (15 wt.‐%) thick film used as a ferroelectric insulator in one‐capacitor (1C) type random access memory device exhibited a remnant polarization of 3.1 µC · cm2, and is a good indication that the unoriented PVDF–CaCl2 films can be used in electronic applications without further stretching process.

Direct Preparation of Nanoscale Thin Films of Poly(vinylidene fluoride) Containing β‐Crystalline Phase by Heat‐Controlled Spin Coating

“…Figure 2 shows the FTIR‐GIRAS of ASP and ASPAN samples prepared at temperatures below and near ambient. ASP‐10 showed a nearly complete β ‐phase, which can be identified from the peak appearing at 1 280 cm −1 16, 31–33. Upon annealing, a small and well‐distinguished peak emerged at around 1 219 cm −1 , which is correlated with the α ‐phase 12.…”

“…Among the common solution processing routes (e.g., spin coating, forming Langmuir‐Blodgett (LB) films, printing technology, etc. ), most recently, forming LB films30 and spin coating31–35 have been reported to favor the formation of PVDF thin films containing the β ‐crystalline phase. Moreover, for microelectronics applications, the well‐established spin‐coating method has been considered to be more suitable for fabricating smooth polymeric coatings on flat substrates36 on an industrial scale35 than the LB technique, which is generally considered to be time‐consuming37 and difficult when fabricating films of fluorine‐containing polymers, due to their rigidity and hydrophobicity 38…”

“…PVDF‐CaCl 2 thin film incorporated with 15 wt.‐% of CaCl 2 showed a higher β ‐phase content. The combination of polar molecular interactions between polymer, solvent, and salt additive (Ca 2+ ··· OCN ··· FC) was reported to render the crystallization of PVDF into the β ‐phase 32…”

Nanocomposite proton conducting membranes based on amphiphilic PVDF graft copolymer

“…A strong peak at 1184 cm -1 was observed in the pristine P(VDF-co-CTFE), assigned to the characteristic absorption of crystalline structures in the polymer (Figure 2(a)). 38 Compared to the pristine polymer, the P(VDF-co-CTFE)-g-P(SSA-co-TMSPMA) graft copolymer exhibited the several absorption bands at 1720, 1132, 1108, 1047 and 1005 cm -1 (Figure 2(b)). The absorption band at 1720 cm -1 is assigned to the carbonyl (C=O) stretching vibration of PTMSPMA units whereas the absorption bands at 1132, 1047, 1005 cm -1 result from the stretching vibrations of both the phenyl rings substituted with sulfonate groups and the sulfonate anions attached to phenyl ring in PSSA units.…”

Synthesis and characterization of AgBr nanocomposites by templated amphiphilic comb polymer

“…A strong peak at 1184 cm À1 was observed in the pristine P(VDF-co-CTFE) copolymer, assigned to the characteristic absorption of crystalline structures in the polymer (Fig. 3a) [30]. Upon graft polymerization with P4VP, strong absorption bands at 1601 and 1560 cm À1 appeared, attributable to the C@N stretching vibration of the pyridine ring (Fig.…”