Cross-Selectivity Enhancement of Poly(vinylidene fluoride-hexafluoropropylene)-Based Sensor Arrays for Detecting Acetone and Ethanol

Abstract

Two methods for cross-selectivity enhancement of porous poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP)/carbon black (CB) composite-based resistive sensors are provided. The sensors are tested with acetone and ethanol in the presence of humid air. Cross-selectivity is enhanced using two different methods to modify the basic response of the PVDF-HFP/CB sensing platform. In method I, the adsorption properties of PVDF-HFP/CB are altered by adding a polyethylene oxide (PEO) layer or by treating with infrared (IR). In method II, the effects of the interaction of acetone and ethanol are enhanced by adding diethylene carbonate (DEC) or PEO dispersed in DEC (PEO/DEC) to the film. The results suggest the approaches used in method I alter the composite ability to adsorb acetone and ethanol, while in method II, they alter the transduction characteristics of the composite. Using these approaches, sensor relative response to acetone was increased by 89% compared with the PVDF-HFP/CB untreated film, whereas sensor relative response to ethanol could be decreased by 57% or increased by 197%. Not only do these results demonstrate facile methods for increasing sensitivity of PVDF-HFP/CB film, used in parallel they demonstrate a roadmap for enhancing system cross-selectivity that can be applied to separate units on an array. Fabrication methods, experimental procedures and results are presented and discussed.

Ionic Liquid Based Polymer Gel Electrolytes for Use with Germanium Thin Film Anodes in Lithium Ion Batteries

“…Only α‐phase peaks are observed in the pure PVDF‐HFP film, however upon addition of the LiTFSI salt there are notable changes in the IR spectrum. In the first instance, there is an additional peak observed at 658 cm −1 which can be attributed to the β‐phase of PVDF‐HFP . A weak peak at 811 cm −1 is also observed which can be attributed to the γ‐phase.…”

“…The IR spectrum obtained for pure PVDF‐HFP is shown in Figures 3(a) and (b). There are several notable peaks obtained including at: 762 cm −1 (C‐F 2 bending mode, α‐phase), 796 cm −1 (C‐F 3 stretching mode, α‐phase), 855 cm −1 (α‐phase),, 872 cm −1 (C‐H 2 wagging of vinylidene, amorphous HFP),, 974 cm −1 (out of plane C−H bending or twisting, α‐phase),– 1058 cm −1 (symmetric stretching of C‐F 3 , amorphous HFP), 1178 cm −1 (asymmetric C−F stretching), 1383 cm −1 (C‐H 2 wagging vibration), and 1404 cm −1 (C‐H 2 scissoring vibration) . Only α‐phase peaks are observed in the pure PVDF‐HFP film, however upon addition of the LiTFSI salt there are notable changes in the IR spectrum.…”

Electron-Beam Irradiation for Boosting Storage Energy Density of Tuned Poly(vinylidene fluoride-hexafluoropropylene)/Graphene Nanoplatelet Polymer Composites

“…As a semi-crystalline material, PVDF and its composites, including P(VDF-HFP), consist of both crystalline and amorphous areas. After casting, they are well known to present a dominant α-phase whereas the crystalline phase with the most useful piezoelectrical and dielectric properties is the planar zig-zag/TTTT β-phase conformation mode [39]. In common with this present work, many previous studies have focused on how to change the α-phase to the polar β-phase.…”

Characterization of Local Structures of Confined Imidazolium Ionic Liquids in PVdF-co-HFP Matrices by High Pressure Infrared Spectroscopy

“…The IR spectrum of pure [HMIM][NTf 2 ] contains vibrational absorptions at 2866, 2934, and 2959 cm −1 corresponding to the three alkyl C–H cations [ 27 , 28 , 29 , 30 , 31 ]. The IR spectrum of pure PVdF-co-HFP revealed two characteristic alkyl C–H peaks at 2979 and 3021 cm −1 [ 34 ]. The alkyl C–H peak of the cation at 2866 cm −1 in Figure 1 a was very slightly shifted compared to the 2869 cm −1 peak obtained on mixing PVdF-co-HFP with the IL ( Figure 1 c).…”

“…Figure 2 a revealed four major vibrational absorptions at 1058 (ν SNS), 1140 (ν s SO 2 ), 1196 (ν CF 3 ), and 1352 (ν a SO 2 ) cm −1 , originating from the IL anion ([NTf 2 ] − ) [ 35 , 36 ]. Pure PVdF-co-HFP showed several characteristic polymer absorptions at 839, 881, 1074, 1179, 1233, and 1404 cm −1 [ 34 ]. The vibrational absorptions at 1196 and 1226 cm −1 for the CF 3 moiety in [NTf2] - overlap significantly with the CF 2 absorptions of PVdF-co-HFP at 1179 and 1233 cm −1 for the mixtures ( Figure 2 b,c).…”