PVDF-HFP Membrane Research Articles

Ionic liquids for the control of the morphology in poly(vinylidene fluoride-co-hexafluoropropylene) membranes

The development of polymer membranes with tailored micro-morphology and wettability is a demand in the areas of filtration, sensors, and tissue engineering, among others. The thermoplastic copolymer poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), is one of the most widely used polymers for these applications due to its good mechanical and thermal properties, biocompatibility and low density. Although the control of the PVDF-HFP morphology is a complicated task, the introduction of ionic liquids (ILs) in the PVDF-HFP matrix opens new perspectives in this area. This work consists of a systematic study of three different protic ionic liquids ([dema][TfO], [MIm][NTf2] and [MIm][Cl]) in the control of PVDF-HFP membranes properties. Different preparation conditions are also analyzed. These results demonstrate how several parameters such as morphology, water absorption capacity and mechanical properties vary depending on the production methodology employed and on the choice of incorporated IL. Pores of different sizes, spherulites and compact structures have been obtained, as well as hydrophilic and highly hydrophobic structures. These results show that ILs play a key role in the optimization of polymer properties and given the large number of available ILs, open up new possibilities for the development of polymer membranes suitable for applications where specific morphologies are desirable.

Preparation of microporous Cellulose/Poly(vinylidene fluoride-hexafluoropropylene) membrane for lithium ion batteries by phase inversion method

In this work, a porous and honeycomb-structured Cellulose/Poly (vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) membrane is prepared via a facile and ecofriendly phase inversion method by using glycerol as pore forming agent. Cellulose acetate, the source of cellulose, is easily converted into cellulose by hydrolysis in the presence of lithium hydroxide. Owing to the unique microstructure, the Cellulose/PVDF-HFP membrane offers several advantages, including high porosity, elevated electrolyte uptake, high ion conductivity, and wide electrochemical window (5.35 V). Compared with conventional polypropylene (PP) separator and PVDF-HFP membrane, the membrane developed in this work enables higher discharge capacity, higher lithium-ion transference number (0.89) and improved rate performance, which is able to maintain a high discharge capacity of 136 mAh g−1 at 8 C, using LiCoO2 as cathode and Li metal as anode. In addition, the Cellulose/PVDF-HFP membrane based batteries exhibit superior cycling performance that can maintain 91.7% capacity after 100 cycles at 0.2 C. The characterization and battery test results demonstrate that the membrane is highly compatible with lithium ion batteries.

Comparative study of PVDF-HFP-curcumin porous structures produced by supercritical assisted processes

In this work, the comparison between PVDF-HFP porous structures loaded with 3% w/w curcumin (Cm), produced by supercritical assisted processes, was performed. In the case of membranes, different operative conditions (from 250bar/35°C to 150bar/55°C) and polymer concentrations (from 10 to 30% w/w) were tested. A cellular membranes morphology was observed and porosity values up to 89% were measured. Cm release was prolonged from 20h to 26h changing the PVDF-HFP membrane concentration from 20 to 30% w/w. PVDF-HFP-Cm aerogels were produced by supercritical drying, operating at 200bar and 45°C. A nanofibrous aerogels morphology was obtained with open and interconnected pores, reaching porosity values of 94%. The maximum Cm release was prolonged up to 44h for 12% w/w PVDF-HFP aerogel. Kosmeyers-Peppas model produced a fair good representation of the Cm release experimental results for PVDF-HFP-Cm membranes and aerogels.

Preparation and characterization of novel modified PVDF-HFP/GO/ODS composite hollow fiber membrane for Caspian Sea water desalination

In this Study, a novel modified PVDF-HFP/GO/ODS hollow fiber membrane fabricated by dry/wet jet spinning. The dope solution containing 12wt% polymer, and different amounts of graphene oxide (GO) nanosheets (0, 1, 3 and 5%) were prepared in NMP as a solvent. Then the composite membranes were silanized using ODS in acidic condition. Various techniques such as SEM, AFM, FTIR, LEP, contact angle (CA) and tensile measurement tests were used to investigate the effects of modifications on the structure, surface chemistry, and performance of the membranes. The modified membrane exhibits a permeation flux of 34.1±1.1kgm−2h−1. Furthermore, the contact angle and LEP were increased from 115°±1.5 and 112±4.5kPa for PVDF-HFP membrane to 162°±1.7 and 181±5.3kPa for modified PVDF-HFP/GO/ODS membrane, respectively. The incorporation of GO in the membrane matrix induces the hierarchy roughness on the membrane surface and provides reactive hydroxyl sites for further chemical modification. Desalination of Caspian Sea water (CSW) was conducted using prepared membranes through direct contact membrane distillation (DCMD). Results showed that salt precipitation and permeation flux reduction partially occurred after 10days for modified membranes. Finally, the membranes recovered by chemical cleaning in HCl solution (pH=5).

Separator for lithium-sulfur battery based on polymer blend membrane

In this work we report a novel way of reducing the polysulfide shuttle in lithium-sulfur batteries by a new separator material. Polyvinylsulfate potassium salt (PVSK) as polymeric additive is introduced into a polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP) matrix membrane to improve the battery performance. PVSK is expected to lower the polysulfide mobility due to interaction with the sulfonic group. PVdF-HFP/PVSK blend membranes are prepared and an UV/Vis polysulfide diffusion test clearly demonstrates the positive effect of PVSK. Electrochemical testing reveals a significant improvement of cycling stability up to more than 200 cycles. In addition, the effect of separator porosity to the polysulfide shuttle is investigated with PVdF-HFP membranes of different porosity. A simple polysulfide diffusion test and potentiostatic charge/discharge cycling clearly demonstrate that low separator porosity is favorable in a lithium-sulfur cell.

Investigation of Antibacterial and Fouling Resistance of Silver and Multi-Walled Carbon Nanotubes Doped Poly(Vinylidene Fluoride-co-Hexafluoropropylene) Composite Membrane.

Composite membranes were successfully prepared using a phase-inversion method. The X-ray powder diffraction (XRD) and energy dispersive X-ray (EDX) profiles has confirmed formation of 4.8 wt % Ag/poly(vinylidene fluoride-co-hexafluoropropene) (PVDF-HFP), 3 wt % Ag-MWCNTs/PVDF-HFP (EDX surface composition of Ag nanoparticles) and 1.5 wt % MWCNTs/PVDF-HFP composite membranes. The MWCNTs crystallites are mainly encapsulated by a layer of PVDF-HFP, as evidenced by disappearance of graphitic peak. The scanning electron microscopy (SEM) images have depicted the formation of microporous structure, with few MWCNTs on the surface and strongly interacting with PVDF-HFP as demonstrated by thermogravimetric analysis (TGA), XRD and Fourier transform infrared (FTIR) data. The data indicated an increase in porosity, swellability and water content of the PVDF-HFP membrane with the addition of MWCNTs and/or Ag nanoparticles, showing an improved hydrophilicity. The 1.5 wt % MWCNTs/PVDF-HFP composite membrane showed good desalination and fouling resistance rates, which correlates with a low water contact angle. The combined effects of Ag nanoparticles and MWCNTs do not promote fouling resistance of PVDF-HFP membranes, as shown during NaCl microfiltration (this is linked with high water contact angle as compared to that of MWCNTs/PVDF-HFP composite). Both 1.5 wt % MWCNTs/PVDF-HFP and 3 wt % Ag-MWCNTs/PVDF-HFP composite membranes prevented the bacteria passing through the membrane (100% bacterial load reduction). The surface of 3 wt % Ag-MWCNTs/PVDF-HFP showed good bactericidal and non-leaching properties of the dopant materials (MWCNTs and Ag), as evidenced by bacterial growth on the edges of the membranes.

A facile approach to fabricate superhydrophobic membranes with low contact angle hysteresis

A robust superhydrophobic polyvinyldene fluoride-co-hexafluoropropylene (PVDF-HFP) electrospun membrane was fabricated by using a modest and versatile coating technique. Inspired by the natural phenomenon of thin layer formation of dust particles on the surfaces. Electrospun mats of PVDF-HFP were coated with tetrafluoroethylene oligomers (OTFE) particles. Dust of the OTFE was created in a closed chamber and used to form a thin layer of OTFE particles on the surface of the electrospun PVDF-HFP membranes. Hot pressing was used then to infuse the loose OTFE deposited layer on the surface of the PVDF-HFP membrane. Scanning electron microscopy images indicate that OTFE particles infused ~2–3µm in the electrospun non-woven network. Static contact angle of water on the PVDF-HFP surface improved from 125° ± 2 to 156° ± 2 after OTFE coating. In addition, OTFE coating did not alter the pore size distribution of PVDF-HFP membrane and permeation flux, whereas it significantly helped in improving the water liquid entry pressure. The prepared membranes were tested in direct contact membrane distillation (DCMD) applied to desalination and reported to achieved 99.9% salt rejection with permeation flux of 13–14kg/m2h. In addition to increasing the hydrophobicity of the membranes, OTFE coating significantly reduces the contact angle hysteresis from ~90° ± 2° to ~10° ± 2°. To show the significance of contact angle hysteresis on membrane performance, high fidelity modeling based on computational fluid dynamic in thermal coupled membrane flow was developed. Results of the temperature, polarization coefficient (TPC) and heat transfer coefficient (h) clearly show the favorable impact of the reduced value of hysteresis and its implication of inducing slip. Under total slip, considerable gain in the TCP is observed and reaching as high as 25%.

Effect of Polyethylene glycol methyl ether blend Humic acid on poly (vinylidene fluoride-co-hexafluropropylene) PVDF-HFP membranes: pH responsiveness and antifouling behavior with optimization approach

Flat sheet asymmetric membranes were fabricated with homogeneous solution of poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) using N-methyl-2-pyrrolidone (NMP) as solvent via phase inversion method. PEGME (Poly ethylene glycol methyl ether) (Mn 5000) blend Humic Acid (HA), of different mole ratio was used as additive. Characterization of the membranes was done by Field emission scanning electron microscope (FESEM), Fourier Transform Infrared (FTIR) spectroscopy, Atomic force microscopy (AFM) and Differential scanning calorimetry (DSC) studies. Liquid-liquid displacement porosimetry (LLDP) study evaluated the morphological parameters, average pore size and pore size distribution. Bovine serum albumin (BSA) (MW - 68,000 Da) was used to study the antifouling effect and pore blocking mechanism of the membranes. The pure water flux (PWF), solute rejection and flux recovery ratio drastically increases for the PEGME blended HA membranes whereas the water contact angle decreases significantly. The pH responsiveness character of the prepared membranes altered the hydraulic permeability and rejection % at different pH. Finally, optimization of the variables contributing towards the PWF and BSA rejection of the desired membrane was performed using Design expert software 9.0 TRIAL through ANOVA (analysis of variance) using the combination of response surface methodology (RSM) and central composite design (CCD).

Preparation of porous hydrophobic poly(vinylidene fluoride-co-hexafluoropropylene) hollow fiber membrane contactors for CO 2 stripping

Abstract Porous hydrophobic poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) hollow fiber membranes were prepared via a wet spinning process using polyethylene glycol (PEG-400) and ortho-phosphoric acid (PA) in the spinning dope. CO2 stripping from diethanolamine (DEA) solution was conducted through the gas–liquid membrane contactor modules. By obtaining cloud point diagrams, higher phase inversion rate was confirmed for the solution with PA. The smaller finger-like macrovoids were resulted when using the non-solvent additives. The membranes with higher surface porosity and smaller mean pore size were produced when using the additives in the spinning dope. The improved PVDF-HFP/PA membrane had the mean pore size of 0.015 µm and permeability of 13,100 GPU. This membrane showed a minimum mass transfer resistance of 15,982 (m/s)−1 which is about 68% less than the resistance of plain PVDF-HFP membrane. The improved PVDF-HFP/PA membrane showed CO2 stripping flux of about 9 × 10−3 mol/m2 s at the liquid velocity of 0.045 m/s.

Effect of polyaniline (PANI) on Poly(vinylidene fluoride-co-hexaflouro propylene) (PVDF-co-HFP) polymer electrolyte membrane prepared by breath figure method

Poly(vinylidene fluoride-co-hexaflouro propylene) is a well-known material for polymer electrolyte membranes (PEMs) due to its low cost, high mechanical integrity and excellent chemical resistance; however, its pure form has limited characteristics that require further modification to achieve optimum results. Therefore, the different dosages of polyaniline (PANI) (10 wt%, 20 wt%, 30 wt%, 40 wt% and 50 wt%) were incorporated into PVDF-HFP blend to fabricate PVDF-HFP/PANI polymer electrolyte membrane by using breath-figure method. The FTIR peaks of PVDF-HFP and PVDF-HFP/PANI membrane confirms the successful incorporation of PANI into PVDF-HFP blend, while TGA, DSC and XRD analysis shows the PANI effect on stability and ionic conductivity of PVDF-HFP membrane. The PVDF-HFP/PANI membrane with 30 wt% PANI found superior with the highest porosity of 83%, electrolyte uptake of 270% and ionic conductivity of 1.96 mS cm−1; however, the other concentrations of PANI were also effective and enhanced the performance of PVDF-HFP membrane. This shows the improved performances of PVDF-HFP membrane were attributed to successful incorporation of PANI and the proposed membrane can be a suitable alternative PEM or a separator for energy devices.

High Performance Electrospun PVdF-HFP/MMT Nanofibrous Composite Membrane Electrolyte for Li-Ion Capacitors

The electrospun poly(vinylidene fluoride-co-hexafluoropropylene)/montmorillonite nanofibrous composite membranes (esCPMs) were prepared by electrospinning technique using a mixture of different amounts of montmorillonite (0, 3, 5, 7 and 10 wt%) into 16 wt% of PVDF-HFP polymer solution in 7:3 wt% of acetone and dimethylacetamide as the solvent. The effect of montmorillonite (MMT) on electrospun PVdF-HFP membrane has been studied by XRD, DSC, TGA and tensile strength analysis. It is found that electrospun PVDF-HFP/MMT nanofibrous composite membrane obtained using 5wt% MMT has a higher porosity, electrolyte uptake, ionic conductivity, electrochemical stability window and showed higher specific capacitance and good compatibility with electrode materials.

A complete carbon counter electrode for high performance quasi solid state dye sensitized solar cell

Abstract The proposed research describes the design and fabrication of a quasi-solid state dye sensitized solar cells (Q-DSSCs) with a complete carbon based counter electrode (CC-CE) and gel infused membrane electrolyte. For CE, the platinized fluorinated tin oxide glass (Pt/FTO) was replaced by the soft cationic functioned multiwall carbon nanotubes (SCF-MWCNT) catalytic layer coated on woven carbon fiber fabric (CFF) prepared on handloom by interlacing of carbon filament tapes. SCF-MWCNT were synthesized by functionalization of cationised lipase from Candida Ragusa. Cationised enzyme solution was prepared at pH ∼3 by using acetic acid. The cationic enzyme functionalization of MWCNT causes the minimum damage to the tubular morphology and assist in fast anchoring of negative iodide ions present in membrane electrolyte. The high electrocatalytic activity and low charge transfer resistance (RCT = 2.12 Ω) of our proposed system of CC-CE shows that the woven CFF coated with cationised lipase treated carbon nanotubes enriched with positive surface ions. The Q-DSSCs fabricated with CC-CE and 5 wt% PEO gel infused PVDF-HFP membrane electrolyte exhibit power conversion efficiency of 8.90% under masking. Our suggested low cost and highly efficient system of CC-CE helps the proposed quasi-solid state DSSCs structure to stand out as sustainable next generation solar cells.

Advanced multi-nozzle electrospun functionalized titanium dioxide/polyvinylidene fluoride-co-hexafluoropropylene (TiO2/PVDF-HFP) composite membranes for direct contact membrane distillation

The unique capabilities of electrospinning technology are being increasingly utilized in the fabrication of hydrophobic membranes to improve the membrane distillation (MD) process in recent years. In this study, hydrophobic titanium dioxide (TiO2) nanoparticles functionalized by fluorosilane were incorporated into electrospun membranes using single, coaxial, and dual nozzles to develop novel membrane architectures for improved physico-chemical properties for MD. By incorporating fluorosilane coated TiO2 into the PVDF-HFP solution during the membrane synthesis and using an advanced multi-nozzle to form various hierarchical membrane structures tuned the size and structure of the nanofibers and made them vastly superior for the application in MD. The single and coaxial nozzle membranes showed contact angles close to 150° and the dual-nozzle membrane assembled bead-on-string fibers achieved superhydrophobicity (i.e., contact angle of 153.4°). To test the functionalized titanium dioxide/polyvinylidene fluoride-co-hexafluoropropylene (TiO2/PVDF-HFP) composite membranes for MD performance, the membranes were subjected to long-term direct contact MD for about two days to monitor their water vapor flux and selectivity. Compared to commercial PVDF membranes, all electrospun F-TiO2/ PVDF-HFP membrane achieved higher water vapor flux of 40Lm−2h−1 (60°C feed and 20°C permeate) with a brine (7.0wt% NaCl) as the feed solution and also exhibited anti-wetting property while maintaining high water flux compared to the membrane without TiO2 incorporation.

Montmorillonite embedded electrospun PVdF–HFP nanocomposite membrane electrolyte for Li-ion capacitors

The electrospun poly(vinylidene fluoride-co-hexafluoropropylene)/montmorillonite nanofibrous composite membranes (esCPMs) were prepared by electrospinning technique using a mixture of different amounts of montmorillonite (0, 3, 5, 7 and 10wt%) into 16wt% of PVDFHFP polymer solution in 7:3wt% of acetone and dimethylacetamide as the solvent. The effect of montmorillonite (MMT) on electrospun PVdF–HFP membrane has been studied by XRD, DSC, TGA and tensile strength analysis. The average diameter of the electrospun nanofibrous composite membrane was about ∼400nm. The physical properties such as porosity, electrolyte uptake and mechanical strength of the electrospun nanofibrous composite membrane were studied in detail. The ionic conductivity and electrochemical stability windows of the electrospun nanofibrous composite membrane containing 1M LiPF6 in EC:DMC (1:1, v/v%) as an electrolyte (esCPME) were studied by AC-impedance and linear sweep voltammetry studies, respectively. It is found that electrospun PVDF–HFP/MMT nanofibrous composite membrane obtained using 5wt% MMT has a higher porosity, electrolyte uptake, ionic conductivity and electrochemical stability window than the other nanofibrous composite membrane systems and are found to be 88.1%, 428%, 2.330×10−3S/cm and 3.1V, respectively. Finally, the charge–discharge studies were carried out by fabricating a prototype Li-ion supercapacitor by sandwiching PVDF–HFP/MMT (5wt%) nanofibrous composite membrane electrolyte in between a carbon anode and LiCo0.2Mn1.8O4 cathode. It showed higher specific discharge capacitance and good compatibility with electrode materials suggesting that the electrospun PVdF–HFP/MMT nanofibrous composite membrane electrolyte could be used as the best candidate for high performance Li-ion capacitors.

CO2 separation through poly(vinylidene fluoride-co-hexafluoropropylene) membrane by selective ion channel formed by tetrafluoroboric acid

In this study, we showed for the first time that polymer electrolyte membranes consisting of tetrafluoroboric acid solution (HBF4) and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) could be utilized for CO2 separation. We utilized tetrafluoroboric acid solution to increase the solubility of CO2 in PVDF-HFP membranes. Strong acidic HBF4 could be easily solvated by water molecules and then well distributed in PVDF-HFP chain. The hydrated protons generated by HBF4 in polymer chains could be selective channels for CO2 transport, resulting in high separation performance. The interaction between fluorine in PVDF-HFP and proton ions in HBF4 was investigated by FT-IR and Raman spectroscopy. Thermal gravimetric analysis (TGA) data demonstrated thermal stability of the membrane after the addition of HBF4 and formation of hydrated proton ions. The hydrated proton ions significantly increased the solubility of CO2 gas, resulting in both high selectivity and high gas permeance for CO2 (CO2/N2=25 and 25 gas permeance unit (GPU), respectively).

Enhanced ionic conductivity and electrochemical capacity of lithium ion battery based on PVDF-HFP/HDPE membrane

Poly(vinylidene fluoride-co-hexafluoropropylene)/high density polyethylene (PVDF-HFP/HDPE) membrane with enhanced ionic conductivity and electrochemical capacity for lithium ion battery application has been successfully prepared by non-solvent induced phase separation (NIPS) technique. HDPE particles with size smaller than 250nm is achieved via optimized inverse emulsion polymerization method. Results indicate that the novel PVDF-HFP/HDPE membrane has ion conductivity of 2.97mScm−1 at 25°C, higher than that 1.92mScm−1 of pristine PVDF-HFP membrane. Additionally, the LiCoO2/Li cells assembled with PVDF-HFP/HDPE membrane show good C-rate and cycling performance which is parallel to the commercial PP membrane.

The Photovoltaic Performances of PVdF-HFP Electrospun Membranes Employed Quasi-Solid-State Dye Sensitized Solar Cells.

The PVdF-HFP nanofiber membranes with different molecular weight were prepared by electrospinning technique and were investigated as solid state electrolyte membranes in quasi solid state dye sensitized solar cells (QS-DSSC). The homogeneously distributed and fully interconnected nanofibers were obtained for all of the prepared PVdF-HFP electrospun membranes and the average fiber diameters of fabricated membranes were dependent upon the molecular weight of polymer. The thermal stability of electrospun PVdF-HFP membrane was decreased with a decrement of molecular weight, specifying the high heat transfer area of small diameter nanofibers. The QS-DSSC fabricated with the lower molecular weight PVdF-HFP electrospun nanofiber membrane exhibited the power conversion efficiency of 1 = 5.38%, which is superior over the high molecular weight membranes and is comparable with the liquid electrolyte. Furthermore, the electrospun PVdF-HFP membrane exhibited long-term durability over the liquid electrolyte, owing to the higher adsorption and retention efficiencies of liquid electrolyte in its highly porous and interconnected nanofibers. Thus the proposed electrospun PVdF-HFP membrane effectively tackled the volatilization and leakage of liquid electrolyte and provided good photoconversion efficiency associated with an excellent stability, which constructs the prepared electrospun membranes as credible solid state candidates for the application of QS-DSSCs.

Theoretical and experimental study of direct contact membrane distillation

Direct contact membrane distillation (DCMD) is characterized as a low-thermal energy process, involving evaporation and a phase change driven by the pressure difference between two fluid channels separated by a hydrophobic membrane. The temperature difference creates a driving pressure between the hot channel (feed) and the cold channel (permeate). This paper demonstrates the performance of the DCMD through high fidelity simulation and experimental observation to reveal a fundamental and qualitative understanding of the spatial distribution of the temperature, mass flux, and heat flux as well as the temperature polarization. The flow model is governed by the Navier–Stokes equations of non-isothermal fluid coupled with the energy equation for the two adjacent channel flow and the middle hydrophobic and porous membrane. The experimental study involved the development of a transparent acrylic DCMD unit operated by two peristaltic pumps where each cycles the feed and the permeate from the corresponding reservoir through the DCMD chambers that are separated by the PVDF–HFP membrane. The hot feed reservoir temperature is maintained at 40°C (4% salinity), whereas the permeate reservoir temperature is kept at 25°C (0% salinity). The system is tested using membranes of prescribed thickness, porosity, and conductivity. The model and experimental results were compared in counterflow configurations and a good agreement between the model and experimental was obtained for temperature distributions, mass flux, and temperature polarization coefficient (TPC). The system metrics were obtained for the DCMD showing a suitable TPC working range (0.3–0.55), a relatively low mass flux yield (5 kg/h m2) and a very low thermal efficiency (1.5%). These results suggest there is still a large potential in DCMD to enhance its overall yield in order to speed up their large-scale commercialization.

Effect of Inclusion of 1-Butyl-3-Methylimidazolium Trifluoromethanesulfonate on CO2 and N2Permeabilities for PVDF and PVDF-HFP Membranes

Effect of Inclusion of 1-Butyl-3-Methylimidazolium Trifluoromethanesulfonate on CO2 and N2Permeabilities for PVDF and PVDF-HFP Membranes

Effect of Inclusion of 1-Butyl-3-Methylimidazolium Trifluoromethanesulfonate on CO2 and N2Permeabilities for PVDF and PVDF-HFP Membranes

The CO2 and N2 permeabilities for polymer inclusion membranes, consisting of 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([bmim][TfO]) in poly (vinylidenedifluoride) (PVDF) and poly (vinilidenedifluoride-co-hexafluoropropylene) (PVDF-HFP), at the temperatures from 298.2 K to 348.2 K, have been evaluated. The PVDF and PVDF-HFP membranes, containing 75 wt% of [bmim][TfO], had the CO2 permeabilities of 585 and 976 barrers, respectively, and the CO2 selectivities of 15 at 348.2 K. These values were higher than those of the supported ionic liquid membrane of [bmim][TfO] (428 barrers and 12). Furthermore, the Differential scanning calorimetry and Raman spectroscopy were performed to analyze the micro-structures of membranes. These analyses indicate that the polymer matrix was plasticized and the polymorphs changed from the non-polar a-phase to the polar b-phase by the addition of [bmim][TfO]. According to the solution-diffusion transport mechanism, it is concluded that the inclusion membranes with the sufficiently plasticized, i.e. phase-changed, PVDF and PVDF-HFP membranes absorbed the larger amount of gas species than the neat [bmim][TfO], and PVDF-HFP is more effective than PVDF for the enhancement in gas absorption.