Preparation Of Polymer Electrolyte Membranes Research Articles

Innovative reactor design for the preparation of polymer electrolyte membranes for vanadium flow batteries from preirradiation induced graft copolymerization of acrylic acid and AMPS on PVDF

Abstract An innovative reactor concept is reported that allows for efficient mass transfer from the liquid phase to the base material and compensates for the growth of the material throughout the synthesis of polymer electrolyte membranes (PEM). The novel reactor allows for the synthesis of PEMs with high reproducibility of their dimensions and properties. PEMs are synthesized via graft copolymerization of the monomers acrylic acid and 2-acrylamido-2-methylpropane sulfonic acid on poly(vinylidene fluoride) films serving as base material, which was activated by electron beam treatment. Both monomers are already containing protogenic groups; thus, follow-up functionalization reactions are avoided. The PEMs were characterized with respect to their electrochemical properties (area specific resistance, recharge current, and ion exchange capacity) relevant for application in vanadium flow batteries and compared to commercially available PEMs.

Preparation of polymer electrolyte membranes based on poly(phenylene oxide) with different side chain lengths of phosphonic acid

ABSTRACTA series of poly(phenylene oxide) (PPO) polymers bearing phosphonic acid groups on the methyl group and on the phenyl ring are synthesized as membrane materials for fuel cell applications. These phosphonic acid‐based PPO membranes exhibited high chemical resistance, dimensional stability, and good proton conductivity even under low humidity condition. Among the membranes, the one in which the phosphonic acid moiety is attached to the polymer main chain with CO(CH2)5 shows highest proton conductivity under overall conditions even though it has the lowest water uptake and IEC value. A well‐defined separation of the hydrophilic and hydrophobic phases suggests the phosphonic acid groups to form proton conduction channels via interchain hydrogen bonding. A high storage modulus of the membranes in various temperature ranges indicates that the membranes are suitable for use under a high temperature and low humidity conditions. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019

Chemically tethered functionalized graphene oxide based novel sulfonated polyimide composite for polymer electrolyte membrane

Novel sulfonated diamine (NSDA) having pendant sulfonic acid group was synthesized. Polycondensation reaction of this NSDA, dianhydride, and graphene oxide (GO) yielded sulfonated imidized graphene oxide (SIGO). Sulfonated imidized graphene oxide(SIGO) along with NSDA, 4,4′-oxydianiline (ODA) and 1,4,5,8-naphthalene tetracarboxylic dianhydride dianhydride(NTDA) were used for the preparation of polymer electrolyte membranes (PEMs). High temperature proton conduction due to the hydrophobic- hydrophilic phase separation resulted from the incorporation of SIGO. 2.28 meq/g of ion exchange capacity (IEC), 11.18 × 10−2 S/cm of proton conductivity at room temperature and bound water of worth 5.1% between temperature ranges of 100 °C to 150 °C were exhibited by NSPI/3 wt%SIGO composite membrane. Maximum power density of 74.9 mWcm−2 was achieved at 70 °C by NSPI/ 3% SIGO in single cell direct methanol fuel cell test. All these results make these composite membranes suitable candidate to be used as PEM.

Preparation of polymer electrolyte membranes with continuous PEG channel via the fusion of self-assembled polycyclooctene-graft-polyethylene glycol copolymer micelles

Small molecular weight polyethylene glycol (PEG 350 g/mol) based polymer electrolyte membranes (PEMs) with continuous lithium ion transport channels are prepared via the fusion of the self-assembled micelles of amphiphilic copolymer. The self-assembled micelles consisted of nonpolar polycyclooctene (PCOE) core and polar PEG shell are formed via dialyzing the dichloromethane solution of amphiphilic polycyclooctene-graft-polyethylene glycol (PCOE-g-PEG) copolymer with ethanol, which is a good solvent for PEG and nonsolvent for PCOE. The resulted electrolyte membrane with bicontinuous morphology is obtained by casting the self-assembled micelle solution in a stainless steel plate and heating at 80 °C for 24 h after mixing with a certain amount of lithium perchlorate (LiClO4). When the content of PEG is 20 wt%, the ion conductivity of the self-assembled PEM can exceed 10−4S/cm at 25 °C, which is 3 orders of magnitude higher than the counter PEM groups prepared via directly casting of the copolymer dichloromethane solution without self-assembled process. While the mechanical strength of the self-assembled PEMs is almost the same as those directly casting ones, in which only PCOE phase is continuous.

Ionic liquid grafted graphene oxide composite to create proton transfer pathways in polymer electrolyte membrane

For the synthesis of polymer electrolyte membrane (PEM), high ionic conductivity and stability are the key challenge. This paper deals with the preparation of polymer electrolyte membranes based on ionic liquid (IL) functionalized graphene oxide (GO) and sulfonated polyether sulfone (SPES). Using a simple solution casting technique, composite membranes have been prepared possessing good physicochemical properties and mechanical stability. Methanol crossover resistance have been measured across the composite membranes and found to be low for IG- 05 membrane (0.53×10−7cm2s−1) with the selectivity of 7.99×105. Composite IG- 05 membrane also exhibit high ionic conductivity of 7.27×10−2S.cm−1 which is around 66% higher than that of SPES membrane.

Response surface method (RSM) for optimization of ionic conductivity of membranes polymer electrolyte poly (vinylidene fluoride) (PVDF) with polyvinyl pyrrolidone (PVP) as pore forming agent

The Membranes Polymer Gel Electrolyte (MPGEs) based poly (vinylidene fluoride) (PVDF) was prepared by a phase inversion method using polyvinyl pyrrolidone (PVP) as a pore-forming agent and N, N-dimethyl acetamide (DMAc) as a solvent and water as non solvet. The membranes were then soaked in 1 M lithium hexafluorophosphate (LiPF6) in ethylene carbonate (EC) / dimethyl carbonate (DMC) / Diethyl carbonate (DEC) (4:2:4 %vol) solution in order to prepare polymer electrolyte membranes. The MPEGs PVDF/PVP/Nanoclay was applied using central composite design (CCD) experimental design to obtain a quantitative relationship between selected membranes prepared parameters namely (PVDF, PVP as pore forming agent and nanoclay filler concentration) and Ionic conductivity MPEGs. The model was used to find the optimum ionic conductivity from polymer electrolyte membranes. The polymer electrolyte membranes show good ionic conductivity on the order of 6.3 - 8.7 x 10-3 S cm-1 at the ambient temperatures. The ionic conductivity tended to increase with PVP and nanoclay concentration and decrease with PVDF composition. The model predicted the maximum ionic conductivity of 8.47 x 10-3 S cm-1 when the PVDF, PVP and nanoclay concentration were set at 8.01 %, 8.04 % and 10.12%, respectively. The first section in your paper.

Preparation of Polymer Electrolyte Membrane with Nanomatrix Channel

Preparation of Polymer Electrolyte Membrane with Nanomatrix Channel

Optimization of ionic conductivity of electrospun polyacrylonitrile/poly (vinylidene fluoride) (PAN/PVdF) electrolyte using the response surface method (RSM)

Polyacrylonitrile/poly (vinylidene fluoride) fibrous membranes were prepared by electrospinning of PAN and PVdF solution and were soaked in 1 M lithium perchlorate (LiClO4) in ethylene carbonate (EC)/diethyle carbonate (DEC) (1:1 wt.%) solution in order to prepare polymer electrolyte membranes. Response surface method (RSM) was used to obtain a quantitative relationship between selected electrospinning parameters, i.e., applied voltage, solution concentration, and PVdF content. The measured response is ionic conductivity of electrolyte membranes. The Box–Behnken method was applied to design of experiments. Importance of parameters in the model was determined by analysis of variance (ANOVA). The model was used to find the maximum ionic conductivity of electrolyte membranes as optimum result. The morphology of fibers was investigated by field emission scanning electron microscopy (FESEM). FESEM results show that the PAN/PVdF membrane has interconnected multifibrous layers with ultrafine porous structure that leads to a high ionic conductivity and efficient lithium ion transport. Produced fibrious membranes show uniform morphology. Average fiber diameter lies between 116 and 379 nm, and membranes have high porosity of 48–90 % and electrolyte uptake of 303–493 %. The polymer electrolyte membranes show good ionic conductivity in the order of 10−3 S cm−1 at ambient temperature. Ionic conductivity decreases with increase of solution concentration and increases with increase of PVdF composition. Voltage has no significant effect on ionic conductivity of the membranes. The model predicted the maximum ionic conductivity of 7.98 mS cm−1 when the voltage was set at 21.57 kV, the solution concentration set at 14.02 wt.%, and the PVdF composition set at 69.48 wt.%.

Preparation of polymer electrolyte membrane with nanomatrix channel through sulfonation of natural rubber grafted with polystyrene

The mechanism of proton transport of a polymer electrolyte membrane (PEM) with nanomatrix channel was investigated with respect to the activation energy of proton conductivity. The PEM with nanomatrix channel was prepared by graft-copolymerization of styrene onto deproteinized natural rubber (DPNR) followed by sulfonation with chlorosulfonic acid. The resulting sulfonated graft-copolymer (SDPNR-graft-PS) was characterized by FT-IR spectroscopy, solid-state 13C CP/MAS NMR spectroscopy, elemental analysis, transmission electron microscopy (TEM) and impedance analysis. The PEM was found to form completely continuous nanomatrix channel consisting of natural rubber particle of about 1μm in average diameter as a dispersoid and sulfonated polystyrene of about 60nm in thickness as a matrix. The value of the activation energy of proton conductivity estimated from the slope of Arrhenius plot was 12kJ/mol for SDPNR-graft-PS, suggesting that the proton transport occurred in a manner of Grotthuss mechanism.

Preparation of Polymers Electrolyte Membranes for Lithium Battery from Styrofoam Waste

Recently, the battery industry has represented one important and growing sector where the use of non-toxic and non-hazardous substitute materials has not rapidly developed. The environmentally friendly polymer electrolyte is required to decrease the risk of environmental pollution caused by toxic materials of battery components. Therefore, in this study was focused on the preparation of the environmentally friendly polymer electrolyte membrane with low cost for lithium-ion battery applications. The preparation of polymer electrolyte membrane was done by casting of polymer solution. The main materials used to prepare polymer electrolyte membranes are sulfonated polystyrene (SPS) obtained from isolation of Styrofoam, hydrolyzed bacterial poly(R-hydroxybutyrate) (PHB), and lithium perchlorate (LiClO4) as an ionic salt. The isolated polystyrene was reacted with acetyl sulfate to form sulfonated polystyrene (SPS). These three main materials were dissolved in an appropriate solvent and mixture until homogenous. The polymer solution was poured into a petri dish, and then their solvent was evaporated. The results showed that the increase LiClO4 content in the membranes, the conductivity of membrane increases, but their mechanical strength decreases and the surface morphology of membranes becomes less uniform and homogenous.

Pendant crosslinked poly(aryl ether sulfone) copolymers sulfonated on backbone for proton exchange membranes

A series of sulfonated poly(aryl ether sulfone) copolymers containing phenyl pendant groups with sulfonic acid groups on the backbone were synthesized through condensation polymerization. The degree of sulfonation (DS) of the copolymers was controlled by changing the feed ratios of sulfonated to unsulfonated monomers. Post‐crosslink reactions are carried out with 4,4′‐thiodibenzoic acid (TDA) as a crosslinker and the carboxylic acid groups in TDA can undergo Friedel–Craft acylation with the phenyls pendent rings in sulfonated poly(arylene ether sulfone)s copolymers to prepare polymer electrolyte membranes for fuel cell applications. The chemical structures of crosslinked and uncrosslinked sulfonated poly(arylene ether sulfone)s copolymers (SPSFs and CSPSFs) were characterized by FTIR, 1H NMR spectra. The thermal and mechanical properties of the membranes were characterized by thermogravimetric analysis and stress–strain test. The dependence of water uptake, methanol permeability, proton conductivity, and selectivity on DS was studied. Transmission electron microscopic observations revealed that SPSFs and CSPSFs membranes form well‐defined microphase separated structures. POLYM. ENG. SCI., 54:2013–2022, 2014. © 2013 Society of Plastics Engineers

Polymerization mechanism for radiation-induced grafting of styrene into alicyclic polyimide films for preparation of polymer electrolyte membranes

Alicyclic polyimides (APIs) derived from 1, 2, 4, 5-pyromellitic dianhydride (PMDA) bis(4-aminocyclohexyl)methane (DCHM) were successfully applied to radiation-induced graft polymerization for developing polymer electrolyte membranes for fuel cells. Pyromellitic-type CoPIs were prepared from PMDA and a mixture of aromatic and alicyclic diamines with certain molar ratios, and the radiation-induced grafting of styrene was then examined using pre-irradiation with a dose of 220kGy, followed by graft polymerization in a bulk styrene solution at 60°C. The grafting into fully aromatized polyimide barely proceeded (degree of grafting (DG) of less than 5%), whereas that of styrene into the API films proceeded with styrene DGs of up to 70%.Electron spin resonance measurements clearly showed that the irradiated API with the highest alicyclic component possessed the largest amount of radicals (up to 1.13 × 1018spins/g). Furthermore, in combination with ultraviolet–visible (UV–vis) spectroscopy, the radical species was identified as a long-lived intermediate with a spectrum containing λmax = 420 and 600nm, and 10% of the radicals were consumed as grafting initiators. Note that the alicyclic structure of the API films is advantageous for radiation-induced graft polymerization because of the generation of high-concentration initiation radicals.The moderate reaction conditions allowed for selective sulfonation on the polystyrene grafts, and not on the API substrates, to give API-based polymer electrolyte membranes (PEMs) with ion exchange capacities (IECs) of 1.7–2.8mmol/g. The PEMs exhibited appropriate proton conductivity (0.06 ≤ σ ≤ 0.34S/cm) and low water uptake (≤100%), together with excellent mechanical properties (tensile strength, 90MPa), compared with conventional PEMs such as Nafion®.

Cross-linked poly(arylene ether ketone) membranes sulfonated on both backbone and pendant position for high proton conduction and low water uptake

A series of cross-linkable poly(arylene ether ketone)s (PAEKs) with sulfonic acid groups on both the backbone and pendant positions are synthesized through direct condensation polymerization. The degree of sulfonation (DS) of the polymer backbone is controlled by changing the feed ratios of sulfonated to unsulfonated monomers. Post-polymerization reactions are successfully employed to prepare polymer electrolyte membranes for fuel cell applications. The chemical structures of the synthesized polymers are confirmed by 1H nuclear magnetic resonance (NMR) and Fourier transform infrared (FT-IR) spectroscopy. The thermal and mechanical properties of the membranes are characterized by thermogravimetric analysis and stress–strain test. The dependence of water uptake, methanol permeability, proton conductivity, and selectivity on DS is studied. The cross-linked sulfonated PAEK (CSPAEK) membranes with DS higher than 120% exhibit higher proton conductivity than those of Nafion® 117. The CSPAEK membranes maintain very low methanol permeability and water uptake. The properties of all the membrane are correlated with ionic cluster dimension measured by small angle X-ray scattering (SAXS).

Pendant-sulfonated poly(arylene ether ketone) (PAEK) membranes cross-linked with a proton conducting reagent for fuel cells

► Pendant sulfonated cross-linked PAEK membranes are prepared for fuel cell application. ► Proton conductivity is comparable to Nafion ® 117. ► Methanol permeability is very low – about a half to a fourth of Nafion ® . ► Cross-linking reduces water uptake and thus enhances dimensional stability. ► The 20% cross-linked system exhibits the best cell performance. Poly(arylene ether ketone) (PAEK) bearing a pendent sulfonic acid group was synthesized to prepare polymer electrolyte membranes for fuel cells. For preparation of this membrane, the precursor possessing the reactive carboxylic acid functional group was first synthesized to control the degree of sulfonation and cross-linking. A variety of essential properties for fuel cell membranes such as proton conductivity, water uptake, methanol permeability, and chemical, thermal, and mechanical stability were investigated. The proton conductivity was comparable to Nafion ® 117 and it did not significantly decrease by addition of the cross-linker because of the sulfonic acid proton conducting group attached to it. Methanol permeability was very low and it decreases with cross-linking density – it decreased down to a fourth of that of Nafion ® at 30% cross-linking density. Cross-linking reduced water uptake and thus enhanced dimensional stability of the membrane. The resistance to oxidation and hydration was also improved by cross-linking. Among a series of cross-linked membranes, the 20% cross-linked system exhibited the best cell performance associated with excellent membrane properties.

Highly Sulfonated and Highly Cross-Linked Poly(ether Ether Ketone) Proton Exchange Membranes

Sulfonated poly(ether ether ketone) with pendant carboxylic acid groups was synthesized and used to prepare polymer electrolyte membranes for fuel cell applications. The cross-linking was employed to limit the extreme water uptake and improve the dimensional stability of the membrane. compared with Nafion 117, this cross-linked membranes were likely far more robust. The proton conductivity, water uptake, methanol permeability, thermal stability and cell performance were investigated in order to evaluate its fuel cell applications. The CSPEEK-20% membrane exhibited a high proton conductivity of 0.05 S cm-1, a methanol permeability of 4.3×10-7 cm2 s-1, and a water uptake of 21%. This especially good cell performance, and high oxidative and hydrolytic stability operation suggested that this cross-linked membrane is a promising candidate in fuel cell applications.

Characterization of polyethyleneterephthalate (PET) based proton exchange membranes prepared by UV-radiation-induced graft copolymerization of styrene

Polymer electrolyte membranes (PEMs) were successfully prepared by simultaneous ultraviolet (UV) radiation-induced graft copolymerization of styrene (35 vol.% concentration) onto poly(ethyleneterephthalate) (PET) film, followed by sulfonation on the styrene monomer units in the grafting chain using 0.05 M chlorosulfonic acid (ClSO 3H). The radiation grafting and the sulfonation have been confirmed by titrimetric and gravimetric analyses as well as Fourier Transform Infrared (FTIR) spectroscopy. The maximum ion-exchange capacity (IEC) of the PEM was measured to be 0.04385 mmol g −1 at its highest level of grafting and sulfonation. They exhibited high thermal and mechanical properties as well as oxidative stability. They are highly stable in H 2SO 4 solutions and can be used in the acidic fuel cells. The membranes showed low water uptake as well as low proton conductivity than Nafion. In this study, the preparation of PEMs from commodity-type polymers is found to be very inexpensive and is a suitable candidate for applications in fuel cells.

Novel poly(arylene ether ketone)s containing sulfonic/carboxylic groups: Synthesis and properties

Novel poly(arylene ether ketone)s containing phenyl- and 4-cyanophenyl substituents were synthesized and subsequently used as starting material to prepare polymer electrolyte membranes for fuel cells application. FTIR and 1H NMR spectra indicated that both a sulfonation reaction on the pendant phenyl and a hydrolysis reaction on the cyano groups occurred simultaneously. After sulfonation/hydrolysis, flexible and transparent membranes with sulfonic and carboxylic groups as the proton conducting sites were prepared. And they all exhibited reasonable and tensile moduli in the range of 0.62–1.50 GPa. The proton conductivities of the membranes cast from the resulting polymers were all higher than 10 −2 S cm −1 at room temperature. At 100 °C, the high proton conductivities of 0.149 and 0.199 S cm −1 were obtained from SPAEK-Ph80 and SPAEK-Ph90, respectively, which were both higher than that of Nafion 117 (0.145 S cm −1). Several other properties relative to their applications as proton exchange membranes, such as water absorption, thermal-oxidative and dimensional stability and methanol crossover were also evaluated. Atomic force microscopy (AFM) was used to observe the membrane microstructure for evidence of microphase separation between ionic and hydrophobic domains.

Nafion Film-Templated Platinum Electrodes for Oxygen Reduction

Nanostructured platinum electrodes were prepared by electrodeposition of platinum onto Nafion-coated gold rotating-disk electrodes (RDEs). The resultant material was characterized in acidic electrolyte by voltammetry and has been examined for electrocatalytic activity toward the oxygen reduction reaction (ORR). The platinum templated with a 3-μm Nafion film exhibited improved oxygen reduction performance in comparison to platinum-modified gold RDE prepared without templating. The mass and specific activities increased by a factor of two for the Nafion film-templated electrode, and the ORR half-wave potential (at 0.5iL) was shown to shift by 60 mV. Considering that the specific surface areas of the 3-μm Nafion film-templated and untemplated Pt were similar (14.1 vs. 11.8 m2 g−1), the enhanced kinetic performance of the former points to subtle catalyst morphology effects. The proposed method could be advantageous for the preparation of polymer electrolyte membrane fuel cell catalyst layers where the Nafion film serves also as the ionic conductor network.

Cross-linked poly(ether ether ketone) membranes with pendant sulfonic acid groups for fuel cell applications

A series of cross-linkable poly(ether ether ketone)s (PEEKs) with pendant sulfonic acid groups were synthesized and used to prepare polymer electrolyte membranes for fuel cells. These transparent and flexible membranes are insoluble in common organic solvents and demonstrated little swelling in hot water. Thermal and mechanical stability of the membranes were evaluated using a thermogravimetric analyzer and strain–stress test, respectively. The methanol permeability of the cross-linked PEEKs with pendant sulfonic acid group membranes is much lower than that of Nafion 117 membrane, by more than 10 times. The conductivity of the cross-linked PEEK membrane with a 5% degree of cross-linking is comparable to that of Nafion 117 at 50 °C (0.053 S cm −1) and even better above 80 °C. This kind of membrane is expected to be a good alternative to Nafion 117 in polymer electrolyte fuel cell applications.

TEMPO addition into pre-irradiated fluoropolymers and living-radical graft polymerization of styrene for preparation of polymer electrolyte membranes

We prepared proton exchange membranes (PEMs) by 2,2,6,6-tetramethylpiperidinyl-1-oxy (TEMPO)-mediated living-radical graft polymerization (LRGP) of styrene into fluoropolymer films and subsequent sulfonation. Poly(vinylidene fluoride) (PVDF) and poly(ethylene- co-tetrafluoroethylene) (ETFE) films were first irradiated and then treated with TEMPO solutions in various solvents. TEMPO addition was confirmed by the test of styrene grafting into TEMPO-treated films at 60 °C, at which the LRGP never proceeds. This test enabled us to differentiate the LRGP from the conventional graft polymerization. In order to gain a deep insight about TEMPO-addition reaction, the TEMPO-penetration behavior into the base polymer films was examined by a permeation experiment and computer simulation. Xylene and dioxane were appropriate solvents for the complete introduction of TEMPO into PVDF and ETFE films, respectively. Then, the LRGP of styrene was performed based on the fully TEMPO-capped films at 125 °C with various solvents. By using an alcoholic solvent, the degree of grafting was enhanced and it reached a maximum of 38%. This grafted film was sulfonated to prepare a PEM showing an ion exchange capacity of 2.2 meq/g and proton conductivity of 1.6×10 −1 S/cm.