Preparation of inorganic–organic hybrid proton exchange membrane with chemically bound hydroxyethane diphosphonic acid

Proton‐conductive inorganic–organic hybrid intermediate‐temperature membranes were prepared from 3‐glycidoxypropyltrimethoxysilane (GPTMS) and 1‐hydroxyethane‐1,1‐diphosphonic acid (HEDPA) by sol–gel process. To prevent the leaching out of phosphonic acid, triethylamine was used as catalyst to promote the reaction of HEDPA and GPTMS to immobilize phosphonic acid groups. Fourier transform infrared spectra revealed that phosphonic acid groups of HEDPA were chemically bounded to organosiloxane network as a result of the reaction of P? OH of HEDPA and epoxy ring of GPTMS. TG‐DSC results indicated that the hybrid membranes were thermally stable up to 250°C. The proton conductivity of the hybrid membranes increased with temperature from 30 to 130°C. The proton conductivity of hybrid membrane with the molar ratio of GPTMS/HEDPA = 2/1 can reach up to 1.0 × 10^?3 S/cm under anhydrous condition at 130°C, which reveals that this membrane is a promising proton exchange membrane for intermediate‐temperature proton exchange membrane fuel cell. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

A synthesis study of phosphonated PSEBS for high temperature proton exchange membrane fuel cells

A series of novel phosphonated proton exchange membranes has been prepared using poly(styrene‐ethylene/butylene‐styrene) block copolymer (PSEBS) as base material. Phosphonic acid functionalization of the polymer was performed by a simple two‐step process, via chloromethylation of PSEBS followed by phosphonation utilizing the Michaels–Arbuzov reaction. The successful phosphonation of the polymers were characterized by NMR and Fourier transform infrared. The phosphonated ester form of the membranes were obtained by solvent evaporation method and hydrolyzed to get a proton conducting membrane. The membrane properties such as ion exchange capacity, water uptake and proton conductivity at various temperatures were examined for their suitability to be utilized as a high temperature polymer electrolyte. Additionally, the morphology, thermal, and mechanical properties of the synthesized membranes were investigated, using scanning electron microscope, thermogravimetric analysis, and tensile test, respectively. The effective (anhydrous) proton conductivity was studied with respect to various degrees of functionalization. From the studies, the membranes were found to have a comparatively good conductivity and one of the membranes reached the maximum value of 5.81 mS/cm² at 140 °C as measured by impedance analyzer. It was found that the synthesized membranes were mechanically durable, chemically, and thermally stable. Hence, the synthesized phosphonated membranes could be a promising candidate for high temperature polymer electrolyte fuel cell applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45954.     

Electrochemical characterization of phosphonic acid cation exchange membrane prepared by plasma-induced graft polymerization

The phosphonic acid cation exchange membrane (CEM) was prepared by plasma-induced grafting of phosphonated glycidyl methacrylate, and its properties were compared with those of sulfonated acid CEM. Although ion exchange capacity and water content of the phosphonic and sulfonic acid CEMs are almost same, the electrical resistance of the phosphonic acid CEM was higher and the transport number was slightly lower compared to the sulfonic acid CEM due to weakly acidic fixed ionic charges. However, those properties of the phosphonic acid CEM were comparable with those of the membranes reported in literature. Current-voltage curves of the membranes showed that the strong fixed charge of sulfonic acid CEM induced more electroconvection of electrolyte near the surface over the limiting current density than phosphonic acid CEM with weaker fixed charge.     

Novel fluorinated polymers bearing phosphonated side chains: synthesis, characterization and properties

A new class of aryl trifluorovinyl ether monomers containing phosphonated oligo(ethylene oxide) units were designed and synthesized. Novel fluorinated polymers containing perfluorocyclobutane and phosphonic acid moieties were prepared from these monomers via the thermal cyclopolymerization and hydrolysis reaction. The structures of these monomers and polymers were characterized by nuclear magnetic resonance spectroscopy and fourier transform spectroscopy. The thermal properties of these polymers were evaluated with differential scanning calorimetry and thermo-gravimetric analysis. The 5% weight loss of these polymers was in range of 258–270 °C in nitrogen, but no glass transition temperatures were detected. The polymers showed good solubility in organic solvents such as dimethyl sulfoxide and N,N-dimethylacetamide. In addition, the basic membrane properties of the membranes such as water uptake and proton conductivity were also measured at room temperature. The membranes exhibited high water uptake (up to 44.7%) due to the high level of phosphonation content. The proton conductivities of the membranes under 100% relative humidity were in the range of 0.032–0.068 S/cm, which entitled them as candidates for proton exchange membranes.     

Electrochemical properties of polyethylene membrane modified with sulfonic and phosphonic acid groups

Ion-exchange membranes modified with sulfonic (-SO₃H) and phosphonic acid (-PO₃H) groups were prepared by radiation-induced grafting of glycidyl methacrylate (GMA) onto polyethylene (PE) films and sub-sequent sulfonation and phosphonation of poly(GMA) graft chains. The surface area, thickness and volume of grafted PE film increased with increasing grafting yield. The specific electrical resistance of PE membrane modified with the -PO₃H and -SO₃H groups decreased with increasing the ion-exchange capacity. The PE membrane modified with -PO₃H group had a lower specific electrical resistance than that of PE membrane modified with -SO₃H group.     

Adhesive and anticorrosive properties of poly(vinylidene fluoride) powders blended with phosphonated copolymers on galvanized steel plates

Fluoropolymers with adhesive and anticorrosive properties were investigated by blending statistical phosphonated copolymers with poly(vinylidene fluoride) (PVDF). In a first part, methacrylic monomers bearing dialkyl phosphonate and phosphonic acid groups were synthesized. Dimethyl(2‐methacryloyloxyethyl)phosphonate was obtained by carrying out a one‐step methacrylation of a commercial phosphonated alcohol. Then, a chemical conversion of the dimethyl phosphonate group to phosphonic acid groups was accomplished by two routes, including on the one hand a trimethylhalosilane and on the other hand an inorganic halide as dealkylation reagents. The resulting monomers were analyzed by nuclear magnetic resonance (NMR) spectroscopy and results were discussed. In a second part, the phosphonated monomers were copolymerized with methyl methacrylate in the presence of 2,2'‐azobis(isobutyronitrile) (AIBN) to give statistical copolymers in high yields. In a third and last part, copolymers were introduced into PVDF as adhesion promoters and anticorrosion inhibitors. Good dry and wet adhesion properties onto galvanized steel plates were obtained with blends containing mainly phosphonic acid groups. Results of corrosion tests show that the phosphonic acid groups maintain some level of adhesion, thereby preventing the spread of corrosion. However, the number of acid groups and their neighbors influence the adhesive and anticorrosive properties of the PVDF coatings. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2277–2287, 2002     

Controlling phosphonic acid substitution degree on proton conducting polyphosphazenes

This paper is to describe the development of a synthetic strategy for the preparation of phosphonic acid functionalized poly(aryloxyphosphazene) membranes with different substitution degree of phosphonic acid. Synthesized polymers have been characterized by standard spectroscopic techniques; FT-IR, ¹H, ³¹P and ¹⁹F NMR and element analysis. Proton conductivities of phosphonic acid substituted polymers have been investigated with impedance spectroscopy at different temperatures. Furthermore, the correlations of the proton conductivity and ion exchange capacity with the substitution degree of phosphonic acid have also been investigated. Thermal properties and water uptake properties of the polymers are also investigated. It is found that the proton conductivity and initial decomposition temperature of the polymers increases up to an appropriate amount of phosphonic acid substitution degree, which can be a useful PEM candidate for fuel cells.     

Comparative ozonization of LDPE and HDPE and grafting of some monomers to elaborate new ion exchange membranes

A comparative study of the ozonization of low density polyethylene (LDPE) and high density polyethylene (HDPE) was carried out. A grafting study of acrylic acid (AA), N,N‐dimethylamino‐2‐ethylmethacrylate (MADAME) and vinyl phosphonic acid (VPA) on LDPE and HDPE was performed in mass and solution. The ozonized polyethylene and the grafting polymers were characterized by IR spectroscopy and elementary analysis. Ion exchange membranes were prepared from grafted copolymers and characterized by the exchange capacity and electrical resistance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4423–4429, 2006     

Fundamental studies of homogeneous cation exchange membranes from poly(2,6‐dimethyl‐1,4‐phenylene oxide): Membranes prepared by simultaneous aryl‐sulfonation and aryl‐bromination

Strong acid homogenous cation exchange membranes were obtained by simultaneously introducing sulfonic and bromine groups into poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO). The ion‐exchange capacity (IEC), water content, transport number, diffusion coefficient, contact angle, and tensile strength of the obtained membranes were studied. The results show that the membrane intrinsic properties are largely dependent on the substitution of bromine: the IEC and water content decrease with bromine content, while the area resistance and permselectivity of the membranes increase with this trend. Therefore, by properly balancing them, a series of homogenous cation exchange membranes having good electrical properties and physical stability can be obtained to comply with different industrial electromembrane processes, such as diffusion dialysis, electrodialysis, electrodeionization, etc. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2238–2243, 2006     

Pervaporation separation of an aqueous organic mixture through a poly(acrylonitrile‐co‐vinylphosphonic acid) membrane

Polyacrylonitrile (PAN)‐based copolymers containing phosphonic acid moiety were synthesized for dehydration of aqueous pyridine solution. The in situ complex, formed between the vinylphosphonic acid (VP) moiety in the membrane and the pyridine in the feed, enhanced separation capacity of poly(acrylonitrile‐co‐vinylphosphonic acid) (PANVP) membranes. All the PAN‐based membranes containing phosphonic acid were very selective toward water. The pervaporation performances of PANVP membranes depended on the content of the phosphonic acid moiety in the membrane and operating temperature. The pervaporation separation of water/pyridine mixtures using PANVP membranes exhibited over 99.8% water concentration in permeate and flux of 4–120 g/m²/h depending on the content of vinylphosphonic acid and operating temperature. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 83–89, 1999     

Preparation and characterization of proton exchange membrane based on polyphosphoric acid modified by PVDF‐HFP

A polyphosphoric acid functionalized proton exchange membrane (PEM) was prepared by a ring opening reaction using the epoxycyclohexylethyltrimethoxysilane (EHTMS) and amino trimethylene phosphonic acid (ATMP) as raw materials and was modified by poly(vinylidene fluoride)–hexafluoro propylene (PVDF‐HFP). The structure of the membranes was characterized by Fourier transform infrared and scanning electron microscopy. The X‐ray photoelectron spectroscopy explores the content of the elements in the membrane related to the ion exchange capacity value. The membranes’ properties including water uptake, swelling ratio, proton conductivity, and hydrolysis stability were studied. Performance tests show that when ATMP/EHTMS = 1/5, conductivity of the PVDF‐HFP modified PEMs increased from 0.83 × 10^?4 S cm^?1 at 20 °C to 9.53 × 10^?3 S cm^?1 at 160 °C, the swelling ratio of membranes decreased from 2.71% to 2.13%. The results indicate that the introduction of F atoms is beneficial to increase the proton conductivity and the dimensional stability. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46737.     

Preparation of polysiloxane phosphonic acid doped polybenzimidazole high‐temperature proton‐exchange membrane

Polysiloxane phosphonic acid doped polybenzimidazole (PBI) high‐temperature membranes were fabricated in this study. Polysiloxane phosphonic acid instead of phosphoric acid was used as a proton conductor to prevent acid from leaking. The membrane samples with different amounts of PBI were prepared and characterized with respect to the structure, thermal properties, oxidative stability, proton conductivity, and mechanical properties. The Fourier transform infrared results show that hydrogen bonds formed between PBI and polysiloxane phosphonic acid. Thermal analysis confirmed that the temperature at which membrane experienced 10% weight loss was above 230°C. None of the membrane samples broke into pieces after Fenton reagent testing. The proton conductivity of the membrane samples with 5% PBI was up to 0.034 S/cm at 140°C under nominally anhydrous conditions. The tensile strength of the membrane samples with 10% PBI was 18.3 MPa. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42956.     

Synthesis of organosiloxane-based inorganic/organic hybrid membranes with chemically bound phosphonic acid for proton-conductors

Proton conductive inorganic-organic hybrid membranes were synthesized from 3-glycidoxypropyltrimethoxysilane (GPTMS) and phosphonoacetic acid (PA) with various ratios by a sol-gel process. Self-standing, homogeneous, highly transparent membranes were synthesized. TG-DTA analyses indicated that these membranes were thermally stable up to 200 °C. The results of FT-IR and ¹³C NMR revealed that phosphonic acid groups of PA were chemically bound to organosiloxane network as a result of reaction between PA and GPTMS. The leach out of phosphonic acid groups from GPTMS-PA to water was reduced compared with phosphoric acid groups from GPTMS-H₃PO_4. The proton conductivity of the hybrid membranes increased with phosphonic acid content. The conductivity of GPTMS/PA with a 1/1.05 ratio at 130 °C was 8.7 × 10⁻² S cm⁻¹ at 100% relative humidity (RH).     

Low molecular weight polyacrylic acid with pendant aminomethylene phosphonic acid groups

Low molecular weight poly(acrylic acid‐co‐vinyl aminomethylene phosphonic acid)s were prepared by consecutively applying the Hofmann degradation and the Mannich reaction to polyacrylamide and poly(acrylamide‐co‐acrylic acid)s. ¹H‐NMR, ³¹P‐NMR, and microanalysis were used for structural analyses. These polymers were tested as anti‐scalent and they showed better anti‐scalent effect than commercial poly(acrylic acid)s. The scale inhibition properties of copolymers increased with increasing amount of aminomethylene phosphonic acid groups. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 870–874, 2000     

Phosphonic acid‐containing polysulfones as anticorrosive layers

As a part of research work to elaborate polymeric materials for metal corrosion protection, we have developed a new family of phosphonic acid‐containing polymers. The synthesis and the characterization of polysulfones bearing alkyl phosphonate ester side groups are first described. These polymers are synthesized by direct polycondensation of a phosphonate ester‐containing bisphenol by aromatic nucleophilic substitution. The physicochemical properties of the resulting polymers are described. Acidic hydrolysis of phosphonate esters results in the formation of phosphonic acid groups. A series of phosphonic acid‐containing polysulfones is therefore obtained and characterized. A preliminary evaluation of the anticorrosive properties of these polymers is described. In 0.25M Na₂SO₄ solution, the corrosion rate of a polymer‐coated mild steel sample is much lower than of the free metal substrate. These results suggest that phosphonic acid‐containing polysulfones might be interesting as anticorrosive coatings. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41890.     

Synthesis and properties of novel fluoroalkyl end‐capped oligomers containing phosphorus segments

New fluoroalkyl end‐capped oligomers containing pendant phosphoric acid groups wereprepared by the reactions of the corresponding monomer with fluoroalkanoyl peroxides. It was demonstrated that not only strong aggregations of fluoroalkyl segments but also hydrogen bonding could interact synergistically to form the highly viscoelastic fluids (gel‐like fluids) in aqueous solutions of these new fluoroalkyl end‐capped oligomers containing pendant phosphoric acid groups. Furthermore, these oligomers were able to reduce the surface tension of water effectively to exhibit a clear breakpoint resembling a CMC, and the modified stainless‐steel surface treated with these oligomers was shown to possess an excellent property imparted by fluorine. More interestingly, these oligomers were found to be potent and selective inhibitors against HIV‐1 replication in vitro. New fluoroalkyl end‐capped phosphonic acid and phosphonate oligomers were also prepared by the reactions of the corresponding phosphonic acid and phosphonate monomers, respectively, by the use of fluoroalkanoyl peroxides. These new fluoroalkyl end‐capped phosphonic acid and phosphonate oligomers were found to have a higher solubility in not only water but also in common organic solvents than that of the corresponding fluorinated oligomers containing pendant phosphoric acid groups, and these new oligomers were able to reduce the surface tension of these solvents quite effectively. Thus, these oligomers are expected to develop as new fluorinated oligosurfactants. Moreover, the modified poly(methyl methacrylate) surface treated with these phosphonate oligomers was clarified to exhibit a good oil‐repellency imparted by fluorine. In addition, fluoroalkyl end‐capped phosphonate homo‐ and cooligomers were found to form monomolecular films at the air–water interface. Therefore, these fluorinated oligomers are suggested to have high potential for new functional materials through not only their excellent properties imparted by both fluorine and phosphorus, but also through their biological properties. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 228–245, 2001     

Radiation‐induced grafting of acrylic acid and sodium styrene sulfonate onto high‐density polyethylene membranes. II. Thermal and chemical properties

Strong acid cation‐exchange membranes were obtained by radiation‐induced grafting of acrylic acid and sodium styrene sulfonate onto high‐density polyethylene (HDPE). Thermal and chemical properties of the cation‐exchange membranes were investigated. The effectiveness of ? SO₃Na containing membranes was conformed in inducing high resistance to oxidative degradation. The char residue of the grafted HDPE is greater than that of ungrafted HDPE. It shows that the branch chains, including ? SO₃Na and ? COOH groups, give catalytic impetus to the charring. The crystallinity of the grafted membranes was decreased when increasing the grafting yield. It was assumed that the decreased crystallinity was due to collective effects of the inherent crystallinity dilution by the amorphous grafted chains and the crystal distortion of the HDPE component. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99:3396–3400, 2006     

A Scalable,Efficient Gold‐Catalyzed Oxidative Phosphonation of sp3 C?H Bonds using Air as Sustainable Oxidant

A scalable, efficient gold‐catalyzed oxidative phosphonation of sp³ C H bonds with various diarylphosphine oxides and dialkyl phosphites has been developed by using air as a sustainable oxidant under mild reaction conditions. It provides an easy access to α‐amino phosphonic compounds in high yields with a broad reaction scope. The safe, convenient and environmentally benign process makes this protocol very promising.     

Polybenzimidazole‐graft‐polyvinylphosphonic acid—proton conducting fuel cell membranes

A new method for the preparation of polybenzimidazole (PBI)‐based membranes, containing high concentrations of immobilized phosphonic acid groups, has been developed. The procedure used is carried out in two steps: (1) Synthesis of modified PBIs, containing 1,2‐dihydroxypropyl groups and preparation of films there from; (2) Introduction of vinylphosphonic acid (VPA) and initiator (cerium ammonium nitrate) in the film, subsequent grafting of VPA from the active sites of the PBI backbone. Membranes with different length of the grafted polyvinylphosphonic acid chains were prepared. The molar ratio grafted VPA units per PBI repeating unit reaches 7.8. Proton conductivity was measured at 120°C and relative humidity (RH) 20–100%. For the membrane with highest concentration of phosphonic acid groups the proton conductivity was 35 mS cm^?1 at 100% RH and 8 mS cm^?1 at 20% RH. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Proton conductive reinforced poly(ethylene‐co‐styrene) membranes

Polymers with ionic conductivity are useful materials for ion exchange membranes, separators, and electrolytes in electrochemical cells. New ionomers are currently being sought to replace the ionomers, which contain fluorine and are harmful to environment and expensive. A new and promising ionomer is a sulfonated ethylene/styrene copolymer. A nearby alternating copolymer with styrene content of 47 mol % was polymerized with metallocene/MAO catalyst. Membranes were prepared by hot‐pressing copolymer films with a glassfiber tissue. Phenyl rings in the copolymers were sulfonated with chlorosulfonic acid as a sulfonating agent. As the alternating structure of the copolymer, sulfonic groups were evenly distributed along the membranes. The membranes were characterized by determining water uptake, ion exchange capacity, proton conductivity, and mechanical properties. The studies revealed that the sulfonated copolymers have promising properties for proton‐conducting applications. All membranes had good ion exchange capacity, ～ 3.5 meq/g, and proton conductivity, over 50 mS/cm. Due to the high water uptake of the sulfonated copolymer, mechanical properties of the membranes were improved by using the glassfiber tissue as reinforcement. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012