Preparation and Characterization of Heterogeneous Cation Exchange Membranes Based on S-Poly Vinyl Chloride and Polycarbonate

This research deals with the preparation of heterogeneous cation exchange membranes by solution-casting techniques using S-polyvinylchloride (S-PVC) and polycarbonate (PC) as binders, cation exchange resin powder as functional groups agent, and tetrahydrofuran as solvent. The effects of polymer binder type and resin ratio loading on morphological, electrochemical, and mechanical properties of prepared membranes were studied and evaluated. Scanning electron microscopy and scanning optical microscopy were used for the membranes structure investigation. Images showed that increase of resin loading in casting solution resulted in a highly uniform phase forming. Moreover resin particles were distributed more uniformly in polycarbonate membranes compared to the polyvinylchloride ones. The water content, surface hydrophilicity, ion exchange capacity, ion concentration, permselectivity, membrane potential, surface charge density, transport number, ionic permeability, flux of ions, and current efficiency were enhanced for the prepared membranes by increase in resin ratio loading. Moreover, the increase of resin ratio in casting solution reduced the mechanical strength of the prepared membranes. The mechanical strength of S-PVC membrane was higher than the PC ones. Furthermore, the increment of resin content caused some decreases in areal electrical resistance and oxidative stability of the prepared membranes. Home-made membranes exhibited appropriate electrochemical properties in comparison with a tested commercial heterogeneous cation exchange membrane in the same experimental conditions. Swelling of the prepared membranes was also negligible compared to the commercial type.     

Preparation and characterization of monovalent ion‐selective poly(vinyl chloride)‐blend‐poly(styrene‐co‐butadiene) heterogeneous anion‐exchange membranes

New types of composite anion‐exchange membranes were prepared by blending of suspension‐produced poly(vinyl chloride) (S‐PVC) and poly(styrene‐co‐butadiene), otherwise known as styrene–butadiene rubber (SBR), as binder, along with anion‐exchange resin powder to provide functional groups and activated carbon as inorganic filler additive. Also, an ultrasonic method was used to obtain better homogeneity. In solutions with mono‐ and divalent anions, the effect of activated carbon and sonication on the morphology, electrochemical properties and selectivity of these membranes was elucidated. For all solutions, ion‐exchange capacity, membrane potential, permselectivity, transport number, ionic permeability, flux and current efficiency of the prepared membranes initially increased on increasing the activated carbon concentration to 2 wt% in the casting solution and then began to decrease. Moreover, the electrical resistance and energy consumption of the membranes initially decreased on increasing the activated carbon loading to 2 wt% and then increased. S‐PVC‐blend‐SBR membranes with additive showed a decrease in water content and a slight decrease in oxidative stability. Also, these membranes showed good monovalent ion selectivity. Structural images of the prepared membranes obtained using scanning optical microscopy showed that sonication increased polymer‐particle interactions and promoted the compatibility of particles with binder. Copyright © 2010 Society of Chemical Industry     

Heterogeneous Cation Exchange Membrane: Preparation,Characterization and Comparison of Transport Properties of Mono and Bivalent Cations

Polycarbonate heterogeneous cation exchange membranes were prepared by solution casting techniques using tetrahydrofuran as solvent and cation exchange resin powder as functional groups agent. The effect of resin ratio loading on properties of prepared membranes was studied. Also, transport properties of the prepared membranes for mono and bivalent cations were evaluated. Scanning electron microscopy and scanning optical microscopy were used for the membranes structure investigation. Images showed that increase of resin ratio in casting solution results in a highly uniform phase to form. Formation and propagation of voids, cavities, and cracks were facilitated through higher resin ratio loading. The water content, surface hydrophilicity, specific surface area, ion exchange capacity, ion concentration, ionic permeability, conductivity, flux, and current efficiency of the membranes were enhanced and their energy consumption, oxidative stability, and mechanical strength were declined by increase of resin ratio loading. Moreover, membranes showed higher ionic flux, current efficiency, and lower energy consumption for sodium ions in comparison with bariums. Furthermore, with the increase of resin loading, permselectivity, membrane potential and transport number of membranes were improved for monovalent ions and diminished for bivalent ones. Also, membranes exhibited lower membrane potential, selectivity, and transport number for bivalent ions in comparison with the monovalent type.     

Electrodialytic transport properties of heterogeneous cation‐exchange membranes prepared by gelation and solvent evaporation methods

The heterogeneous cation‐exchange membranes were prepared by employing two different methods: immersing the cation‐exchange resin‐loaded membranes in gelation bath; evaporating the solvent upon casting a uniform solution of cation‐exchange resin on a glass plate. The effect of resin loading on the electrochemical properties of the membranes was evaluated. The permselectivity of these heterogeneous membranes and transport number of calcium ions relative to sodium ions was evaluated with respect to the extent of resin loading and the methods of preparation. It is found that the membrane potential, transport number, permselectivity, and relative transport number are prominently high in the solvent evaporation method compared with the gelation method. The transport number of calcium ions relative to sodium ions in the solvent evaporation method increased monotonously with increasing resin loading. However, the increase of resin loading did not influence much on the relative transport numbers in the gelation method. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 198–207, 2006     

Preparation and Electrochemical Characterization of Monovalent Ion Selective Poly (Vinyl Chloride)-Blend-Poly (Styrene-Co-Butadiene) Heterogeneous Cation Exchange Membrane Coated with Poly (Methyl Methacrylate)

In this research, polyvinylchloride/ styrene-butadiene-rubber blend heterogeneous cation exchange membranes were prepared by solution casting technique using tetrahydrofuran as solvent and cation exchange resin powder as functional groups agent. Poly methyl methacrylate (PMMA) was also employed as membrane surface modifier by emulsion polymerization technique to improve the membrane selectivity and anti-fouling property. The effect of used emulsion composition on properties of home-made membranes was studied. SOM images showed uniform particles distribution and relatively uniform surfaces for the membranes. Results revealed that surface modification of membrane led to decrease in water content, ion exchange capacity, and ionic permeability in composite membranes. Membrane potential, transport number, selectivity, ionic concentration, and membrane surface electrical resistance all were increased by the PMMA coating on membrane surface. Also, the results showed that decrease of (Methyl methacrylate (MMA): Sodium dodecyl benzene solfanate (SDBS)) ratio in used emulsion during the modification process led to decrease in water content, IEC and permeability in composite membranes. Conversely, opposite trends were found for membrane potential, transport number, selectivity, and electrical resistance by (MMA: SDBS) ratio decreasing in used emulsion. Composite membranes exhibited higher potential, selectivity, transport number, and permeability for monovalent ions compared to bivalent ones. Modified membranes showed good ability in (monovalent/ bivalent) ions separation.     

Preparation and characterization of nanocomposite heterogeneous cation exchange membranes modified by silver nanoparticles

We prepared polyvinylchloride based nanocomposite heterogeneous cation exchange membranes by solution casting technique using cation exchange resin powder as functional groups agent and tetrahydrofuran as solvent. Silver nanoparticles were also used as fillers in membrane fabrication. The effect of silver nanoparticles concentration in casting solution on membrane physico/chemical and antibacterial characteristics was studied. The SEM images showed compact structure for the modified membranes. X-ray diffraction results also revealed that membrane crystallinity was clearly changed by increase of nanoparticle concentration. Membrane selectivity and transport number were enhanced initially by increase in nanoparticle content up to 4%wt in prepared membrane, and then showed decreasing trend by more increase in additive concentration from 4 to 8%wt. Selectivity and transport number were enhanced another time by further increase in nanoparticle loading ratio from 8 to 16%wt. Opposite trend was found for the membranes’ average grain size by variation in additive content. Ionic flux was also clearly enhanced by using Ag nanoparticles in membrane matrix. Moreover, modified membranes showed good ability in decrease of Escherichia coli growth rate.     

Preparation and characterization of poly (vinyl chloride)-blend-poly (carbonate) heterogeneous cation exchange membrane: Investigation of solvent type and ratio effects

In this research polyvinylchloride/polycarbonate blend heterogeneous cation exchange membranes were prepared by solution casting technique using cation exchange resin powder as functional groups agent. Tetrahydrofuran (THF) and dimethylformamide (DMF) were utilized as solvents. The effect of solvent type and ratio (THF/DMF mixture) on properties of prepared membranes was studied. SEM and SOM images showed relatively uniform particle distribution and also uniform surface for the membranes. Images showed that at high DMF ratio decrease of polymer conformation with particles surface reduces the compatibility of polymer-particle. The membrane ion exchange capacity and permeability were enhanced initially by increase of DMF ratio up to 5% (v/v) in casting solution and then they began to decrease with more DMF ratio. Results showed that membrane potential, transport number, selectivity and thermal stability all were decreased by DMF ratio increasing. Conversely, membrane water content, specific surface area and roughness showed opposite trends. Membrane electrical resistance initially declined by increase in DMF content up to 15% (v/v) and then it began to increase. The increase of electrolyte concentration also led to decrease in membrane transport number and selectivity. Membrane with (95:5) (v/v) solvent ratio (THF:DMF) exhibited more appropriate performance compared to others.     

Synthesis and Characterization of a Novel Surfactant-Enhanced Chlorinated-Polypropylene Heterogeneous Anion Exchange Membrane

A novel heterogeneous anion exchange membrane containing a non-ionic surfactant as an additive was made via dry and wet phase inversion. The effects of the drying time at different additive ratios on properties of membranes were investigated. The selectivity and the fixed ion concentration were increased by increasing the drying time, while conductivity, water uptake, and the ion exchange capacity were lower. Incorporation of an appropriate amount of additive had a positive effect on the membrane properties. The most selective membrane with remarkable nitrate/ chloride selectivity of 3.1 was obtained at an “additive/ total solid” ratio of 0.03 and 24 h drying time.     

Tailoring the ionic transfer characteristics of polyvinyl chloride-based heterogeneous ion exchange membranes by embedding carboxy methyl cellulose in membrane channels

Polyvinyl chloride-based heterogeneous cation exchange membranes were modified by embedding carboxy methyl cellulose in ionic transfer channels of membrane. The effect of CMC to PVC blend ratios on properties of membranes was studied. SOM images showed uniform distribution and surfaces for prepared membranes relatively. The SEM images showed uniform and dense structure for the membranes. The XRD pattern also demonstrated amorphous structure for the membranes. Membrane water content was improved from 25 to 39 % by increase of CMC concentration up to 32 %wt. Similar trend was found for membrane surface hydrophilicity. The membrane ion exchange capacity, fixed ion concentration, membrane potential, charge density, transport number, permselectivity, and ionic flux were enhanced initially by increase of CMC ratio up to 16 %wt and then began to decrease by increase in CMC concentration from 16 to 32 %wt. The membrane oxidative stability and areal electrical resistance showed decreasing trends by utilizing of carboxy methyl cellulose in the membrane matrix. Membrane transport number and selectivity were also increased by increase of electrolyte concentration. Similar trend was found for the membrane electrical conductivity by increase of electrolyte concentration. Also prepared membranes showed higher transport number, selectivity, and areal electrical resistance at pH 7 compared to other pH values.     

Identification of optimum synthesis conditions for a novel anion exchange membrane by response surface methodology

The Response Surface Methodology (RSM) was employed for the optimization of the synthesis conditions of an anion exchange membrane. A novel chlorinated‐polypropylene heterogeneous anion exchange membrane was made via phase inversion. A nonionic surfactant was incorporated into the composition as an additive to enhance the membrane properties. The membrane performance was measured in terms of ion exchange capacity (IEC) and permselectivity. An experimental design was used to quantify the effects of variables including the ratio of resin/polymer, the ratio of additive/total solid, and the ratio of solvent/polymer, on IEC and permselectivity. For each function, a quadratic model was developed to correlate the relationship between variables and the response. The results demonstrated the accuracy of the two models. The anion exchange membrane with the best combination of a high IEC and high permselectivity was synthesized with a solvent/polymer ratio of 18.63 (v/w), resin/polymer ratio of 1 (w/w), and additive/total solid ratio of 0.02 (w/w). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39888.     

Effect of polymers blend ratio binder on electrochemical and morphological properties of PC/S‐PVC‐based heterogeneous cation‐exchange membranes

In this research, heterogeneous cation exchange membranes were prepared by the casting‐solution technique using polycarbonate (PC) and S‐polyvinylchloride (S‐PVC) as binders along with cation exchange resin as functional group agent. The effect of blend ratio (PC to S‐PVC) of polymer binder on structure and electrochemical properties of the prepared membranes were elucidated. The morphology of the prepared membranes was investigated by scanning electron microscopy (SEM) and scanning optical microscopy (SOM). The images show that the addition of PC ratio in the casting solution results in formation of a membrane with more inner cavities and micro voids. The electrochemical properties and mechanical strength tests were conducted. Water content, ion exchange capacity, ion permeability, flux, current efficiency, and oxidative stability of the prepared membranes initially were decreased by increasing the PC ratio in the casting solution and then it began to increase. The blending of S‐PVC and PC polymers results in membranes with lower mechanical strength. Membrane potential, surface charge density, perm‐selectivity, cationic transport number, electrical resistance, and energy consumption were initially improved by the increment of PC ratio in the casting solution and then it decreased. The membrane with 70% PC exhibited the highest flux, maximum current efficiency, and minimum energy consumption. However, the selectivity of this membrane was low compared with the other prepared membranes. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation of novel heterogeneous cation‐permeable membranes from blends of sulfonated poly(phenylene sulfide) and poly(ether sulfone)

Novel heterogeneous cation‐exchange membranes using poly (ether sulfone)(PES) as binder and sulfonated poly(phenylene sulfide) (SPPS) powder as polyelectrolyte were prepared by the solution casting‐immersion method. Compared with a conventional route for heterogeneous membrane, the steps of milling resin into fine powders and the pressing at high temperature are avoided, and thus permits a simple technique for the preparation of such membrane. The effect of the particle size and loading of SPPS resin on the properties of the membranes such as ion‐exchange capacity, water content, electrical resistance, transport number, diffusion coefficient of electrolytes, etc., have been studied. It is shown that the membrane fundamental properties are largely dependent on both the resin loading and the particle size of SPPS resin. By adjusting these two important parameters, one can obtain heterogeneous membrane with both good conductivity, selectivity, and proper water content for different industrial purposes such as electrodialysis, diffusional dialysis, etc. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 167–174, 2004     

Effect of hydrophilic additive and PVC polymerization degree on morphology and electrochemical properties of PVC‐based heterogeneous cation‐exchange membrane

Membrane solution composition is one of the important factors that determine properties of ion‐exchange membranes. In this study, PVC‐based heterogeneous cation‐exchange membranes were prepared by the solution casting method. Effects of a hydrophilic additive [poly(ethylene glycol), PEG400] and degree of polymerization of poly(vinyl chloride) (PVC) on the morphology and electrochemical properties of the cation‐exchange membranes were investigated. The results revealed that the hydrophilic additive can improve membrane properties, including water uptake (Wu), ion‐exchange capacity (IEC), conductivity, and permselectivity. The improvements might be associated with an increase in accessibility of functional sites in the membrane matrix due to a higher hydrophilicity, indicated by a reduction of water contact angle and the greater void fraction shown by scanning electron microscopy. However, the permselectivity slightly decreased when the additive concentration was increased further. Meanwhile, increasing the degree of polymerization and PVC concentration resulted in higher permselectivity and lower conductivity, which might be due to a better resin distribution and a lower void fraction. Overall, the prepared membranes had relatively good conductivities (up to ～2.5 mS/cm) and permselectivities (up to ～0.92). In general the conductivity increased with increasing Wu and IEC, while the permselectivity showed the opposite trends. This could be associated with the efficacy of Donnan exclusion indicated by the IEC/Wu ratio and the Donnan equilibrium constant of the cation (K⁺). © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46690.     

负载离子液体的阳离子交换膜在烯烃/烷烃分离中的应用

制备了负载胆碱赖氨酸盐离子液体（[Ch][Lys]）的阳离子交换膜,测定并表征其膜的性能,研究其在电渗析下分离1-己烯/n-己烷的能力。结果表明,膜含水率和离子交换容量随离子交换树脂质量分数和离子液体含量的增加而增大;膜的面电阻随树脂质量分数增大而减小,随离子液体含量的增大而增大;膜中添加离子液体明显提高了其分离1-己烯/n-己烷的能力,当阳离子交换树脂含量为70%、离子液体添加量为15%时,所制的阳离子交换膜对1-己烯分离的选择性最高,其值可达9.5。     

Sulfonated poly(ether sulfone)/silica composite membranes for direct methanol fuel cells

A series of sulfonated poly(ether sulfone) (SPES)/silica composite membranes were prepared by sol–gel method using tetraethylorthosilicate (TEOS) hydrolysis. Physico–chemical properties of the composite membranes were characterized by thermogravimetric analysis (TGA), X‐ray diffraction (XRD), scanning electron microscope–energy dispersive X‐ray (SEM–EDX), and water uptake. Compared to a pure SPES membrane, SiO₂ doping in the membranes led to a higher thermal stability and water uptake. SEM–EDX indicated that SiO₂ particles were uniformly embedded throughout the SPES matrix. Proper silica loadings (below 5 wt %) in the composite membranes helped to inhibit methanol permeation. The permeability coefficient of the composite membrane with 5 wt % SiO₂ was 1.06 × 10^?7 cm²/s, which was lower than that of the SPES and just one tenth of that of Nafion® 112. Although proton conductivity of the composite membranes decreased with increasing silica content, the selectivity (the ratio of proton conductivity and methanol permeability) of the composite membrane with 5 wt % silica loading was higher than that of the SPES and Nafion® 112 membrane. This excellent selectivity of SPES/SiO₂ composite membranes could indicate a potential feasibility as a promising electrolyte for direct methanol fuel cell. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation of defect-free asymmetric membranes for gas separations

A technique was developed to prepare defect-free, asymmetric, polymer membranes for gas separation. The preparation method eliminates the need for coatings, which are usually required to render asymmetric, polymer based, membranes gas selective. In this method, a casting solution containing a polymer, solvent, and salt additive is given a desired shape and immersed in a coagulation bath containing a nonsolvent. The nonsolvent is selected to have a low affinity for both the solvent and salt additive. After the complete coagulation of the membrane, the additive salt is leached out in a second bath. This leads to the formation of an asymmetric membrane that has a well-interconnected porous network. The fine membrane structure is preserved by solvent exchange before it is finally dried. Polyetherimide (PEI) (Ultem® 1000) membranes were prepared from casting solutions containing 23, 25, and 26.5% (wt) PEI, various amounts of lithium nitrate and N-methyl-2-pyrrolidinone (NMP). Membrane performance was determined for the separation of oxygen from air. The effects of polymer concentration, additive salt concentration and the drying process on oxygen permeance, and the actual separation factor of the membrane are discussed. The addition of a small amount of solvent to the coagulation bath improved the leaching of the salt additive and produced membranes with a more open structure. A polymer concentration of 23% produced membranes with the highest performance. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1471–1482, 1999     

Electrochemical Properties of Chemically Treated Polyvinylchloride‐Based Heterogeneous Cation‐Exchange Membrane

Chemical treatment is a facile method for improving electrochemical properties of a heterogeneous ion‐exchange membrane. In this work, polyvinylchloride (PVC)‐based heterogeneous cation‐exchange membrane is prepared by a dry–wet phase inversion process. The membrane is treated with a sulfuric acid solution in a room and a high temperature (80 °C). Effects of the treatment procedure and hydrophilic additive on membrane electrochemical properties are investigated. Chemically treated PVC and PVC/additive heterogeneous cation‐exchange membranes show a change in membrane electrochemical properties in terms of water uptake (Wu), conductivity, ion‐exchange capacity (IEC), and permselectivity (Ps). In general, Wu and conductivity increase after the chemical treatment. Significant improvement is observed when a high temperature is used. Meanwhile, the conductivity is more pronounced for PVC/additive membranes. The improvement may be associated with an increase in hydrophilicity. A significant increase in IEC is also observed for modified PVC/additive membrane. This may be associated with the removal or leaching of the additive during the treatment which in turn increases the portion of ion‐exchange resins in the membrane. Most of the modified membranes show a decrease in Ps. It may be due to a decrease in the effectiveness of Donnan effect indicated by Donnan equilibrium constant (K+). POLYM. ENG. SCI., 59:E219–E226, 2019. © 2018 Society of Plastics Engineers     

Preparation of bipolar membranes (I)

The bipolar membranes were prepared by charged material of polysulfone as a base. The bipolar membranes were composed of a solvent‐resistant anion exchange layer with a crosslinking matrix prepared by the reaction of chloromethylated polysulfone in DMF with diamine, an interfacial layer made from chloromethylated polysulfone solution in DMF containing cation exchange resin and amine, and a cation exchange layer made from sulfonated polysulfone dispersing cation resin powder. The prepared bipolar membrane can exhibit lower voltage drop over 100 mA/cm². The critical requirement for producing bipolar membranes of low potential drop is the creation of a thin interfacial region with a low electrical resistance and a suitable chemical structure, which act to catalyze water splitting. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1658–1663, 2001     

聚苯并咪唑/改性聚环氧氯丙烷阴离子交换膜的性能

通过缩聚法制备了含氟聚苯并咪唑(FPBI),以1–甲基咪唑和聚环氧氯丙烷为原料,制备了咪唑盐修饰的聚环氧氯丙烷(Im PECH),并通过溶液浇铸法制备了FPBI/Im PECH复合膜。系统地研究了复合膜中Im PECH含量的不同对复合膜的力学性能、热稳定性、离子电导率、离子交换容量(IEC)、吸水率、溶胀度等性能的影响。研究结果表明,随着Im PECH含量的增加,复合膜的吸水率、溶胀度、IEC、离子电导率逐渐增加,依然能够保持良好的力学性能和热稳定性。FPBI/Im PECH复合膜在80℃下最高电导率达到55.74 m S/cm,并展示了优异的耐碱性,该复合阴离子交换膜有望在碱性阴离子交换膜燃料电池中得到应用。     

Study on radiation grafting of acrylic acid onto fluorine-containing polymers. II. Properties of membrane obtained by preirradiation grafting onto poly(tetrafluoroethylene)

Some properties of the membranes obtained by the preirradiation grafting of acrylic acid onto poly(tetrafluoroethylene) (PTFE) film have been studied. The dimensional change by grafting and swelling, water uptake, electric conductivity, and mechanical properties of the grafted PTFE films were measured and were found to increase as the grafting proceeds. These properties were found to be dependent mainly on the degree of grafting regardless of grafting conditions except higher monomer concentration (80 wt %). The electric conductivity and mechanical properties of the membranes at 80 wt % monomer concentration is lower than those at a lower monomer concentration. The results suggest that the membranes obtained at 80-wt % acrylic acid solution have a somewhat heterogeneous distribution of electrolyte groups as compared with those prepared at a monomer concentration less than 60 wt %. X-ray microscopy of the grafted films revealed that the grafting begins at the part close to the film surface and proceeds into the center with progressive diffusion of monomer to give finally the homogeneous distribution of electrolyte groups. The membranes show good electrochemical and mechanical properties which make them acceptable for the practical uses as cation exchange membrane.