Preparation and characterization of ABS/HIPS heterogeneous anion exchange membrane filled with activated carbon

Acrylonitrile‐butadiene‐styrene (ABS)/high impact polystyrene (HIPS) blend heterogeneous anion exchange membranes were prepared by phase inversion method using tetrahydrofuran as solvent and anion exchange resin powder as functional group agent. Activated carbon was selected as inorganic filler additive. The additive concentration effect on properties of the prepared membranes was studied. Ultrasonic method was used to help appropriate dispersion of particles in the membrane's matrix. Scanning optical microscopy showed that sonication has a significant influence on distribution of resin particles in the membrane matrix and makes it possible to form more uniform phase. Moreover, images showed a relatively uniform surface for membranes. The increase of activated carbon concentration in casting solution led to a decline in membrane water content. The ion exchange capacity, membrane potential, permselectivity, transport number, ion permeability, ionic flux, and current efficiency of prepared membranes all were increased initially by the increase in additive concentration up to 1% wt and then they showed decrease trend with higher increase in additive concentration from 1 to 4% wt. Conversely, the electrical resistance and energy consumption showed opposite trends. In addition, with more additive loading, the oxidative stability of membranes was slightly decreased and their thermal stability was increased. Membrane with 1% wt additive loading exhibited higher efficiency and electrochemical properties in comparison with other prepared membranes in this research. Furthermore, prepared membranes exhibited suitable electrochemical properties compared to a commercial heterogeneous anion exchange membrane with the same experimental conditions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

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.     

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     

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 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.     

降冰片烯类季铵型阴离子交换膜的制备

通过环状烯烃双键打开, 首尾相接形成聚合物的方法, 设计合成了含有季铵阳离子作为功能化基的降冰片烯衍生物单体QRPhNB, 通过开环异位聚合(ROMP)制备得到阴离子交换膜材料, 流延成膜后的分析结果表明:当单体与降冰片二烯1:2投料时所得到的阴离子交换膜的IEC值为1.26 mequiv·g^-1, 其最高离子传导率为20.05 mS·cm^-1;吸水率为14.3%。     

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.     

Polyphosphazene membranes. III. Solid‐state characterization and properties of sulfonated poly[bis(3‐methylphenoxy)phosphazene]

Poly[bis(3‐methylphenoxy)phosphazene] was sulfonated in a solution with SO₃ and solution‐cast into 100–200‐μm‐thick membranes from N,N‐dimethylacetamide. The degree of polymer sulfonation was easily controlled and water‐insoluble membranes were fabricated with an ion‐exchange capacity (IEC) as high as 2.1 mmol/g. For water‐insoluble polymers, there was no evidence of polyphosphazene degradation during sulfonation. The glass transition temperature varied from −28°C for the base polymer to −10°C for a sulfonated polymer with an IEC of 2.1 mmol/g. The equilibrium water swelling of membranes at 25°C increased from near zero for a 0.04‐mmol/g IEC membrane to 900 % when the IEC was 2.1 mmol/g. When the IEC was < 1.0 mmol/g, SO₃ attacked the methylphenoxy side chains at the para position, whereas sulfonation occurred at all available aromatic carbons for higher ion‐exchange capacities. Differential scanning calorimetry, wide‐angle X‐ray diffraction, and polarized microscopy showed that the base polymer, poly[bis(3‐methylphenoxy)phosphazene], was semicrystalline. For sulfonated polymers with a measurable IEC, the 3‐dimensional crystal structure vanished but a 2‐dimensional ordered phase was retained. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 387–399, 1999     

改性季铵化壳聚糖阴离子交换膜的制备与表征

以壳聚糖（CS）为原料,2,3-环氧丙基三甲基氯化铵（GTA）为醚化剂,通过亲核取代反应制备了季铵化壳聚糖（QCS）,用傅立叶变换红外光谱（FT-IR）表征了产物的结构,结果表明产物结构与目标产物的结构相符。以QCS为原料,醋酸溶液为溶剂,通过加入交联剂戊二醛（GA）和荷正电聚苯乙烯（PS）微球,制备了一系列改性QCS阴离子交换膜,并对其含水率、溶胀度、离子交换量等性能进行了测定。结果表明：交联剂的加入可有效抑制QCS膜的形变,降低了其溶胀度,微乳液的加入会在一定程度上提高复合膜的离子交换能力,交联度为4%、微乳液用量为15%（v/v）时离子交换膜的含水率趋于稳定。     

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.     

季铵化改性PSA的结构与性能研究

通过氯甲基化反应,制得了氯甲基化聚芳砜酰胺(CMPSA),并研究了聚芳砜酰胺(PSA)氯甲基化反应的影响因素。用流延法制成CMPSA膜,将CMPSA膜通过季铵化反应、离子交换制得了季铵化聚芳砜酰胺(QAPSA)阴离子交换膜。利用FT-IR和1H-NMR对其进行结构表征。并测定了QAPSA膜的离子交换容量(IEC)、离子电导率、吸水率和溶胀度。结果表明,QAPSA阴离子交换膜在室温下离子电导率为1.025×10-2S/cm,且具有良好的尺寸稳定性。     

Study of effect of two sulfonating agents on electrochemical properties of surface-modified polyethersulfone membrane

The work deals with the selection of sulfonating agent and preparation of polymeric coating on membrane step by step. The surface modification of a commercial ultrafiltration polyethersulfone (PES) membrane was covalently attached to the poly(styrene-co-divinylbenzene-co-4-vinylbenzylchloride). The whole process was tracked step by step using analytical methods. Chlorosulfonic acid and trimethylsilyl chlorosulfonate were tested as sulfonating agents. Ion-exchange capacity (IEC), water content, specific resistance, and permselectivity were measured and scanning electron microscope analyzed the surface of the cation exchange membrane. The best results were achieved using 5 wt % chlorosulfonic acid as sulfonating agent. IEC reached values of up to 2.44 meq g⁻¹ of dry matter, permselectivity of 93.6%, area resistances of 10.1 Ω cm², and specific resistance around 299 Ω cm. The prepared cation exchange PES membrane with chlorosulfonic acid can be used in electrochemical processes, for example, in electrodialysis. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48826.     

Preparation of Branch Polyethyleneimine (BPEI) Crosslinked Anion Exchange Membrane Based on Poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS)

Anion exchange membranes with chemical stability, high conductivity, and high mechanical properties play an important role in alkaline fuel cells. Here, a series of CPX anion exchange membranes based on poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) and branch polyethyleneimine (BPEI) are achieved by casting, in which BPEI acts as both a crosslinking agent and an OH⁻ conducting functional group. The introduction of BPEI facilitates the formation of good hydrophilic/hydrophobic microphase separation structure, thus improving the ion transport channel of CPX membrane. The physicochemical and electrochemical properties of the CPX membrane are significantly improved when the mass ratio of SEBS to BPEI is within an appropriate range. The OH⁻ conductivity of the CP2 membrane (the mass ratio of SEBS to BPEI is 2) can reach 66.63 mS cm⁻¹ at 80 °C, and more than 80% initial OH⁻ conductivity is maintained in 1.0 m NaOH solution for 20 d at 60 °C. The strategy of using a polymer with excellent alkali resistance and oxidation resistance as the main body and introducing a conductive group that can construct microphase separation can simultaneously improve the conductivity and membrane stability. This viable strategy is a promising construction method for anion exchange membranes that can be applied to fuel cells.     

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     

Preparation of bipolar membranes. II

The bipolar multilayer membrane was prepared by a new technique. The interfacial layer and cation layer were formed by only one step. The anion and cation layers were made from the same material from which chloromethylated polysulfone was used as a basic material. The bipolar membranes were composed of a solvent‐resistant anion layer with crosslinking matrix by the reaction of chloromethylated polysulfone in DMF with diamine; an ultrathin interfacial layer from chloromethylated polysulfone solution in DMF, containing cation‐exchange resin and both quaternary and nonquaternary amine groups; and a cation layer from chloromethylated polysulfone dispersing cation resin powder. The prepared bipolar membrane exhibits a lower voltage drop over 100 mA/cm² and stable performances at a long‐term operation. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1733–1738, 2001     

PEI交联的PECH/nylon复合阴离子交换膜的制备及性能研究

聚环氧氯丙烷（PECH）是一种线性高分子聚合物,具有较好的稳定性和成膜性能,且以PECH为基体制备阴离子交换膜,可避免致癌物质如氯甲醚、双氯甲醚的使用,但存在机械强度差与吸水性较大等缺点。本研究采用聚乙烯亚胺（PEI）作为交联剂,通过其与PECH发生交联反应,在其内部形成网状结构限制PECH膜在水中的过度溶胀,从而增强膜的机械强度,同时引入尼龙网布（nylon）作为支撑材料进一步提高膜的力学性能,制备了QCPECH/nylon复合阴离子交换膜。研究结果表明,制备的P1膜在电渗析应用过程中的脱盐效率（94.8%）比商业膜（Neosepta AMX）的脱盐效率（92.4%）更高,由此可见,用PEI交联的PECH/nylon复合阴离子交换膜在电渗析脱盐中具有潜在的发展前景。     

Surface modification of mesoporous silica by radiation induced graft polymerization of styrene and subsequent sulfonation for ion-exchange applications

In this study, the fabrication of silica-grafted-sulfonated styrene (S-g-SSt) resin by grafting of styrene onto silanized silica via gamma radiation-induced polymerization and subsequent sulfonation of the grafted styrene is described. The grafting was strongly affected by the reaction conditions; absorbed dose, monomer concentration, and the type of solvent used. The structural analysis of the silica and all the relevant products were carried out by FTIR, SEM, TGA, XRD, and BET. FTIR analysis confirmed the presence of styrene onto silica and subsequent sulfonation. The BET nitrogen adsorption–desorption isotherms indicated that grafting occurs on the surface as well as inside the pores. Finally, the ion exchange capacity (IEC) of the fabricated S-g-SSt was evaluated by ion exchange titrations (back titration method). The IEC was found to be in the range of 0.43–2.97 meq/g depending on the degree of grafting. The facile fabrication method and high IEC value (2.97 meq/g) could lead to potential application of the fabricated S-g-SSt resin in ion exchange resin in waste water treatment and metal recovery. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48835.     

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.     

Characterization of acrylic acid‐grafted PP membranes prepared by plasma‐induced graft polymerization

Acrylic acid (AA)‐g‐polypropylene (PP) membranes were prepared by grafting AA on to a microporous PP membrane via plasma‐induced graft polymerization. The grafting of AA to the PP membrane was investigated using Fourier transform infrared spectroscopy (FTIR). Pore‐filling of the membranes was confirmed by field emission‐scanning electron microscopy (FESEM) and energy dispersing X‐ray (EDX). Ion exchange capacity (IEC), membrane electric resistance, transport number and water content were measured and analyzed as a function of grafting reaction time. The prepared AA‐g‐PP membranes showed moderate electrochemical properties as a cation‐exchange membrane. In particular, membranes with a degree of grafting of 155% showed good electrical properties, with an IEC of 2.77 mmol/g dry membrane, an electric resistance of 0.4 Ω cm² and a transport number of 0.96. Chronopotentiometric measurements indicated that AA‐g‐PP membranes, with a high IEC had a sufficient conducting region in the membrane. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

A simple determination of counter-ionic permselectivity in an ion exchange membrane from bi-ionic membrane potential measurements: permselectivity of anionic species in a novel anion exchange membrane

A new method is proposed here for determining counter-ions permselectivity through an ion exchange membrane. The theoretical base of the method is Henderson equation. After simplifying at special experimental conditions, a linear relationship between the bi-ionic membrane potential term and concentration ratio, i.e., [exp(z_AF(−ΔE_T)/RT)−1]∝[C_A,L/C_B,L] can be obtained, from the slope of which, the permselectivity of counter-ions can be achieved. This method is very simple in operation and less time and money consuming. The method is exemplified by common 1–1, 2–2 and 2–1 counter-ions pair through a novel and published anion exchange membrane. The accuracy and the validity of the method is tested by three aspects: (1) the experimental [exp(z_AF(−ΔE_T)/RT)−1]∝[C_A,L/C_B,L] curve approaches a straight line (2) the predicted order of counter-ions conforms to the results evaluated in a practical electrodialysis process; and (3) the results calculate from different referenced counter-ions for the same counter-ions pair agree well with each other.