Sulfonated poly(ether ether ketone)‐induced porous poly(ether sulfone) blend membranes for the separation of proteins and metal ions

Asymmetric ultrafiltration (UF) membranes were prepared by the blending of poly(ether sulfone) (PES) and sulfonated poly(ether ether ketone) (SPEEK) polymers with N,N′‐dimethylformamide solvent by the phase‐inversion method. SPEEK was selected as the hydrophilic polymer in a blend with different composition of PES and SPEEK. The solution‐cast PES/SPEEK blend membranes were homogeneous for all of the studied compositions from 100/0 to 60/40 wt % in a total of 17.5 wt % polymer and 82.5 wt % solvent. The presence of SPEEK beyond 40 wt % in the casting solution did not form membranes. The prepared membranes were characterized for their UF performances, such as pure water flux, water content, porosity, and membrane hydraulic resistance, and morphology and melting temperature. We estimated that the pure water flux of the PES/SPEEK blend membranes increased from 17.3 to 85.6 L m^?2 h^?1 when the concentration of SPEEK increased from 0 to 40 wt % in the casting solution. The membranes were also characterized their separation performance with proteins and metal‐ion solutions. The results indicate significant improvement in the performance characteristics of the blend membranes with the addition of SPEEK. In particular, the rejection of proteins and metal ions was marginally decreased, whereas the permeate flux was radically improved. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effects of heat treatment on the properties of heterogeneous cation permeable membranes from blends of poly(ether sulfone)/sulfonated poly(phenylene sulfide) and phenolphthalein poly(ether ether ketone)/sulfonated poly(phenylene sulfide)

The effects of heat treatment on the properties of membranes prepared from blends of poly(ether sulfone)/sulfonated poly(phenylene sulfide) (SPPS) and phenolphthalein poly(ether ether ketone)/SPPS were studied in detail. The membranes' fundamental properties, including water content, transport number, diffusion coefficient of electrolytes, flux, and so on, changed with both treated temperature and time, whereas the ion‐exchange capacity and electrical resistance remained approximately unchanged. The trends may have been due to the possible structural change resulted from the shrinking of the polymers forming the membranes. Furthermore, the membranes also retained a good physical appearance at temperatures below 220°C. Therefore, a series of heterogeneous membranes with desired conductivities and selectivities as well as proper water contents, which could satisfy different industrial purposes, such as electrodialysis, diffusional dialysis, and proton exchange, were achieved by simple heat treatment for a proper time and at a proper temperature. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 494–499, 2005     

Preparation of poly(ether sulfone) nanofibers by gas‐jet/electrospinning

Poly(ether sulfone) (PES) nanofibers were prepared by the gas‐jet/electrospinning of its solutions in N,N‐dimethylformamide (DMF). The gas used in this gas‐jet/electrospinning process was nitrogen. The morphology of the PES nanofibers was investigated with scanning electron microscopy. The process parameters studied in this work included the concentration of the polymer solution, the applied voltage, the tip–collector distance (TCD), the inner diameter of the needle, and the gas flow rate. It was found from experimental results that the average diameter of the electrospun PES fibers depended strongly on these process parameters. A decrease in the polymer concentration in the spinning solutions resulted in the formation of nanofibers with a smaller diameter. The use of an 18 wt % polymer solution yielded PES nanofibers with an average diameter of about 80 nm. However, a morphology of mixed bead fibers was formed when the concentration of PES in DMF was below 20 wt % during gas‐jet/electrospinning. Uniform PES nanofibers with an average diameter of about 200 nm were prepared by this electrospinning with the following optimal process parameters: the concentration of PES in DMF was 25 wt %, the applied voltage was 28.8 kV, the gas flow was 10.0 L/min, the inner diameter of the needle was 0.24 mm, the TCD was 20 cm, and the flow rate was 6.0 mL/h. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Cellulose acetate–poly(ether sulfone) blend ultrafiltration membranes. II. Application studies

Ultrafiltration membranes are largely applied as macromolecular solutes and heavy‐metal‐ion separation from aqueous streams. Cellulose acetate and poly(ether sulfone) blend ultrafiltration membranes were prepared by the precipitation phase‐inversion technique in 100/0, 95/5, 85/15, and 75/25% polymer blend compositions in the absence and presence of a polymeric additive, poly(ethylene glycol) 600, at different additive concentrations and were used for the rejection of proteins trypsin, pepsin, egg albumin, and bovine serum albumin; a maximum of 94% rejection was achieved. The toxic heavy metal ions copper, nickel, and cadmium from dilute aqueous solutions were subjected to rejection by the blend membranes by complexation of the ions with the water‐soluble polymeric ligand, polyethyleneimine (PEI). Permeate flux studies of proteins and metal ions were performed simultaneously with the rejection experiments. The atomic absorption spectra results reveal maximum rejection for copper complex and a minimum rejection of about 60% for the cadmium complex. The rejection and permeate flux of the blend membranes were compared with those of pure cellulose acetate membranes. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3659–3665, 2004     

聚醚砜/磺化聚醚醚酮共混膜的制备和性能

采用流延法制备了聚醚砜(PES)含量不同的PES/磺化聚醚醚酮(SPEEK)共混膜。PES与SPEEK具有良好的相容性。所制备PES/SPEEK共混膜的含水率、溶胀度和甲醇透过系数均随PES含量的增加而降低。虽然共混膜的质子传导性能有所降低.但阻醇性能和溶胀性能提高,这说明PES/SPEEK共混膜是一种很好的直接甲醇燃料电池用固体高分子电解质膜材料。     

Synthesis and characterization of poly(ether sulfone)‐graft‐polydimethylsiloxane copolymers

Novel poly(arylene ether sulfone) (PAES) polymers containing polydimethylsiloxane (PDMS) side chains were synthesized and characterized with NMR and Fourier transform infrared spectroscopy. The thermal properties of the copolymers were evaluated with differential scanning calorimetry and thermogravimetric analysis. The polymers showed perfect thermal stability, as the decomposition temperatures were all above 380°C, and exhibited glass‐transition temperatures in the range 130–188°C. Furthermore, the surface properties of the copolymers were evaluated by X‐ray photoelectron spectroscopy and contact angle analysis. The results show that the hydrophobic abilities of the graft copolymer surfaces were improved significantly compared to PAES through the introduction of the PDMS chains. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Nanostructured membranes based on sulfonated poly(aryl ether sulfone) and silica for fuel‐cell applications

Nanostructured sulfonated poly(aryl ether sulfone) (SPSU) membranes were made from SPSU/silica composites through the addition of amorphous, precipitated, and micronized silica particles (Tixosil 333) and short or segmented linear structures. Linear and branched segments of silica were obtained from the in situ reaction of tetraethoxysilane (TEOS) in an SPSU solution through a sol–gel acid‐catalyzed process. Different amounts of silica in the SPSU composites were prepared to evaluate their influence on the ionic conductivity, the water and alcohol solution sorption capacities, and the stability in an ethanol medium. The effect of silica (Tixosil) on the conductivity was higher than that of the silica made from TEOS in SPSU composites. The conductivities of the membranes containing 10% Tixosil and 6.6% silica prepared from TEOS were measured at 80°C; their values were 60 and 33 mS/cm, respectively. Furthermore, a membrane made of a silica blend (5% Tixosil and 3% TEOS) in SPSU attained a value of 92 mS/cm, whereas the commercial membrane Nafion 117, used as a reference, had a conductivity of 54 mS/cm measured under the same conditions. All those composites membranes could be used as components in hydrogen fuel cell. However, only the SPSU/2% Tixosil composite could be used in both hydrogen and ethanol direct fuel cells. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Adhesion property of sulfonated poly(arylene ether sulfone)s

Sulfonated poly(arylene ether sulfone)s (S‐PESs) were synthesized from sulfonated 4,4′‐dichlorodiphenylsulfone (S‐DCDPS), 4,4′‐dichlorodiphenylsulfone (DCDPS), and 4,4′‐biphenol through variations in the molar ratio of S‐DCDPS to DCDPS from 10/90 to 40/60. The S‐PES sodium form was characterized with Fourier transform infrared, ¹H‐NMR, thermogravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis, and the intrinsic viscosity and solubility were also evaluated. The sodium form was then subjected to acidification by immersion in 1.5M HCl for 24 h at room temperature, which was followed by washing with deionized water. The S‐PES adhesive properties were measured with single laboratory shear samples with aluminum alloys, and the failure mode was investigated. The synthesized S‐PESs exhibited increased glass‐transition temperatures with increased S‐DCDPS/DCDPS ratios; their acid forms provided much lower glass‐transition temperatures than their sodium forms. In addition, the S‐PES sodium form exhibited a high intrinsic viscosity, which indicated a high molecular weight. The S‐PES acid form exhibited an adhesion strength similar to that of the sodium form, and the single‐lap‐shear strength increased with 10% S‐PES and then decreased with 20, 30, and 40% S‐PES. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1211–1218, 2004     

Preparation of poly(ether sulfone) hollow fiber UF membrane for removal of NOM

In this study, a high performance poly(ether sulfone) (PES) hollow fiber ultrafiltration (UF) membrane has been prepared for removal of natural organic matter (NOM). The membrane was spun from a dope solution containing PES/poly (vinyl pyrrolidone) (PVP 40K)/N‐methyl‐2‐pyrrolidone (NMP) by using a wet‐spinning process. Characterization of the membrane in terms of pure water flux, molecule weight cut‐off (MWCO), and retention for a model humic acid (HA) were conducted, and the fouling resistance was analyzed. The experimental results showed that the membrane had a pure water permeability of 20 × 10^?5 L m^?2 h^?1 Pa^?1 and a nominal MWCO of 6000 Da. The results also showed that the membrane retention for humic acid was over 97% and both productivity and selectivity for HA increased with increasing feed velocity. The PES membrane in this study exhibited a much lower fouling tendency than the commercial polysulfone membrane. SEM images revealed that the membrane had an outer dense skin and a porous inner surface. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 430–435, 2006     

Crystallization and melting behavior of poly(ether ether ketone)/poly(aryl ether sulfone) blends

The crystallization and melting behavior of poly(ether ether ketone) (PEEK) in blends with poly(aryl ether sulfone) (PES) prepared by melt mixing are investigated by differential scanning calorimetry (DSC) and wide‐angle X‐ray scattering (WAXS). The presence of PES is found to have a notable influence on the crystallization behavior of PEEK, especially when present in low concentrations in the PEEK/PES blends. The PEEK crystallization kinetics is retarded in the presence of PES from the melt and in the rubbery state. An analysis of the melt crystallization exotherm shows a slower rate of nucleation and a wider crystallite size distribution of PEEK in the presence of PES, except at low concentrations of PES, where, because of higher miscibility and the tendency of PES to form ordered structures under suitable conditions, a significantly opposite result is observed. The cold crystallization temperature of the blends at low PES concentration is higher then that of pure PEEK, whereas at a higher PES concentration little change is observed. In addition, the decrease in heat of cold crystallization and melting, which is more prevalent in PEEK‐rich compositions than in pure PEEK, shows the reduction in the degree of crystallinity because of the dilution effect of PES. Isothermal cold crystallization studies show that the cold crystallization from the amorphous glass occurs in two stages, corresponding to the mobilization of the PEEK‐rich and PES‐rich phases. The slower rate of crystallization of the PEEK‐rich phase, even in compositions where a pure PEEK phase is observed, indicates that the presence of the immobile PES‐rich phase has a constraining influence on the crystallization of the PEEK‐rich phase, possibly because of the distribution of individual PEEK chains across the two phases. The various crystallization parameters obtained from WAXS analysis show that the basic crystal structure of PEEK remains unaffected in the blend. Further, the slight melting point depression of PEEK at low concentrations of PES, apart from several other morphological reasons, may be due to some specific interactions between the component homopolymers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2906–2918, 2003     

Preparation and electrochemical characterization of sulfonated polysulfone cation‐exchange membranes: Effects of the solvents on the degree of sulfonation

Sulfonated polysulfone cation‐exchange membranes with various degrees of sulfonation were prepared by a treatment with chlorosulfonic acid in different solvents of various polarities, and the effect of the solvent polarity on the degree of sulfonation was explored. These membranes were characterized by their ion‐exchange capacity, volume fraction of water, and electrochemical properties. The counterion transport numbers, permselectivity, and fixed charge densities of these membranes were estimated from membrane potential data and varied with the degree of sulfonation, concentration, and external salt concentration. The counterion mobility in the membrane phase was also estimated from membrane conductance measurements. These membrane were found to have good electrochemical properties and are suitable for various types of electromembrane processes. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2344–2351, 2005     

Viscosity behavior of microwave‐heated and conventionally heated poly(ether sulfone)/dimethylformamide/lithium bromide polymer solutions

This article investigates the viscosity behavior of new membrane dope solutions of poly(ether sulfone) (PES) and dimethylformamide with low‐molecular‐weight halogenated lithium bromide (LiBr) additives prepared with two different techniques: (1) a microwave (MW) technique and (2) a conventional heating (CH) technique. In addition, the influence of different concentrations of anhydrous halogenated LiBr additives (0–5 wt %) on the viscosity behavior is analyzed. The viscosity of the dope solutions was assessed with a conical rheometer equipped with a high‐viscosity adapter. The results revealed that the pure PES solutions prepared by the MW and CH techniques exhibited pseudoplastic and Newtonian behavior, respectively. Both the MW and CH PES solutions containing the LiBr additives exhibited dilatant behavior, which obeyed the power law. The apparent viscosity of all the dope solutions prepared with the MW technique was lower than that of those prepared with the CH technique. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Poly(ether ether ketone)/poly(aryl ether sulfone) blends: Relationships between morphology and mechanical properties

Mechanical properties such as the tensile modulus, yield (break) strength, and elongation to break (or yield) are measured for multiphase poly(ether ether ketone) (PEEK)/poly(aryl ether sulfone) (PES) blends. Specimens with three different levels of thermal histories (quenched, as‐molded, and annealed) are prepared in order to study their effects on the mechanical properties of PEEK/PES blends. Synergistic behavior is observed in the tensile modulus and tensile strength of the blends in almost the whole range of compositions. The ductility of quenched blends measured as the elongation to break (yield) shows an unexpected synergistic behavior in the blend containing 90 wt % PEEK, although a negative deviation from additive behavior is observed in the rest of the compositions. A ductile–brittle transition is observed between 50 and 75 wt % PEEK in the blend. The ductile–brittle transition in as‐molded blends shifts to 75–90 wt % PEEK. Annealed blends show predominantly brittle behavior in the whole composition range. The experimental data are further correlated with the theoretically predicted results based on various composite models. Although the prediction based on these equations fails to fit the experimental data in the whole composition range, the simplex equations that are normally used for blends showing synergistic behavior produced a reasonable fit to the experimental data. The mechanical properties obtained for different blend compositions are further correlated with their morphology as observed by scanning electron microscopy. Morphological observation shows a two‐phase morphology in PES‐rich blends, which is an interlocked morphology in which the disperse phase is not clearly visible in PEEK‐rich blends, and a cocontinuous type of morphology for a 50/50 composition. Considerable permanent deformation of both the disperse and matrix phase, especially in the case of quenched tensile specimens, demonstrates the remarkable adhesion present between the two phases. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2887–2905, 2003     

Synthesis and characterization of poly(ether sulfone) and poly(ether sulfone ketone) copolymers

Poly(ether sulfone) and poly(ether sulfone ketone) copolymers (I–V) were synthesized by the nucleophilic substitution reaction of 4,4′-dihydroxy diphenyl sulfone (DHDPS, A) with various mole proportions 4,4′-difluoro benzophenone (DFBP, B) and 4,4′-difluoro diphenyl sulfone (DFDPS, C) using sulfolane as solvent in the presence of anhydrous K₂CO₃. The polymers were characterized by physicochemical and spectroscopic techniques. All polymers were found to be amorphous, and the glass transition temperature (T_g) was found to increase with the sulfonyl content of the polymers. ¹³C-nuclear magnetic resonance (NMR) spectral data was interpreted in terms of the compositional triads, BAB, BAC, CAC, ABA, and ABB, and indicate that transetherification occurs at high concentration of DFBP units in the polymer (IV). The good agreement between the observed and calculated feed ratios validates the triad analysis. Thermal decomposition studies reveal that the thermal stability of the polymers increases with increase in the carbonyl content in the polymer. Activation energies for thermal decomposition were found to be in the range of 160–203 kJ mol⁻¹ with the cleavage of ϕ SO₂ bond being the preponderant mode of decomposition and depended on the block length of the sulfonyl unit. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2113–2121, 1999     

Preparation and characterization of poly(vinyl chloride)‐graft‐acrylic acid membrane by electron beam

Poly(vinyl chloride) (PVC) was irradiated by electron beam in vacuum at 20 KGy to produce living free radicals, and then reacted with acrylic acid (AA) in solution to obtain the PVC‐g‐AA copolymers. The copolymers were characterized by Fourier transform infrared spectroscopy. Porous membranes were prepared from copolymers by the phase inversion technique. The morphology of PVC‐g‐AA membranes was studied by field emission scanning electron microscopy. The mean pore size and pore size distribution were determined by a mercury porosimeter. The mean pore size was 0.19 μm, and the bulk porosity was 56.02%. The apparent static water contact angle was 89.0°. The water drop penetration rate was 2.35 times to the original membrane. The maximum stress was 4.10 MPa. Filtration experiments were carried out to evaluate the fouling resistance of the PVC‐g‐AA membrane. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Fouling reduction of a poly(ether sulfone) hollow‐fiber membrane with a hydrophilic surfactant prepared via non‐solvent‐induced phase separation

Membrane fouling is still a crucial problem, especially in applications for water treatment. When fouling takes place on membrane surfaces, it causes flux decline, leading to an increase in production cost due to increased energy demand. The selection of the right membrane material and a special treatment of the membrane are required to avoid membrane fouling. This article reports the fouling resistance of a poly(ether sulfone) (PES) hollow‐fiber membrane modified with hydrophilic surfactant Tetronic 1307. Experiments on several methods of fouling were carried out to investigate the effect of the addition of nonionic surfactant Tetronic 1307 on membrane fouling. The effectiveness of a chemical agent [sodium hypochlorite (NaClO)] in the reduction of bovine serum albumin (BSA) deposition on the membrane surface was also evaluated. Permeation results showed that the fouling of a PES blend membrane with Tetronic 1307 was lower than that of the original PES membrane in the case of BSA filtration. A treatment with a 100 ppm NaClO solution was capable of removing BSA cake formation and effective at improving the relative permeability. The permeability of a PES blend membrane with Tetronic 1307 was almost 2 times higher than the original permeability when the membrane was treated with a 100 ppm NaClO solution because both BSA and Tetronic 1307 could be decomposed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of poly(aryl ether sulfone)s with metallophthalocyanine pendant unit

A series of novel poly(aryl ether sulfone) copolymers containing dicyanophenyl group were prepared by the reaction of bis(4‐chlorophenyl)sulfone with (3,4‐dicyano) phenylhydroquinone and 4,4′‐isopropylidenediphenol. On this basis, a series of poly(aryl ether sulfone)s containing metallophthalocyanine units were synthesized by the reaction of poly(aryl ether sulfone)s containing dicyanophenyl group with excessive amounts of 1,2‐dicyanobenzene and the corresponding metal salt in quinoline. All these copolymers were found to have high glass transition temperature and thermal stability. These copolymers were found to be soluble in common solvents, and capable of forming transparent films by solution casting. The copolymers containing metallophthalocyanine units showed strong optical absorption in the visible region, and exhibited blue photoluminescence in solution. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3457–3461, 2006     

Sulfonated poly(ether ether sulfone) copolymers for proton exchange membrane fuel cells

Novel aromatic sulfonated poly(ether ether sulfone)s (SPEESs) with tert‐butyl groups were synthesized by aromatic nucleophilic polycondensation of disodium 3,3′‐disulfonate‐4,4′‐dichlorodiphenylsulfone (SDCDPS), 4,4′‐dichlorodiphenylsulfone (DCDPS), and tert‐butylhydroquinone (TBHQ). The resulting copolymers showed very good thermal stability and could be cast into tough membranes. The morphology of the membranes was investigated with atomic force microscopy. The proton conductivity of SPEES‐40 membranes increased from 0.062 S/cm at 25°C to 0.083 S/cm at 80°C, which was higher than the 0.077 S/cm of Nafion 117 under the same testing conditions. These copolymers are good candidates to be new polymeric electrolyte materials for proton exchange membrane fuel cells. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1443–1450, 2007     

Phase morphology and mechanical properties of a poly(ether sulfone)‐modified bismaleimide resin

The polymerization‐induced phase‐separation behavior of a thermoplastic [poly(ether sulfone) (PES)]‐ modified thermosetting bismaleimide resin during isothermal curing was investigated with differential scanning calorimetry, time‐resolved light scattering, and scanning electron microscopy with various contents and molecular weights of PES. The results suggested that the phase structure changed from a dispersed structure to a bicontinuous structure to phase inversion with an increase in the PES content. Three kinds of PES with different molecular weights were used to study the effects of the molecular weight on the phase structure and mechanical properties of modified systems. With higher molecular weight PES, a phase‐inversion morphology could be obtained at lower PES contents. The curing conversion of bismaleimide was affected by the composition of the blend. The curing rate decreased with an increase in the PES content. A blend with 15 wt % PES of a suitable molecular weight had a higher tensile strength and elongation at break than that without PES. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

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