Surface Modifying Macromolecules Research Articles

Novel siliceous mesoporous phosphotungstic acid embedded chitosan/LSMM polymer membrane for direct methanol fuel cells

Direct Methanol Fuel Cells (DMFCs) research focuses on improving Proton Exchange Membranes (PEMs) to enhance ion exchange and proton conduction. Although Nafion® is stable both chemically and thermally, however it suffers methanol crossover. In this study, a novel composite PEM was introduced by blending chitosan (CS), hydrophilic surface modifying macromolecules (LSMM), and mesoporous siliceous phosphotungstic acid (mPTA-Si) at varying loadings. Notably, the CS/LSMM membrane with 0.25 wt% of mPTA-Si content and optimized hot pressing technique conditions (5 tonnes, 90 s and 135 °C) exhibited superior performance, with a proton conductivity of 0.097 S/cm and a power density of 60 mW/cm2. Additionally, properties such as tensile strength and ion exchange capacity surpassed those of pure CS by 14 % and 56.12 %, respectively. The unique characteristics of CS, mPTA, and LSMM collectively contributed to the promising attributes of the CS/LSMM/0.25mPTA-Si membrane for enhancing fuel cell performance.

Liquid-liquid extraction of phenolic wastewater through a surface modified poly(vinylidene fluoride-co-hexafluoropropylene) hollow fiber membrane contactor and process optimization

BackgroundStrict environmental regulations have been recognized for phenolic wastewater treatment due to toxicity of the phenolic compounds. In this study, solvent extraction of a phenolic wastewater was investigated via a liquid-liquid membrane contactor system. MethodsPorous poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) hollow fiber membranes were modified by coating an ultra-thin layer of hydrophobic surface modifying macromolecule (SMM). The membranes were characterized by various tests such as SEM-EDS, nitrogen permeation, overall porosity, contact angle and critical water entry pressure (CEPw). Significant findingsFrom SEM, an open structure with combination of finger-like and sponge-like structure was produced. The membrane exhibited high surface hydrophobicity (water contact angle of 109°) with good wetting resistance, overall porosity of 82% and mean pore size of 18 nm. From response surface methodology (RSM), the maximum phenol extraction flux of 2.02 × 10−3 kg/m2s was estimated by the model at the optimum process variables as phenol concentration of 448 mg/L, feed temperature of 42 °C, aqueous phase flowrate of 196 mL/min and organic phase flowrate of 117 mL/min. The coefficient of determination (R2) of 0.972 showed a close proximity between the model and the experimental data. The membrane showed a reasonable flux that can be a favorable alternative for industrial phenolic wastewater treatment.

Improved hemocompatibility of polysulfone hemodialyzers with Endexo® surface modifying molecules.

Anticoagulation therapy is widely used to reduce clotting during hemodialysis (HD), but may cause adverse effects in end-stage kidney disease patients. A new hemodialyzer with a membrane modified by surface modifying molecule was developed to improve hemocompatibility that aimed to reduce the need for anticoagulation during dialysis treatments. We compared membrane surface characteristics and in vitro hemocompatibility of the new hemodialyzer to the standard polysulfone (PSF) hemodialyzer membrane. Scanning electron microscopy, contact angle measurement (68° ± 3° test vs. 41.6° ± 6° control), and X-ray photoelectron spectrometry measurement for fluorine atomic % (7.4% ± 0.4% test vs. not detectable control), showed that the membrane surface was modified with surface modifying macromolecule (SMM1) but maintained membrane structure and surface hydrophilicity. Zeta potential of the blood-contacting surface showed that the absolute surface charge was reduced at neutral pH (-3.3mV ± 1.1mV test vs. -15.6mV ± 1.0mV control). Platelet count reduction was significantly less for the SMM1-modified dialyzer (40.88% ± 21.89%) compared to the standard PSF dialyzer (62.62% ± 34.13%), along with Platelet Factor 4 (1824.10ng/ml ± 436.26 ng/ml test vs. 2479.00 ng/ml ± 852.96 ng/ml control). These studies demonstrate the successful incorporation of SMM1 into the new hemodialyzer with the expected results. Our in vitro experiments indicate that the SMM1-modified hemodialyzers could improve hemocompatibility compared to standard PSF hemodialyzers and have the potential to minimize the patient's anticoagulant requirements during HD. Additional research with SMM1 additives incorporated into the entire dialysis circuit and use in a clinical settings are required to confirm these promising findings.

Seawater Desalination by Modified Membrane Distillation: Effect of Hydrophilic Surface Modifying Macromolecules Addition into PVDF Hollow Fiber Membrane.

Hollow fiber membranes of polyvinylidene fluoride (PVDF) were prepared by incorporating varying concentrations of hydrophilic surface-modifying macromolecules (LSMM) and a constant amount of polyethylene glycol (PEG) additives. The membranes were fabricated by the dry-wet spinning technique. The prepared hollow fiber membranes were dip-coated by hydrophobic surface-modifying macromolecules (BSMM) as the final step fabrication. The additives combination is aimed to produce hollow fiber membranes with high flux permeation and high salt rejection in the matter of seawater desalination application. This study prepares hollow fiber membranes from the formulation of 18 wt. % of PVDF mixed with 5 wt. % of PEG and 3, 4, and 5 wt. % of LSMM. The membranes are then dip-coated with 1 wt. % of BSMM. The effect of LSMM loading on hydrophobicity, morphology, average pore size, surface porosity, and membrane performance is investigated. Coating modification on LSMM membranes showed an increase in contact angle up to 57% of pure, unmodified PVDF/PEG membranes, which made the fabricated membranes at least passable when hydrophobicity was considered as one main characteristic. Furthermore, The PVDF/PEG/4LSMM-BSMM membrane exhibits 161 °C of melting point as characterized by the DSC. This value indicates an improvement of thermal behavior shows so as the fabricated membranes are desirable for membrane distillation operation conditions range. Based on the results, it can be concluded that PVDF/PEG membranes with the use of LSMM and BSMM combination could enhance the permeate flux up to 81.32 kg·m−2·h−1 at the maximum, with stable salt rejection around 99.9%, and these are found to be potential for seawater desalination application.

Fabrication and characterization of modified PVDF hollow fiber membrane coated with hydrophobic surface modifying macromolecules for desalination application

Polymeric membrane distillation (MD) can be used as a desalination application. It is a promising technology owing to mechanical stability, flexibility, and chemical resistance. However, polymeric-based MD needs to improve further due to low flux permeation in rejecting salt from seawater feed. PVDF hollow fiber membrane consisted of the hydrophilic (LSMM) and hydrophobic (BSMM) surface modifying macromolecules was fabricated. LSMM structure is end-capped by OH bonds which show hydrophilic nature while BSMM consists of a hydrophobic CF bond. By determining the appropriate ratio of LSMM and BSSM loading in the PVDF substrate, it could enhance the MD performance. LSMM could improve the hydrophilic nature at the lumen of the PVDF hollow fiber membrane which can promote the water flux permeation. On the other hand, the positioning of BSMM at the shell layer of the PVDF hollow fiber membrane through dip coating could lead to greater vapor transport. The effect of BSMM loading on the hydrophobicity, morphology, average pore size, porosity, thermal, and membrane performance was investigated. The BSMM loading at 1.5 wt% exhibited the highest contact angle value of 118.76°. Meanwhile, SEM images revealed finger-like structures as well as the LSMM and BSMM structures at the inner and outer layers of the modified PVDF membranes, respectively. The hollow fiber coated with 1.5 wt% BSMM offered the highest salt rejection percentage of 99.99%. Meanwhile, 1.0 wt% BSMM coated PVDF/PEG/LSMM membrane showed a maximum flux of 20.74 kg/m2.h. Furthermore, the melting point of the resulting membranes was 161 °C with various BSMM loadings which is the typical condition range for membrane distillation operation. In conclusion, the BSMM coating agent has a huge potential to improve the membrane’s hydrophobicity and performance.

Safety of a Novel Dialyzer Containing a Fluorinated Polyurethane Surface-Modifying Macromolecule in Patients with End-Stage Kidney Disease

Background: By inhibiting the adsorption of protein and platelets, surface-modifying macromolecules (SMMs) may improve the hemocompatibility of hemodialyzers. This trial aims to assess the performance and safety of a novel dialyzer with a fluorinated polyurethane SMM, Endexo™. Methods: This prospective, sequential, multicenter, open-label study (NCT03536663) was designed to meet regulatory requirements for clinical testing of new hemodialyzers, including assessment of the in vivo ultrafiltration coefficient (Kuf). Adults prescribed thrice-weekly hemodialysis were eligible for enrollment. After completing 12 hemodialysis sessions with an Optiflux® F160NR dialyzer, patients received 38 sessions with the dialyzer with Endexo. Evaluated parameters included the in vivo Kuf of the dialyzer with Endexo extent of removal of urea, albumin, and β2-microglobulin (β2M), as well as complement activation. Results: Twenty-three patients received 268 hemodialysis treatments during the Optiflux period, and 18 patients received 664 hemodialysis treatments during the Endexo period. Three serious adverse events were reported, and none of them were considered device related. No overt complement activation was observed with either dialyzer. Both dialyzers were associated with comparable mean increases in serum albumin levels from pre- to posthemodialysis (Optiflux: 7.9%; Endexo: 8.0%). These increases can be viewed in the context of a mean increase in hemoglobin of approximately 5% and a mean ultrafiltration volume removed of approximately 2.2 L. The corrected mean β2M removal rate was 47% higher during the Endexo period (67.73%). Mean treatment times (208 vs. 205 min), blood flow rates (447.7 vs. 447.5 mL/min), dialysate flow rates (698.5 vs. 698.0 mL/min), urea reduction ratio (82 vs. 81%), and spKt/V (2.1 vs. 1.9) were comparable for the Endexo and Optiflux periods, respectively. The mean (SD) Kuf was 15.85 (10.33) mL/h/mm Hg during the first use of the dialyzer with Endexo (primary endpoint) and 16.36 (9.92) mL/h/mm Hg across the Endexo period. Conclusions: The safety of the novel dialyzer with Endexo was generally comparable to the Optiflux dialyzer, while exhibiting a higher β2M removal rate.

Preparation of hydrophilic polycaprolactone/modified ZIF-8 nanofibers as a wound dressing using hydrophilic surface modifying macromolecules

In this study, a simple one-step method was introduced to prepare suitable PCL wound dressing by using a small amount of hydrophilic surface modifying macromolecule (LSMM) with ends capped with Polyethylene glycol and aminated zeolitic imidazolate frameworks (MZIF-8) as a drug carrier for curcumin to accelerate the healing process while improve drug loading and controlled drug release. First, LSMM was synthesized and its chemical structure and average molecular weight were characterized by FTIR and gel permeation chromatography. Afterward, PCL nanofibers containing LSMM and curcumin loaded MZIF-8 were prepared and characterized. The surface contact angle of PCL nanofibers containing 1 wt% LSMM was reduced from 130 to 31° due to LSMM molecules migration to the nanofiber surface. Furthermore, tensile strength test results showed that the incorporation of MZIF-8 nanoparticles significantly improved the mechanical properties of the nanofibers. Finally, all samples were evaluated for cell cytotoxicity which confirmed the biocompatibility of the samples. Fibroblast cell adhesion was also evaluated and results indicated that fibroblast cell adhesion was improved when 1 wt% LSMM was added.

Effects of hydrophilic surface macromolecule modifier loading on PES/O-g-C3N4 hybrid photocatalytic membrane for phenol removal

HydrophiLic surface modifying macromolecules (LSMM) modified polyethersulfone (PES) based photocatalytic membranes have been successfully prepared. This hybrid photocatalytic membrane applying oxygen-doped graphitic carbon nitride (g-C3N4) as a photocatalyst was successfully fabricated via phase inversion technique in flat sheet form at ambient temperature. The potential of LSMM as membrane modifier was explored in detail under various loadings (1–5 wt%). The results show that the LSMM addition successfully increased the membrane hydrophilicity which may consequently prevent the membrane from comprehensive fouling. More appearance of g-C3N4 on the membrane surface was observed by Scanning Electron Microscopy (SEM) and Atomic Force Microscope (AFM) analyses upon the LSMM addition. However, the trend tended to decline at the loading beyond 4 wt% of LSMM. At 4 wt% of LSMM, the PES/g-C3N4 membrane successfully decreased phenol concentration up to 35.78% and rejected 14.73% of phenol. From the water flux result, the application of LSMM in water treatment application was hindered by the flux deterioration but a considerably high flux for an ultrafiltration membrane. The results indicate that the introduction of LSMM in the PES/g-C3N4 hybrid photocatalytic membrane showed the great potential of LSMM as a membrane surface modifier for photocatalytic activities and membrane separation performance.

Influence of Air-Gap Length on CO2 Stripping from Diethanolamine Solution and Water Performance of Surface Modified PVDF Hollow Fiber Membrane Contactor

Surface Modifying Macromolecule (SMM) blended PVDF hollow fibers (HFs) were spun at different air-gaps (o to 20 cm) and used for CO2 stripping from aqueous DEA solution and water. The manufactured fibers were firstly subjected to various characterization tests such as contact angle and critical water entry pressure measurement to evaluate the HF hydrophobicity and wetting resistance, respectively. The pure helium permeation experiments were also conducted to obtain membrane pore size and effective porosity. Morphology of the HFs was investigated by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The SEM images showed that both outer and inner diameters of HFs decreased significantly by increasing air-gap length which mainly because of elongation of HF caused by gravity while travelling through the air-gap. Also, the gradual decrease in roughness on the external surface of the produced HFs was observed from the AFM images. It was found that the increase of liquid velocity enhances the CO2 stripping flux. It was found that 10 cm air-gap gave maximum stripping flux of 3.34 x 10(-2) and 1.34 x 10(-3) (mol/m(2)s) for DEA solution and water, respectively. The increase in gas velocity, on the other hand, did not affect the stripping flux significantly. It was observed that the increase of temperature from 25 to 80 degrees C led to the marked enhancement of stripping flux from 6.30 x 10(-3) to 3.34 x 10(-2) (mol/m(2)s) and 6.5 x 10(-5) to 1.34 x 10(-3) (mol/m(2)s), for DEA solution and water, respectively. Furthermore, the increase in DEA concentration from 0.25 to 1 mol/L, led to the enhancement of the stripping flux from 6.84 x 10(-3) to 3.34 x 10(-2) (mol/m(2)s) at a liquid velocity of 0.7 m/s. It was concluded that the HF spun at 10 cm air-gap exhibited the best stripping performance among all fabricated HFs.

Performance of PES/LSMM-OGCN Photocatalytic Membrane for Phenol Removal: Effect of OGCN Loading.

In designing a photocatalytic oxidation system, the immobilized photocatalyst technique becomes highly profitable due to its promising capability in treating organic pollutants such as phenols in wastewater. In this study, hydrophilic surface modifying macromolecules (LSMM) modified polyethersulfone (PES) hybrid photocatalytic membranes incorporated with oxygenated graphitic carbon nitride (OGCN) was successfully developed using phase inversion technique. The effectiveness of the hybrid photocatalytic membrane was determined under different loading of OGCN photocatalyst (0, 0.5, 1.0, 1.5, 2.0, and 2.5 wt%). The best amount of OGCN in the casting solution was 1.0 wt% as the agglomeration did not occur considering the stability of the membrane performance and morphology. The highest flux of 264 L/m2·h was achieved by PES/LSMM-OGCN1.5wt% membrane. However, the highest flux performance was not an advantage in this situation as the flux reduced the rejection value due to open pores. The membrane with the highest photocatalytic performance was obtained at 1.0 wt% of OGCN loading with 35.78% phenol degradation after 6 h. Regardless of the lower rejection value, the performance shown by the PES/LSMM-OGCN1.0wt% membrane was still competent because of the small difference of less than 1% to that of the PES/LSMM-OGCN0wt% membrane. Based on the findings, it can be concluded that the optimisation of the OGCN loading in the PES hybrid photocatalytic membrane indeed plays an important role towards enhancing the catalyst distribution, phenol degradation, and acceptable rejection above all considerations.

Surface Characterization by X–Ray Photoelectron Spectroscopy of Polyethersulfone Hollow Fiber Membranes Modified with Surface Modifying Macromolecules

Novel charged–surface modifying macromolecules (cSMMs) were synthesized and incorporated into polyethersulfone(PES) hollow fiber membranes for water separation application. The macromolecules were synthesized with diisocynate, polypropylene oxide and poly(ethylene glycol)–hydroxybenzene sulfonate (PEG–HBS). In this study, the surface of polyethersulfone hollow fiber membranes prepared by the phase inversion method was modified using 1 wt.% of SMM and 22 wt.% PES concentration in the polymer casting solution. The effect of cSMM on PES hollow fiber membrane modification was investigated. Elemental analysis shows enrichment of oxygen and sulfone on the modified PES membrane bulk properties. In addition, the glass transition temperature confirms the miscibility of the cSMM in PES. Important relations between surface characteristics due to SMM modification with the PES membrane for water separation performance with respect to XPS characterization also highlighted.

Effect of Temperature on Sulfonated Poly (Ether Ether Ketone) Blended with Charged Surface Modifying Macromolecule Membrane for DMFCs

The purpose of this research was to determine the behavior of modified sulfonated poly (ether ether ketone) (SPEEK) with degree of sulfonation (DS) 68% blended by charged surface modifying macromolecule (cSMM) at different operating temperatures (room to 80°C) for direct methanol fuel cell application. The fabricated SPEEK (68)/cSMM membrane was compared with SPEEK (68) and Nafion112 membranes in terms of water uptake, proton conductivity, and methanol permeability at relatively high temperatures. The water uptake of SPEEK (68)/ cSMM was higher than that of SPEEK (68) and Nafion112 over the temperature ranges studied; however it was dissolved at 80°C. Proton conductivity of SPEEK (68)/cSMM showed improvement compared to SPEEK (68) at temperature range, but still lower than Nafion112, moreover methanol permeability behavior of fabricated membrane was lower at high temperatures as compared to that of SPEEK and Nafion112 and better overall performance was allocated to the fabricated membrane at 60°C.These results indicate that SPEEK (68)/cSMM membrane is promising to be used as a proton exchange membrane in direct methanol fuel cell.

Influence of Surface Modifying Macromolecules (SMMs) on Polyethersulfone Hollow Fiber Membranes for Water Separations

The objective of this work is to modify the polyethersulfone (PES) hollow fiber membranes by blending with Surface Modifying Macromolecules (SMMs) which were able to introduce charges at the membrane surface. To study the effects of SMMs, PES solutions with and without blending SMMs were spun by the dry–wet phase inversion method. The membranes were characterized by ionic solutes permeation and Field Emission Scanning Electron Microscopy (FESEM). There was no significant difference in the membrane morphology between the membranes with and without SMM blending, indicating that the morphology of the base polymer remained relatively unchanged. However, based on Energy Dispersive X–ray (EDX) analysis, the presence of SMM’s elements at the surface of the SMM blended membranes was detected. The pure water permeation rates were found two times increased with the existence of SMMs, while rejection towards ionic solutes remained relatively unchanged.

Recent Advances in Thin Film Composite (TFC) Reverse Osmosis and Nanofiltration Membranes for Desalination

Reverse osmosis (RO) by polymeric membranes is known to be among the successful technologies for brackish and seawater desalination. For the development of these polymeric RO membranes, two different techniques have been used – the phase inversion method for asymmetric membranes, such as cellulose acetate membrane and the interfacial polymerization for thin film composite (TFC) membranes. Despite the high quality of the water produced by TFC–RO process, TFC membranes are susceptible to fouling. After a long period of academic and industrial researches, it is generally accepted that hydrophilicity, surface charge, and surface roughness of the TFC membrane surface are the major factors which affect the membrane susceptibility to fouling. As a result, several recent studies have focused on tailoring these properties with the aim of producing TFC membranes with reduced fouling as well as enhanced flux and salt rejection for use in desalination.In this study, authors present a comprehensive summary of the most recent findings in the literature focusing on the enhancement of TFC RO and nanofiltration membrane performance in desalination applications, by tailoring membrane characteristics. The authors would then present a new concept for the preparation of TFC membranes by interfacial polymerization on porous polysulfone support using novel additives, namely, surface modifying macromolecules (SMMs). Hydrophilic SMMs (LSMMs) were synthesized both ex–situ and in–situ within the organic solvent of the TFC system. The RO performance results showed that the addition of the ex–situ LSMM significantly decreased the salt rejection of the membrane and slightly reduced the flux, while in the case of the in–situ LSMM, salt rejection was improved but the flux declined at different rates for different LSMM concentrations. The membrane prepared by the in–situ LSMM exhibited less flux decay over an extended operational period.

Preparation and Characterization of Blending Sulfonated Poly(ether ether ketone) with Charged Surface Modifying Macromolecules

Charged surface modifying macromolecule (cSMM) end capped with sulfonic group was prepared and blended into sulfonated poly(ether ether ketone) (SPEEK). The modified membrane was characterized for polymer electrolyte membrane application; i.e. a SPEEK/cSMM blend membrane was compared to a SPEEK membrane and a Nafion 112 membrane for the thermal and mechanical stability, hydrophilicity and water uptake. Thermal and mechanical stability of the blend membrane were slightly reduced from that of the SPEEK membrane but still higher than that of the Nafion 112 membrane. The cSMM which was end–capped with sulfonic group has increased the total –SO3H group in the blend membrane. As a result, the blend membrane showed an increase in hydrophilicity and water uptake as compared to the pristine membrane. The addition of cSMM with an additional –SO3– charge has enabled the water uptake to be increased which is crucial to enhance the proton conductivity that of SPEEK. Moreover, the extra –SO3– can facilitate the transfer of proton better. This study found that cSMM is a good candidate as an additive for SPEEK in improving its function as polymer electrolyte membrane.

Preparation and characterization of hydrophilic surface modifier macromolecule modified poly (ether sulfone) photocatalytic membrane for phenol removal

A modified poly (ether sulfone) (PES) by hydrophilic surface modifying macromolecules (LSMM) incorporated with oxygenated graphitic carbon nitride (OGCN) photocatalyst (PES/OGCN-LSMM) was successfully prepared as a hybrid photocatalytic membrane. The effect of solvent evaporation time during membrane fabrication was studied by focusing on the positioning of LSMM in order to provide the desirable properties of the PES/OGCN-LSMM hybrid membrane for phenol removal performance by photocatalytic and separation. The PES/OGCN-LSMM membranes exhibited a decreased value of contact angle as the solvent evaporation time increased. The SEM images revealed a dense top layer supported by finger-like structures underneath, which was formed for the membranes at 0–4 min solvent evaporation time, while a sponge-like microvoid structure was observed at 5 min of solvent evaporation time. It is interesting to highlight that as the evaporation time increased, the pure water flux decreased as the result of compact denser membrane. Benefitting the special feature of LSMM that tends to migrate upwards upon mixing, the LSMM effectively assisted OGCN photocatalyst to the top layer of the membrane. This was revealed by SEM top surface images that more OGCN photocatalyst particles were seen distributed on the dense top layer of the membrane upon longer solvent evaporation time supported by the membrane topography analysis. It was found that the phenol reduction by rejection and photocatalytic tests was the highest at 5 min solvent evaporation time, whilst water flux was the lowest. The obtained results showed that the LSMM has indeed assisted the positioning of OGCN towards the top layer of the membrane and consequently increased the photocatalytic activity of the membrane on phenol.

Optimal modification of poly(vinylidene fluoride) membrane surface by using surface-modifying macromolecules for application in membrane distillation

Optimal modification of poly(vinylidene fluoride) membrane surface by using surface-modifying macromolecules for application in membrane distillation

Separation of macromolecular proteins and removal of humic acid by cellulose acetate modified UF membranes

Surface modifying macromolecules (SMMs) were synthesized with various polyurethane pre polymers end-capped with different groups and blended into the casting solution of cellulose acetate (CA) to prepare surface modified ultra-filtration (UF) membranes for water filtration applications. The surface modification of the CA membranes was confirmed by the FTIR and static contact angle (SCA) measurements. The membranes so prepared had the typical characteristics of UF membranes as confirmed by scanning electron microscopy (SEM). Membrane properties were studied in terms of membrane compaction, percentage water content (%WC), pure water flux (PWF), membrane hydraulic resistance (Rm), molecular weight cut-off (MWCO), average pore size and porosity. The result showed that PWF, %WC, MWCO and pore size increased whereas the Rm decreased by the addition of SMMs. The significant effect of SMMs on the fouling by humic acid (HA) was also observed. It was found that the cSMM-3 membrane, in which SMM was synthesized with diethylene glycol (DEG) and hydroxyl benzene sulfonate (HBS) was blended, had the highest flux recovery ratio FRR (84.6%), as well as the lowest irreversible fouling (15.4%), confirming their improved antifouling properties. Thus, the SMM modified CA membranes had proven, to play an important role in the water treatment by UF.

Effect of PVDF blending on the structure and performance of PEI hollow fiber membrane in CO2 separation process

The surface hydrophobicity of membrane is a key factor in contactor applications where the penetration of liquid into membrane pores has negative effect on the contactor performance. Therefore, different methods have been proposed for surface modification. Blending hydrophobic polymers such as surface modifying macromolecules (SMM) has been investigated in our earlier researches. In this study, the effect of polyvinylidene fluoride (PVDF) blending on the surface and bulk morphology of polyetherimide (PEI) hollow fiber membrane and its performance in membrane gas absorption process was studied. It was found that the pore size increased from 112nm to 210nm from the neat PEI membrane to the PEI membrane spun from the solution blended with 0.25wt% PVDF. At the same time, the contact angle increased from 78.3 and 84.3. Furthermore, the absorption flux of PVDF blended membrane enhanced by 13% compared to the neat PEI membrane.

Enhancing proton conduction of sulfonated poly (phenylene ether ether sulfone) membrane by charged surface modifying macromolecules for H2/O2 fuel cells

Blend membranes comprising sulfonated poly (phenylene ether ether sulfone) (SPEES) - charged surface modifying macromolecules (cSMMs) were fabricated as an alternative proton exchange membrane (PEM) for H2/O2 fuel cell applications. Prepared membranes were characterized by determining the ion exchange capacity, water uptake, proton conductivity, oxidative stability and dimensional stability. The water uptake of SPEES/cSMM blended membrane was found to be higher than that of the pristine SPEES and the Nafion 117 membranes. Proton conductivity of the blend membranes is in the range of 10−3 to 10−2 S/cm. The conductivity of the prepared membranes increases with temperature, in particular, the poly (propylene glycol) – hydroxy benzene sulfonate (PPG-HBS) blended SPEES membrane shows rise in conductivities from 1.61 × 10−2 S/cm (25 °C) to 5.22 × 10−2 S/cm (80 °C). Surface morphology of the membranes was investigated by tapping mode atomic force microscopy (AFM), which indicates that the nodule size and surface roughness are increased by the incorporation of cSMM into the SPEES matrix. Surface modified blended membranes exhibited excellent thermal stability and acceptable dimension stability in 80 °C, which implies that the SPEES/cSMM blended membranes are promising materials for PEMFC application.