Preparation and characterization of Silicalite‐1/PDMS surface sieving pervaporation membrane for separation of ethanol/water mixture

To improve the pervaporation performance of Silicalite‐1/PDMS composite membrane by adding a small amount of Silicalite‐1 zeolite, novel Silicalite‐1/PDMS surface sieving membranes (SSMs) were prepared by attaching Silicalite‐1 particles on the PDMS membrane surface. The obtained membranes and traditional mixed‐matrix membranes (MMMs) were characterized by SEM, XRD, TGA, FT‐IR, and pervaporation separation of ethanol–water mixture. Effects of Silicalite‐1 particles content, feed temperatures, and feed compositions on the separation performance were discussed. From the cross‐section view SEM images of SSMs, a two‐layer structure was observed. The thickness of the Silicalite‐1 layer was about 300 nm to 2 μm. The TGA analysis indicates that the zeolite concentration in 3 wt % SSM is lower than 10 wt % MMMs. In the ethanol/water pervaporation experiment, the separation factor of Silicalite‐1/PDMS SSMs increased considerably compared with pure PDMS membrane. When the suspensions concentrations of Silicalite‐1 particles reached 3 wt %, the separation factor was about 217% increase over pure PDMS membrane and 52.9% increase over 10 wt % Silicalite‐1/PDMS MMMs. As the ethanol concentration in the feed increases, the separation factor of SSMs increases, whereas permeation flux decreases. At the same time, with increasing operating temperature, the permeation flux of SSMs increased. The stability of SSMs at high temperature is better than the traditional MMMs. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42460.     

Preparation and characterization of cellulose triacetate membranes via thermally induced phase separation

A series of cellulose triacetate (CTA) membranes were prepared via thermally induced phase separation (TIPS) process with dimethyl sulfone (DMSO2) and polyethylene glycol (PEG400) as a crystallizable diluent and an additive, respectively. The phase separation behavior of CTA/DMSO2/PEG400 ternary system was investigated in detail by optical microscopy, differential scanning calorimetry and wide angle X‐ray diffraction. This ternary system dynamically undergoes solid‐solid phase separation and thus the CTA membranes possess cellular, lacy, plate‐, or even ellipse‐shaped pores. However, we can modulate the pore structure, porosity, water flux, and mechanical properties of the membranes by varying polymer concentration, composition of the mixed diluent, and cooling condition. Due to the intrinsic hydrophilicity, the prepared CTA membranes have better antifouling property than polysulfone membranes. These porous membranes were used as supports to fabricate thin‐film composite forward osmosis (FO) membranes, which show good water permeability and selectivity. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44454.     

Preparation of enduringly antifouling PVDF membrane with compatible zwitterionic copolymer via thermally induced phase separation

The compatible zwitterionic copolymers of poly(methyl methacrylate [3‐(methacryloylamino)propyl]dimethyl(3‐sulfopropyl)ammonium‐hydroxide) p(MMA‐MPDSAH) with different MPDSAH ratio are synthesized by free radical polymerization. A serial of copolymers are obtained successfully with narrow molecular weight dispersion. The MPDSAH branch ratio varies from 5% to 20%. It is initially applied to fabricate enduringly antifouling poly(vinylidene fluoride) (PVDF) membrane through a simple approach of blending by thermally induced phase separation (TIPS). The influence of zwitterionic copolymer on membrane morphology is studied by scanning electron microscopy. It was proven effective to improve the hydrophilic property of PVDF membrane as the water contact angles dramatically decreased from 80° to 40°, leading to a significant enhancement of antifouling ability. The absorbed bull serum albumin (BSA) content on modified membranes has cut almost 50%. The residual content of p(MMA‐MPDSAH) in membrane is over 40% and able to reach 80% even at vigorous rinsing by controlling copolymer structure. It guarantees the modified membrane has vested enduringly antifouling ability. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41362.     

Influence of a sorbitol‐based nucleating agent modified with silsesquioxanes on the non‐isothermal crystallization of isotactic polypropylene

This article investigates the effect of modifying the polypropylene (iPP) α‐phase nucleating agent 1,3:2,4‐bis(3,4‐dimethylbenzylidene) sorbitol (DMDBS) with tetrasilanolphenyl silsesquioxane (phPOSS). It has been proven that an increasing amount of silsesquioxane leads to differences in the crystallization behavior. What is more, it has been observed that the nucleation effect that results from the addition of sorbitol derivatives is suppressed by phPOSS activity. To understand the influence of phPOSS addition on the crystallization kinetics of PP/DMDBS/phPOSS composites that have been prepared by melt processing in a twin screw extruder, differential scanning calorimetry, rotational rheometry and Fourier transform infrared spectroscopy are performed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40131.     

Surface‐modified MgO nanoparticle enhances the mechanical and direct‐current electrical characteristics of polypropylene/polyolefin elastomer nanodielectrics

Polypropylene (PP)/polyolefin elastomer (POE) blends and MgO/PP/POE nanocomposites were fabricated by melt blending. The morphology, mechanical, and electrical properties of the nanocomposites were investigated. Scanning electron microscopy showed that the surface‐modified MgO nanoparticles were well dispersed in the polymer matrix at low loadings of less than 3 phr. X‐ray diffraction demonstrated that the crystalline phases of PP in the composites were changed and that the β phase significantly increased. An examination of the electrical properties revealed that the direct‐current (dc) electric breakdown strength and space‐charge suppression effect were remarkably improved by the introduction of the surface‐modified MgO nanoparticles. In addition, obvious enhancements in the tensile modulus and strength were obtained as a result of the synergistic toughening of the POE and MgO nanoparticles. Thus, MgO/PP/POE nanocomposites with enhanced mechanical and electrical properties have great potential to be used as recyclable insulation materials for high‐voltage dc cables with large transmission capacities and high operating temperatures. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 132, 42863.     

Preparation of PVDF/poly(tetrafluoroethylene‐co‐vinyl alcohol) blend membranes with antifouling propensities via nonsolvent induced phase separation method

Poly(vinylidene fluoride) (PVDF) was blended with a new amphiphilic copolymer, poly(tetrafluoroethylene‐co‐vinyl alcohol) [poly(TFE‐VA)], via non‐solvent induced phase separation (NIPS) method to make membranes with superior antifouling properties. The effects of the VA/TFE segment ratio of the copolymer and the copolymer/PVDF blend ratio on the properties of the prepared membranes were studied. Membranes with similar water permeabilities, surface pore sizes, and rejection properties were prepared and used in bovine serum albumin (BSA) filtrations with the same initial water flux and almost the same operating pressure, to evaluate the sole effect of membrane material on fouling propensity. While the VA/TFE segment ratio strongly affected the membrane antifouling properties, the effects of the copolymer/PVDF blending ratio were not so drastic. Membrane surface hydrophilicity increased, and BSA adsorption and fouling decreased upon blending a small amount of amphiphilic copolymer with a high VA/TFE segment ratio with PVDF (copolymer/PVDF blending ratio 1:5). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43780.     

Fabrication of nanodiamond‐based composite monolithic column and its application in separation of small molecules

A nanodiamond‐based composite monolithic column was fabricated by redox initiation for high‐performance liquid chromatography. In the fabrication process, functionalized nanodiamond was used as the functional monomer, dipentaerythritol hexaacrylate and 1,10‐decanediol diacrylate as cross‐linking agents, polyethylene glycol 400 and 1‐propanol as coporogens, and dibenzoyl peroxide and N,N‐dimethyl aniline as initiators. Compared to polymer monolithic columns without nanodiamond, a nanodiamond‐based composite monolithic column prepared under the same conditions exhibited relatively high resolution and efficiency. Characterizations of the resulting nanocomposite were carried out, including scanning electron microscopy, mercury intrusion porosimetry, nitrogen adsorption–desorption isotherm measurement, and thermogravimetric analysis. The ND‐based composite monolith exhibited a uniform and reticular skeleton microstructure, thermal stability, and mechanical stability. In addition, the nanodiamond‐based composite monolithic column was used to separate a series of small molecules with good resolution and reproducibility in high‐performance liquid chromatography. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43776.     

Enhanced water flux through ultrafiltration polysulfone membrane via addition‐removal of silica nano‐particles: Synthesis and characterization

In the present paper, hierarchically structured ultrafiltration polysulfone (PSf) membrane was prepared to explore the effect of addition and subsequent removal of SiO₂ nano‐particles on the membrane morphology, hydrophilicity, and separation properties. The PSf based membranes namely PSf, PSf/SiO₂ and PSf/WSiO₂ (i.e. SiO₂ nano‐particles was acid‐washed and removed from PSf/SiO₂), were synthesized and characterized by different characterization methods. Pure water flux through the membranes was determined using a filtration unit operating at a continuous dead‐end flow mode. The modification enhanced the morphology, hydrophobicity, porosity and transport properties of the modified membranes, although the molecular weight cut‐off (MWCO) of the membranes was not changed considerably. In comparison, PSf/WSiO₂ membrane exhibited excellent pure water flux (about 4.5 times the flux of PSf, and 17 times the flux of PSf/SiO₂), although antifouling property of PSf/SiO₂ in separation of bovine serum albumin (BSA) was better than that of PSf and PSf/WSiO₂ membranes. The results suggested that the addition/removal of sacrificial solid fillers within/from a membrane matrix may provide a promising strategy to enhance PSf membrane transport property. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43556.     

Preparation and testing of Nafion/titanium dioxide nanocomposite membrane electrode assembly by ultrasonic coating technique

Membrane electrode assemblies with Nafion/nanosize titanium dioxide (TiO₂) composite membranes were manufactured with a novel ultrasonic‐spray technique (UST) and tested in proton exchange membrane fuel cell (PEMFC). The structures of the membranes were investigated by scanning electron microscopy (SEM), X‐ray diffraction (XRD), and thermogravimetric analysis. The composite membranes gained good thermal resistance with insertion of TiO₂. The SEM and XRD techniques have proved the uniform and homogeneous distribution of TiO₂ and the consequent enhancement of crystalline character of these membranes. The existence of nanometer size TiO₂ has improved the thermal resistance, water uptake, and proton conductivity of composite membranes. Gas diffusion electrodes were fabricated by UST. Catalyst loading was 0.4 (mg Pt) cm^?2 for both anode and cathode sides. The membranes were tested in a single cell with a 5 cm² active area operating at the temperature range of 70°C to 110°C and in humidified under 50% relative humidity (RH) conditions. Single PEMFC tests performed at different operating temperatures indicated that Nafion/TiO₂ composite membrane is more stable and also performed better than Nafion membranes. The results show that Nafion/TiO₂ is a promising membrane material for possible use in PEMFC at higher temperature. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40541.     

Preparation and characterization of polybutylene‐succinate/poly(ethylene‐glycol)/cellulose nanocrystals ternary composites

Ternary composites were prepared by twin screw extrusion from polybutylene‐succinate (PBS), poly(ethylene‐glycol) (PEG), and cellulose nanocrystals (CNC). The aim of the work is to improve the physical–mechanical properties of PBS by the addition of CNC. A PEG/CNC masterbatch was prepared in order to achieve a good dispersion of hydrophilic CNC in the hydrophobic PBS. The influence of the nanoparticle content on the polymer properties was studied. Regarding the thermal properties fractioned crystallization phenomena of PEG was observed during cooling from the melt. No significant nucleating effect of the nanocellulose was observed. The material containing 4 wt % of CNC showed the best mechanical performance among the nanocomposites studied due to the combination of high modulus and elongation at break with a low detrimental in strength compared with the PBS/PEG blend. Moreover, no nanocellulose agglomerations were observed in its FESEM micrograph. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43302.     

Preparation and properties of hydrophobic poly(vinylidene fluoride)–SiO2 mixed matrix membranes for dissolved oxygen removal from water

The application of the membrane method for removing dissolved oxygen (DO) from water on the laboratory scale was studied. Flat mixed matrix membranes were composed of poly(vinylidene fluoride) (PVDF) and hydrophobic nanosilica particles, which were used to improve the DO removal process. The SiO₂ particles were modified by a silane coupling agent and examined by Fourier transform infrared spectroscopy. It was shown that the surface of the SiO₂ particles was bonded to hydrophobic long‐chain alkane groups through chemical bonding. The effects of adding SiO₂ particles on the membrane properties and morphology were examined. The results show that the porosity and pore size of the membrane were affected by the introduction of SiO₂ particles, and the cross‐sectional morphology of the PVDF composite membranes changed from fingerlike macrovoids to a spongelike structure. The membrane performance of DO removal was evaluated through the membrane unit by a vacuum degassing process. It was found that the SiO₂/PVDF hybrid membranes effectively improved the oxygen removal efficiency compared with the original PVDF membranes. The maximum permeation flux was obtained when the loading amount was 2.5 wt %. The effect of the downstream vacuum level was also investigated. The experimental results show that the SiO₂/PVDF hybrid membranes had superior performances and could be an alternative membrane for removing DO from water. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40430.     

Hydrophilic goethite nanoparticle as a novel antifouling agent in fabrication of nanocomposite polyethersulfone membrane

The goethite nanoparticle was used as a multifunctional additive to fabricate antifouling polyethersulfone (PES) nanofiltration membranes. The goethite/PES membranes were synthesized via the phase inversion method. The scanning electron microscopy (SEM) photographs showed an increase in pore size and porosity of the prepared membranes with blending of the goethite. The static water contact angle measurements confirmed a hydrophilic modification of the prepared membranes. With increase in the goethite content from 0 to 0.1 wt %, the pure water flux increased up to 12.7 kg/m² h. However, the water permeability decreased using high amount of this nanoparticle. Evaluation of the nanofiltration performance was performed using the retention of Direct Red 16. It was observed that the goethite/PES membranes have higher dye removal capacity (99% rejection) than those obtained from the unfilled PES (89%) and the commercial CSM NE 4040 NF membrane (92%). In addition, the goethite/PES blend membranes showed good selectivity and antifouling properties during long‐term nanofiltration experiments with a protein solution. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43592.     

Modified zeolitic–midazolate framework 8/poly(ether‐block‐amide) mixed‐matrix membrane for propylene and propane separation

In this study, we fabricated a dual‐layer PES–poly(ether‐block‐amide) (PEBA) composite membrane that included zeolitic–midazolate framework 8 (ZIF‐8) particles and evaluated it for propylene and propane separation under pure and mixed feed conditions. To improve the performance, compatibility, and distribution of particles in the polymer matrix, the ZIF‐8 particles were modified by 3‐(triethoxysilyl) propyl amine (APTES) and 3‐(trimethoxysilyl) propyl amine (APTMS) amino silane coupling agents. Particle modification did not have much effect on the structure and particle size and slightly reduced the membrane specific surface area. The modified particles tended to be in the soft section. At the high loading rate of modified particles, their appropriate compatibility increased the membrane gas permeability () and selectivity. APTES with the proper chain length compared with APTMS had a higher and the same selectivity. The best performance (by 32.1 gpu) was found in PES–PEBA–ZIF‐8–APTES 20%. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46273.     

Preparation of PVDF/CaCO3 hybrid hollow fiber membranes for direct contact membrane distillation through TIPS method

Poly(vinylidene fluoride) (PVDF)–CaCO₃ hybrid hollow fiber membranes with a cellular structure and prominent permeability were fabricated via the thermally induced phase separation method for membrane distillation. CaCO₃ nanoparticles were introduced to the casting solution to improve the properties of the membranes. The effect of CaCO₃ dosage on the morphology was investigated. The prepared membranes were characterized by differential scanning calorimetry, SEM, and atomic force microscopy. The results showed that liquid–liquid phase separation preceded solid–liquid phase separation during the spinning process. Low dosages of CaCO₃ had a strong influence on the crystallization of PVDF molecules. The contact angle of the membrane increased with the addition of CaCO₃ nanoparticles. The maximum dead end pure water flux was as high as 1295.5 L/(m² h). The direct‐contact membrane distillation flux of the optimized PVDF/CaCO₃ hybrid membrane achieved 63.98 kg/(m² h) at the feed temperature of 90 °C. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43372.     

Polymerized high internal phase emulsion monoliths for the chromatographic separation of engineered nanoparticles

PolyHIPEs of ethylene glycol dimethacrylate (EGDMA) and styrene/divinylbenzene were prepared by polymerization of water‐in‐oil high internal phase emulsions (HIPEs) within high pressure liquid chromatography (HPLC) columns. The columns were incorporated into a HPLC system affixed to an inductively‐coupled plasma mass spectrometer, and their potential for the separation of engineered nanoparticles was investigated. Triplicate injections of 5 and 10 nm gold particles injected onto a poly(styrene‐co‐divinylbenzene) polyHIPE column produced an average difference in retention time of 135 s. On a poly(EGDMA) column, triplicate injections of dysprosium containing polystyrene particles of 52 and 155 nm produced a difference in retention time of 8 s. In both cases the smaller particles eluted from the column first. Comparison, using scanning electron microscopy, of the polyHIPE columns after the separations, against freestanding monoliths produced from the same HIPEs, revealed no apparent change in the internal porous structure of the polyHIPEs. © 2015 The Authors Journal of Applied Polymer Science Published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 132, 41229.     

Preparation and characterization of hydrophilic and antifouling poly(ether sulfone) ultrafiltration membranes modified with Zn–Al layered double hydroxides

Zn–Al layered double hydroxide (LDH)‐entrapped poly(ether sulfone) (PES) ultrafiltration membranes with four different weight percentages, 0.5, 1.0, 2.0, and 3.0%, were prepared by a phase‐inversion method. Characterization by scanning electron microscopy, atomic force microscopy and contact angle (CA), equilibrium water content, porosity, average pore size, mechanical strength, and ζ potential measurement were used to evaluate the morphological structure and physical and chemical properties of membranes. Static protein adsorption, filtration, and rejection experiments were conducted to study the antifouling properties, water permeability, and removal ability of the modified membranes. The results show that significant change occurred in the membrane morphology and that better hydrophilicity, water permeability, and antifouling ability were also achieved for the PES/LDH membranes when a proper amount of LDH was used. For example, the CA value decreased from 66.60 to 50.21°, and the pure water flux increased from 80.21 to 119.10 L m^?2 h^?1 bar^?1 when the LDH loading was increased from 0 to 2.0 wt %. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43988.     

Hydrophilic modification of a poly(ether sulfone) flat‐sheet ultrafiltration membrane applied to coking sewage

In this article, a new modified poly(ether sulfone) flat‐sheet ultrafiltration membrane, which is expected to effectively handle coking sewage, was prepared by an immersion precipitation phase‐inversion technique to settle the wastewater treatment problem in coking plants. Nanometer TiO₂ particle–poly(ethylene glycol) (PEG) blends were used as additives to modify the membranes by a blending method. The effects of different PEG mass concentrations on the membrane structure and properties were studied. The pure water flux and chemical oxygen demand (COD) rejection rate were analyzed as aggregative indicators by the comprehensive evaluation method, and then, the optimal PEG mass concentration was determined. The results show that the best modified effect was obtained at a PEG mass concentration of 0.25%. When coking sewage in a secondary settling tank was filtered with such membranes, the COD rejection rate reached 90.68%, and the water flux was 127.21 L m^?2 h^?1. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45149.     

CO2 Adsorption capacity of activated N‐doping porous carbons prepared from graphite nanofibers/polypyrrole

In this study, N‐doping porous carbons (NPCs) with a 3D aperiodic hierarchical and layered structure were prepared by the sodium hydride (NaOH) activation of graphite nanofibers (GNFs)/polypyrrole (PPY) composites. The effects of the N groups and structural features on the CO₂ adsorption capacity of NPCs were investigated by N₂ full isotherms, XRD, SEM, and TEM. The CO₂ adsorption capacity was measured by the CO₂ isothermal adsorption at 25°C and 1 atm. It was found that GNFs served as a substrate and layered graphitic carbons were formed by the thermal annealing of PPY. The content of N groups and textural properties of NPCs were enhanced with increasing activation temperature, resulting in improved CO₂ adsorption capacity. The CO₂ adsorption isotherms showed that GPK‐600 exhibited the best CO₂ adsorption capacity of 88.8 mg/g when the activation temperature was 600°C. The result indicates that the pore size and its distribution of NPCs lead to feasible contact CO₂, and the presence of high N groups on the NPCs could have resulted in further stabilization of the surface effect. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40517.     

Evaluation of hydrophilic cellulose nanofiber dispersions in a hydrophobic isotactic polypropylene composite

An effective approach for the evaluation of dispersed hydrophilic cellulose nanofibers (CNFs) in hydrophobic isotactic polypropylene (iPP) is presented using scattering and microscopic techniques for fiber analysis on nanometer and micrometer scales. iPP composites reinforced with CNF fibrous fillers were characterized by small-angle light scattering, small-angle X-ray scattering, and polarized optical microscopy measurements in the molten state in order to evaluate the shape of CNF fillers and/or larger aggregates formed from these fibers. The best dispersion results in the molten state coincided with low concentrations of CNFs. We observed the effect of CNFs on the acceleration of iPP crystal growth using wide-angle X-ray scattering and differential scanning calorimeter measurements. It was even possible to observe the nucleation morphology around CNF fibrous fillers using transmission electron microscopy.     

Studies on the surface properties of mixed‐matrix membrane and its antifouling properties for humic acid removal

A major factor limiting the use of ultrafiltration (UF) membrane in water treatment process is the membrane fouling by natural organic matter such as humic acid (HA). In this work, neat PVDF and PVDF/TiO₂ mixed‐matrix membranes were prepared and compared in terms of their antifouling properties. Two commercial types of TiO₂ namely PC‐20 and P25 were embedded to prepare the mixed matrix membranes via in situ colloidal precipitation method. The contact angles for the mixed‐matrix membranes were slightly reduced while the zeta potential was increased (more negatively charged) compared with the neat membrane. Filtration of HA with the presence of Ca²⁺ demonstrated that mixed‐matrix membrane could significantly mitigate the fouling tendency compared with the neat membrane with flux ratio (J/J₀) of 0.65, 0.70, and 0.82 for neat PVDF membrane, PVDF/TiO₂ mixed‐matrix membrane embedded with P25 and PC‐20, respectively. PC‐20 with higher anatase polymorphs exhibited better antifouling properties due to its hydrophilicity nature. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013