静电层层自组装改性SPPESK/PWA质子交换膜

运用直接掺杂法制备的磺化聚芳醚砜酮/磷钨酸(SPPESK/PWA)复合质子交换膜存在PWA流失严重的问题,影响了膜的正常使用。为了解决这一问题,以壳聚糖(CS)和PWA为聚阴阳离子电解质对,对复合膜进行静电层层(LBL)自组装改性研究,对膜的吸水率、溶胀度、质子传导率等性能进行了表征,并测试了膜中PWA的稳定性。经测定,SPPESK/PWA/(CS/PWA)₂的质子传导率达到154mS/cm(80℃),高于相应的SPPESK膜(118mS/cm)及SPPESK/PWA膜(147mS/cm);SPPESK/PWA/(CS/PWA)₄在80℃水中浸泡30天后,膜的质量损失率由18.45%降为11.81%,电导率损失率由32.20%降为16.77%。结果表明,该方法不仅提高了复合膜的质子传导率,并且有效抑制了PWA的流失。     

Montmorillonite‐reinforced sulfonated poly(phthalazinone ether sulfone ketone) nanocomposite proton exchange membranes for direct methanol fuel cells

To produce a composite membrane with high conductivity and low permeability, SPPESK with a degree of sulfonation of 101% was carefully selected for the preparation of montmorillonite (MMT)‐reinforced SPPESK using solution intercalation. The fundamental characteristics such as water uptake, swelling ratio, proton conductivity, methanol permeability, and mechanical properties of the composite membranes were studied. Water uptake is improved when organic MMT (OMMT) loading increase. The composite membranes with CTAB‐MMT loading of 4–0.5% show 0.143–0.150 S cm^?1 proton conductivity at 80°C, which approaches the value of Nafion112. In addition, methanol permeability was decreased to 6.29 × 10^?8 cm² s^?1 by the addition of 6 wt % OMMT. As a result, the SPPESK‐MMT composite membrane is a good candidate for use in direct methanol fuel cells. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39852.     

Fabrication of amorphous calcium carbonate composite particles‐polymer multilayer films by a layer‐by‐layer method

Organic–inorganic hybrid multilayer films were prepared on a precoated cationic glass substrate by using a layer‐by‐layer (LbL) electrostatic self‐assembly technique with poly(diallyldimethylammonium chloride) as a polycation and submicron‐sized stable amorphous calcium carbonate (ACC) composite particles. The ACC composite particles (ACP) stabilized with poly(acrylic acid) were obtained by a carbonate controlled‐addition method. The average particles size of ACP was (1.8 ± 0.4) × 10² nm. An ethanolic dispersion of ACP was used for the LbL electrostatic self‐assembly technique on the precoated substrate due to instability of ACP in water. The deposition of the particles was confirmed by SEM analysis. The film thickness of the multilayer assembly increased from 230 to 710 nm with increasing the deposition layers. The FTIR spectra of scratched multilayer samples showed characteristic broaden peaks of ACC. The amorphous phase was stable after the LbL assembly process as well as after 2 months in a dry film state. POLYM. COMPOS., 36:330–335, 2015. © 2014 Society of Plastics Engineers     

Ionically Cross‐Linked Proton Conducting Membranes for Fuel Cells

For improving stability without sacrificing ionic conductivity, ionically cross‐linked proton conducting membranes are fabricated from Na⁺‐form sulfonated poly(phthalazinone ether sulfone kentone) (SPPESK) and H⁺‐formed sulfonated poly(2,6‐dimethyl‐1,4‐phenylene oxide) (SPPO). Ionically acid‐base cross‐linking between sulfonic acid groups in SPPO and phthalazone groups in SPPESK impart the composite membranes the good miscibility and electrochemical performance. In particular, the composite membranes possess proton conductivity of 60–110 mS cm⁻¹ at 30 °C. By controlling the protonation degree of SPPO within 40–100 %, the composite membranes with favorable cross‐linking degree are qualified for application in fuel cells. The maximum power density of the composite membrane reaches approximately 1100 mW cm⁻² at the current density of 2800 mA cm⁻² at 70 °C.     

Dielectric relaxations in phosphoric acid‐doped poly(2,5‐benzimidazole) and its composite membranes

Poly(2,5‐benzimidazole) (ABPBI)—a promising high‐temperature polymer electrolyte membrane—is characterized over a wide range of temperature (?50 to 220 °C) using broadband dielectric spectroscopy (BDS) to understand the various relaxation processes. The undoped ABPBI membrane shows two major secondary relaxations and a primary α relaxation. The effect of phosphoric acid (PA) and phosphotungstic acid grafted zirconium dioxide (PWA/ZrO₂) nanoparticles on the chain relaxation and the proton conductivity is investigated. The phosphoric acid alters the relaxation trends, increases the number of free ions in the polymer matrix, and therefore the conductivity. The shift in the peak frequencies of different chain relaxation processes in the presence of PA and PWA/ZrO₂ is attributed to the increase in free volume and the consequent easy motion of the polymer chains. The Fourier transform infra‐red (FTIR) spectroscopy of ABPBI and the acid‐doped composites show all the relevant peaks corresponding to C?C, C?N stretching, and phosphoric acid/phosphates, confirming the formation of ABPBI and doping with PA. The proton conductivity of the membranes is estimated from electrochemical impedance spectroscopy (EIS). To establish the effect of change in crystallinity on relaxations and proton conductivity, the undoped and PA‐doped membranes are characterized using thermogravimetric analysis and in situ XRD at high temperatures. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44867.     

Chitosan/CaCO3 solvent‐free nanofluid composite membranes for direct methanol fuel cells

Natural polyelectrolyte chitosan (CS) has been considered to be a promising proton‐exchange membrane material for direct methanol fuel cells due to its low cost and excellent methanol barrier ability. To further improve the ionic conductivity and mechanical property of CS, calcium‐carbonate solvent‐free nanofluids (CaCO₃‐SF) with unique flow behavior were prepared by an ion‐exchange method, and then used a novel nanofiller to modify CS to fabricate composite membranes. The surface‐grafted organic long chains on the surface of CaCO₃ nanoparticles could promote the homogeneous dispersion of CaCO₃ in the CS matrix, and thus improve the interfacial bonding and facilitate the load transfer from the matrix to stiff CaCO₃. When the content of CaCO₃‐SF was 6 wt%, the tensile strength and fracture elongation of the composite membrane were 28.25 MPa and 17.17%, respectively, which increased by 25% and 36% when compared with those of pure membrane. Moreover, the ? SO₃H groups in the structure of organic long chains could form new proton transport sites, and thus enhance the proton conductivity of the membranes. Consequently, when compared with pure CS membrane (0.0131 S cm^?1), incorporation of 6 wt% CaCO₃‐SF (0.0250 S cm^?1) exhibited about onefold increase of proton conductivity. POLYM. ENG. SCI., 59:2128–2135, 2019. © 2019 Society of Plastics Engineers     

Preparation and characterization of poly(vinylidene fluoride)/sulfonated poly(phthalazinone ether sulfone ketone) blends for proton exchange membrane

Poly(vinylidene fluoride)/sulfonated poly(phthalazinone ether sulfone ketone) (PVdF/SPPESK) blend membranes are successfully prepared by solution blending method for novel proton exchange membrane (PEM). PVdF crystallinity, FTIR‐ATR spectroscopy, thermal stability, morphology, water uptake, dimension stability, and proton conductivity are investigated on PVdF/SPPESK blends with different PVdF contents. XRD and DSC analysis reveal that the PVdF crystallinity in the blends depends on PVdF content. The FTIR‐ATR spectra indicate that SPPESK remains proton‐conducting function in the blends due to the intactness of ? SO₃H group. Thermal analysis results show a very high thermal stability (T_d1 = 246–261°C) of the blends. PVdF crystallinity and morphology study demonstrate that with lower PVdF content, PVdF are very compatible with SPPESK. Also, with lower PVdF content, PVdF/SPPESK blends possess high water uptake, e.g., P/S 10/90 and P/S 15/85 have water uptake of 135 and 99% at 95°C, respectively. The blend membranes also have good dimension stability because the swelling ratios are at a fairly low level (e.g., 8–22%, 80°C). PVdF/SPPESK blends with low PVdF content exhibit very high proton conductivity, e.g., at 80°C, P/S 15/85 and P/S 10/90 reach 2.6 × 10^?2 and 3.6 × 10^?2 S cm^?1, respectively, which are close to or even higher than that (3.4 × 10^?2 S cm^?1) of Nafion115 under the same test condition. All above properties indicate that the PVdF/SPPESK blend membranes (particularly, with 10–20% of PVdF content) are very promising for use in PEM field. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

PWA/silica doped sulfonated poly(ether sulfone) composite membranes for direct methanol fuel cells

A novel sulfonated poly(ether sulfone) (SPES)/phosphotungstic acid (PWA)/silica composite membranes for direct methanol fuel cells (DMFCs) application were prepared. The structure and performance of the obtained membranes were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), water uptake, proton conductivity, and methanol permeability. Compared to a pure SPES membrane, PWA and SiO₂ doped membranes had a higher thermal stability and glass transition temperature (T_g) as revealed by TGA‐FTIR and DSC. The morphology of the composite membranes indicated that SiO₂ and PWA were uniformly distributed throughout the SPES matrix. Proper PWA and silica loadings in the composite membranes showed high proton conductivity and sufficient methanol permeability. The selectivity (the ratio of proton conductivity to methanol permeability) of the SPES‐P‐S 15% composite membrane was almost five times than that of Nafion 112 membrane. This excellent selectivity of SPES/PWA/silica composite membranes indicate a potential feasibility as a promising electrolyte for DMFC. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Composite Proton‐Conducting Membranes for PEMFCs

Composite membranes are of interest for PEMFCs and DMFCs. This paper describes a basic study of the influence of silica on the proton conductivity: (i) added as a filler to poly(vinylidene fluoride‐hexafluoropropylene) and poly(benzimidazole)‐based membranes activated with H₃PO₄, or (ii) included in the matrix of class II hybrids based on tetraethoxysilane and poly(ethylene glycol) and activated with phosphotungstic acid (PWA). The addition of acidic silica as a filler determines proton conductivity increases up to one order of magnitude for filler amounts which strongly depend on the proton transport mechanism, and on the nature (free or partially free) of the activating acid. The increase of the silica content in the hybrid matrix induces a more complex behaviour which also depends on the amount of PWA.     

Sulfonated poly(ether sulfone)/phosphotungstic acid/attapulgite composite membranes for direct methanol fuel cells

Novel composite sulfonated poly(ether sulfone)(SPES)/phosphotungstic acid (PWA)/attapulgite (AT) membranes were investigated for direct methanol fuel cells (DMFCs). Physical–chemical properties of the composite membranes were characterized by FTIR, DSC, TGA, SEM‐EDX, water uptake, tensile test, proton conductivity, and methanol permeability. Compared with a pure SPES membrane, PWA, and AT doping in the membrane led to a higher thermal stability and glass transition temperature (T_g) as revealed by TGA and DSC. Tensile test indicated that lower AT content (3%) in the composite can significantly increase the tensile strength, while higher AT loading demonstrated a smaller contribution on strength. Proper PWA and AT loadings in the composite membranes can increase the proton conductivity and lower the methanol cross‐over. The proton conductivity of the SPES‐P‐A 10% composite membrane reached 60% of the Nafion 112 membrane conductivity at room temperature while the methanol permeability was only one‐fourth of that of Nafion 112 membrane. This excellent performances of SPES/PWA/AT composite membranes could indicate a potential feasibility as a promising electrolyte for DMFC. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Sulfonated polyimide/chitosan composite membrane for vanadium redox flow battery: Membrane preparation,characterization, and single cell performance

A novel sulfonated polyimide/chitosan (SPI/CS) composite membrane was prepared from self‐made SPI (50% of sulfonation degree) through an immersion and self‐assembly method, which was successfully applied in vanadium redox flow battery (VRB). The proton conductivity of SPI/CS composite membrane is effectively improved compared to the plain SPI membrane. The VO²⁺ permeability coefficient across SPI/CS composite membrane is 1.12 × 10^?7 cm² min^?1, which is only one tenth of that of Nafion® 117 membrane. Meanwhile, the proton selectivity of SPI/CS composite membrane is about eight times higher than that of Nafion® 117 membrane. In addition, the oxidative stability SPI/CS composite membrane is superior to that of pristine SPI membrane. The VRB single cell using SPI/CS composite membrane showed higher energy efficiency (88.6%) than that using Nafion® 117 membrane, indicating that SPI/CS composite membrane is a promising proton conductive membrane for VRB application. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Sulfonation of poly(phthalazinone ether sulfone ketone) by heterogeneous method and its potential application on proton exchange membrane (PEM)

A series of sulfonated PPESK (SPPESKs) were synthesized through a heterogeneous sulfonation process with fuming sulfuric acid as sulfonating agent in a chloroform solvent. Membranes prepared from SPPESKs were investigated and proved to be candidates of proton exchange membrane in fuel cell operating at high temperature and low humidity. The heterogeneous sulfonation reaction is verified to first occur on the interface of the acid phase and the chloroform phase, then went on in the acid phase. SPPESKs with sulfonation degree (DS) up to 2.0 are obtained through a new reprecipitation method. Effects of reaction temperature, reaction time, acid/polymer ratio, and chloroform/polymer ratio on the sulfonation reaction are reported in details. An increase in sulfonation degree results in the increase of hydrophilicity, bringing about a substantial gain in proton conductivity. SPPESK membranes exhibit high water uptake of about 105.4% with DS of 1.01, almost two times higher than that of Nafion® with similar dimensional variation. Conductivity values at 35°C, 60% R.H. ranging from 10^?3 to 10^?2 S/cm were measured, which are comparable to or higher than that of Nafion® 112 (1.635 × 10^?2 S/cm) under the same test condition. Thermogravimetric analysis shows that SPPESK membranes are stable up to 290°C in N₂. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1002–1009, 2007     

Composite membranes of chitosan and titania‐coated carbon nanotubes as promising materials for new proton‐exchange membranes

Titania‐coated carbon nanotubes (TCNTs) were obtained by a simple sol–gel method. Then chitosan/TCNT (CS/TCNT) composite membranes were prepared by stirring chitosan/acetic acid and a TCNT/ethanol suspension. The morphology, thermal and oxidative stabilities, water uptake and proton conductivity, and mechanical properties of CS/TCNT composite membranes were investigated. The CNTs coated with an insulated and hydrophilic titania layer eliminated the risk of electronic short‐circuiting. Moreover, the titania layer enhanced the interaction between TCNTs and chitosan to ensure the homogenous dispersion of TCNTs in the chitosan matrix. The water uptake of CS/TCNT composite membranes was reduced owing to the decrease of the effective number of the ? NH₂ functional groups of chitosan. However, the CS/TCNT composite membranes exhibited better performance than a pure CS membrane in thermal and oxidative stability, proton conductivity, and mechanical properties. These results suggest that CS/TCNT composite membranes are promising materials for new proton‐exchange membranes. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43365.     

Enhanced Proton Conductivity of Sulfonated Poly(ether ether ketone) Membrane Embedded by Dopamine‐Modified Nanotubes for Proton Exchange Membrane Fuel Cell

Design and fabrication of alternative proton exchange membrane (PEM) with high proton conductivity is crucial to the commercial application of PEM fuel cell. Inspired by the bioadhesion principle, dopamine‐modified halloysite nanotubes (DHNTs) bearing –NH₂ and –NH– groups are facilely synthesized by directly immersing natural halloysite nanotubes (HNTs) into dopamine aqueous solution under mild conditions. DHNTs are then embedded into sulfonated poly(ether ether ketone) (SPEEK) matrix to prepare hybrid membranes. HNTs‐filled hybrid membranes are prepared for comparison. The microstructure and physicochemical properties of the membranes are extensively investigated. Fourier transform infrared analysis implies that ordered acid–base pairs (e.g., –S–O^–…⁺H–HN–, –S–O^–…⁺H–N–) are formed at SPEEK–DHNT interface through strong electrostatic interaction. In such a way, continuous surface‐induced ion‐channels emerge along DHNTs. Although the incorporation of DHNTs reduces the channel size, water uptake, and area swelling of the hybrid membranes, which in turn would reduce the vehicle‐type proton transfer, the acid–base pairs create continuous pathways for fast proton transfer with low energy barrier via Grotthuss mechanism. Consequently, DHNT‐filled hybrid membrane with 15% DHNTs achieves a 30% increase in proton conductivity and a 52% increase in peak power density of single cell when compared with SPEEK control membrane, particularly.     

PWA-13X-CS复合质子交换膜的性能研究

用13X分子筛负载无机质子导体-磷钨酸,然后加入壳聚糖(CS)中制备得到PWA-13X-CS复合质子交换膜,对其进行扫描电镜表征,测试了其吸水率、溶胀度、质子导电率、甲醇渗透系数等性质。结果表明PWA-13X-CS复合质子交换膜溶胀度较小,机械性能较好,质子导电率明显高于壳聚糖空白膜,且随温度升高呈上升趋势,其质子导电活化能低于壳聚糖空白膜,甲醇渗透系数小于Nafion117膜。将其与同样添加负载磷钨酸的13X分子筛的聚酰亚胺复合膜及聚乙烯醇复合膜性能进行对比,结果表明PWA-13X-CS复合质子交换膜综合性能较优,在直接甲醇燃料电池中具有较好的应用潜力。     

Imidazole/(HPO3)3‐doped sulfonated poly (ether ether ketone) composite membrane for fuel cells

A novel gel of imidazole/(HPO₃)₃ was synthesized and incorporated into sulfonated poly (ether ether ketone) (SPEEK) to fabricate composite proton exchange membranes. The composite membranes were characterized by alternating current impedance (AC), thermogravimetry (TG), differential scanning calorimetry (DSC), X‐ray diffraction (XRD), scanning electron microscope (SEM) and mechanical property test. Based on the electrochemical performance investigation, the proton conductivity of the membrane is intimately correlated with the temperature and the mass ratio of imidazole/(HPO₃)₃ in the composite. The SPEEK/imidazole/(HPO₃)₃?4 composite membrane (with 44.4 wt % of imidazole/(HPO₃)₃) has the optimized performance at 135°C. Mover, the strength of the composite membranes is almost comparable to that of Nafion membrane. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41946.     

Partially Sulfonated Poly(1,4‐phenylene ether‐ether‐sulfone) and Poly(vinylidene fluoride) Blend Membranes for Fuel Cells

Blend membranes based on high conductive sulfonated poly(1,4‐phenylene ether‐ether‐sulfone) (SPEES) and poly(vinylidene fluoride) (PVDF) having excellent chemical stability were prepared and characterized for direct methanol fuel cells. The effects of PVDF content on the proton conductivity, water uptake, and chemical stability of SPEES/PVDF blend membranes were investigated. The morphology, miscibility, thermal, and mechanical properties of blend membranes were also studied by means of scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA) measurements. The blend membrane containing 90 wt.% SPEES (degree of sulfonation – DS = 72%) and 10 wt.% PVDF (M_w = 180,000) exhibits optimum properties among various SPEES72/PVDF membranes. Addition of PVDF enhanced resistance of the SPEES membrane against peroxide radicals and methanol significantly without deterioration of its proton conductivity. It's proton conductivity at 80 °C and 100% relative humidity is higher than Nafion 115 while it's methanol permeability is only half of that of Nafion 115 at 80 °C. The direct methanol fuel cell performance of the SPEES membranes was better than that of Nafion 115 membrane at 80 °C.     

Electrospinning preparation of a graphene oxide nanohybrid proton‐exchange membrane for fuel cells

Proton‐exchange membrane (PEM) is a core component of fuel cells that provides a channel for proton migration and transport. Prevailing PEMs fabricated using well‐established casting techniques have several limitations such as low proton conductivity, high fuel permeability, and poor stability. To overcome these shortcomings, this article introduces a graphene oxide (GO)‐based nanohybrid Nafion nanofiber membrane prepared using a facile electrospinning technique. On the one hand, electrospinning nanofibers provide efficient transport paths for protons, which tremendously enhance the proton conductivity. On the other hand, GO doping in PEM improves the self‐humidification, stabilities (mechanical, thermal, and chemical), and proton conductivity and reduces the fuel permeability. In this research, nanofiber membranes were obtained from Nafion solutions containing 0, 0.1, and 0.2 wt % GO via electrospinning. The morphology, structure, mechanical properties, proton conductivity, water uptake, and swelling properties of the membranes were studied. The results demonstrated that the comprehensive performance of PEM was significantly improved. The new findings may promote the wide application of PEM fuel cells. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46443.     

Modification of sulfonated poly(ether ether ketone) membranes by impregnation with the ionic liquid 1‐butyl‐3‐methylimidazolium tetrafluoroborate for proton exchange membrane fuel cell applications

Sulfonated poly(ether ether ketone) (SPEEK) membranes were modified by impregnation with the ionic liquid (IL) 1‐butyl‐3‐methylimidazolium tetrafluoroborate (BMI.BF₄) by immersion into an IL aqueous solution for different periods of time. The modified membranes were investigated by thermogravimetric analyses (TGA), differential scanning calorimetry (DSC), ion exchange capacity (IEC), and conductivity. The SPEEK membrane immersed into the IL aqueous solution for 2 min showed greater dimensional and thermal stability than the pristine SPEEK membrane, and achieved higher decomposition temperatures. It also presented a higher conductivity value (1.0 mS cm^?1), indicating that BMI.BF₄ is a promoter of proton conductivity. The membrane electrode assembly (MEA) produced reached maximum values of power density of 0.13 W cm^?2 and current density of 0.54 A cm^?2 during fuel cell operation. The results indicate that the SPEEK membrane modified by immersion for 2 min is promising for use in a proton exchange membrane fuel cell. Its performance yielded values very close to those obtained with Nafion, which reaches maximum values of power density of 0.19 W cm^?2 and current density of 0.77 A cm^?2. POLYM. ENG. SCI. 56:1037–1044, 2016. © 2016 Society of Plastics Engineers     

Dynamic layer‐by‐layer self‐assembly of organic–inorganic composite hollow fiber membranes

Multilayer membranes constructed layer‐by‐layer (LbL) is finding increasing importance in many separation applications. The efficient construction of LbL multilayer on to hollow fiber substrates may offer many new opportunities for industrial applications. An organic–inorganic composite hollow fiber membrane has been developed using a dynamic LbL self‐assembly. This poly(acrylic acid)/poly(ethyleneimine) multilayer was dynamically assembled onto the inner surfaces of ceramic hollow fiber porous substrates pretreated by Dynasylan Ameo silane coupling agents. The hollow fibers were subsequently heat crosslinked to obtain stable permselective membranes. The formation of multilayers on the hollow fibers was characterized with a SEM, EDX, an electrokinetic analyzer and IR spectra. The effects of layer number, feed temperature and water content in the feed on the pervaporation performance have been investigated. To the best of our knowledge, this is the first report of LbL assembly of polymer building blocks onto ceramic hollow fiber porous substrates. © 2011 American Institute of Chemical Engineers AIChE J, 58: 3176–3182, 2012