Sulfonated poly(arylene ether nitrile)-based hybrid membranes containing amine-functionalized GO for constructing long-range ionic nanochannels

To simultaneously balance proton conduction and methanol diffusion, the acid-base hybrid membranes based on sulfonated poly(arylene ether nitrile) (SPEN) with 3-aminopropyltriethoxysilane functionalized graphene oxide (NGO) are prepared by solution-casting method. The loading of NGO is varied to explore the influence on cross-sectional morphology, dimensional stability, proton conductivity and methanol permeability of composite membranes. In this way, the interfacial ionic nanochannels are established at the interface of NGO and SPEN, constructing the long-range ionic nanochannels to provide fast proton transfer. Meanwhile, the formation of more zigzag transportation channels could effectively prevent methanol diffusion. The improved properties of the composite membranes can be attributed to the excellent interfacial interactions induced by acid-base and hydrogen bonding interactions. The composite membrane with 1 wt% NGO shows high proton conductivity (0.104 S·cm^?1 at 20 °C) and low methanol permeability (1.74 × 10^?7 cm²·s^?1 at 20 °C), exhibiting higher selectivity (5.977 × 10⁵ S cm^?3s) compared with pure SPEN and Nafion 117 membranes. Therefore, it will provide a feasible pathway to conquer the trade-off effect between proton conductivity and methanol resistance for direct methanol fuel cells (DMFC) applications.     

Synthesis and electrochemical properties of blend membranes of polysulfone and poly (acrylic acid-co-2-(2-(piperazin-1-yl) ethylamino)-2-hydroxyethyl methacrylate) for proton exchange membrane fuel cell

In this work, new piperazine containing copolymer membrane was developed from acrylic acid and 2-(2-(piperazin-1-yl)ethylamino)-2-hydroxyethyl methacrylate through free radical polymerization method by means of AIBN as an initiator, in bulk. The monomer feed ratio was varied to obtain various copolymers having a different composition. The developed copolymer was blended in polysulfone (PSF) at 3 and 6 wt% using N,N′-Dimethylformamide solvent. The FTIR spectra and 1H NMR spectral data have proved the presence of copolymer that has hydrophilic functional group which influences the better proton conductivity. The membranes were characterized by their morphology using scanning electron microscope and x-ray diffraction analysis. The hydrophilic nature of the membranes is proved through high water uptake ratio. The exchangeable proton at the carboxylic acid group has enhanced the high ion exchange capacity. The blend membranes have higher water uptake, low swelling rate and higher ion exchange capacity than that of neat PSF membrane. The fabrication of fuel cell and studies on proton exchange capacity indicates that the prepared membranes have proton conductivity of as high as 8.77 × 10^?4 S cm^?1. Low methanol crossover was obtained about 2.112 × 10^?6 cm²s^?1 when compared to the pristine membrane.     

New anhydrous proton exchange membranes based on fluoropolymers blend imidazolium poly (aromatic ether ketone)s for high temperature polymer electrolyte fuel cells

The blend polymer membranes were synthesized from the methylimidazolium poly (aromatic ether ketone) (MeIm-PAEK) and fluoropolymers (PVDF and PVDF-HFP) with excellent thermal stability and improved dimensional stabilities for high-temperature polymer electrolyte fuel cells. The MeIm-PAEK exhibited good compatibility with PVDF or PVDF-HFP without phase separation. High phosphoric acid doping contents of the blend membranes were achieved at elevated temperatures with acceptable swellings. The acid doped blend membranes displayed lower dimensional swellings and higher mechanical strength compared to the MeIm-PAEK membrane, which allowed the blend membranes to obtain higher acid doping contents and proton conductivities. The MeIm-PAEK/10%PVDF membrane with a phosphoric acid doping content of 700 wt% showed a proton conductivity as high as 0.192 S cm^?1 at 180 °C under the non-humidified condition and a tensile strength of 4.3 MPa at room temperature.     

Comprehensive performance enhancement of polybenzimidazole based high temperature proton exchange membranes by doping with a novel intercalated proton conductor

On the study of high temperature proton exchange membrane (HTPEM), the trade-off between proton conductivity and physico-chemical property (such as mechanical strength, dimensional stability and methanol resistance) remained a main obstacle for comprehensive performance enhancement. To address this issue, novel HTPEM was prepared by doping phosphotungstic acid intercalated ferric sulfophenyl phosphate (FeSPP-PWA) into polybenzimidazole (PBI) via hot pressed method. Intense hydrogen bonding network was built between PBI and FeSPP-PWA, rendering construction of proton channels and reinforcement of physico-chemical property. As a novel proton conductor, FeSPP-PWA facilitated formation of efficient proton transfer pathway. The layered morphology and inorganic intrinsity of FeSPP-PWA also improved the mechanical and dimensional stability while reducing the methanol permeability of the PBI/FeSPP-PWA membranes. The composite membrane exhibited good thermal stability up to 200 °C. The proton conductivity of PBI/FeSPP-PWA (30 wt%) reached 110 mS cm^?1 at 170 °C and 100% RH, and was 69.3 mS cm^?1 at 180 °C and 50% RH. The PBI/FeSPP-PWA also showed low methanol permeability and high membrane selectivity for application in direct methanol fuel cells.     

Potential of sodium alginate/titanium oxide biomembrane nanocomposite in DMFC application

A proton exchange membrane was synthesized consuming a sodium alginate biopolymer as the matrix and titanium oxide as the nanofiller. The titanium oxide content varied from 5 to 25 wt%. The biomembrane nanocomposite performs better than the pristine sodium alginate membrane based on liquid uptake, methanol permeability, proton conductivity, ion exchange capacity, and oxidative stability outcomes. The unique properties of sodium alginate and titanium oxide lead to outstanding interconnections, thus producing new materials with great characteristics and enhanced performance. The highest proton conductivity achieved in this study is 17.3 × 10^‐3 S cm^‐1, which performed by SAT5 (25 wt%) membranes at 70°C. An optimal content of titanium oxide enhances the conductivity and methanol permeability of the membrane. Additionally, the hydrophilicity of pure sodium alginate is greatly reduced and achieves a good liquid uptake capacity and swelling ratio. The characteristics of the SA/TiO₂ biomembrane nanocomposite were determined with field emission scanning electron microscope, Fourier transform infrared, X‐ray diffraction, thermal gravimetric analysis/differential scanning calorimetry, and mechanical strength analysis.     

Synergistic effect of graphene oxide and carbon nanotubes on sulfonated poly(arylene ether nitrile)-based proton conducting membranes

A strategy to prepare graphene oxide (GO)/carbon nano-tubes (CNTs)/sulfonated poly(arylene ether nitrile) (SPEN) composite membranes aimed for the proton exchange membrane is presented herein. GO and CNTs were incorporated into SPEN to improve the performances of proton exchange membrane. To study the synergistic effect of GO and CNTs, GO/SPEN and CNTs/SPEN membranes were also fabricated. The influences of GO and CNTs upon the microstructures, including thermal and mechanical properties, water uptake, swelling, proton conductivity and methanol permeability of composite membranes were investigated in detail. The membranes combining GO and CNTs could effectively avoid the self-agglomeration of GO or CNTs. In such a way, efficient proton transport channels were constructed by homogeneous dispersion of GO and CNTs within SPEN, leading to enhancement of proton conductivity. The proton conductivity of GO/CNTs/SPEN composite membrane with the ratio of 2:2 achieved the highest value of 0.1197 S/cm at 20 °C. Meanwhile, low methanol permeability (2.015 × 10^?7 cm² s^?1) was still maintained. Consequently, the combination of CNTs and GO exhibited a favorable synergistic effect on the selectivity of proton exchange membrane, which is better than pure SPEN, Nafion 117, GO/SPEN, and CNTs/SPEN membranes. This feasibility study could provide an alternative approach to design GO/CNTs-based proton-conducting membranes for DMFC applications.     

Enhanced properties of SPEEK with incorporating of PFSA and barium strontium titanate nanoparticles for application in DMFCs

Novel blend nanocomposite proton‐exchange membranes were prepared using sulfonated poly (ether ether ketone) (SPEEK), perfluorosulfonic acid (PFSA), and Ba_0.9Sr_0.1TiO₃ (BST) doped‐perovskite nanoparticles. The membranes were evaluated by attenuated total reflection, X‐ray diffraction spectroscopy, water uptake, proton conductivity, methanol permeability, and direct methanol fuel cell test. The effect of two additives, PFSA and BST, were investigated. Results indicated that both proton conductivity and methanol barrier of the blend nanocomposite membranes improved compared with pristine SPEEK and the as‐prepared blend membranes. The methanol permeability and the proton conductivity of the blend membrane containing 6 wt% BST obtained 3.56 × 10^?7 cm² s^?1 (at 25 °C) and 0.110 S cm^?1 (at 80 °C), respectively. The power density value for the optimum blend nanocomposite membrane (15 wt% PFSA and 6 wt% BST) (54.89 mW cm^‐2) was higher than that of pristine SPEEK (31.34 mW cm^‐2) and SPF15 blend membrane (36.12 mW cm^‐2).     

Incorporating graphene oxide to improve the performance of Nafion-mordenite composite membranes for a direct methanol fuel cell

The proton exchange membrane is one of the critical parts of a direct methanol fuel cell. High proton conductivity and low methanol permeability are required. To enhance the performance of a direct methanol fuel cell, graphene oxide was incorporated to Nafion-mordenite composite membranes to enhance the compatibility and to decrease methanol permeability. It was found that the membrane with silane grafted on graphene oxide-treated mordenite with a graphene oxide content of 0.05% presented the highest proton conductivity (0.0560 S·cm⁻¹, 0.0738 S·cm⁻¹ and 0.08645 S·cm⁻¹ at 30, 50, and 70 °C, respectively). This was about 1.6-fold of the recast Nafion and commercial Nafion 117 and was about 1.5-fold of that without graphene oxide incorporation. Finally, the operating condition was optimized using response surface methodology and the maximum power density was investigated. Power density of about 4-fold higher than that of Nafion 117 was obtained in this work at 1.84 M and 72 °C with a %Error between the model prediction and the fuel cell experiment of 0.082%.     

Crosslinked SPEEK/AMPS blend membranes with high proton conductivity and low methanol diffusion coefficient for DMFC applications

The crosslinked sulfonated poly (ether ether ketone)/2-acrylamido-2-methyl-1-propanesulfonic acid (SPEEK/AMPS) blend membranres were prepared and evaluated as proton exchange membranes for direct methanol fuel cell (DMFC) applications. The structure and morphology of SPEEK/AMPS membranes were characterized by FTIR and SEM, respectively. The effects of crosslinking and AMPS content on the performance of membranes were studied and discussed in detail. The proton conductivity and methanol diffusion coefficient of SPEEK/AMPS membranes increased gradually with the increase of AMPS content. Most SPEEK/AMPS membranes exhibited higher proton conductivity than Nafion^® 117 (0.05 S cm⁻¹ at 25 °C). However, all the membranes possessed much lower methanol diffusion coefficient compared with Nafion^® 117 (2.38 × 10⁻⁶ cm² s⁻¹) under the same measuring conditions. Even the methanol diffusion coefficient (8.89 × 10⁻⁷ cm² s⁻¹) of SPEEK/AMPS 30 sample with the highest proton conductivity (0.084 S cm⁻¹ at 25 °C) was only about one third of that of Nafion^® 117. The selectivity of all the SPEEK/AMPS membranes was much higher in comparison with Nafion^® 117 (2.8 × 10⁴ S s cm⁻³). In addition, the SPEEK/AMPS membranes possessed relatively good thermal and hydrolytic stability. These results suggested that the SPEEK/AMPS membranes were particularly promising to be used as proton exchange membranes in DMFCs, and the high proton conductivity, low methanol diffusion coefficient and high selectivity were their primary advantages for DMFC applications.     

High temperature proton exchange porous membranes based on polybenzimidazole/ lignosulfonate blends: Preparation,morphology and physical and proton conductivity properties

Porous polybenzimidazole (PBI) based blend membranes were prepared by adding different amounts of lignosulfonate (LS) in the presence of LiCl salt. The morphology characteristics of the PBI/LS blends were investigated by FT-IR, atomic force microscopy (AFM) and scanning electron microscopy (SEM) analyses. The relation between the membrane morphology and membrane proton conductivity was studied. Results showed that LS content has a significant influence on the membrane morphology. High amount of LS in the blend created micro-pores within the membrane where increase in the LS content up to 20 wt% resulted in membranes containing pores with a mean diameter of about 0.8 μm. The resulting PBI/LS (0–20 wt%) membranes indicated high PA doping levels, ranging from 3 to 16 mol of PA per mole of PBI repeat units, which contributed to their unprecedented high proton conductivities of 4–96 mS cm⁻¹, respectively, at 25 °C. The effect of temperature on the proton conductivity of blends was also investigated. The results showed that by rising the temperature, the proton conductivity increases in PBI/LS blends. In the blend containing 20 wt% LS, proton conductivity increased from 98 mS cm⁻¹ at 25 °C to 187 mS.cm⁻¹at 160 °C which can be considered as an excellent candidate for use in both high and low temperature proton exchange membrane fuel cells.     

Engineering mesoporosity promoting high-performance polymer electrolyte fuel cells

Proton exchange membranes (PEMs) are a vital component in fuel cells (FCs) that attract significant research interest for the present hydrogen energy use. High proton conductivity of PEMs under various operation conditions highly influences the integrated performance of FCs that determines their commercial applications. Hence mesoporous superacidic sulfated zirconia (S-ZrO₂) is fabricated and introduced into Nafion matrix to construct hybrid PEMs. The mesoporosity of S-ZrO₂ is demonstrated highly controllable. High mesoporosity leads to increased amount of sulfonic groups (SO₃H) aggregating on S-ZrO₂ surface. When introduced in PEMs, the highly mesoporous S-ZrO₂ chemically enhances the amount of proton-containing groups, structurally improves the density of ion channels, and reserves water as effective reservoirs, which resultantly maintains high proton conductivity under variable conditions, and thus the performance of assembled FCs. The S-ZrO₂ exhibits the highest surface area of 181 m² g^?1. The hybrid PEMs loaded with 10 wt% such S-ZrO₂ achieve a highest proton conductivity of 0.83 S cm^?1 that is ～7 time of that for pristine Nafion^® membranes. The power density at 0.6 V of FCs with the hybrid PEMs is 786 mW cm^?2, much higher than that for commercial Nafion 211.     

Potential membranes derived from poly (aryl hexafluoro sulfone benzimidazole) and poly (aryl hexafluoro ethoxy benzimidazole) for high-temperature PEM fuel cells

Poly (aryl hexafluoro sulfone benzimidazole) and poly (aryl hexafluoro ethoxy benzimidazole), termed as PArF₆SO₂BI and PArF₆OBI, are synthesized and characterized systematically. PArF₆SO₂BI membranes illustrate good chemical stability in terms of oxidative weight loss due to the electron-withdrawing sulfone functional group. PArF₆OPBI membranes exhibit weak chemical stability after immersion in Fenton's solution. Many of the membranes show good conductivities. Higher conductivities of 3.26 × 10^?2 S cm^?1 at 160 °C with 286.8 wt% acid doped level for 3:1 (2.335 mmol of 4,4′-sulfonyldibenzoic acid and 7.005 mmol of 2, 2-bis(4-carboxyphenyl) hexafluoropropane) ratio of PArF₆SO₂BI and 7.31 × 10^?2 S cm^?1 with 356.9 wt% for 3:1 ratio of PArF₆OBI are observed. PArF₆SO₂BI and PArF₆OPBI membranes exhibit good conductivity, thermal and mechanical stabilities which are crucial requirements for high temperature fuel cells.     

In-situ preparation of cross-linked hybrid anion exchange membrane of quaternized poly (styrene-b-isobutylene-b-styrene) covalently bonded with graphene

Introducing graphene into polymer matrix is an effective way to enhance performances of anion exchange membrane (AEM). However, utilizing the advantages of graphene by physical approach is limited due to the weak interface interaction between graphene and polymer matrix. Herein, we report an effective strategy to covalently bond graphene with polymer matrix to improve the interface interaction and further to improve the properties of AEM. A series of cross-linked quaternized graphene-based hybrid AEM were fabricated by covalently bonding poly (vinylbenzyl chloride) grafted graphene (GN-g-PVBC) copolymer with chloromethyl functionalized poly (styrene-b-isobutylene-b-styrene) (SIBS) through the cross-linker (N,N,N′,N′-tetramethyl-1,6-hexanediamine) by in-situ synthetic approach. The interface interaction between graphene and QSIBS is greatly enhanced according to micromorphology characterization of the hybrid membrane. The cross-linked quaternized hybrid AEM containing 0.55 wt% of GN-g-PVBC exhibits obviously improved dynamical mechanical properties (storage modulus: 418 MPa), ion conductivity (1.81 × 10² S cm^?1), methanol barrier property (5.19 × 10^?7 cm² s^?1), selectivity (3.49 × 10⁴ S s cm^?3) at 60 °C and especially a comparably excellent chemical stability to that of Nafion 115 due to the enhanced interface interaction between graphene and the polymer matrix.     

HT-PEMs based on nitrogen-heterocycle decorated poly (arylene ether ketone) with enhanced proton conductivity and excellent stability

The proton transport can be enhanced by properly controlling the chemical structure of side chains. In this work, polyelectrolytes supported on poly (arylene ether ketone), decorated with four kinds of nitrogen-heterocycles, were prepared as alternative materials for high-temperature proton exchange membrane (HT-PEM) applications. Particularly, the “prominent basic” alongside backbone makes positive imidazole group more effective than other three to promote phosphoric acid doping, enhance proton conductivity and avoid phosphoric acid leakage. The obtained BrPAEK-MeIm1.6 membranes (1.6 imidazole/unit), with PA doping level of 19.2 in 1 h acid absorption process, exhibited the conductivity of 0.091 S cm^?1 at 170 °C. Under harsh experimental conditions, membrane with higher imidazole exhibited relatively higher phosphoric acid retention ability (27% enhancement). The stability of proton conductivity has also been demonstrated, which indicates that the PA/BrPAEK-MeIm1.6 come to an equilibrium state with 77.7% of initial conductivity after 5 h. Then, there is almost negligible conductivity loss within 30 h. These results provide a basic understanding of nitrogen-heterocyclic addition and PA absorption and open up avenues for further research in this area.     

The effective methanol-blocking and proton conductivity membranes based on sulfonated poly (ether ether ketone ketone) and polyorganosilicon with functional groups

To solve the conflict between high proton conductivity and low methanol crossover of pristine sulfonated aromatic polymer membranes, the polyorganosilicon doped sulfonated poly (ether ether ketone ketone) (SPEEKK) composite membranes were prepared by introducing polyorganosilicon additive with various functional groups into SPEEKK in this study. Scanning electron microcopy (SEM) images showed the obtained membranes were compact. No apparent agglomerations, cracks and pinholes were observed in the SEM images of composite membranes. The good compatibility between polymer and additive led to the interconnection, thus producing new materials with great characteristics and enhanced performance. Besides, the dual crosslinked structure could be formed in composite membranes through the condensation of silanols and the strong interaction between matrix and additive. The formation of dual crosslinked structure optimized the water absorption, enhanced the hydrolytic stability and oxidative stability of membranes. Especially, the incorporation of additive improved the strength and flexibility of composite membranes at the same time, meaning that the life of the composite membranes might be extended during the fuel cell operation. Meanwhile, the proton conductivity improved with increasing additive content due to the loading of more available acidic groups. It is noteworthy that at 25% additive loading, the proton conductivity reached a maximum value of 5.4 × 10⁻² S cm⁻¹ at 25 °C, which exceeded the corresponding value of Nafion^@ 117 (5.0 × 10⁻² S cm⁻¹) under same experimental conditions. The composite membrane with 20 wt% additive was found to produce the highest selectivity (1.22 × 10⁵ S cm⁻³) with proton conductivity of 4.70 × 10⁻² S cm⁻¹ and methanol diffusion coefficient of 3.85 × 10⁻⁷ cm² s⁻¹, suggesting its best potential as proton exchange membrane for direct methanol fuel cell application. The main novelty of our work is providing a feasible and environment-friendly way to prepare the self-made polyorganosilicon with various functional groups and introducing it into SPEEKK to fabricate the dual crosslinked membranes. This design produces new materials with outstanding performance.     

The composite electrolyte with an insulation Sm2O3 and semiconductor NiO for advanced fuel cells

Novel Sm₂O₃?NiO composite was prepared as the functional electrolyte for the first time. The total electrical conductivity of Sm₂O₃?NiO is 0.38 S cm^?1 in H₂/air condition at 550 °C. High performance, e.g. 718 mW cm^?2, was achieved using Sm₂O₃?NiO composite as an electrolyte of solid oxide fuel cells operated at 550 °C. The electrical properties and electrochemical performance are strongly depended on Sm₂O₃ and NiO constituent phase of the compositions. Notably, surprisingly high ionic conductivity and fuel cell performance are achieved using the composite system constituting with insulating Sm₂O₃ and intrinsic p-type conductive NiO with a low conductivity of 4 × 10^?3 S cm^?1. The interfacial ionic conduction between two phases is a dominating factor giving rise to significantly enhanced proton conduction. Fuel cell performance and further ionic conduction mechanisms are under investigation.     

An enhanced proton conductivity and reduced methanol permeability composite membrane prepared by sulfonated covalent organic nanosheets/Nafion

Sulfonated covalent organic nanosheets (SCONs) with a functional group (−SO₃H) are effective at reducing ion channels length and facilitating proton diffusion, indicating the potential advantage of SCONs in application for proton exchange membranes (PEMs). In this study, Nafion-SCONs composite membranes were prepared by introducing SCONs into a Nafion membrane. The incorporation of SCONs not only improved proton conductivity, but also suppressed methanol permeability. This was due to the even distribution of ion channels, formed by strong electrostatic interaction between the well dispersed SCONs and Nafion polymer molecules. Notably, Nafion-SCONs-0.6 was the best choice of composite membranes. It exhibited enhanced performance, such as high conductivity and low methanol permeability. The direct methanol fuel cell (DMFC) with Nafion-SCONs-0.6 membrane also showed higher power density (118.2 mW cm⁻²), which was 44% higher than the cell comprised of Nafion membrane (81.9 mW cm⁻²) in 2 M methanol at 60 °C. These results enabled us to work on building composite membranes with enhanced properties, made from nanomaterials and polymer molecules.     

Polybenzimidazole/zwitterion-coated polyamidoamine dendrimer composite membranes for direct methanol fuel cell applications

The zwitterion-coated polyamidoamine (ZC-PAMAM) dendrimer with ammonium and sulfonic acid groups has been synthesized and used as filler for the preparation of PBI-based composite membranes for direct methanol fuel cells. Polybenzimidazole (PBI)/ZC-PAMAM dendrimer composite membranes were prepared by casting a solution of PBI and ZC-PAMAM dendrimer, and then evaporating the solvent. The presence of ZC-PAMAM dendrimer was confirmed by FT-IR and energy-dispersive X-ray spectroscopy (EDS) mapping of sulfur and oxygen elements. The water uptake, swelling degree, proton conductivity, and methanol permeability of the membranes increased with the ZC-PAMAM dendrimer content. For the PBI/ZC-PAMAM-20 membrane with 20 wt% of ZC-PAMAM, it shows a proton conductivity of 1.83 × 10⁻² S/cm at 80 °C and a methanol permeability of 5.23 × 10⁻⁸ cm² s⁻¹. Consequently, the PBI/ZC-PAMAM-20 demonstrates a maximum power density of 26.64 mW cm⁻² in a single cell test, which was about 2-fold higher than Nafion-117 membrane under the same conditions.     

A novel membrane for DMFC - Na2Ti3O7 nanotubes/Nafion composite membrane

In this study, novel sodium titanate (Na₂Ti₃O₇) nanotube/Nafion^® composite membranes were prepared by a solution casting method. The properties of these composite membranes were studied using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Additionally, the water uptake, methanol permeability, proton conductivity, and selectivity of the composite membranes were measured to evaluate the applicability of these membranes in DMFCs. It was found that the addition of Na₂Ti₃O₇ nanotubes enhanced the water uptake and reduced the methanol permeability of the composite membranes. The proton conductivity and methanol permeability depend on the Na₂Ti₃O₇ nanotube content. Using the selectivity, the optimal nanotube contents was found to be 5 wt%. The new composite membrane was found to have significantly higher selectivity than a pure Nafion^® membrane and thus has good potential to outperform Nafion^® in DMFCs.     

Preparation and characterization of self-crosslinked organic/inorganic proton exchange membranes

A series of silicon-containing sulfonated polystyrene/acrylate (Si-sPS/A) nanoparticles are successfully synthesized via simple emulsion polymerization method. The Si-sPS/A latexes show good film-forming capability and the self-crosslinked organic/inorganic proton exchange membranes are prepared by pouring the Si-sPS/A nanoparticle latexes into glass plates and drying at 60 °C for 10 h and 120 °C for 2 h. The potential of the membranes in direct methanol fuel cells (DMFCs) is characterized preliminarily by studying their thermal stability, ion-exchange capacity, water uptake, methanol diffusion coefficient, proton conductivity and selectivity (proton conductivity/methanol diffusion coefficient). The results indicate that these membranes possess excellent thermal stability and methanol barrier due to the existence of self-crosslinked silica network. In addition, the proton conductivity of the membranes is in the range of 10⁻³-10⁻² S cm⁻¹ and all the membranes show much higher selectivity in comparison with Nafion^® 117. These results suggest that the self-crosslinked organic/inorganic proton exchange membranes are particularly promising in DMFC applications.