Sulfonated PEEK-WC membranes for possible fuel cell applications

Coarse-Grained Modeling of Ion-Containing Polymers

Ion-containing polymers have continued to be an important research focus for several decades due to their use as an electrolyte in energy storage and conversion devices. Elucidation of connections between the mesoscopic structure and multiscale dynamics of the ions and solvent remains incompletely understood. Coarse-grained modeling provides an efficient approach for exploring the structural and dynamical properties of these soft materials. The unique physicochemical properties of such polymers are of broad interest. In this review, we summarize the current development and understanding of the structure-property relationship of ion-containing polymers and provide insights into the design of such materials determined from coarse-grained modeling and simulations accompanying significant advances in experimental strategies. We specifically concentrate on three types of ion-containing polymers: proton exchange membranes (PEMs), anion exchange membranes (AEMs), and polymerized ionic liquids (polyILs). We posit that insight into the similarities and differences in these materials will lead to guidance in the rational design of high-performance novel materials with improved properties for various power source technologies.

Synthesis and characterization of sulfonated poly(ether ether ketone)/zinc cobalt oxide composite membranes for fuel cell applications

A new series of polymer composite membranes was fabricated using a linear sulfonated poly(ether ether ketone) (SPEEK) polymer with zinc cobalt oxide (ZCO) as an inorganic filler and evaluated for fuel cell applications. SPEEK was obtained by the direct sulfonation of PEEK using concentrated sulfuric acid, and appropriate quantities of ZCO were loaded into it to yield the polymer composites. Proton nuclear magnetic resonance studies revealed the degree of sulfonation of SPEEK to be 55%, while morphological studies confirmed the successful incorporation of inorganic fillers into the polymer matrix. To evaluate the suitability of the prepared composite membranes for fuel cell applications, their physicochemical properties were studied in detail. The pristine SPEEK membrane exhibited a proton conductivity of 0.009 S cm−1 at 30°C, whereas the values for the composite membranes loaded with 2.5 to 10 wt% of ZCO were in the range 0.012–0.020 S cm−1. Moreover, the composite membranes showed excellent thermal stability up to 370°C. Indeed, the membranes obtained by the incorporation of ZCO into the SPEEK polymer show potential for fuel cell applications.

Synthesis of polyether ether ketone membrane with pendent phosphonic acid group and determination of proton conductivity and thermal stability

Incorporation of phosphonic acid groups in the polymer backbone by direct phosphonation or by polymerization of prefunctionalized monomers requires harsh reaction conditions. The present research work reported an easy synthesis strategy of phosphonic acid-containing diphosphonated polyether ether ketone (P-PEEK) by polycondensation of difluoro benzophenone and phosphonated bisphenol A (BPA). Phosphonation of BPA was carried out by monophosphoazylation followed by rearrangement in the presence of organolithium compound at −78°C. Nuclear magnetic resonance (NMR) imaging, Fourier transform infrared, and electrospray ionization mass spectrometry were performed to acquire complete structural information about the synthesized monomer and polymer. Degree of phosphonation of the synthesized polymer calculated from proton NMR spectra was as high as 70%. Thermal properties of the P-PEEK were checked using a differential scanning calorimeter (DSC) and a thermogravimetric analyzer. Moderate increase in melting point and glass transition temperature ( Tg) were observed from the DSC analysis. Solubility of the polymer was improved significantly in the common organic solvents that permitted the polymer to be solution casted. Solid electrolyte membrane exhibited through plane proton conductivity of 7.5 × 10−5 S cm−1 at 25°C under fully hydrated conditions.

The Effects of Sulfonated Poly(ether ether ketone) Ion Exchange Preparation Conditions on Membrane Properties

A low cost cation exchange membrane to be used in a specific bioelectrochemical system has been developed using poly(ether ether ketone) (PEEK). This material is presented as an alternative to current commercial ion exchange membranes that have been primarily designed for fuel cell applications. To increase the hydrophilicity and ion transport of the PEEK material, charged groups are introduced through sulfonation. The effect of sulfonation and casting conditions on membrane performance has been systematically determined by producing a series of membranes synthesized over an array of reaction and casting conditions. Optimal reaction and casting conditions for producing SPEEK ion exchange membranes with appropriate performance characteristics have been established by this uniquely systematic experimental series. Membrane materials were characterized by ion exchange capacity, water uptake, swelling, potential difference and NMR analysis. Testing this extensive membranes series established that the most appropriate sulfonation conditions were 60 °C for 6 h. For mechanical stability and ease of handling, SPEEK membranes cast from solvent casting concentrations of 15%–25% with a resulting thickness of 30–50 µm were also found to be most suitable from the series of tested casting conditions. Drying conditions did not have any apparent impact on the measured parameters in this study. The conductivity of SPEEK membranes was found to be in the range of 10⁻³ S cm⁻¹, which is suitable for use as a low cost membrane in the intended bioelectrochemical systems.

Membrane materials for addressing energy and environmental challenges

Our modern society must solve various severe problems to maintain and increase our quality of life: from water stress to global warming, to fossil fuel depletion, to environmental pollution. The process intensification (PI) strategy is expected to contribute to overcoming many of these issues by facilitating the transition from a resource-intensive to a knowledge-intensive industrial system that will guarantee sustainable growth. Membrane operations, which respond efficiently to the requirements of the PI strategy, have the potential to replace conventional energy-intensive separation techniques, which will boost the efficiency and reduce the environmental impact of separations as well as conversion processes. This work critically reviews the current status and emerging applications of (integrated) membrane operations with a special focus on energy and environmental applications.

Novel melt-processable poly(ether ether ketone)(PEEK)/inorganic fullerene-like WS(2) nanoparticles for critical applications

The combination of high-performance thermoplastic poly(ether ether ketone) (PEEK) with inorganic fullerene-like tungsten disulfide (IF-WS(2)) nanoparticles offers an attractive way to combine the merits of organic and inorganic materials into novel polymer nanocomposite materials. Here, we report the processing of novel PEEK/IF-WS(2) nanocomposites, which overcome the nanoparticle agglomerate formation and provide PEEK-particle interactions. The IF-WS(2) nanoparticles do not require exfoliation or modification, making it possible to obtain stronger, lighter materials without the complexity and processing cost associated with these treatments. The nanocomposites were fabricated by melt blending, after a predispersion step based on ball milling and mechanical treatments in organic solvent, which leads to the dispersion of individually IF-WS(2) nanoparticles in the PEEK matrix as confirmed by scanning electron microscopy. In order to determine the performance of the PEEK/IF-WS(2) nanocomposites for potential critical applications, particularly for the aircraft industry, we have extensively investigated these materials with a wide range of structural, thermal, and mechanical techniques using time-resolved synchrotron X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry, dynamic-mechanical analysis, and tensile and impact tests as well as thermal measurements. Modulus, tensile strengh, thermal stability, and thermal conductivity of PEEK exhibited remarkable improvement with the addition of IF-WS(2).