Silicone-containing polymer blend electrolyte membranes for fuel cell applications

Polymer electrolyte membranes are developed from blends of chemically durable silicone-containing epoxy (Si-Epoxy) and proton conducting sulfonic polyimide (SPI). A charge-transfer (CT) complex is formed between electron-donating dihydroxynaphthalene units in Si-Epoxy, and electron-accepting naphthalenediimide units in SPI, as confirmed via X-ray diffraction and visible spectroscopy. The blend membranes show comparable mechanical strength to Nafion 211, but the elongation to break is much lower, indicating better resistance to deformation under strain stress, attributed to CT complex formation. The chemical durability of the blend membranes was much higher than pure SPI according to Fenton's test, also attributed to CT complex formation. Meanwhile, the proton conductivity is dependent on the sulfonic acid content of the SPI, which in turn affects the fuel cell performance. The maximum proton conductivity was measured to be 23.1 mS cm⁻¹ at 80°C and 90 %RH for a 1:1 blend, and the membranes were successfully incorporated into PEFCs.     

Nanometer-scale physically adsorbed thermoresponsive films for cell culture

Physical adsorption was used to produce nanometer thick thermoresponsive films with a view to nonenzymatic cell detachment. Two polymers were investigated, poly-(N-isopropylacrylamide) and poly (N-isopropylacrylamide-co-N-tertbutylacrylamide). Substrates were prepared above and below the polymers’ LCST to investigate the effect of polymer conformation on the prepared substrates. Endothelial cells were seeded on the prepared films; cell proliferation was higher on the films produced below the polymers’ LCST than on those prepared above and cells detached from the surfaces upon temperature reduction. Physical adsorption of poly-(N-isopropylacrylamide)–based films is a viable approach to produce substrates compliant with cell growth and temperature modulated detachment.     

Novel polysulfone/sulfonated polyaniline/niobium pentoxide polymer blend nanocomposite membranes for fuel cell applications

New series of polymer nanocomposite membranes were prepared from polysulfone (PSU), sulfonated polyaniline (SPANI) and niobium pentoxide (Nb₂O₅) by solution casting technique. In order to assess the suitability of the polymer electrolytes in fuel cell applications, the membranes were characterized with respect to their physicochemical properties. Scanning electron microscope, X-ray diffraction, and X-ray photoelectron spectroscopy data confirmed the successful incorporation of nanofillers into the polymer matrix. The membrane loaded with 10 wt% of niobium pentoxide into PSU/SPANI exhibited a proton conductivity of 0.0674 S cm⁻¹, whereas the control membrane showed 0.0110 S cm⁻¹. The incorporation of niobium pentoxide into pristine polymer not only improved the ionic conductivity but also enhanced the thermal and oxidative stabilities. The substantial results achieved with the organic–inorganic polymer composites derived from PSU-SPANI and Nb₂O₅ have been established and can be viable materials for electrolyte in fuel cell applications.     

Development of chitosan/Spirulina bio‐blend films and its biosorption potential for dyes

Chitosan/Spirulina bio‐blends (CSBB) in films form were developed to be an alternative/renewable biosorbent, able to remove anionic and cationic dyes from aqueous solutions. CSBB potential as biosorbent was investigated for cationic dye Methylene Blue (MB), and anionic dyes Tartrazine Yellow (TY) and Reactive Black 5 (RB5). Chitosan and Spirulina samples were obtained and characterized, and CSBB films were prepared with different chitosan/Spirulina ratios. The CSBB films characteristics, as, mechanical properties, thermal profile, crystallinity, functional groups, morphology, and biosorption potential were strongly dependent of chitosan/Spirulina ratio. CSBB films preserved its mechanical structures at pH from 4.0 to 8.0. The biosorption capacities were 120, 110, and 100 mg g^?1 for RB5, TY, and MB, respectively. The increase of chitosan amount favored the TY and RB5 biosorption; however, the increase of Spirulina amount favored the MB biosorption. Thus, the CSBB in film form is a renewable biosorbent suitable to remove anionic and cationic dyes from aqueous solutions. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44580.     

Preparation and characterization of sulfonated block‐graft copolyimide/sulfonated polybenzimidazole blend membranes for fuel cell application

Polymer electrolyte blend membranes composed of sulfonated block‐graft polyimide (S‐bg‐PI) and sulfonated polybenzimidazole (sPBI) were prepared and characterized. The proton conductivity and oxygen permeability coefficient of the novel blend membrane S‐bg‐PI/sPBI (7 wt%) were 0.38 S cm^?1 at 90 °C and 98% relative humidity and 7.2 × 10^?13 cm³(STP) cm (cm² s cmHg)^?1 at 35 °C and 76 cmHg, respectively, while those of Nafion^® were 0.15 S cm^?1 and 1.1 × 10^?10 cm³(STP) cm (cm² s cmHg)^?1 under the same conditions. The apparent (proton/oxygen transport) selectivity calculated from the proton conductivity and the oxygen permeability coefficient in the S‐bg‐PI/sPBI (7 wt%) membrane was 300 times larger than that determined in the Nafion membrane. Besides, the excellent gas barrier properties based on an acid ? base interaction in the blend membranes are expected to suppress the generation of hydrogen peroxide and reactive oxygen species, which will degrade fuel cells during operation. The excellent proton conductivity and gas barrier properties of the novel membranes promise their application for future fuel cell membranes. © 2015 Society of Chemical Industry     

Porous polymer derived ceramic (PDC)-montmorillonite-H3PMo12O40/SiO2 composite membranes for microbial fuel cell (MFC) application

Ceramic membranes can serve as viable alternatives to the less mechanically stable polymeric membranes utilized in microbial fuel cells (MFCs). In this work, a series of polymer-derived ceramic (PDC) proton exchange composite membranes with large ion exchange capacity (IEC) values, high cation transport numbers, and low oxygen diffusion coefficients have been synthesized at various pyrolysis temperatures using a pressing technique. These materials were composed of a polysiloxane matrix mixed with proton-conducting fillers such as montmorillonite and H₃PMo₁₂O₄₀/SiO₂ at different ratios. By tuning the average pore sizes of the membranes between 0.1 and 1?µm and their hydrophilic/hydrophobic characteristics, the maximum IEC of 0.6072 mequiv/g and cation transport number of 0.6988 were obtained, which is 67% and 72% of polymeric nafion performance, respectively. In addition, the minimal oxygen mass transfer coefficient achieved by this approach was equal to 5.62?×?10^?4 cm/s, which is very close to the commercial nafion membrane value. The fabricated PDC composite membranes meet all the essential criteria required for their use in MFC applications and represent a high potential to overcome limitations of polymeric membrane.