Enhanced water retention and stable dynamic water behavior of sulfonated poly(ether ether ketone) membranes under low humidity by incorporating humidity responsive double-shelled hollow spheres

Abstract

Many efforts have been devoted to maintaining the water content at a constant level in water retention proton exchange membranes, especially under a low humidity. It is necessary to develop a method for enhancing the water retention with a stable dynamic water behavior. Herein, humidity responsive double-shelled hollow spheres (DSHSs) were incorporated into a sulfonated poly(ether ether ketone) (SPEEK) matrix membrane to simultaneously enhance its water retention and improve its dynamic water behavior. The water retention of the DSHS incorporated SPEEK membrane was considerably increased compared to that of the SPEEK membrane due to the presence of a central cavity and gap between the inner and outer shell of the DSHSs. The humidity responsive DSHSs could rapidly adjust the water distribution within the SPEEK matrix and compensate the water evaporated under a low humidity, which is similar to the function of a vacuole in plant cells. As a result, the dynamic water behavior of the SPEEK/DSHS hybrid membranes was significantly improved. As a benefit from this, a continuous water network in the hybrid membranes could be maintained for a long time to enhance the proton conductivity of the hybrid membranes under a low humidity. A mechanism was proposed for the interpretation of these phenomena. The nanostructure of the hybrid membranes was studied by smallangle X-ray scattering (SAXS) and field emission scanning electron microscopy (FESEM).

Synergy between Isomorphous Acid and Basic Metal–Organic Frameworks for Anhydrous Proton Conduction of Low-Cost Hybrid Membranes at High Temperatures

“…Under hydrated conditions, proton transfer activation energies (E a ) of these hybrid membranes are calculated to be less than 0.15 eV ( indicating that the protons mainly migrated via hopping mechanism. 47,48 The E a of the CS/A-X membranes has lower values than that of the pure CS membrane probably because of the presence of the acid groups and acid−base pairs, which would allow more protons migrate via Grotthuss mechanism.…”

“…To explore the roles of MOFs in membranes, we used the optimized loading of MOF A (15%) and MOF B (6%) in respective single MOF-filled hybrid membranes to prepare dual MOF-filled ones, that is CS/ A -6 + B -15, which demonstrated the increase of conductivity (0.052 S/cm), compared with single MOF-filled membranes under the identical conditions (Table ). Under hydrated conditions, proton transfer activation energies ( E a ) of these hybrid membranes are calculated to be less than 0.15 eV (Table ), indicating that the protons mainly migrated via hopping mechanism. , The E a of the CS/ A - X membranes has lower values than that of the pure CS membrane probably because of the presence of the acid groups and acid–base pairs, which would allow more protons migrate via Grotthuss mechanism. The E a value of CS/ A -6 + B -15 is 0.131 eV, which is higher than the pure CS membranes and the composite membranes.…”

Double shelled hollow SnO2/polymer microsphere as a high-capacity anode material for superior reversible lithium ion storage

“…In our previous work, a series of functional hollow polymer microspheres with a double shell structure were designed and synthesized, which were incorporated into a sulfonated poly(ether ether ketone) matrix membrane to simultaneously enhance its water retention and improve its dynamic water behaviour for use in direct methanol fuel cells, by verifying the proton conductivity of the polymeric shells. 35 In the present work, hollow double shelled SnO 2 / poly(ethylene glycol dimethacrylate-co-methacrylic acid) (SnO 2 / (PEGDMA-co-MAA)) microspheres were designed and prepared by the selective removal of the silica inner core from the corresponding SiO 2 /SnO 2 /P(EGDMA-co-MAA) tri-layer microspheres, which were synthesized by combining a hydrothermal method for formation of the sandwiched SnO 2 layer and a distillation precipitation polymerization method for the construction of the P(EGDMA-co-MAA) shell layer. These double shell hollow hybrid microspheres exhibited good lithium ion storage properties with highly reversible and stable capacity retention aer prolonged cycles.…”

Ultra-robust, highly proton-conductive polymer carbon dot membranes through bioinspired complexation

“…6,7 Over the past decades, the organic-inorganic hybridization method has been widely utilized to regulate the physicochemical microenvironment and multiple interactions in membranes to synergistically improve proton conductivity and mechanical stability. [8][9][10] The sizes of commonly used inorganic llers (such as SiO 2 , 11 carbon nanotubes (CNTs 12 ), halloysite nanotubes (HNTs 13 ), graphene oxide (GO 14 ), MXenes, 15 and g-C 3 N 4 16 are usually tens to hundreds of nanometers, and the high density of inorganic llers and poor interface compatibility oen result in serious agglomeration even at lower ller content (<10 wt%), limiting the improvement of proton conductivity and mechanical stability of composite membranes. In recent years, zerodimensional polymer carbon dots (PCDs) have attracted intensive research interest attributed to their small size (usually 2-8 nm), lightweight, facile synthetic routes, and excellent interface compatibility with polyelectrolytes.…”