Poly(p-phenylene)-based membranes with cerium for chemically durable polymer electrolyte fuel cell membranes.

A poly(p-phenylene)-based multiblock polymer is developed with an oligomeric chain extender and cerium (CE-sPP-PPES + Ce) to realize better performance and durability in proton exchange membrane fuel cells. The membrane performance is evaluated in single cells at 80 °C and at 100% and 50% relative humidity (RH). The accelerated stability test is conducted 90 °C and 30% RH, during which linear sweep voltammetry and hydrogen permeation detection are monitored periodically.

Porous Polyethylene Supports in Reinforcement of Multiblock Hydrocarbon Ionomers for Proton Exchange Membranes.

Hydrocarbon (HC)-based block copolymers have been recognized as promising candidates for proton exchange membranes (PEMs) due to their distinct hydrophilic-hydrophobic separation, which results in improved proton transport compared to that of random copolymers. However, most PEMs derived from HC-based ionomers, including block copolymers, encounter challenges related to durability in electrochemical cells due to their low mechanical and chemical properties. One method for reinforcing HC-based ionomers involves incorporating the ionomers into commercially available low surface tension PTFE porous substrates.

Hydrocarbon-Based Composite Membrane Using LCP-Nonwoven Fabrics for Durable Proton Exchange Membrane Water Electrolysis.

A new hydrocarbon-based (HC) composite membrane was developed using liquid crystal polymer (LCP)-nonwoven fabrics for application in proton exchange membrane water electrolysis (PEMWE). A copolymer of sulfonated poly(arylene ether sulfone) with a sulfonation degree of 50 mol% (SPAES50) was utilized as an ionomer for the HC membranes and impregnated into the LCP-nonwoven fabrics without any surface treatment of the LCP. The physical interlocking structure between the SPAES50 and LCP-nonwoven fabrics was investigated, validating the outstanding mechanical properties and dimensional stability of the composite membrane in comparison to the pristine membrane.

Multi-Block Copolymer Membranes Consisting of Sulfonated Poly(-phenylene) and Naphthalene Containing Poly(arylene Ether Ketone) for Proton Exchange Membrane Water Electrolysis.

Glassy hydrocarbon-based membranes are being researched as a replacement for perfluorosulfonic acid (PFSA) membranes in proton exchange membrane water electrolysis (PEMWE). Here, naphthalene containing Poly(arylene Ether Ketone) was introduced into the Poly(-phenylene)-based multi-block copolymers through Ni(0)-catalyzed coupling reaction to enhance interactions of the naphthalene units. It is discovered that there is an optimum input ratio of the hydrophilic monomer and NBP oligomer for the multi-block copolymers with high ion exchange capacity (IEC) and polymerization yield.

Aluminum Diethylphosphinate-Incorporated Flame-Retardant Polyacrylonitrile Separators for Safety of Lithium-Ion Batteries.

Herein, we developed polyacrylonitrile (PAN)-based nanoporous composite membranes incorporating aluminum diethylphosphinate (ADEP) for use as a heat-resistant and flame-retardant separator in high-performance and safe lithium-ion batteries (LIBs). ADEP is phosphorus-rich, thermally stable, and flame retardant, and it can effectively suppress the combustibility of PAN nanofibers. Nanofibrous membranes were obtained by electrospinning, and the content of ADEP varied from 0 to 20 wt%.

Cross-Linked Composite Gel Polymer Electrolyte Based on an H-Shaped Poly(ethylene oxide)-Poly(propylene oxide) Tetrablock Copolymer with SiO Nanoparticles for Solid-State Supercapacitor Applications.

Achieving high ionic conductivity, wide voltage window, and good mechanical strength in a single material remains a key challenge for polymer-based electrolytes for use in solid-state supercapacitors (SCs). Herein, we report cross-linked composite gel polymer electrolytes (CGPEs) based on multi-cross-linkable H-shaped poly(ethylene oxide)-poly(propylene oxide) (PEO-PPO) tetrablock copolymer precursors, SiO nanoparticles, and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, an ionic liquid (IL). Self-standing CGPE membranes with a high IL content were prepared using in situ cross-linking reactions between the silane groups present in the precursor and the SiO surface.

Alcohol-Treated Porous PTFE Substrate for the Penetration of PTFE-Incompatible Hydrocarbon-Based Ionomer Solutions.

For a mechanically tough proton exchange membrane, a composite membrane incorporated with a porous polymer substrate is of great interest to suppress the ionomer swelling and to improve the dimensional stability and mechanical strength of the ionomers. For the composite membranes, good impregnation of substrate-incompatible ionomer solution into the substrate pores still remains one of the challenges to be solved. Here, we demonstrated a facile process (surface treatment with solvents compatible with both substrate and the ionomer solution) for the fabrication of the composite membranes using polytetrafluoroethylene (PTFE) as a porous substrate and poly(arylene ether sulfone) (SPAES) as a hydrocarbon-based (HC) ionomer.

Low-Voltage Reversible Electroadhesion of Ionoelastomer Junctions.

Electroadhesion provides a simple route to rapidly and reversibly control adhesion using applied electric potentials, offering promise for a variety of applications including haptics and robotics. Current electroadhesives, however, suffer from key limitations associated with the use of high operating voltages (>kV) and corresponding failure due to dielectric breakdown. Here, a new type of electroadhesion based on heterojunctions between iono-elastomer of opposite polarity is demonstrated, which can be operated at potentials as low as ≈1 V.

Reinforced anion exchange membrane based on thermal cross-linking method with outstanding cell performance for reverse electrodialysis.

A poly(ethylene)-reinforced anion exchange membrane based on cross-linked quaternary-aminated polystyrene and quaternary-aminated poly(phenylene oxide) was developed for reverse electrodialysis. Although reverse electrodialysis is a clean and renewable energy generation system, the low power output and high membrane cost are serious obstacles to its commercialization. Herein, to lower the membrane cost, inexpensive polystyrene and poly(phenylene oxide) were used as ionomer backbones.

Functional polymers for growth and stabilization of CsPbBr perovskite nanoparticles.

We introduce an approach to synthesize polymer-stabilized CsPbBr3 perovskite nanoparticles (NPs) using ammonium bromide-functionalized polymers as both bromide precursors and stabilizing ligands. The polymer-passivated NPs exhibit significant advantages over conventional perovskite NPs owing to their facile dispersion in polymer matrices and enhanced optoelectronic stability.

Polybenzimidazole/Nafion hybrid membrane with improved chemical stability for vanadium redox flow battery application.

In order to increase the chemical stability of polybenzimidazole (PBI) membrane against the highly oxidizing environment of a vanadium redox flow battery (VRFB), PBI/Nafion hybrid membrane was developed by spray coating a Nafion ionomer onto one surface of the PBI membrane. The acid-base interaction between the sulfonic acid of the Nafion and the benzimidazole of the PBI created a stable interfacial adhesion between the Nafion layer and the PBI layer. The hybrid membrane showed an area resistance of 0.

Hydrophilic Channel Alignment of Perfluoronated Sulfonic-Acid Ionomers for Vanadium Redox Flow Batteries.

It is known that uniaxially drawn perfluoronated sulfonic-acid ionomers (PFSAs) show diffusion anisotropy because of the aligned water channels along the deformation direction. We apply the uniaxially stretched membranes to vanadium redox flow batteries (VRFBs) to suppress the permeation of active species, vanadium ions through the transverse directions. The aligned water channels render much lower vanadium permeability, resulting in higher Coulombic efficiency (>98%) and longer self-discharge time (>250 h).

Tunable Upper Critical Solution Temperature of Poly(N-isopropylacrylamide) in Ionic Liquids for Sequential and Reversible Self-Folding.

We demonstrate sequential folding of micropatterned polymer actuators by tuning the upper critical solution temperature (UCST) of poly(N-isopropylacrylamide) (PNIPAM) copolymers in the ionic liquid (IL) 1-ethyl-3-methylimidazolium bis(trifluoro-methylsulfonyl) imide. Incorporation of comonomers having different hydrogen-bonding capacities, acrylic acid and methyl acrylate, is shown to shift the UCST of PNIPAM to higher and lower temperatures, respectively. Relying on the ability to tune the transition temperature through copolymerization along with the wide thermal range afforded by the IL as a solvent, we fabricated a photopatterned self-folding device which shows reversible and sequential bending of three sets of hinges.

Size Control and Fractionation of Ionic Liquid Filled Polymersomes with Glassy and Rubbery Bilayer Membranes.

We demonstrate control over the size of ionic liquid (IL) filled polymeric vesicles (polymersomes) by three distinct methods: mechanical extrusion, cosolvent-based processing in an IL, and fractionation of polymersomes in a biphasic system of IL and water. For the representative ionic liquid (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([EMIM][TFSI])), the size and dispersity of polymersomes formed from 1,2-polybutadiene-b-poly(ethylene oxide) (PB-PEO) and polystyrene-b-poly(ethylene oxide) (PS-PEO) diblock copolymers were shown to be sensitive to assembly conditions. During mechanical extrusion through a polycarbonate membrane, the relatively larger polymersomes were broken up and reorganized into vesicles with mean size comparable to the membrane pore (100 nm radius); the distribution width also decreased significantly after only a few passes.

Oil-in-Oil Emulsions Stabilized by Asymmetric Polymersomes Formed by AC + BC Block Polymer Co-Assembly.

We demonstrate a facile route to asymmetric polymersomes by blending AC and BC block copolymers in oil-in-oil emulsions containing polystyrene (PS) and polybutadiene (PB) in chloroform (CHCl3). Polymersomes were prepared by mixing polystyrene-b-poly(ethylene oxide) (SO) and polybutadiene-b-poly(ethylene oxide) (BO) in the oil-in-oil emulsion, where the droplets and continuous phase are PS- and PB-rich, respectively. The polymersome structure was directly visualized using dye-labeled SO and BO with confocal fluorescence microscopy; SO and BO with a high O block fraction co-assemble to produce asymmetric polymersomes.

Anhydrous Proton Conducting Polymer Electrolyte Membranes via Polymerization-Induced Microphase Separation.

Solid-state polymer electrolyte membranes (PEMs) exhibiting high ionic conductivity coupled with mechanical robustness and high thermal stability are vital for the design of next-generation lithium-ion batteries and high-temperature fuel cells. We present the in situ preparation of nanostructured PEMs incorporating a protic ionic liquid (IL) into one of the domains of a microphase-separated block copolymer created via polymerization-induced microphase separation. This facile, one-pot synthetic strategy transforms a homogeneous liquid precursor consisting of a poly(ethylene oxide) (PEO) macro-chain-transfer agent, styrene and divinylbenzene monomers, and protic IL into a robust and transparent monolith.

Permeability of Rubbery and Glassy Membranes of Ionic Liquid Filled Polymersome Nanoreactors in Water.

Nanoemulsion-like polymer vesicles (polymersomes) having ionic liquid interiors dispersed in water are attractive for nanoreactor applications. In a previous study, we demonstrated that small molecules could pass through rubbery polybutadiene membranes on a time scale of seconds, which is practical for chemical transformations. It is of interest to determine how sensitive the rate of transport is to temperature, particularly for membranes in the vicinity of the glass transition (Tg).

Location and Influence of Added Block Copolymers on the Droplet Size in Oil-in-Oil Emulsions.

We have investigated the effect of added polystyrene-b-poly(ethylene oxide) (SO) copolymer on the stability of oil-in-oil (O/O) emulsions containing polystyrene (PS) and poly(ethylene glycol) (PEG) in chloroform (CHCl3) and directly visualized the location of SO in the emulsions by using dye-labeled SO (SO*) with confocal laser scanning microscopy (CLSM). The emulsion formed by PS/PEG/CHCl3 = 14/6/80 (wt %) consisted of a droplet phase of PS in CHCl3 and a continuous phase containing PEG in CHCl3. SO*s with various molecular weights (Mn,SO) and volume fractions of the PS block in SO (fPS) were prepared via living anionic polymerization and subsequent end-esterification.

Photoreversible gelation of a triblock copolymer in an ionic liquid.

The reversible micellization and sol-gel transition of block copolymer solutions in an ionic liquid (IL) triggered by a photostimulus is described. The ABA triblock copolymer employed, denoted P(AzoMA-r-NIPAm)-b-PEO-b-P(AzoMA-r-NIPAm)), has a B block composed of an IL-soluble poly(ethylene oxide) (PEO). The A block consists of a random copolymer including thermosensitive N-isopropylacrylamide (NIPAm) units and a methacrylate with an azobenzene chromophore in the side chain (AzoMA).

Interfacial tension-hindered phase transfer of polystyrene-b-poly(ethylene oxide) polymersomes from a hydrophobic ionic liquid to water.

We examine the phase transfer of polystyrene-b-poly(ethylene oxide) (PS-PEO) polymersomes from a hydrophobic ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI]), into water. The dependence of the phase transfer on the molecular weight and PEO volume fraction (fPEO) of the PS-PEO polymersomes was systematically studied by varying the molecular weight of PS (10,000-27,000 g/mol) as well as by varying the volume fraction of PEO (fPEO) between 0.1 and 0.

Vesicles and reverse vesicles of an ionic liquid in ionic liquids.

First evidence and the mechanism of formation of closed bilayer structures by a single chain amino acid ionic liquid (IL), L-proline isopropylester laurylsulfate in both hydrophilic and hydrophobic ILs, is reported. Such ionic self-assemblies are shown to be guided by fine balance of solvophobic effects and ionic arrangements via hydrogen bonding and electrostatic interactions.