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Non-aqueous lithium-ion redox flow batteries (Li-RFBs) have recently garnered much interest because of their high operating voltage and energy density. Albeit these outstanding advantages, challenges, such as poor cyclability and efficiency, still remain in employing the practical application. In an attempt to address these problems, a series of 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) and TEMPO derivatives catholytes were prepared and investigated as redox-active materials. Electrochemical evaluation exhibited that the introduction of polar and electron-withdrawing substituents to TEMPO was able to enhance the rate capability and cycling stability, when compared to those with the neat TEMPO. Extensive analysis of the electrochemical properties revealed that the electrophilic heteroatom stabilized the radical as well as alleviated the catholyte degradation. Overall, a careful selection of redox-active species demonstrates great promise in improving the current redox flow battery technology.

Poly(2,6-dimethyl-1,4-phenylene ether) (PPE)/Nylon 66 blends have been considered as the potential heat resistant engineering plastics with high mechanical toughness and flame retardancy, suitable for high temperature applications. However, incompatibility between PPE and Nylon 66 and poor thermal stability of Nylon 66 degrade mechanical toughness and flame retardancy. In this work, for the first time, the PPE/Nylon 66 blends with high mechanical toughness and flame retardancy simultaneously have been prepared through newly synthesized compatibilizer of PPE grafted with fumaric acid (PPE-g-FA) and environmental-friendly non-halogen organic phosphinate flame retardant. The PPE/Nylon 66 blend achieved not only V0 grade flame retardancy with the help of improved fire resistance through the solid phase reaction of non-halogenic flame retardant, but also large impact strength larger than 10 kJ/m2 due to the strong compatibility of PPE-g-FA.

Silica nanoparticles were chemically grafted onto a porous polyethylene separator to improve the adhesion strength, thermal stability, and electrochemical performance of a polyolefin separator. A surface activation via UVO plasma treatment, followed by silane hybridization yielded a polymeric binder-free, thin coating of SiO2 nanoparticles onto the separator. The chemical grafting provided a much stronger adhesive strength (> 2.5 N/cm), reduced thermal shrinkage (

Carbon molecular sieve (CMS) membranes are a promising candidate for natural gas processing due to their peculiar pore structure-induced excellent separation performance. Formulating ultrathin, defect-free CMS hollow fiber membranes is, however, still challenging due to damage on porous sub-structures induced by thermal relaxation of polymer chains during pyrolysis. Herein, we report a new methodology enabling high separation performance and good plasticization resistance in CMS fiber membranes by uniform integration of double-stranded polysilsesquioxanes into the polyimide matrix. Our polyimide/ladder-structured polysilsesquioxane CMS fibers substantially enhanced CO2 permeance by as much as 546% compared to the precursor fiber analogues due to the thin molecular sieve selective layer. Also, poly(dimethylsiloxane) coating delayed physical aging, still showing a high CO2 permeance of 354 GPU with CO2/CH4 selectivity of 56 after 72 days of aging. Furthermore, they exhibited excellent plasticization resistance up to a CO2 partial pressure of 13.2 bar with CO2/CH4 separation factor of 74 for an equimolar CO2/CH4 feed mixture.

A series of UV-curable hybrid composite blends containing a carboxylic acid functionalized polyimidewith varying amounts of high molecular weight (~1 K) PEG-grafted ladder-structured polysilsesquioxanes copolymerized with methacryl groups were fabricated and their structural, thermal, mechanical, and surface properties characterized. At a composite weight ratio of polyimide above 50 wt.%, a stark shift from amorphous to crystalline polyethylene glycol (PEG) phases were observed, accompanied by a drastic increase in both surface moduli and brittleness index. Moreover, fabricated composites were shown to have a wide range water contact angle, 9.8&deg, &ndash, 73.8&deg, attesting to the tunable surface properties of these amphiphilic hybrid polymer composites. The enhanced mechanical properties, combined with the utility of tunable surface hydrophilicity allows for the possible use of these hybrid polymer composites to be utilized as photosensitive polyimide negative photoresists for a myriad of semiconductor patterning processes.

Modern electrochemical energy conversion devices require more advanced proton conductors for their broad applications. Phosphonated polymers have been proposed as anhydrous proton conductors for fuel cells. However, the anhydride formation of phosphonic acid functional groups lowers proton conductivity and this prevents the use of phosphonated polymers in fuel cell applications. Here, we report a poly(2,3,5,6-tetrafluorostyrene-4-phosphonic acid) that does not undergo anhydride formation and thus maintains protonic conductivity above 200 °C. We use the phosphonated polymer in fuel cell electrodes with an ion-pair coordinated membrane in a membrane electrode assembly. This synergistically integrated fuel cell reached peak power densities of 1,130 mW cm−2 at 160 °C and 1,740 mW cm−2 at 240 °C under H2/O2 conditions, substantially outperforming polybenzimidazole- and metal phosphate-based fuel cells. Our result indicates a pathway towards using phosphonated polymers in high-performance fuel cells under hot and dry operating conditions. Phosphonated polymers have been proposed as anhydrous proton conductors for fuel cells but anhydride formation of phosphonic acid functional groups lowers conductivity. A synergistically integrated phosphonated poly(pentafluorostyrene) is shown to maintain high protonic conductivity above 200 °C.

A series of ladder-like polysilsesquioxanes (LPSQs) containing the UV-curable methacryoxypropyl (MA) and different organic functional (R) groups (propyl, hexyl, cyclohexyl, phenyl or naphthyl) at the fixed MA/R molar ratio were synthesized as hard coating materials. The LPSQ hard coating films prepared by a simple UV curing process exhibited excellent optical transparency in the visible light range. X-ray diffraction analysis of the LPSQ films characterized how their intermolecular chain-to-chain distance and thus chain packing density varied according to the organic functional group. In addition, the hardness, elastic modulus and scratch resistance of the LPSQ films were evaluated by nanoindentation and nanoscratch tests. Although the mechanical properties of the LPSQ films were affected by both the chain rigidity of the organic functional group and the chain packing density of the siloxane backbones, chain rigidity played the dominant role in determining their mechanical robustness. Hence, despite its lowest chain packing density, the LPSQ film with the naphthyl group exhibited the best mechanical properties due to its high chain rigidity derived from the increased aromaticity of the naphthyl group. This study suggests the key factor when designing mechanically durable, scratch resistant hard coating films is the chain rigidity of the film network.

An effective method to enhance the durability of polymer electrolyte membrane fuel cells (PEMFCs) is reported. PEMFC performance loss is mitigated by exposing the electrodes of fuel cells to dry nitrogen gas periodically at high temperature. This method extends the lifetime of fuel cells significantly compared to their non-treated counterparts. The impact of treatment temperature and exposure time on PEMFC durability is reported, using potential cycling accelerated stress tests. The enhanced durability is attributed to the suppression of “ionomer relaxation” that occurs under the nearly water saturated operating conditions of a PEMFC cathode.

This paper reports the recycling of flexible printed circuit board (FPCB) waste through carbonization of polyimide by dual pyrolysis processes. The organic matter was recovered as pyrolyzed oil at low temperatures, while valuable metals and polyimide-derived carbon were effectively recovered through secondary high temperature pyrolysis. The major component of organics extracted from FPCB waste comprised of epoxy resins were identified as pyrolysis oils containing bisphenol-A. The valuable metals (Cu, Ni, Ag, Sn, Au, Pd) in waste FPCB were recovered as granular shape and quantitatively analyzed via ICP-OES. In attempt to produce carbonaceous material with increased degree of graphitization at low heat-treatment conditions, the catalytic effect of transition metals within FPCB waste was investigated for the efficient carbonization of polyimide films. The morphology of the carbon powder was observed by scanning electron microscopy and graphitic carbonization was investigated with X-ray analysis. The protocols outlined in this study may allow for propitious opportunities to salvage both organic and inorganic materials from FPCB waste products for a sustainable future.

A new method for enhancing condensable gas-induced plasticization resistance of aromatic polyimides (PIs) as well as increasing the flux of gas penetrants with negligible selectivity loss was demonstrated via a so-called bromination/debromination-induced thermal crosslinking. Our newly developed crosslinking approach essentially loosened the polymeric chain packing of 6FDA-Durene PIs by forming ethylene crosslinking bonds, while retaining its rigid PI backbone. As the degree of crosslinking increased, the permeability increased with trivial selectivity loss. Notably, the 75% bromination/debromination-induced crosslinked PI membranes drastically improved CO2 and C3H6 permeabilities by as much as 157% and 172%, respectively, compared to those of the pristine-PI analogs due to the debromination-induced free volume enhancement, while maintaining good selectivity due to the crosslinked ethylene bridges. As a result, outstanding separation performances for CO2/N2, CO2/CH4 and C3H6/C3H8 gas pairs have been obtained, and most importantly, a high tolerance to CO2- or C3H6-induced plasticization was observed up to CO2 or C3H6 pressure of 24 and 10 atm, respectively. Our current crosslinking approach can be extended to industrially attractive hollow fiber forms of various aromatic PIs for high plasticization resistance as well as high flux.

To data, combination of Pt-based bimetallic nanocrysatals and the graphene support have significantly contributed to enhance the oxygen reduction reaction (ORR) performance relative to electrocatalysts based on monometallic Pt nanoparticles (NPs) primarily due to the unique ligand effects and benefits of the carbon support. In this study, we propose a new structure of bimetallic electrocatalysts to realize the synergistic effects on the ORR performance through effective integration of the fine-sized Pt NPs, PdPt bimetallic nanocrystals, and non-covalently functionalized graphene with ionic polymers. The facile wet-chemical methods were applied to synthesize fine-sized (2–5 nm) spherical Pt NPs doped large-sized (20–50 nm) non-spherical PdPt bimetallic NPs on the electronically negative ionic polymer-functionalized graphene support (Pt-on-PdPt/fG). This Pt-on-PdPt/fG with synergistic effects based on enlarged active surface area, ligand, and interfacial linking effects, exhibits substantially enhanced ORR activity (specific activity: 1.89 mA c m Pt − 2 at 0.9 VRHE) and durability in comparison to the commercial Pt/C (specific activity: 0.23 mA c m Pt − 2 at 0.9 VRHE). To this end, the effective integration of newly designed fine-sized Pt NPs doped bimetallic nanocrystals and unique graphene supports with the well-interactive ability could be a good platform to develop the advanced electrocatalysts for the efficient ORR.

Thermally curable hybrid ionogel electrolytes consisting of epoxy-functionalized POSS, amine-terminated polypropylene glycol, and ionic liquid electrolyte, 1 M LiTFSI in BMPTFSI were fabricated to give ionic conducting epoxy networks with cubic inorganic star networks crosslinked with lithium ion dissociating polypropylene glycol linkers. Characterization of these hybrid ionogels revealed high ion conduction, exceptional thermal stability, and electrochemical stability. Lithium ion capacitors fabricated with these hybrid ionogels revealed exceptional performance on par with the neat liquid ionic liquid electrolyte, and far superior over ionogels fabricated with conventional organic crosslinkers, due to the mechanical robustness and lithium ion dissociative character imparted by the POSS and PPG functionalities.

In this study, a liquid state sulfur polymer (LSP) was employed as asphalt pavement materials. The LSP/epoxy asphalt (LSPA) was easily fabricated by mixing LSP and epoxy resin at room temperature. The workability of as-mixed LSP/epoxy mixture was explored by controlling the ratio of epoxy. The asphalt mixture with the epoxy content below 50 wt% exhibited reliable flowability above approximately 12.5 cm. The solidification of LSP was successfully accompanied by simultaneous curing of epoxy. For practical application of pavement on road, the Marshall stability, indirect tensile strength and wheel tracking test were performed. The Marshall stability and indirect tensile strength of the LSPA exhibited an approximate 2-fold increase compared to neat asphalt. Moreover, exceptional durability of the LSPA was achieved through the controllable crushed depth of the pavement under wheel passes of 25,000 cycles. For practical repairing test on the road, the LSPA was cast on a pothole prepared on asphalt road. Our as-cast asphalt materials were suitable to heal potholes with seamless interface and the hardening was accomplished within a very short time of 1 h. The hardened LSPA exhibited excellent adhesion strength of approximately 1.95 MPa, enabling the elimination of gaps arising from traffic cycles and climate variation.

A series of multi-crosslinkable, self-healing, ladder-structured polysilsesquioxane inorganic-organic hybrid materials were developed to enhance the mechanical properties through tandem UV-curing and Diels-Alder chemistry. The introduction of UV-curable acryl- or epoxy groups allowed for a higher degree of crosslink density while bringing the inorganic backbones closer together for highly efficient self-healing properties, all with a singular material as the ternary organic functional groups consisting of UV-curable function, diene, and dienophile were tethered to the well-defined inorganic backbone. Exceptional thermal stability (>400 °C), optical transparency (>95%), solution processability, as well as robust surface mechanical properties in both bulk (pencil hardness 6H) and nanoscale (elastic modulus > 9 GPa), properties which can be adroitly recovered through mild and rapid thermal treatment hold great promise for next generation hybrid smart coating materials for application in optoelectronic devices.

Most inorganic nucleating agents for poly(ethylene terephthalate) (PET) have limited nucleating ability due to poor compatibility with PET. Polyhedral oligomeric silsesquioxanes (POSS) is a type of cage-shaped organic/inorganic hybrid nanoparticles with three different particle sizes: octameric (T8), decameric (T10), and dodecameric (T12). POSS is considered as a promising nucleating agent for PET because the inorganic moieties contribute to high thermal stability and nucleation and the organic moieties can be tethered to PET chains. In contrast to T8 POSS, the nucleation ability of T12 POSS for PET has been poorly reported. In this study, our newly synthesized aminopropyl functionalized T12 POSS (A-POSS) is proposed as a potential nucleating agent for PET. The amine group of A-POSS is able to be chemically conjugated to PET chains, thereby giving a more homogeneous dispersion of T12 POSS in PET than non-functional T12 Phenyl POSS (N-POSS). Its PET composites gave a ∼1.2 fold higher crystallization temperature and ∼2.7 fold higher shear-induced crystallization rate over pristine PET. Such nucleating effects for PET is more effective than those of non-functional T12 POSS and the more widely studied T8 POSS. This strategy is potentially beneficial for the high-shear melt processes of PET such as spinning and film extrusion.

Heteroleptic ruthenium-complexed ladder-like structured polysilsesquioxane (LPSQ-Ru) was synthesized by post coordination reaction of bidentate ligand side chains in LPSQ with reactive Ru(II) complexes, which was well characterized by 1H and 29Si NMR, FT-IR, and spectroscopic techniques. The photophysical properties of LPSQ-Ru were examined by UV and PL analyses in both solution and solid states, comparing to analogous polymers of ruthenium-complexed polystyrene (PS-Ru). Obtained absorptions of LPSQ-Ru and PS-Ru were broadened ranging from 390-490 nm regardless of the states. However, LPSQ-Ru exhibited higher and shaper PL emission spectrum in comparison to that of PS-Ru, particularly in the solid state, because Ru-complexes in LPSQ were much effectively isolated, preventing their aggregations due to the rigid double strained siloxane backbone. This extinguished photophysical property in LPSQ-Ru kept after intensive thermal treatment at 250 °C for 90 min, which was not achieved in PS-Ru (~5-fold decrease). These differences originated from the backbone structures were also appeared in electrochemical properties in the solid states.

A multifunctional crosslinkable and ionic-group functionalized ladder-like polysilsesquioxane was synthesized and utilized for the fabrication of hybrid ionogels for lithium ion batteries. The ionic-group functionalized ladder-like polysilsesquioxane combined the synergistic effects of hybrid materials in improving the thermal stability of conventional battery electrolytes, whilst maintain facile solution processability and chemically crosslinkable function in ionic conducting ionic liquid electrolyte media. Fabricated iongel electrolytes exhibiting exceptional thermal stability, mechanical properties, high ionic conductivity, and electrochemical stability. Lithium ion batteries fabricated with the hybrid ionic ladder-like polysilsesquioxane ionogels exhibited initial discharge capacities on par with neat liquid electrolytes, good rate performance, as well as stable cyclability and excellent Coulombic efficiency.

A new methodology for fabrication of inorganic–organic hybrid ionogels and scaffolds is developed through facile cross-linking and solution extraction of a newly developed ionic polyhedral oligomeric silsesquioxane with inorganic core. Through design of various cationic tertiary amines, as well as cross-linkable functional groups on each arm of the inorganic core, high-performance ionogels are fabricated with excellent electrochemical stability and unique ion conduction behavior, giving superior lithium ion battery performance. Moreover, through solvent extraction of the liquid components, hybrid scaffolds with well-defined, interconnected mesopores are utilized as heterogeneous catalysts for the CO2-catalyzed cycloaddition of epoxides. Excellent catalytic performance, as well as highly efficient recyclability are observed when compared to other previous literature materials.

An in-depth examination of the self-healing properties of both dienophile and diene functionalized ladder-like structured polysilsesquioxane copolymers and terpolymers was investigated. Through functionalization of both diene and dienophile on the double-stranded siloxane backbone with ternary n-alkyl functional groups acting as chain mobility control, the effect of chain mobility and chemical structure on self-healing and mechanical properties were elucidated. All of the single component self-healing hybrid materials exhibited fast healing times (∼5 min), and their de-crosslinked adducts exhibited exceptional retention of solubility in common organic solvents for good reusability, all while having inherent high thermal stability and optical transparency.

A series of trimethylsilyl-capped hybrid ladder-like polysilsesquioxane (LPSQ-TMS) derivatives were synthesized comprising an inorganic backbone functionalized with various organic side moieties and compositional ratios with application towards gate dielectrics or surface modifying materials. The surface energy (γ) and roughness (Rq) values of the LPSQ-TMS coated SiO2 dielectrics were considerably affected by the side moieties of the polymer series; methyl, n-propyl, phenyl (P), naphthyl (N), methacryloxypropyl (MA), and fluorooctyl moieties. The γ values varied from 17.0 to 42.0 mJ m−2, while the Rq values also ranged from 0.34 to 1.10 nm. On polymer-treated SiO2 dielectrics possessing smooth and semiconductor-compatible surface properties, pentacene developed terrace-like crystallites formed through layer-by-island growth modes, a stark contrast to the three-dimensionally grown crystal islands formed on rough or extremely hydrophobic surfaces, which led to unfavorable conduction pathways. Depending on the order of conjugation and interconnections between the pentacene domains, the average mobility (μFET) values of the resulting 50 nm thick pentacene organic field-effect transistors were varied by two orders of magnitude and reached 0.8 cm2 V−1 s−1, specifically, for both the P- and MA-substituted LPSQ-TMS treated SiO2 dielectrics (γ = 37.0 mJ m−2 and Rq = 0.40 nm). Moreover, we were able to demonstrate that a thermally cured 500 nm thick LPSQ-TMS layer on an Au gate-patterned flexible polyimide substrate could yield pentacene OFETs with μFET values as high as 0.60 cm2 V−1 s−1, comparable to that of the LPSQ-TMS treated SiO2 system. Also, the proper introduction of organic substituents to LPSQ improved the gate-bias stress stability for high performance OFETs.

A series of ionic liquids containing imidazolium, pyrrolidinium, or ether-functionalized pyrrolidinium cations incorporated with the same counter anion of bis(fluorosulfonyl)imide (FSI − ) were synthesized to investigate the effects of the cation structures on the physical and electrochemical properties of ionic liquids. The introduction of the polar ether group was able to compensate for the loss of the mobility of pyrrolidinium cation-based ionic liquids, while maintaining the high thermal and electrochemical stability. Extensive examinations of these ionic liquids in electric double-layer capacitor (EDLC) cells were performed to investigate their voltage stability under various operating conditions. Electrochemical evaluation revealed that the cell fabricated with ether-functionalized pyrrolidinium ionic liquid could deliver larger capacitance values and stable cycling performance compared with the cell containing imidazolium-based ionic liquid at high operating voltage; demonstrating its possible applications as high voltage electrolytes for EDLCs.

The durability of alkaline anion exchange membrane (AEM) electrolyzers is a critical requirement for implementing this technology in cost-effective hydrogen production. Here, we report that the electrochemical oxidation of the adsorbed phenyl group (found in the ionomer) on oxygen evolution catalysts produces phenol, which may cause performance deterioration in AEM electrolyzers. In-line 1H NMR kinetic analyses of phenyl oxidation in a model organic cation electrolyte shows that catalyst type significantly impacts the phenyl oxidation rate at an oxygen evolution potential. Density functional theory calculations show that the phenyl adsorption is a critical factor determining the phenyl oxidation. This research provides a path for the development of more durable AEM electrolyzers with components that can minimize the adverse impact induced by the phenyl group oxidation, such as the development of novel ionomers with fewer phenyl moieties or catalysts with less phenyl-adsorbing character.

Membrane-based separation technology is attractive for upgrading small-scale natural gas due to the benefits of the pressure-driven process with a small footprint. Very few carbon molecular sieve (CMS) membranes with high N2/CH4 separation efficiency have been reported since the relationship between CMS structure and separation performance has not been fully elucidated. Here, we report the significance of controlling the effective pore size in our newly developed hybrid CMS matrix for enhanced N2/CH4 selectivity based on experimental characterizations and density functional theory (DFT) calculations. A new class of CMS membranes with an excellent N2/CH4 selectivity is demonstrated by pyrolysis of a homogeneous, hydrogen-bonded blend of BTDA-Durene:DABA (3:2) polyimide and ladder-structured poly(phenyl-co-3-(2-aminoethylamino)propyl)silsesquioxane (LPDA64). DFT calculations suggest that electron accumulation at SiOx phases of hybrid CMS membranes strongly hinders the diffusion of CH4 compared to N2 due to a larger electron overlap, resulting in a smaller effective pore size. Moreover, elevating the pyrolysis temperatures enhanced the N2/CH4 solubility selectivity due to the strong repulsive interaction between the newly formed ultramicropores with CH4. As a result, the hybrid CMS membranes showed an excellent single gas and N2/CH4/C2H6 (20/76/4) mixed gas N2/CH4 selectivity (28 and 16, respectively).

A photosensitive ladder-structured polysilsesquioxane was synthesized for the development of flexible copper clad laminates through electroless plating of Cu. The developed ladder-structured polysilsesquioxane with controlled structure enabled easy introduction of protected thiol and allyl functional group, which under acidic conditions, the thiol group becomes deprotected. This deprotected thiol group enables UV-initiated thiol-ene curing of the exposed regions, while the unexposed regions containing free thiol groups act as seed initiators for Cu electroless plating, and the corresponding negative pattern fabrication process also possible. Through this facile method, we were able to develop flexible copper clad laminates of tunable Cu interconnect width size of high electrical conductivity according to photomask pattern and the insulating dielectric surrounding layer exhibiting low dielectric constant and low loss behavior without any corrosive Cu etching steps.

An investigation into the hydrolysis kinetics of an aqueous base-catalyzed sol-gel reaction yielding ladder-like polysilsesquioxanes was studied using NMR. Under various variables of monomer concentration, water concentration, solvent type, and monomer type, the various effects on molecular weight and degree of condensation were elucidated. Moreover, the various rate orders and rate constants were calculated and compared with previous reports of the hydrolysis of organosilane precursors. Through this study we were able to ascertain the optimal conditions of hydrolysis-polycondensation for obtaining highly condensed, high molecular weight ladder-like polysilsesquioxanes.

Boron containing ionogels were fabricated through chemical crosslinking of boron allyloxide with polyethylene glycol dimethacrylate in an ionic liquid electrolyte solution to obtain mechanically robust gels. Because of the relatively small concentration of crosslinking agent required to fully solidify the ionic liquid electrolyte, good characters of high ionic conductivity, high thermal stability, and good electrochemical stability were observed. A spectroscopic investigation of the boronic ionogels revealed that the lithium mobility was noticeably enhanced compared with ionogels fabricated without the boronic crosslinker, leading to promising Li-ion battery performance at elevated temperatures.

A comprehensive and fundamental gas transport study of ladder-structured polysilsesquioxanes (LPSQs) was systematically performed by investigating the effects of various alkyl substituents, different copolymer ratios, and UV-irradiation induced photo-crosslinking on gas separations. Overall, LPSQ membranes are more suitable for CO 2 /N 2 and CO 2 /H 2 separations due to a relatively high affinity towards CO 2 as well as rubbery polymer properties. The gas transport in LPSQ membranes was well interpreted by two important parameters, the inter-chain distance and the side chain mobility. A combination of larger inter-chain distance and higher side chain rigidity tends to increase the fractional free volume, resulting in higher gas permeability. Also, it was successfully demonstrated that the separation performance of LPSQ membranes can be predicted by using a logarithmic permeability relationship based on the transport characterization for a series of ladder-structured poly(phenyl- co -methacryloxypropyl)silsesquioxanes. Lastly, the UV-curing process reduced the permeability of LPSQ membranes, increasing the selectivity due to the restricted chain mobility.

The incorporation of pyrene-functionalized poly(methyl methacrylate)-b-poly(dimethylaminoethyl methacrylate) (PMMA-b-PDMAEMA) ionic block copolymer-wrapped carbon nanotubes (PBCNTs) with graphene oxide (GO) allows compact decoration of metal nanoparticles (NP) for use as robust catalysts. This well-tailored concept of the PBCNT-GO functional carbon support provides various features, including a two-dimensional (2D) structure, dimensional stability, versatile solubility (from toluene to water), enhanced diffusion of reagents, and recyclability. Among the various compositions of GO and PBCNT, 50 wt% of the PBCNT additive-containing support (PBCGO55) showed great hybridization potential for Ag, Au, and Pd NPs. In particular, the hybridization of PBCGO55 with Pd NPs (Pd-PBCGO55) displayed superior morphological features with compact decoration of ultra-fine NPs (1–3 nm), larger surface area, higher density of edge and corner atoms, better dispersion stability, and lesser aggregation of the decorated Pd NPs in comparison with the other hybrid catalysts. In the catalytic reduction of 4-nitrophenol (4-NP), the Pd-PBCGO55 hybrid catalyst exhibited the best catalytic performance, resulting in highly enhanced reaction rate constant (k) of 9.73 min−1 and catalytic activity of 141.8 mol mol−1 min−1, exhibiting a 50-fold increased rate constant and 30-fold increased catalytic activity in comparison to Ag-GO without PBCNT (k = 0.19 min−1, catalytic activity = 4.58 mol mol−1 min−1).

Supercritical methanol is a popular fluid as a supercritical medium for decrosslinking reaction of crosslinked polyethylene. However, due to its toxicity, a safe alternative medium is much to be desired. In this work, various sub- and supercritical fluids with different polarity characters were investigated to find a safe alternative medium for continuous decrosslinking of silane-crosslinked polyethylene (S-XLPE). Like methanol, all examined fluids, including ethanol, propanol, and water, exhibited first-order reaction kinetics regarding the gel content in the continuous decrosslinking process. The reaction rate constant values were observed as 2.806, 2.569, 2.383, and 2.130 min −1 in supercritical methanol, supercritical ethanol, supercritical 2-propanol, and subcritical water at 380 °C, respectively. As a non-toxic fluid with reaction kinetics very comparable to that of methanol, ethanol was found to be the best alternative medium for the continuous decrosslinking reaction of S-XLPE.

For the first time, an inorganic-organic hybrid polymer binder was used for the coating of hybrid composites on separators to enhance thermal stability and to prevent formation of lithium dendrite in lithium metal batteries. The fabricated hybrid-composite-coated separators exhibited minimal thermal shrinkage compared with the previous composite separators (5% change in dimension), maintenance of porosity (Gurley number ∼400 s/100 cm(3)), and high ionic conductivity (0.82 mS/cm). Lithium metal battery cell examinations with our hybrid-composite-coated separators revealed excellent C-rate and cyclability performance due to the prevention of lithium dendrite growth on the lithium anode even after 200 cycles under 0.2-5C (charge-discharge) conditions. The mechanism for lithium dendrite prevention was attributed to exceptional nanoscale surface mechanical properties of the hybrid composite coating layer compared with the lithium metal anode, as the elastic modulus of the hybrid-composite-coated separator far exceeded those of both the lithium metal anode and the required threshold for lithium metal dendrite prevention.

We present a new polyethylene glycol-functionalized polysilsesquioxane, a ladder-like structured poly(poly(ethylene oxide)-co-methacryloxypropyl)silsesquioxane) (PEO-SQ) hybrid-type polymer gelator to fabricate hybrid ionogel electrolytes for lithium ion capacitors. The organic-inorganic hybrid polymer gelator contains not only an inorganic ladder-like polysilsesquioxane backbone for the thermal and electrochemical stability, but also dual organic pendant groups consisting of free-dangling PEO chains and unsaturated methacryloxypropyl groups for enhanced lithium ion dissociation and thermal curing function, respectively. The successful crosslinking of 1 M LiTFSI in N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BMPTFSI) ionic liquid with only a small amount of PEO-SQ hybrid crosslinker (5 wt%) gave non-leaking ionogels with high thermal stability (⿼400 °C), large ionic conductivities, and excellent lithium ion capacitor C-rate performance and cyclability, comparable to those of neat ionic liquid electrolyte and superior over conventional organic ionogels fabricated with organic crosslinkers without PEO-moeities.

We present a capacitive humidity sensor with molecularly engineered polyimide (PI) sensing layer. Molecularly engineered PIs were successfully prepared by synthesizing polyamic acids (PAAs) through blending of 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) with 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA), pyromellitic dianhydride (PMDA), and 4,4-(hexafluoroisopropylidene) diphthalic anhydride (6-FDA) as monomer, followed by thermal imidization, respectively. The molecularly engineered PIs exhibited high thermal stability as well as controllable water uptake properties. Capacitive performances of the humidity sensor with PIs were efficiently increased via simple molecular blending.

Herein, we investigated the effect of thermo-oxidative crosslinking of siloxanes on the C3H6/C3H8 separation performance of carbon molecular sieve (CMS) membranes derived from polymer blends of a fluorine-containing polyimide and a ladder-structured polysilsesquioxane (PI/LPSQ). The PI/LPSQ precursors self-generated fluorinated gases, which possibly lead to the cleavage of double-stranded siloxanes during pyrolysis. At the same time, residual siloxanes underwent thermo-oxidative crosslinking, which resulted in densification into nonporous inorganic SiO2 phases. Such impermeable SiO2 phases adversely affected the gas diffusion, decreasing C3H6 permeability but contributed to the significant enhancement in the C3H6/C3H8 selectivity up to as much as 67, because of the substantially enhanced diffusivity selectivity. Density functional theory-based pore size distribution analysis exhibited that the narrower pores in the range of 5.0–5.5 A emerged for the PI/LPSQ (80/20 w/w) CMS, supporting the enhancement in C3H6/C3H8 selectivity. Also, PI/LPSQ (80/20 w/w) CMS fibers aged for 30 days showed C3H6 permeance of 2.9 GPU and a C3H6/C3H8 selectivity of 57. Furthermore, the techno-economic analysis verified the economic feasibility of the proposed membrane for the C3H6/C3H8 separation process. It reflected that higher C3H6 permeability plays a significant role in reducing the total cost of C3H6/C3H8 separation process as long as the C3H6/C3H8 selectivity is above 30, implying the significance of anti-aging in CMS hollow fiber membranes.

Development of highly active and durable electrocatalysts that can effectively electrocatalyze oxygen reduction reactions (ORR) still remains one important challenge for high-performance electrochemical conversion and storage applications such as fuel cells and metal-air batteries. Herein, we propose the combination of molybdenum-doped PdPt@Pt core-shell octahedra and the pyrene-functionalized poly(dimethylaminoethyl methacrylate)-b-poly[(ethylene glycol) methyl ether methacrylate] ionic block copolymer-functionalized reduced graphene oxide (Mo-PdPt@Pt/IG) to effectively augment the interfacial cohesion of both components using a tunable ex situ mixing strategy. The rationally designed Mo-PdPt@Pt core-shell octahedra have unique compositional benefits, including segregation of Mo atoms on the vertexes and edges of the octahedron and 2-3 shell layers of Pt atoms on a PdPt alloy core, which can provide highly active sites to the catalyst for ORR along with enhanced electrochemical stability. In addition, the ionic block copolymer functionalized graphene can facilitate intermolecular charge transfer and good stability of metal NPs, which arises from the ionic block copolymer interfacial layer. When the beneficial features of the Mo-PdPt@Pt and IG are combined, the Mo-PdPt@Pt/IG exhibits substantially enhanced activity and durability for ORR relative to those of commercial Pt/C. Notably, the Mo-PdPt@Pt/IG shows mass activity 31-fold higher than that of Pt/C and substantially maintains high activities after 10 000 cycles of intensive durability testing. The current study highlights the crucial strategies in designing the highly active and durable Pt-based octahedra and effective combination with functional graphene supports toward the synergetic effects on ORR.

The durability of alkaline anion exchange membrane fuel cells (AEMFCs) is a critical requirement for implementing this technology in cost-effective energy conversion. However, the lifetime of current AEMFCs is short, ca.

We report for the first time that ZIF-8 crystals undergo an Ostwald-ripening-like process without degradation in the presence of a ligand vapor. The ripening process is dependent on the defect density of the crystals: the more defective the more amenable to the ripening. The process was adapted to synthesize ultra-thin ZIF-8 membranes by vapor-phase secondary growth.

A novel ionic mixture of an imidazolium-based room-temperature ionic liquid containing ethylene-oxide-functionalized phosphite anions is fabricated, which, when doped with lithium salt, self-assembles into a smectic-ordered ionic liquid crystal through Coulombic interactions between the ion species. Interestingly, the smectic order in the ionic-liquid-crystal ionogel facilitates ionic transport.