Accelerated Single Li-Ion Transport in Solid Electrolytes for Lithium-Sulfur Batteries: Poly(Arylene Ether Sulfone) Grafted with Pyrrolidinium-Terminated Poly(Ethylene Glycol).

Polymeric solid electrolytes have attracted tremendous interest in high-safety and high-energy capacity lithium-sulfur (Li─S) batteries. There is, however, still a dilemma to concurrently attain high Li-ion conductivity and high mechanical strength that effectively suppress the Li-dendrite growth. Accordingly, a rapidly Li-ion conducting solid electrolyte is prepared by grafting pyrrolidinium cation (PYR+)-functionalized poly(ethylene glycol) onto the poly(arylene ether sulfone) backbone (PAES-g-2PEGPYR). The PYR+ groups effectively immobilize anions of Li-salts in Li-conductive PEGPYR domains phase-separated from PAES matrix to enhance the single-ion conduction. The tailored PAES-g-2PEGPYR membrane shows a high Li-ion transference number of 0.601 and superior ionic conductivity of 1.38 mS cm-1 in the flexible solid state with the tensile strength of 1.0 MPa and Young's modulus of 1.5 MPa. Moreover, this PAES-g-2PEGPYR membrane exhibits a high oxidation potential (5.5 V) and high thermal stability up to 200 (C. The Li/PAES-g-2PEGPYR/Li cell stably operates for 1000 h without any short circuit, and the rechargeable Li/PAES-g-2PEGPYR/S cell discharges a capacity of 1004.7 mAh g-1 at C/5 with the excellent rate capability and the prominent cycling performance of 95.3% retention after 200 cycles.

Ethylene Glycol-Choline Chloride Based Hydrated Deep Eutectic Electrolytes Enabled High-Performance Zinc-Ion Battery.

Aqueous rechargeable zinc-ion batteries (ARZIBs) are considered as an emerging energy storage technology owing to their low cost, inherent safety, and reasonable energy density. However, significant challenges associated with electrodes, and aqueous electrolytes restrict their rapid development. Herein, ethylene glycol-choline chloride (Eg-ChCl) based hydrated deep-eutectic electrolytes (HDEEs) are proposed for RZIBs. Also, a novel V10O24·nH2O@rGO composite is prepared and investigated in combination with HDEEs. The formulated HDEEs, particularly the composition of 1 ml of EG, 0.5 g of ChCl, 4 ml of H2O, and 2 M ZnTFS (1-0.5-4-2 HDEE), not only exhibit the lowest viscosity, highest Zn2+ conductivity (20.38 mS cm-1), and the highest zinc (Zn) transference number (t+ = 0.937), but also provide a wide electrochemical stability window (>3.2 V vs ZnǁZn2+) and enabledendrite-free Zn stripping/plating cycling over 1000 hours. The resulting ZnǁV10O24·nH2O@rGO cell with 1-0.5-4-2 HDEE manifests high reversible capacity of ≈365 mAh g-1 at 0.1 A g-1, high rate-performance (delivered ≈365/223 mAh g-1 at 0.1/10 mA g-1) and enhanced cycling performance (≈63.10% capacity retention in the 4000th cycle at 10 A g-1). Furthermore, 1-0.5-4-2 HDEE support feasible Zn-ion storage performance across a wide temperature range (0-80 °C) FInally, a ZnǁV10O24·nH2O@rGO pouch-cell prototype fabricated with 1-0.5-4-2 HDEE demonstrates good flexibility, safety, and durability.

High Performance Solid-State Lithium-Sulfur Battery Enabled by Multi-Functional Cathode and Flexible Hybrid Solid Electrolyte.

With its superior theoretical energy density as well as abundance and environment-friendliness, the lithium-sulfur battery (LiSB) is a potential candidate to replace the traditional energy storage and generation systems. An innovative design is proposed for the high-performance solid-state LiSB system by combining the multi-functional cathode comprising the sulfur-loaded Al2 O3 -modified carbon nanotubes (S@ACNTs) and the flexible hybrid solid electrolyte (HSE). Assembled with S@ACNTs active material, the polycation poly(diallyldimethylammonium bis(trifluoromethylsulfonyl)imide) (PDATFSI) binder exhibits high Li+ conductivity of 0.45 mS cm-1 at room temperature, good thermal stability up to 450 °C, high adhesive strength with aluminum current collector up to 24 MPa, sustainable non-flammability, and desirable flexibility. When assembled with HSE membrane, the S@ACNTs/PDATFSI-60IL cathode layer demonstrates effective polysulfide trapping behavior and superior compatibility (65 Ω), resulting in high discharge capacity of 1203 mAh g-1 at 0.2 C in the 1st cycle, and long-term stability up to 91.69% of the discharge capacity after 200 cycles of charge/discharge process.

Alkaline Stable Anion Exchange Membranes Based on Cross-Linked Poly(arylene ether sulfone) Bearing Dual Quaternary Piperidines for Enhanced Anion Conductivity at Low Water Uptake.

Alkaline stable anion exchange membranes based on the cross-linked poly(arylene ether sulfone) grafted with dual quaternary piperidine (XPAES-DP) units were synthesized. The chemical structure of the synthesized PAES-DP was validated using 1H-NMR and FT-IR spectroscopy. The physicochemical, thermal, and mechanical properties of XPAES-DP membranes were compared with those of two linear PAES based membranes grafted with single piperidine (PAES-P) unit and conventional trimethyl amine (PAES-TM). XPAES-DP membrane showed the ionic conductivity of 0.021 S cm-1 at 40 °C which was much higher than that of PAES-P and PAES-TM because of the possession of more quaternary ammonium groups in the cross-linked structure. This cross-linked structure of the XPAES-DP membrane resulted in a higher tensile strength of 18.11 MPa than that of PAES-P, 17.09 MPa. In addition, as the XPAES-DP membrane shows consistency in the ionic conductivity even after 96 h in 3 M KOH solution with a minor change, its chemical stability was assured for the application of anion exchange membrane fuel cell. The single-cell assembled with XPAES-DP membrane displayed a power density of 109 mWcm-2 at 80 °C under 100% relative humidity.

Integration of iron oxide nanoparticles and polyaspartamide biopolymer for MRI image contrast enhancement and an efficient drug-delivery system in cancer therapy.

We integrate superparamagnetic iron oxide nanoparticles with polyaspartamide (PA) biopolymer to form a biological construct that functions as a tracking, targeting and drug-delivery system for cancer diagnosis and therapy. Iron oxide nanoparticles with uniformly distributed average spherical diameters of around 10 nm and superparamagnetic characteristics play a key role in increasing the transverse 1/T 2 relaxation rate or darkening the T 2-weighted MR image for cancer diagnosis using MRI. In in vitro MRI testing on cancer cells, the MR images of samples with the bio-constructshow a much clearer contrast effect than those of controls. The PA biopolymer plays an essential role in enhancing the hydrophilicity and biocompatibility of the bio-construct. In addition, as a multifunctional polymer, PA is conjugated with biotin and doxorubicin (Dox) functional groups to enhance targeting and impairment of cancer cells. In in vivo testing on cancer tumors, injection with the bio-construct decreased the magnitude of cancer tumor volume growth by three times compared with that of uninjected controls. The physicochemical characteristics of the bio-construct and the roles of biotin and Dox functional groups are examined and discussed in detail.

Intercalated Poly (2-Acrylamido-2-methyl-1-propanesulfonic Acid) into Sulfonated Poly (1,4-Phenylene ether-ether-sulfone) Based Proton Exchange Membrane: Improved Ionic Conductivity.

A series of hybrid proton exchange membranes were synthesized via in situ polymerization of poly (2-acrylamido-2-methyl-1-propanesulfonic acid) PMPS with sulfonated poly (1,4-phenylene ether-ether-sulfone) (SPEES). The insertion of poly (2-acrylamido-2-methyl-1-propanesulfonic acid) PMPS, between the rigid skeleton of SPEES plays a reinforcing role to enhance the ionic conductivity. The synthesized polymer was chemically characterized by fourier-transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance 1H NMR spectroscopy to demonstrate the successful grafting of PMPS with the pendent polymer chain of SPEES. A variety of physicochemical properties were also investigated such as ion exchange capacity (IEC), proton conductivity, water uptake and swelling ratio to characterize the suitability of the formed polymer for various electrochemical applications. SP-PMPS-03, having the highest concentration of all PMPS, shows excellent proton conductivity of 0.089 S cm-1 at 80 °C which is much higher than SPEES which is ~0.049 S cm-1. Optimum water uptake and swelling ratio with high conductivity is mainly attributed to a less ordered arrangement polymer chain with high density of the functional group to facilitate ionic transport. The residual weight was 93.35, 92.44 and 89.56%, for SP-PMPS-01, 02 and 03, respectively, in tests with Fenton's reagent after 24 h. In support of all above properties a good chemical and thermal stability was also achieved by SP-PMPS-03, owing to the durability for electrochemical application.

Free-Standing Ion-Conductive Gels Based on Polymerizable Imidazolium Ionic Liquids.

A free-standing ion-conductive gel is formed by spontaneous self-assembly of the amphiphilic ionic liquid 1-tetradecyl-3-methylimidazolium chloride (C14MIm·Cl) and the cross-linkable monomer 6-hexanediol diacrylate (HDODA) in a mixed solvent of 1-octene, 1-butanol, and water. The ionic conductivity of this ion gel is 24 mS cm-1 at 33 °C. To enhance the mechanical strength of the ion gels, the acrylate ionic liquid 1-(2-acryloyloxyundecyl)-3-methylimidazolium bromide (A-C11MIm·Br) was added, leading to significant morphological changes of the HDODA phase from spherical, ellipsoid, angular platelets to interconnected with increasing addition of the acrylate ionic liquid and consequent enhancement in the mechanical strength of the resulting ion gels. Small angle X-ray scattering data reveal that the ion gels are composed of bicontinuous phase. The formation of the anisotropic HDODA structures upon introduction of the acrylate ionic liquid was accompanied by a change of the bicontinuous phase to be undulated, which increased the ionic path through the formed film, resulting in reduced ionic conductivity. Such coaxial structured gels may be a promising route for developing highly ion-conductive as well as mechanically stable solid electrolyte systems.

Synthesis of Hollow Doughnut Shape Mesoporous Silica Nanoparticle: A Case of Self-Assembly Composite Templates.

The new class of silica nanoparticles with unprecedented structural morphology is synthesized by hydrolysis of tetraethyl orthosilicate (TEOS) in the presence of cetyltrimethylammonium bromide (CTAB), l-arginine, and ammonium metatungstate (AMT) composite template, all in aqueous ethanol. The morphology of the synthesized mesoporous silica nanoparticles (MSNs) can be tuned from a spherical to a hollow doughnut shape through a hollow sphere by controlling the concentration of AMT in the composite template. The formation mechanism of the hollow doughnut shaped MSNs (hd-MSNs) is well-explored by means of zeta potential, high-resolution transmission electron microscopy (HRTEM) with elemental mapping analysis, and X-ray photoelectron spectroscopy. The unique structure of the hd-MSNs as well as their high thermal and mechanical stability is expected to result in their application in shape-selective catalysis, drug-delivery, and sensors.

Bioadhesive Nanoaggregates Based on Polyaspartamide-g-C18/DOPA for Wound Healing.

Biocompatible adhesive nanoaggregates were synthesized based on polyaspartamide copolymers grafted with octadecylamine (C18) and 3,4-dihydroxyphenylalanine (DOPA), and their adhesive properties were investigated with regard to wound healing. The chemical structure and morphology of the synthesized polyaspartamide-g-C18/DOPA nanoaggregates were analyzed using 1H-nuclear magnetic resonance spectroscopy (1H NMR), dynamic light scattering (DLS), and transmission electron microscope (TEM). The in vitro adhesive energy was up to 31.04 J m-2 for poly(dimethylacrylamide) gel substrates and 0.1209 MPa for mouse skin, and the in vivo wound breaking strength after 48 h was 1.8291 MPa for C57BL/6 mouse. The MTT assay demonstrated that the synthesized polymeric nanoaggregates were nontoxic. The polyaspartamide-g-C18/DOPA nanoaggregates were in vivo tested to mouse model and demonstrated successful skin adhesion, as the mouse skin was perfectly cured in their dermis within 6 d. As this material has biocompatibility and enough adhesive strength for wound closure, it is expected to be applied as a new type of bioadhesive agent in the human body.

Pore size and concentration effect of mesoporous silica nanoparticles on the coefficient of thermal expansion and optical transparency of poly(ether sulfone) films.

Mesoporous silica nanoparticles (MSNs) with uniform size (<50 nm) yet with different pore diameters were synthesized, and used as fillers in poly(ether sulfone) (PES) films in order to decrease their coefficient of thermal expansion (CTE) without sacrificing optical transparency. Here, both CTE and optical transparency of the MSN/PES nanocomposite films gradually decreased with increasing MSN concentration. The PES films containing MSNs with larger pores showed the best performance in CTE and optical transparency. While the CTE decreased by 32.3% with increasing MSN content up to 0.5 wt%, the optical transparency decreased by only less than 6.9% because of the small and uniform particle size of less than 50 nm, which minimizes light scattering. This pore size effect is more clearly observed via an annealing process, which enables the polymer chains to slowly move and fill in the free volume in the pores of the MSN, and thus restricts the thermal motion. The effect of the silica nanoparticles was investigated not only on the thermal stability but also on the mechanical stability. We expect the MSNs synthesized in this study to be used as a promising filler to enhance the thermal and mechanical stability of the PES substrate without sacrificing its optical transparency.

Intracellular uptake and pH-dependent release of doxorubicin from the self-assembled micelles based on amphiphilic polyaspartamide graft copolymers.

Biodegradable and pH-sensitive graft copolymers based on polysuccinimide (PSI) were synthesized as intracellular drug carriers. Hydrophobic octadecylamine (C18) and hydrophilic O-(2-aminoethyl) polyethylene glycol (PEG, Mw 5000) were grafted on a PSI backbone for amphiphilicity, enabling the formation of a self-assembled micellar structure in aqueous medium. Biotin was conjugated at the end of the PEG segment as the cell penetrating ligand, and hydrazone hydrate was introduced as a cleavable linkage for the release of pH sensitive drug, doxorubicin. The chemical structure of the polymer and degree of substitution of the graft segments were confirmed by Fourier transform infrared (FTIR) and (1)H NMR spectroscopy. The size and distribution of the polymer micelles were investigated by dynamic light scattering. The average diameter of the polymer micelles was 290-310 nm with a narrow distribution. Less than 30% of the total DOX loaded in the polymeric micelles was released at pH 7.4, whereas >75% was released at pH 5 in 70 h because of the cleavage of the hydrazone bond in acidic conditions. For the cytotoxicity test, the MCF-7 cell viability in the presence of biotin-conjugated polymer was much lower than that in the presence of a nonconjugated one, as the former had higher probability of cell penetration aided by a biotin ligand. The DOX uptake in MCF-7 cells was analyzed by the confocal laser scanning microscopy. More DOX uptake was observed in acidic conditions because of the cleavage of hydrazone groups in the polymer.

Fluorescent dye labeled iron oxide/silica core/shell nanoparticle as a multimodal imaging probe.

PURPOSE: To develop an MRI/optical multimodal imaging probe based on dye-conjugated iron oxide/silica core/shell nanoparticle, and investigate the distance-dependent fluorescence quenching through careful control of the distance between the iron oxide core and fluorescent dyes. METHODS: Different size of core/shell nanoparticles were prepared by varying the silica shell width. PEGylation on the surface of silica shell was followed to improve the stability of particles in the physiological condition. In vitro cytotoxicity was evaluated by the MTT assay on a HeLa cell line and in vivo imaging of subcutaneous SCC7 xenografted mice was performed using MRI/optical imaging modalities. RESULTS: Diameter and ζ-potential of the nanoparticles were measured, and TEM images demonstrated the mono-disperse nature of the particles. Quenching efficiency of the dyes on the surface was nearly 100% in the smallest nanoparticle, while almost no quenching effect was observed for the largest nanoparticle. In vitro cytotoxicity showed nearly 90% cell viability at 0.15 Fe mg/mL, a comparable concentration for clinical use. The tumor area was significantly darkened after the nanoparticle injection due to the high transverse relaxivity value of the nanoparticles. Fluorescence signal was affected by the particle size due to the distance-dependent quenching/dequenching behaviour.

Electro-osmotic drag effect on the methanol permeation for sulfonated poly(ether ether ketone) and nafion 117 membranes.

Electro-osmotic drag effect on the methanol permeation was investigated for sulfonated poly(ether ether ketone) (sPEEK) membrane, and its result was compared with that of Nafion 117 membrane. The electro-osmotic drag coefficient was determined from the limiting current density measured at different temperature. The methanol permeability of sPEEK membrane increased with temperature but its temperature dependence was not as strong as that of Nafion 117 membrane. The methanol permeability or the total methanol flux of Nafion 117 membrane was at least twice higher than that of sPEEK70 membrane (sPEEK membrane with 70% sulfonation degree), as the methanol permeation was highly contributed by the electro-osmotic drag effect. This higher electro-osmotic drag of Nafion 117 membrane is attributed to the bigger ion cluster and waster channel in nanophase and thus more free water absorption than sPEEK membrane.

Biodegradable polyaspartamide-g-C18 /DOPA/GLY-NEO nano-adhesives for wound closure/healing with antimicrobial activity.

This study was focused on the development of biodegradable nano-adhesives with efficient sealing and antibiotic effects for wound healing. Biodegradable polyaspartamide (PASPAM) was grafted with several functional groups to implement diverse roles-octadecylamine (C18 ) for nano-aggregate formation, dopamine (DOPA) for adhesive function, neomycin (NEO) for inhibition of bacterial infection. Specifically, NEO was conjugated to PASPAM with a pH-sensitive glycine (GLY) linker for targeted delivery on the acidic wound site. About 60% of the drug was ramteleased at pH 6.0, while about 22% was released at pH 7.4, showing the faster drug release pattern of nano-adhesives in the acidic environment. The C18 /DOPA/GLY-NEO-g-PASPAM nano-adhesives showed the bacterial viability higher than 70% at pH 7.4, but about 40% at pH 6.0. The wound breaking strength of the polymer-treated skin was much higher than that of the bare skin. According to the in vivo wound healing test using a mouse model, C18 /DOPA/GLY-NEO-g-PASPAM nano-adhesives showed much faster healing performance than sutures. From those results, C18 /DOPA/GLY-NEO-g-PASPAM nano-adhesives are expected to be utilized as effective adhesives that promote the wound healing with inhibition of bacterial infection.

A Facile and Sustainable Enhancement of Anti-Oxidation Stability of Nafion Membrane.

•OH radicals are the main cause of chemical degradation of Nafion membranes in fuel cell operation. Although the cerium ion (Ce3+/4+, Ce) is reported as an effective •OH radical quencher, its membrane application has critical limitations associated with the reduction of membrane proton conductivity and its leaking. In this study, the Ce-grafted graphitic carbon nitrides (g-C3N4) (CNCe) nano-particles are synthesized and embedded in Nafion membranes to prolong the •OH radical scavenging effect. The synthesis of CNCe nano-particles is evaluated by X-ray diffraction, energy dispersive X-ray analysis, and transmission electron microscopy. Compared with the pristine and Ce-blended Nafion membranes, the CNCe imbedded ones show tremendous improvement in long-term anti-oxidation stability. While the fluoride emission rates of Nafion are 0.0062 mg·cm-2·h-1 at the anode and 0.0034 mg·cm-2·h-1 at the cathode, those of Nafion/CNCe membranes are 0.0037 mg·cm-2·h-1 at the anode and 0.0023 mg·cm-2·h-1 at the cathode. The single cell test for Nafion/CNCe membranes at 80 °C and 50% relative humidity illustrates much better durability than those for Nafion and Nafion/Ce, indicating its superior scavenging effect on •OH radicals.

Oxidative Stress-Induced Silver Nano-Carriers for Chemotherapy.

Recently, silver nanoparticles (AgNPs) have been extensively explored in a variety of biological applications, especially cancer treatment. AgNPs have been demonstrated to exhibit anti-tumor effects through cell apoptosis. This study intends to promote cell apoptosis further by increasing oxidative stress. AgNPs are encapsulated by biocompatible and biodegradable polyaspartamide (PA) (PA-AgNPs) that carries the anti-cancer drug Doxorubicin (Dox) to inhibit cancer cells primarily. PA-AgNPs have an average hydrodynamic diameter of 130 nm, allowing them to move flexibly within the body. PA-AgNPs show an excellent targeting capacity to cancer cells when they are conjugated to biotin. In addition, they release Dox efficiently by up to 88% in cancer environments. The DCFDA experiment demonstrates that the Dox-carried PA-AgNPs generate reactive oxidation species intensively beside 4T1 cells. The MTT experiment confirms that PA-AgNPs with Dox may strongly inhibit 4T1 cancer cells. Furthermore, the in vivo study confirms that PA-AgNPs with Dox successfully inhibit tumors, which are about four times smaller than the control group and have high biosafety that can be applied for chemotherapy.

Superstrong, superstiff, and conductive alginate hydrogels.

For the practical use of synthetic hydrogels as artificial biological tissues, flexible electronics, and conductive membranes, achieving requirements for specific mechanical properties is one of the most prominent issues. Here, we demonstrate superstrong, superstiff, and conductive alginate hydrogels with densely interconnecting networks implemented via simple reconstructing processes, consisting of anisotropic densification of pre-gel and a subsequent ionic crosslinking with rehydration. The reconstructed hydrogel exhibits broad ranges of exceptional tensile strengths (8-57 MPa) and elastic moduli (94-1,290 MPa) depending on crosslinking ions. This hydrogel can hold sufficient cations (e.g., Li+) within its gel matrix without compromising the mechanical performance and exhibits high ionic conductivity enough to be utilized as a gel electrolyte membrane. Further, this strategy can be applied to prepare mechanically outstanding, ionic-/electrical-conductive hydrogels by incorporating conducting polymer within the hydrogel matrix. Such hydrogels are easily laminated with strong interfacial adhesion by superficial de- and re-crosslinking processes, and the resulting layered hydrogel can act as a stable gel electrolyte membrane for an aqueous supercapacitor.

pH-Sensitive micelles with cross-linked cores formed from polyaspartamide derivatives for drug delivery.

A series of polyaspartamide derivatives were synthesized by grafting O-(2-aminoethyl)-O'-methylpoly(ethylene glycol) 5000 (MPEG), 1-(3-aminopropyl) imidazole (API), and cinnamate onto polysuccinimide (PSI) with the respective degrees of substitution adjusted by the feed molar ratio. The chemical structure of the prepared polymer was confirmed using FT-IR and (1)H NMR spectroscopy. A new pH-sensitive polymeric micelle based on the synthesized polymer was prepared and characterized, and its pH-sensitive properties were characterized by the measurement of light transmittance and particle sizes at varying pH values. pH-dependent aggregation and deaggregation behavior was clearly observed in the polymer aqueous dispersion system. Photo-cross-linking of the cinnamate branches cross-linked the core of the micelles. The core cross-linked micelles showed high stability over a wider pH range and displayed obvious pH-dependent swelling-shrinking behavior instead of micelle-unimer transition behavior. This micelle system overcame the drawback of the facile disintegration of normal polymeric micelles and showed obvious delayed paclitaxel release in in vitro drug delivery experiments.

Bone targeting nano-aggregates prepared from self-assembled polyaspartamide graft copolymers for pH sensitive DOX delivery.

Nanoparticles with bone targeting ability and pH-sensitivity were prepared with polyaspartamide (PASPAM) derivatives based on polysuccinimide (PSI) grafted with octadecylamine (C18), hydrazine (HYD) and polyethylene glycol (PEG, Mw: 5000). For the bone targeting, alendronate (ALN), which has bone affinity, was grafted to PEG and doxorubicin (DOX) was conjugated with linkers of acid sensitive hydrazone bonds, which can be cleaved most effectively in an intracellular acidic environment. At pH 5.0, ∼75% of the drug was released from ALN-PEG/C18/HYD-DOX-g-PASPAM due to the effective cleavage of HYD under the acidic condition. Also, ALN-PEG/C18/HYD-DOX-g-PASPAM particles were more effectively adsorbed on the surface of bone than PEG/C18/HYD-DOX-g-PASPAM. According to an in vivo antitumor activity test, the volume of tumor treated with ALN-PEG/C18/HYD-DOX-g-PASPAM decreased (1550 mm3) when compared with the PBS control sample (3850 mm3), proving that ALN-PEG/C18/HYD-DOX-g-PASPAM is an effective drug delivery system for the treatment of bone metastasis of breast cancer.

Polymer Electrolyte Membranes.

Recently, polymer electrolyte membranes have been used in various electrochemical energy devices and other applications, such as fuel cells, lithium secondary batteries, redox flow batteries, electrodialysis, and membrane capacitive deionization [...].