Ethylene Oxide Chains Research Articles

High-Frequency Heating of a Multiply Protonated Poly(ethylene oxide) Chain in a Vacuum

Heating of a multiply protonated poly(ethylene oxide) chain in an intense high-frequency electric field in a vacuum is studied using molecular dynamics simulations. The rate of absorption of the field energy by the chain is determined at the field frequencies from 0.5 to 150 GHz. The absorption spectrum depends on the number of attached protons n, and also on the temperature of the chain. At low n and high temperatures, the spectrum consists of several distinct peaks with the most intense peak at a frequency of about 10 GHz. When n is large, the peaks are less pronounced and the energy absorption rate reaches a maximum at the lowest studied frequency.The effect of n on the energy absorption rate depends on the field frequency. While at low and high frequencies the energy absorption rate increases almost in proportion to n, near the main absorption peak it decreases.This indicates that there are two different mechanisms of the energy absorption. Firstly, the chain absorbs energy during resonant vibrations that occur at several frequencies. Secondly, the chain absorbs energy through a process that occurs over a wide frequency range and becomes more intense with decreasing frequency.

Polycation ionic liquid tailored PEO-based solid polymer electrolytes for high temperature lithium metal batteries

Poly(ethylene oxide) (PEO)-based polymer electrolytes are promising candidates for solid-state electrolytes in safer, next generation lithium metal batteries. Despite their benefits however, PEO-based electrolyte exhibits highly crystalline ethylene oxide chains that provide poor ionic conductivity and, thus severely limit its practical application. Here, we report the use of hydroxypropyl trimethylammonium bis(trifluoromethane) sulfonimide chitosan salt (HACC-TFSI), which is an amorphous poly(ionic liquid) based biomass chitosan derivative, as a modifier for PEO-based solid polymer electrolytes (SPEs) to address these deficiencies. Hybrid SPEs with HACC-TFSI display enlarged amorphous regions with enhanced ionic conductivity. Interactions between quaternary ammonium cations and TFSI− anions in hybrid SPEs are also found to promote dissociation between Li+ and TFSI−, which further increases ionic mobility. Moreover, the electrochemical stability, mechanical strength, and thermal stability of hybrid SPEs are collectively superior to blank SPEs without HACC-TFSI. LiFePO4/SPEs/Li full-cells assembled using 10wt% HACC-TFSI in PEO (10%HACC-TFSI/SPEs) electrolyte provide a capacity of 161.3 mAh g−1 and operate with excellent cycle performances at 0.2 C and 60 °C. Even when the temperature is increased to 150 °C, LiFePO4/SPEs/Li cells with 10%HACC-TFSI/SPEs still display remarkable cycle performance with 73% capacity retention after 100 cycles at 1 C rate.

Preparation of Highly Swelling/Antibacterial Cross-Linked N-Maleoyl-Functional Chitosan/Polyethylene Oxide Nanofiber Meshes for Controlled Antibiotic Release.

Due to the cell affinity of chitosan (CS) and the hydrophilicity of polyethylene oxide (PEO), CS/PEO composited nanofiber meshes (NFMs) have been extensively used as wound healing dressings for skin tissue regeneration. Nonetheless, numerous innate drawbacks of the NFM system such as the use of toxic spinning solvents and cross-linkers, moderate water regain capacity, and lack of triggered release function significantly hampered their biomedical applications. In order to enhance their performances in promoting cell growth and preventing bacterial infection, highly swelling cross-linked N-maleoyl-functional chitosan (MCS)/PEO NFMs have been developed as the next-generation CS/PEO NFM system through an acid-free electrospinning process and a UV-irradiated cross-linked treatment without the use of aldehyde-containing cross-linkers. With the simultaneous introduction of ethylene oxide chains and disulfide bonds in the cross-linkages, this new NFM system displays enhanced swelling capability, antibacterial ability, triggered antibiotic release, and high biocompatibility. These biomedical merits enable the new NFM systems to be utilized as tissue scaffolds, especially for functional wound healing dressings.

Fast lithium ion transport in solid polymer electrolytes from polysulfide-bridged copolymers

Solid polymer electrolytes (SPEs) are being intensively pursued as a means to develop safe, stable and long-life Li-ion batteries. However, the low Li+ conductivity and transference number in SPEs still impede all-solid-state polymer batteries from practical commercialization. Here, lithium polysulfides that cause a shuttle effect problem in Li–S batteries are reduced on a Poly(ethylene oxide) (PEO) chain as an effective way to stimulate Li+ transport. It is shown that the product of the reduction (main –S4Li) dramatically increases Li+ transport while forming a strong interaction with the PEO matrix through intermolecular interactions. In contrast to PEO electrolytes, the –S4Li grafted electrolyte membranes have a lithium transfer number almost 3 times higher, and the LiFePO4|ScPEO|Li cell shows an ultra-long cycle life exceeding 1200 cycles with a capacity decay of 0.024% per cycle at 1 C. The results reveal lithium polysulfides tremendous potential in a solid-state electrolyte system for improving the ion transport and cycling stability.

Nanocomposite solid polymer electrolytes based on semi-interpenetrating hybrid polymer networks for high performance lithium metal batteries

This research reports the synthesis of nanocomposite solid polymer electrolytes (ncSPEs) for solid state lithium metal batteries. These materials are composed of a controlled hybrid organic-inorganic network of glycidyl POSS® and Jeffamine® ED2003, in which linear high molecular weight poly (ethylene oxide) (PEO) chains are entangled to improve both mechanical and electrochemical properties of the ncSPE. Synthesis and preparation of self-standing membranes are achieved with a facile one-pot catalyst-free method with considerably reduced amount of organic solvent, which is a plus toward a future scale-up. We found that the component ratio plays a crucial role in ncSPEs’ performance as a simple variation (i.e. cross-linking degree) is sufficient to completely change the electrochemical behavior of the solid state cell. For instance, increasing POSS® amount guarantees better resistance to lithium dendrites penetration, better electro-oxidation stability, and significantly extends cycle life in Li/ncSPE/LiFePO4 solid state cells. Furthermore, besides improving cell performance at higher C-rate of Li/LiFePO4 cells, this PEO-based ncSPE gives better response than reference PEO-LiTFSI electrolyte in high voltage Li/LiNi0.6Mn0.2Co0.2O2 cells with up to 10 cycles at 60 °C with discharge capacity retention above 80%. Despite the poor performance, to the best of our knowledge, this electrolyte is one of the few examples of PEO-based solid polymer electrolytes being capable of cycling with high voltage cathodes.

A Discrete Platinum(II) Amphiphile: Construction, Characterization, and Controllable Self-Assembly in Different Solvents.

"Coordination-driven self-assembly" offers us an efficient method to fabricate 3D metallacages and 2D metallacycles with controllable shape and size via simple building blocks. Herein, a new discrete platinum(II) amphiphile (AOM), which contains hydrophilic tris(ethylene oxide) chains and a hydrophobic porphyrin unit, was constructed successfully by using "coordination-driven self-assembly". From various characterization methods, such as UV-vis spectroscopy, dynamic light scattering, transmission electron microscopy, scanning electron microscopy, and small-angle X-ray scattering, we found that AOM can self-assemble into vesicles, curved vesicles with open ends, and at last stable bilayer nanotubes in aqueous solution at room temperature and flexible cross-linked structures at about 60 °C. In contrast, AOM formed rigid bilayer nanosheets of micrometers in width and millimeters in length in n-hexane. We hope this investigation will pave the way for the fabrication of controllable soft materials.

Molecular-weight dependence of simulated glass transition temperature for isolated poly(ethylene oxide) chain

ABSTRACT Molecular dynamics simulations have been performed with chemically realistic coarse-grained potentials to assess the effects of molecular weight on the glass transition temperatures (Tg ) of single-chain particle of poly(ethylene oxide) in a vacuum. It is found that all the long isolated chains form impact globule like configurations, and higher molecular weight and lower temperature lead to more perfect sphericity. With increasing molecular weight, the simulated Tg of the isolated chain tends to increase whereas the Tg of the bulk undergoes a slight change. The confinement effects are associated with localisation of chain ends at the surface and specific surface areas. More importantly, the Tg shift can be quantified by the solubility parameter that includes the contribution of conformational change. As compared to the conventional definition that only sums intermolecular interactions, such solubility parameter is a better metric in simulations to explain the confinement effects since it does not depend upon the degree of equilibration as the Tg . These results can be quite valuable to clarifying glass transition behaviour of polymers films.

Poly (Ethylene Oxide)-Based Block Copolymer Electrolytes Formed via Ligand-Free Iron-Mediated Atom Transfer Radical Polymerization.

The Br-terminated poly (ethylene oxide) (PEO-Br) is used as a green and efficient macroinitiator in bulk Fe-catalyzed atom transfer radical polymerization (ATRP) without the addition of any organic ligands. The polymerization rate is able to be mediated by PEO-Br with various molecular weights, and the decrease in redox potential of FeBr2 in cyclic voltammetry (CV) curves indicates that an increased coordination effect is deteriorated with the depressing reaction activity in the longer ethylene oxide (EO) chain in PEO-Br. In combination with the study of different catalysts and catalytic contents, the methyl metharylate (MMA) or poly (ethylene glycol) monomethacrylate (PEGMA) was successfully polymerized with PEO-Br as an initiator. This copolymer obtained from PEGMA polymerization can be further employed as a polymer matrix to form the polymer electrolyte (PE). The higher ionic conductivity of PE was obtained by using a high molecular weight of copolymer.

The Effect of Oligo(Ethylene Oxide) Side Chains: A Strategy to Improve Contrast and Switching Speed in Electrochromic Polymers.

Solution-processable electrochromic polymers (ECPs) with high performance are urgently needed for extensive applications. Nevertheless, they suffer from slow switching speed because of low ionic conductivities. Herein, we present an effective strategy to improve the contrast and switching speed in ECPs via facile side-chain engineering. A novel electrochromic thieno[3,2-b]thiophene-based polymer (PmOTTBTD) is designed and successfully synthesized by introducing oligo(ethylene oxide) side chains with high ionic conductivity. Compared to the counterpart POTTBTD without modification by oligo(ethylene oxide) chains, PmOTTBTD demonstrates nearly double contrast (42 % vs. 24 %) with a fast oxidation switching process that just takes half of the time when detected under 400 nm, as well as much higher coloration efficiencies (e. g. 239.04 cm2 C-1 vs. 226.26 cm2 C-1 @ 400 nm and 314.04 cm2 C-1 vs. 174.00 cm2 C-1 @ 650∼700 nm). Besides, PmOTTBTD exhibits excellent stability with negligible decay after 3000 cycles. Our work suggests a facile strategy that could be adopted to realize high-performance ECPs via molecular design tuning.

Surface plasmon resonance imaging coupled to on-chip mass spectrometry: a new tool to probe protein-GAG interactions.

A biosensor device for the detection and characterization of protein-glycosaminoglycan interactions is being actively sought and constitutes the key to identifying specific carbohydrate ligands, an important issue in glycoscience. Mass spectrometry (MS) hyphenated methods are promising approaches for carbohydrate enrichment and subsequent structural characterization. In the study herein, we report the analysis of interactions between the glycosaminoglycans (GAGs) heparin (HP) and heparan sulfate (HS) and various cytokines by coupling surface plasmon resonance imaging (SPRi) for thermodynamic analysis method and MALDI-TOF MS for structural determination. To do so, we developed an SPR biochip in a microarray format and functionalized it with a self-assembled monolayer of short poly(ethylene oxide) chains for grafting the human cytokines stromal cell-derived factor-1 (SDF-1α), monocyte chemotactic protein-1 (MCP-1), and interferon-γ. The thermodynamic parameters of the interactions between these cytokines and unfractionated HP/HS and derived oligosaccharides were successively determined using SPRi monitoring, and the identification of the captured carbohydrates was carried out directly on the biochip surface using MALDI-TOF MS, revealing cytokine preferential affinity for GAGs. The MS identification was enhanced by on-chip digestion of the cytokine-bound GAGs with heparinase, leading to the detection of oligosaccharides likely involved in the binding sequence of GAG ligands. Although several carbohydrate array-based assays have been reported, this study is the first report of the successful analysis of protein-GAG interactions using SPRi-MS coupling.

Dynamic Chelate Effect on the Li+-Ion Conduction in Solvate Ionic Liquids

Lithium–glyme solvate ionic liquids (Li–G SILs), which typically consist of a lithium-ion (Li+) solvated by glymes of oligoethers and its counter anion, are expected as promising electrolytes for lithium secondary batteries. Additionally, a specific ligand-exchange Li+ conduction mechanism was proposed at the electrode/electrolyte interface of the cell using Li–G SILs. To reveal Li+ conduction in SILs, Li–G SILs with varying ethylene oxide chain lengths were investigated using various techniques that are sensitive to solution structure and dynamics. We found good correlations between the relaxation time of the slowest dielectric mode and the ionic conductivity as well as viscosity. We propose that a dynamic chelate effect, which is closely related to solvent exchange and/or contact ion-pair formation/dissociation, is important for Li+ conduction in these Li–G SILs.

Fluorinated polyhedral oligomeric silsesquioxanes end-capped poly(ethylene oxide) giant surfactants: precise synthesis and interfacial behaviors

Interfacial behavior of giant surfactants with precisely tethered molecular nanoparticles (MNPs) is an important topic. In this article, by the combination of hydrosilylation, esterification, and CuAAC ‘‘click’’ chemistry, poly(ethylene oxide) (PEO) chains were end-capped with particle-like aryl-trifluorovinyl ether functionalized polyhedral oligomeric silsesquioxane (FVPOSS) to construct “one-head one-tail” and “bola-form” giant surfactants. The giant surfactants are spread at air/water interface, and surface pressure-area (π-A) isotherms reveal their interfacial behaviors under compression. Atomic force microscope (AFM) images indicate that the giant surfactants show fractal growth behavior after transferred to the silicon substrate at different surface pressure through the procedure of Langmuir-Blodgett (LB) film deposition. The results are useful for understanding the assembly of giant surfactants at the interface and developing of nanostructured functional materials.

Synthesis and cytotoxicity of quercetin/hyaluronic acid containing ether block segment

This study is about preparation of natural quercetin type surfactants. The preparation involves polycondensing quercetin (QT) and propylene glycol in the presence of an acid catalyst so as to make quercetin more water soluble; performing ring opening polymerization between polyoxyethylene chains (MW: 2000, 4000, 6000, 8000, 10,000) changed by polyethylene glycol and succinic anhydride so as to obtain an ether block surfactant; and then introducing hydrolyzed hyaluronic acid (HA) by means of esterification while preparing a series of natural QT/HA-type surfactants through condensation. The synthetized products were analyzed using Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (1H-NMR,13C-NMR) for their structures, and assayed for their surface active properties, including their surface tension, fluorescence, contact angles, and emulsification properties. The experimental results show that the surface activity of the QT/HA-type surfactants decreased with the ethylene oxide chain length. Among all the surfactants, the QP2H surfactant exhibited the most efficient emulsification ability, lowest surface tension, and good emulsification stability. The synthetized products were assessed for safety through in vitro cytotoxicity and MTT assays with HaCaT cell lines. According to the results, QP2H, that was similar to oil in terms of HLB value, showed outstanding emulsion stability, and its zeta potential suggested low risk of colloidal agglutination due to repulsion between its emulsion drops. However, as proven in tests with HaCaT cell lines, QT-HA containing ether block surfactants when applied in cosmetics are safe. No significant cytotoxicity was observed in any case with a concentration less than 0.01 wt% (10 mg/mL). With CMC lower than 0.01 wt%, they would not hurt skin when used in cosmetics.

Enhancement of intestinal absorption of coenzyme Q10 using emulsions containing oleyl polyethylene acetic acids

Emulsions have often been prepared to improve absorption of lipophilic compounds that have poor solubility. Coenzyme Q10 (CoQ10) is a lipophilic compound that has been used as an anti-aging supplement. We focused on oleyl polyethyleneoxy acetic acid, an oxa acid derivative, to prepare emulsions of CoQ10 with the expectation of application to oral pharmaceutics. Oxa acids were purified and classified into four groups based on the average length of the ethylene oxide chain. The emulsion that were prepared using the four oxa acid groups were administered to rats and the plasma concentration profiles of CoQ10 were analyzed. The absorption of CoQ10 was improved in all emulsion groups compared with that in the powder group. The emulsion using oxa acid (n = 9.0) greatly increased the plasma concentration of CoQ10. Absorption was also improved by using emulsions containing larger percentage of oxa acids (6%, 15% and 23%) to compared with the same oxa acid (n = 9.0). The effects of oxa acids on cell viability were almost the same as those of conventional surfactants such as polyoxyethylene (20) sorbitan monooleate (Tween 80). The results showed that oxa acids are useful to prepare emulsions for oral administration and that the absorption of CoQ10 using oxa acids is significantly improved by using our formulations.

Block Copolymers‐Based Nanoporous Thin Films with Tailored Morphology for Biomolecules Adsorption

AbstractThe adsorption of myoglobin (Mb) onto nanoporous thin films build up using block‐copolymers (BCPs) is analyzed. The nanoporous thin films, fabricated by exploiting self‐assembly of lamellar BCPs and the concept of sacrificial block, are characterized by a well‐defined morphology containing nanochannels of width ≈20 nm delimited by polystyrene (PS) domains, decorated with pendant poly(ethylene oxide) (PEO) chains. The adsorption of Mb onto the nanoporous material is studied by means of UV–visible spectroscopy, quartz crystal microbalance, and neutron reflectometry measurements. In order to determine the role of nanopores, experiments are also conducted by using supports made of nonporous PS thin films and nude glass slides. The results indicate that the BCP‐nanoporous material exhibits a remarkably higher adsorption capability than PS and glass. As PEO exhibits a low degree of protein adsorption, this result may be essentially attributed to the presence of the nanopores. The large surface area, the opened pore structure, and the trapping effect of the pores are the main factors determining the increased Mb adsorption capability of the BCP‐based support. Yet, the presence of PEO chains decorating the PS walls at porous surface does not prevent Mb biomolecules to establish good interactions with the support.

Specific Features of the Rheological Behavior of a Protic Oligomeric Ionic Liquid of Cationic Type with Basic Sites of Two Types in the Region of the Solid–Liquid Transition

The structure and rheological behavior of a reactive oligomeric ionic liquid (OIL) have been studied. The OIL has a linear structure and contains ionic fragments of two types at both ends of oligo(ethylene oxide) chain. The ionic fragments are represented by secondary amino groups and nitrogen-containing heterocycles protonated with ethane sulfonic acid. The results obtained using rotational rheometry in different dynamic regimes indicate that, in the linear region of deformation at temperatures T G '). The boundary, which is located at nearly 30°C, is characterized by equality between G ' and G '' in a wide range of strain amplitudes. The structural transformations induced by thermal and mechanical energies have been explained using a hypothesis of the existence of micellar structures and a “normal micelle–reverse micelle” transition in the OIL, as well as changes in micelle shapes. The analysis of the temperature dependences for the viscoelastic characteristics and scattered light intensity, as well as the data of DSC and optical microscopy, has led to the hypothesis that at, T = 21–28°C, the OIL may occur in an ordered state similar to the liquid-crystalline one.

Tailored Melting Temperatures and Crystallinity of Poly(ethylene oxide) Induced by Designed Chain Defects

The odd–even effect of a homologous series of two poly(ethylene oxide) chains separated by (CH2)n spacers and joined by two 1,2,3-triazole rings with 2 ≤ n ≤ 8 (PEO11-TR-(CH2)n-TR-PEO11) is reporte...

Characterization of polyethermethylsiloxanes using ultra-high performance liquid chromatography-electrospray ionization and time-of-flight mass spectrometry

Polyethermethylsiloxanes (PEMSs) are silicone based polymers formed by attaching one or more ethylene oxide (EO)/propylene oxide (PO) chains to a siloxane chain. As the siloxane chain is lengthened, the polarity of the PEMSs are reduced. Little research has been conducted on the use of ultra-high performance liquid chromatography (UHPLC)-mass spectrometry (MS) to analyze PEMS oligomers with more than 4 siloxane groups because of their low polarity and poor solubility in water and acetonitrile (ACN). In this study, we developed a high chromatographic resolution method for PEMS and polyether oligomers using the water-ACN-isopropanol (IPA) tertiary solvents gradient. PEMSs oligomers containing one EO pendant chain and 3–13 silicone groups were analyzed. More than 102 PEMS oligomers and 21 polyether oligomers were separated within 45 min and identified by accurate molecular masses. During this gradient elution process, different chromatographic modes were used: both precipitation-redissolution and adsorption mode for PEMSs, adsorption mode for EO chains in polyethers, and exclusion mode for EO chains in PEMSs. This efficient separation method for PEMSs would broaden the characterization of silicone surfactants. Also, it is beneficial to establish the relationship between surfactant structure, synthetic route and performance optimization.

Free Surface-Induced Glass-Transition Temperature Suppression of Simulated Polymer Chains

Glass-transition temperatures (Tg’s) in poly(ethylene oxide) chains of 250 monomers as typical examples have been extensively simulated with the systematically coarse-grained potentials. The studie...

Langmuir-Blodgett Films of C60-end-capped Poly(ethylene oxide)

Buckyballs (C60) are linked to one end and two ends of linear poly(ethylene oxide) (PEO) chains through highly efficient click chemistry to obtain giant amphiphilic molecules C60-PEO and C60-PEO-C60, respectively. C60-PEO and C60-PEO-C60 molecules are spread on water surface and then transferred to solid substrates with Langmuir-Blodgett (LB) film deposition approach. C60-PEO and C60-PEO-C60 exhibit fractal growth behavior on the solid substrate under certain conditions owing to the crystallization ability of PEO segment. PEO chain length and the end capped mode both affect the fractal growth pattern.