Poly(ethylene oxide)-sodium perchlorate electrolytes in solid-state sodium cells

The behaviour of poly(ethylene oxide)-sodium perchlorate as electrolyte in solid-state batteries was characterized by impedance spectroscopy with respect to the conductivity and chemical reactivity of the sodium/polymer interface. Formation of a corrosion layer on the sodium electrode was found, and the growth of this layer was followed during open circuit and cycling conditions. It is concluded that the surface resistance is a major contribution to the cell impedance.     

Poly(ethylene oxide) and its blends with sodium alginate

A series of blends based on poly(ethylene oxide) (PEO) and sodium alginate (NaAlg) were prepared by solution casting method. The blends thus obtained were characterized by using Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), tensile strength test, contact angle measurements and atomic force microscopy (AFM). FT-IR studies indicate that there are the hydrogen bonding interactions due to the ether oxygen of PEO and the hydroxyl groups of NaAlg. The thermal stability of the blends was slightly affected with increasing NaAlg content. DSC results showed that both melting point and crystallinity depend on the composition of the blends. Mechanical properties of the blend films were improved compared to those of homopolymers. Surface free energy components of the blend films were calculated from contact angle data of various liquids by using Van Oss-Good methodology. It was found that the surfaces both of the blends are enriched in low surface free energy component, i.e. NaAlg. This conclusion was further confirmed by the AFM images observation of the surface morphology of these blends.     

Practical applications of modified poly(ethylene oxide) networks

Modified poly(ethylene oxide) (PEO) networks have been studied as phase transfer catalysts, flocculates and solvent-free polymer electrolytes. The activity of the hydrogels has been investigated with respect to the structure and crosslinking density of the networks, their degree of quaternization and amphiphilic properties (hydrophilicity coefficients). It has been found that the microenvironment of the active sites (EO segments and ammonium ions) affects the catalytic activity and sorption ability of the modified networks. Hydrophobic organic compounds such as sodium picrate and bromophenolblue are bound predominantly to the lipophilic quaternary ammonium ions. A stable level of electrical conductivity of 5.0×10⁻⁵ S cm⁻¹ was achieved without using of additives. A probable mechanism of ion transport within the networks has been proposed. Potential applications of PEO-based materials as solvent-free solid polymer electrolytes are also discussed.     

Mesogenic structures and charge-transfer reactions in poly(ethylene oxide) complexes

After discussion of a schematic model for the crystalline phases of some poly(ethylene oxide) (PEO)-Na⁺ complexes with organic anions, three types of material are discussed. (i) Complexes of sodium salts of organic acids substituted by hydrophobic groups are deposited from methanol as macrodomains of uniaxially oriented material; these rearrange to microdomain morphologies on heating above ca. 60°C. Similar anions substituted by polar groups form spherulitic complexes or they rearrange thermotropically to microdomain structures. (ii) The preparation of polythiocyanogen by a ‘canal’ polymerisation within a PEO-NaSCN lattice is described and its extraction to give a material of conductivity ca. 10^?1S cm^?1 after doping is discussed, (iii) Charge-transfer reactions with PEO-NaI and tetracyano-quinodimethan (TCNQ) to give films having conductivities of 10^?3-10Ω^?1 cm^?1 are also described.     

Poly(ethylene oxide)–polyelectrolyte blends: viscometric and thermal analysis behaviour

The miscibility of binary poly(ethylene oxide) (PEO) and sodium poly(4‐styrene sulphonate) (PSS) or [3,6]‐ionene (ION) systems, was analysed in aqueous solutions and in the solid state by viscometry and thermal analysis, respectively. Both techniques indicate partial miscibility of PEO–PSS and immiscibility of PEO–ION blends. In water solution, the partial miscibility of the PEO–PSS system is probably due to the counterion Na⁺ which can partially provide the driving force association in a similar manner to that observed for PEO–surfactant systems. In blend films, the PEO–polyelectrolyte interaction is also analysed in terms of the effect on the PEO crystallization observed through optical microscopy, and the results indicate compatibility between the components in the PEO–PSS system. © 2000 Society of Chemical Industry     

Electrospinning of sodium alginate with poly(ethylene oxide)

Another natural biopolymer, sodium alginate, has been electrospun from aqueous solution by blending with a non-toxic, biocompatible, synthetic polymer poly(ethylene oxide) (PEO). The interaction between sodium alginate and PEO has been evidenced by FTIR and conductivity change, which is thought to be the main reason for the successful electrospinning. The solution properties of sodium alginate/PEO blends have been measured, including viscosity, conductivity and surface tension. The morphology and mechanical properties of the electrospun mats have been investigated. Smooth fibers with diameters around 250 nm are obtained from 3% solutions of varied alginate/PEO proportions ranging from 1:1 to 0:1. Tensile strength around 4 MPa is found with smooth fiber mats. The anti-water property of the electrospun mats has been improved by a combination of hexamethylene diisocyanate and aqueous calcium chloride cross-linkings.     

聚氧乙烯苯胺醚在聚氨酯半硬泡制品中的应用

聚氧乙烯苯胺醚是一种优良的聚氨酯半硬泡扩链剂，主要其在聚氨酯半硬泡配方中应用对半硬泡制品性能的影响。     

Nonaqueous emulsion copolymerization of ethyl methacrylate/lauryl methacrylate in propylene glycol. II. Adsorption of poly(ethylene oxide)–polystyrene–poly(ethylene oxide) triblock copolymer on latex particles

The adsorption behavior of various poly(ethylene oxide)–polystyrene–poly(ethylene oxide) (PEO‐PS‐PEO) triblock copolymer (TBC) s on acrylic latex particles in propylene glycol was studied. The composition of the PEO‐PS‐PEO triblock polymers varied from 41 to 106 in each PEO block length and from 18 to 41 in the PS block length. The location of the PEO‐PS‐PEO TBC was determined by analyzing for the physically adsorbed amount on the latex surface, the anchored mount on the surface, the entrapped amount inside the particle, and the “free” PEO‐PS‐PEO TBCs in the propylene glycol. A contour graph technique was applied to analyze the experimental data, which showed that a minimum existed for the physically adsorbed portion at a PS block length of about 30 units. When the PS block length was less than 30 units, the adsorption decreased with increasing PS block length, indicating rearrangement of mixed PEO brush and adsorbed PS block. When the PS block was greater than 30 units, the adsorption increased with increasing block length because of the poor solvency of the PS block in the propylene glycol medium, resulting in a collapse of the PS chain. Considering the binding energy between the PS block and the latex particle surface, which governs adsorption, it was hypothesized that a lower block length limit exists, below which no adsorption takes place. The solubility of the PS block in propylene glycol guides the important upper block length limit. The anchored fraction of the block copolymer increased continuously with increasing PS block length in the entire region investigated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1963–1975, 2001     

Ionic conductivity studies of poly(ethylene oxide)-lithium salt electrolytes in high-pressure carbon dioxide

We have measured ionic conductivity of PEO-LiX [anion X=N(CF₃SO₂)₂ (TFSI), ClO₄, CF₃SO₃, BF₄, NO₃, and CH₃SO₃] polymer electrolytes in CO₂ at pressures varied from 0.1 to 20 MPa. From the temperature dependence in supercritical CO₂, a large increase in the conductivity for PEO-LiBF₄ and LiCF₃SO₃ electrolytes has been observed. Permeation of the CO₂ molecules gave rise to the plasticization for crystal domains in the electrolytes, which is related to the reduction in transition point of the Arrhenius plot corresponding to the melting of crystal PEO. Relation between the conductivity and CO₂ reduced density revealed that the electrolytes containing fluorinated anions such as ‘CO₂-philic’ BF₄ and CF₃SO₃ increase in the conductivity with increasing the density. This indicates that the salt dissociation was promoted by the CO₂ permeation and the Lewis acid-base interactions between fluorinated anions and CO₂ molecules.     

Crystalline structures in ultrathin poly(ethylene oxide)/poly(methyl methacrylate) blend films

Amorphous poly(ethylene oxide)/poly(methyl methacrylate) (PEO/PMMA) blend films in extremely constrained states are meta-stable and phase separation of fractal-like branched patterns happens in them due to heterogeneously nucleated PEO crystallization by diffusion-limited aggregation. The crystalline branches are viewed flat-on with PEO chains oriented normal to the substrate surface, upon increasing PMMA content the branch width remains invariant but thickness increases. It is revealed that PMMA imposes different effects on PEO crystallization, i.e. the length and thickness of branches, depending on the film composition.     

Dielectric properties and structures of melt‐compounded poly(ethylene oxide)–montmorillonite nanocomposites

The dielectric dispersion and relaxation process in melt‐compounded hot‐pressed poly(ethylene oxide) (PEO)–montmorillonite (MMT) clay nanocomposite films of 0–20 wt % MMT concentration were investigated over the frequency range 20 Hz to 1 MHz at ambient temperature. X‐ray diffraction study of the nanocomposites evidences that the PEO has been intercalated into the MMT interlayer galleries with a helical‐type multilayer structures, which results the formation of unique parallel plane PEO–MMT layered structures. The relaxation times corresponding to PEO chain segmental motion were determined from the loss peak frequencies of different dielectric formalisms and the same is used to explore the interactions compatibility between PEO molecules and the MMT nano platelets. It is revealed that the loading of only 1 wt % MMT in PEO matrix significantly increases the PEO chain segmental motion due to intercalation, which further varies anomalously with increase of MMT concentration. The real part of dielectric function at 1 MHz, relaxation time, and dc conductivity of these melt‐compounded nanocomposites were compared with the aqueous solution‐cast PEO–MMT films. Considering the comparative changes in the values of various dielectric parameters, the effect of synthesization route on the intercalated/exfoliated‐MMT structures and the PEO chain dynamics were discussed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Fractional Crystallization Kinetics of Poly(ethylene oxide) in Its Blends with Poly(butylene succinate): Molecular Weight Effects

The fractional crystallization kinetics and phase behavior of PEO with different molecular weights (MWs) in its miscible crystalline/crystalline blends with PBS are studied. Both fractional crystallization kinetics and phase segregation of PEO in PBS/PEO blends are dramatically influenced by its MW. PEO with a medium MW (20 kDa) shows a significant fractional crystallization in the blends with PBS crystallized at a high T_IC,PBS, which, however, is dramatically depressed in the blends with a very low or high MW of PEO. This indicates that the PEO component with a medium MW is more ready to segregate into the interlamellar region of PBS crystals than those with a very low or high MW. The MW‐dependent fractional crystallization kinetics and phase segregation of PEO component in the PBS/PEO blends are discussed.

     

Synthesis and characterization of poly(methylphenylsilylene)–poly(ethylene oxide) and poly(methylphenylsilylene)–polyisoprene multiblock copolymers

Multiblock copolymers were synthesized through condensation reactions of end‐groups of α,ω‐dichloro‐poly(methylphenylsilylene) with hydroxyl end‐groups of poly(ethylene glycol) or the chain‐ends of ‘living’ polyisoprenyl disodium. Optimum conditions have been sought through kinetic studies and by investigation of model reactions. The overall molecular weight distribution of poly(methylphenylsilylene)‐block‐poly(ethylene oxide) is characterized in terms of Flory's theory of condensation reactions, while the limiting step in the reaction is tentatively attributed to the formation of aggregates. © 2001 Society of Chemical Industry     

Crystal structure of the poly(ethylene oxide)–p-nitrophenol molecular complex

A crystalline complex of poly(ethylene oxide) (PEO) and p-nitrophenol (PNP) was studied by differential scanning calorimetry, X-ray diffraction, and FTIR spectroscopy, The phase diagram of this system is characterized by a peritectic reaction, and reveals the formation of a new crystal form different from those of PEO, and PNP. The triclinic unit cell of the complex was determined from the X-ray diffraction patterns of differently oriented samples obtained by mechanical deformations or spherulitic crystallizations. Finally, the molecular packing and the conformation adopted by the PEO chains were determined by FTIR spectroscopy. Polarization measurements have shown that the aromatic rings are very nearly normal to the c parameter (chain axis) and that the 1–4 axes of PNP molecules are parallel to the a^* reciprocal parameter (spherulitic growth direction). Finally, a new (t₂ gt₂ gt₃) conformation is proposed for the PEO chains on the basis of a normal mode analysis and the calculation of the intramolecular energy.     

Crystallization Kinetics and Hydrophilicity Improvement of Biodegradable Poly(butylene succinate) in its Miscible Blends with Poly(ethylene oxide)

The spherulitic morphology and growth, overall isothermal crystallization kinetics and hydrophilicity of PBSU were investigated by POM, DSC and WCA measurements in its miscible blends with PEO. The Hoffman‐Lauritzen equation was employed to analyze the spherulitic growth rates of neat and blended PBSU, which show a crystallization regime transition between regime II and III. The overall crystallization rates of PBSU decreased with increasing crystallization temperature, regardless of blend composition, while the crystallization mechanism does not change. A significant improvement in the hydrophilicity of PBSU can be achieved by blending with different weight fractions of PEO, which may be essential for the practical application of PBSU/PEO blends.

     

Crystallization of poly(ethylene oxide) in i-polypropylene–poly(ethylene oxide) blends

A two-stage stable system of isotactic polypropylene–poly(ethylene oxide) blend, in which poly(ethylene oxide) can be permanent either in molten or in crystallized states in the temperature range from 280 to 327 K, was described. The behavior of that blend was explained in terms of fractionated crystallization. A fine dispersion of poly(ethylene oxide) inclusions is required for efficient suppression of crystallization initiated by heterogeneous nuclei. The application of a thin film of polypropylene-poly(ethylene oxide) 9 : 1 blend obtained by quenching for multiuse erasable and rewritable carriers for visible information has been demonstrated. The same sample exhibits different dynamic mechanical properties when poly(ethylene oxide) inclusions are molten or crystallized. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2047–2057, 1997     

Melting behaviour of poly(butylene succinate) in miscible blends with poly(ethylene oxide)

The melting behavior of poly(butylene succinate) (PBSU) in miscible blends with poly(ethylene oxide) (PEO), which is a newly found polymer blends of two crystalline polymers by our group, has been investigated by conventional differential scanning calorimetry (DSC). It was found that PBSU showed double melting behavior after isothermal crystallization from the melt under certain crystallization conditions, which was explained by the model of melting, recrystallization and remelting. The influence of the blend composition, crystallization temperature and scanning rate on the melting behavior of PBSU has been studied extensively. With increasing any of the PEO composition, crystallization temperature and scanning rate, the recrystallization of PBSU was inhibited. Furthermore, temperature modulated differential scanning calorimetry (TMDSC) was also employed in this work to investigate the melting behavior of PBSU in PBSU/PEO blends due to its advantage in the separation of exotherms (including crystallization and recrystallization) from reversible meltings (including the melting of the crystals originally existed prior to the DSC scan and the melting of the crystals formed through the recrystallization during the DSC scan). The TMDSC experiments gave a direct evidence of this melting, recrystallization and remelting model to explain the multiple melting behavior of PBSU in PBSU/PEO blends.     

Liquid–liquid extraction of copper(II)–EDTA chelated anions with microporous hollow fibers

The rates of extraction of Cu(II)–EDTA (ethylenediaminetetraacetic acid) chelated anions from aqueous solutions across microporous hollow fibers to kerosene solutions of Aliquat 336 (a quaternary amine) were measured. Experiments were performed as a function of aqueous pH, the chelated anion concentration, the organic amine concentration, and temperature. From experiments performed on the temperature dependence of extraction rate, it was shown that the resistance of interfacial chemical reaction was negligible. It was shown that the extraction rate increased with increasing concentrations of both the chelated anions and the amine. However, the aqueous pH had little effect on extraction rate under the ranges studied. The mass transfer mechanism of this extraction process was also discussed. © 2000 Society of Chemical Industry     

Gelatin/Poly(ethylene oxide) Blend Films with Compositional Gradient: Fabrication and Characterization

In this study, novel protein/biodegradable polymer blend biomaterials‐gelatin/poly(ethylene oxide) blend films with compositional gradients were successfully fabricated by a dissolution/diffusion method. Two kinds of compositional gradient films, which were different in gradient structure, were prepared. The compositional gradient structure in the films was characterized by polarized optic microscopy, ATR‐FTIR, and trans‐FT‐IR mapping measurement. In addition, the mechanical properties of the gradient films were characterized with reference to their gradient structure. It is found that the compositional gradient films have better mechanical properties than the pure gelatin film. These protein/biodegradable polymer compositional gradient films have a potential for many biomedical applications.