PEO/P(VdF-HFP) blend based Li+ ion-conducting composite polymer electrolytes dispersed with dedoped (insulating) polyaniline nanofibers

Composite polymer electrolyte membranes composed of poly(ethylene oxide) (PEO), poly(vinylidene fluoride-hexafluoropropylene) {P(VdF-HFP)} blends, dedoped (insulating) polyaniline (PAni) nanofibers, and LiClO₄ as salt have been synthesized with varying fraction of dedoped PAni nanofibers (from 2 to 10 wt.%). The ionic conductivity of PEO–P(VdF-HFP)–LiClO₄ electrolyte system increases with increase in the fraction of dedoped polyaniline nanofibers. This could be attributed to the incorporation of nanofibers (aspect ratio >50), which may provide high ion conducting path along the interface due to Lewis acid–base interactions between Li⁺ ions and lone pair of electrons of nitrogen atom of polyaniline. However, at higher fraction (>6 wt.%), the nanofibers get phase separated from the polymer matrix and form domain-like structures, which may act as physical barrier to the conduction of Li⁺ ions resulting in decreased ionic conductivity. Electrochemical potential window and interfacial stability of nanofibers dispersed polymer electrolyte membranes are also better than that of nanofibers free membranes.     

Effects of lithium salt and poly(4‐vinyl phenol) on crystalline and amorphous phases in poly(ethylene oxide)

Effects of a strong‐interacting amorphous polymer, poly(4‐vinyl phenol) (PVPh), and an alkali metal salt, lithium perchlorate (LiClO₄), on the amorphous and crystalline domains in poly(ethylene oxide) (PEO) were probed by differential scanning calorimetry (DSC), optical microscopy (OM), and Fourier transform infrared spectroscopy (FTIR). Addition of lithium perchlorate (LiClO₄, up to 10% of the total mass) led to enhanced T_g's, but did not disturb the miscibility state in the amorphous phase of PEO/PVPh blends, where the salt in the form of lithium cation and ClO anion was well dispersed in the matrix. Competitive interactions between PEO, PVPh, and Li⁺ and ClO ions were evidenced by the elevation of glass transition temperatures and shifting of IR peaks observed for LiClO₄‐doped PEO/PVPh blend system. However, the doping distinctly influenced the crystalline domains of LiClO₄‐doped PEO or LiClO₄‐doped PEO/PVPh blend system. LiClO₄ doping in PEO exerted significant retardation on PEO crystal growth. The growth rates for LiClO₄‐doped PEO were order‐of‐magnitude slower than those for the salt‐free neat PEO. Dramatic changes in spherulitic patterns were also seen, in that feather‐like dendritic spherulites are resulted, indicating strong interactions. Introduction of both miscible amorphous PVPh polymer and LiClO₄ salt in PEO can potentially be a new approach of designing PEO as matrix materials for electrolytes. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3357–3368, 2006     

Alkali metal ion conductors based on sulfonated poly(p-phenylene terephthalamide)

To obtain thermally stable and mechanically strong sodium and lithium conducting polymers, we prepared Na⁺ and Li⁺ poly(phenylene terephthalamide sulfonate salts) (MW ～ 5500). We also synthesized oligo(ethylene oxide) (3, 5, or 7 units of ethylene oxide) substituted ethylene carbonate and poly[oxymethylene-oligo(oxyethylene)]. These are high boiling point liquids with high dielectric constants as well as metal chelating properties. Polyelectrolyte systems were prepared by mixing Na⁺ or Li⁺ poly(phenylene terephthalamide sulfonate) salts with various amounts of modified ethylene carbonate and/or poly[oxymethylene-oligo(oxyethylene)]. Films (0.1–0.5 mm thick) obtained from the blends were found to have considerable mechanical strength; forming free standing films. The ionic conductivities of the Na⁺ and Li⁺ polyelectrolyte systems were 10^?6?10^?5 S/cm at 25°C. Thermal properties of these blend systems were investigated in detail. © 1994 John Wiley & Sons, Inc.     

羧化聚苯醚／聚（苯乙烯—乙烯吡啶）共混相容性

用ＤＳＣ、ＤＭＡ研究了羧化聚苯醚（ＣＰＰＯ）／聚（苯乙烯－乙烯吡啶）（ＰＳＶＰ）共混体系的相容性，结果表明，与ＣＰＰＯ／ＰＳ体系相比，乙烯吡啶基的引入大大提高了共混相容性．这主要是由于ＣＰＰＯ中的羧基与ＰＳＶＰ中的吡啶基之间通过质子转移形成的正负离子间的相互作用，推动了两组分分子的均匀混合．     

Ionic conductivities of the complexes of LiClO4 and alternating copolymers of oligomeric poly(ethylene oxide) having biphenyl units in the backbone

A series of copolymers of predominantly poly(ethylene oxide) (PEO) with biphenyl (BP) units in the backbone were synthesized. The solid polymer electrolytes (SPEs) were prepared from these copolymers (BP-PEG) employing lithium perchlolate (LiClO₄) as a lithium salt and their ionic conductivities were investigated to exploit the structure–ionic conductivity relationships as a function of chain length ratio between the flexible PEO chains and rigid BP units. The ionic conductivity increases with increasing PEO length in BP-PEG. The salt concentrations in BP-PEG/LiClO₄ complexes were also changed and the results show that maximum conductivity is obtained at [EO]/[Li⁺]≈8. The reasons for these findings are discussed in terms of the number of charge carriers and the mobility of the polymer chain.     

Synthesis and ionic conductivity of hyperbranched poly(glycidol)

A novel hyperbranched poly(glycidol) (HPG) was prepared and characterized. The synthesized HPG was used as a substrate of a polymer electrolyte. The ionic conductivity of a blend of HPG, polyurethane (PU), and salt was studied. The ionic conductivity of HPG/PU/LiClO₄ was about 6.6 × 10^?6 S · cm^?1 at 20 °C and 6.3 × 10^?4 S · cm^?1 at 60 °C. The results indicated that HPG showed higher solubility for salt than linear polyether when both had the same [O]/[Li⁺] molar ratio. The main reason was that more cavities and a lower degree of chain entanglement in HPG resulted in a lower glass‐transition temperature and were beneficial for decreasing the aggregation of salt or enhancing the ionic conductivity. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2225–2230, 2001     

Conductivity enhancement mechanism of the poly(ethylene oxide)/modified‐clay/LiClO4 systems

This study demonstrates that adding clay that was organically modified by dimethyldioctadecylammonium chloride (DDAC) and d2000 surfactants increases the ionic conductivity of polymeric electrolyte. A.C. impedance, differential scanning calorimetric (DSC), and Fourier transform infrared (FTIR) studies revealed that the silicate layers strongly interact with the dopant salt lithium perchlorate (LiClO₄) within a poly(ethylene oxide) (PEO)/clay/LiClO₄ system. DSC characterization verified that the addition of a small amount of the organic clay reduces the glass‐transition temperature of PEO as a result of the interaction between the negative charge in the clay and the lithium cation. Additionally, the strength of such a specific interaction depends on the extent of PEO intercalation. With respect to the interaction between the silicate layer and the lithium cation, three types of complexes are assumed. In complex I, lithium cation is distributed within the PEO phase. In complex II, lithium cation resides in an PEO/exfoliated‐clay environment. In complex III, the lithium cation is located in PEO/agglomerated‐clay domains. More clay favors complex III over complexes II and I, reducing the interaction between the silicate layers and the lithium cations because of strong self‐aggregation among the silicate layers. Notably, the (PEO)₈LiClO₄/DDAC‐modified clay (DDAC‐mClay) composition can form a nanocomposite electrolyte with high ionic conductivity (8 × 10^?5 S/cm) at room temperature. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1342–1353, 2002     

Effects of PEO length and phenyl unit structure on ionic conductivities of the complexes of LiClO4 and alternating copolymers of PEO having various phenyl units in the backbone

A series of copolymers of predominantly poly(ethylene oxide) (PEO) with mono-phenyl (HQ), biphenyl (BP) units, or both of them (HQ/BP) in the backbone were synthesized. The solid polymer electrolytes (SPEs) were prepared from three different types of copolymers (HQ-PEG, BP-PEG, and HQ/BP-PEG) employing lithium perchlorate (LiClO₄) as a lithium salt at a fixed salt concentration of [EO]/[Li⁺]=8. Their ionic conductivities were investigated to exploit the structure–ionic conductivity relationships as a function of structural change in rigid phenyl units and chain length ratio between flexible PEO chain and rigid phenyl units. As more rigid phenyl units were incorporated in the backbone chain, the formation inter- and intra-molecular complex with LiClO₄ became weaker and lower ionic conductivities were observed. And it was also found that higher ionic conductivity is obtained with increasing PEO chain length because inter- and intra-molecular dissociation power of PEO increases.     

Mechanical properties and morphology of epoxy/poly(vinyl acetate)/poly(4-vinyl phenol) brominated system

Diglycidyl ether of bisfenol-A (DGEBA)/poly(vinyl acetate) (PVAc)/poly(4-vinyl phenol) brominated (PVPhBr) ternary blends cured with 4,4’-diaminodiphenylmethane (DDM) were investigated by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA) and scanning electron microscopy (SEM). Homogeneous (DGEBA+DDM)/PVPhBr networks with a unique T _g are generated. Ternary blends (DGEBA+DDM)/PVAc/PVPhBr are initially miscible and phase separate upon curing arising two T _gs that correspond to a PVAc-rich phase and to epoxy network phase. Increasing the PVPhBr content the T _gof the PVAc phase move to higher temperatures as a consequence of the PVAc-PVPhBr interactions. Different morphologies are generated as a function of the blend composition.     

Effect of temperature on the intrinsic viscosity of poly(ethylene glycol)/poly(vinyl pyrrolidone) blends in aqueous solutions

In this work the intrinsic viscosity of poly(ethylene glycol)/poly(vinyl pyrrolidone) blends in aqueous solutions were measured at 283.1–313.1 K. The expansion factor of polymer chain was calculated by use of the intrinsic viscosities data. The thermodynamic parameters of polymer solution (the entropy of dilution parameter, the heat of dilution parameter, theta temperature, polymer–solvent interaction parameter and second osmotic virial coefficient) were evaluated by temperature dependence of polymer chain expansion factor. The obtained thermodynamic parameters indicate that quality of water was decreased for solutions of poly(ethylene oxide), poly(vinyl pyrrolidone) and poly(ethylene oxide)/poly(vinyl pyrrolidone) blends by increasing temperature. Compatibility of poly(ethylene oxide)/poly(vinyl pyrrolidone) blends were explained in terms of difference between experimental and ideal intrinsic viscosity and solvent–polymer interaction parameter. The results indicate that the poly(ethylene glycol)/poly(vinyl pyrrolidone) blends were incompatible.     

Thermo‐mechanical Properties of PEO‐PU/PAN Semi‐Interpenetrating Polymer Networks and their LiClO4 Salt‐Complexes

This paper is an investigation on the thermo‐mechanical properties of a new class of materials, which holds promise for its potential use as solid polymer electrolytes, i.e., SPE material. A series of poly(ethylene oxide)‐polyurethane/poly(acrylonitrile) (PEO‐PU/PAN) semi‐IPNs, along with their LiClO₄ salt complexes, were characterized for their thermal, mechanical and dimensional stability using DSC, TG‐DTA, UTM and DMTA. The glass transition temperature (T_g) of both the undoped and doped semi‐IPNs, obtained by DSC, remained well below room temperature (～?50°C to ?35°C), satisfying one of the essential requirements to serve as a SPE host matrix. The crystallization process in the PEO segments of the PEO‐PU/PAN semi‐IPNs was prevented at higher salt concentrations, which is attributed to the Li⁺ ion mediated pseudo‐crosslinks. Good thermal stability of the semi‐IPNs was evident from the degradation onset temperature (T₀～240°C) with a three‐stage degradation process, which is independent of the PAN content as observed from differential thermogravimetric studies. The incorporation of PAN in the PEO‐PU networks results in improved mechanical properties, such as tensile strength and modulus while retaining the flexibility of the semi‐IPNs. The peak temperatures and storage modulus obtained from DMTA correlates well with the observations of DSC and tensile measurements.     

Crystallization and melting behavior of poly(ethylene oxide)/poly(n-butyl methacrylate) blends

The phase diagram, crystallization and melting behavior of poly(ethylene oxide) (PEO)/poly(n-butyl methacrylate) (PnBMA) blends have been investigated using differential scanning calorimetry and optical microscopy. The results show that the blends are miscible up to 85 °C and show an lower critical solution temperature-type demixing at a higher temperature. The isothermal crystallization studies of the blends indicate a reduction in the overall rate of crystallization. Analysis of isothermal crystallization data by means of Avrami equation leads to average values of the Avrami index of 2.5 for pure PEO and 3.0 for the different blend compositions. The melting behavior of the blends reveals double endotherms, which is ascribed to both secondary crystallization and recrystallization. The melting point depression study yielded χ₁₂=0, indicating a relatively low interaction strength.     

Non-isothermal crystallization kinetics of poly(trimethylene terephthalate)/poly(ethylene 2,6-naphthalate) blends

The glass-transition temperature and non-isothermal crystallization of poly(trimethylene terephthalate)/poly(ethylene 2,6-naphthalate) (PTT/PEN) blends were investigated by using differential scanning calorimeter (DSC). The results suggested that the binary blends showed different crystallization and melting behaviors due to their different component of PTT and PEN. All of the samples exhibited a single glass-transition temperature, indicating that the component PTT and PEN were miscible in amorphous phase. The value of T_g predicted well by Gordon-Taylor equation decreased gradually with increasing of PTT content. The commonly used Avrami equation modified by Jeziorny, Ozawa theory and the method developed by Mo were used, respectively, to fit the primary stage of non-isothermal crystallization. The kinetic parameters suggested that the PTT content improved the crystallization of PEN in the binary blend. The crystallization growth dimension, crystallization rate and the degree of crystallinity of the blends were increased with the increasing content of PTT. The effective activation energy calculated by the advanced iso-conversional method developed by Vyazovkin also concluded that the value of E_a depended not only on the system but also on temperature, that is, the binary blend with more PTT component had higher crystallization ability and the crystallization ability is increased with increasing temperature. The kinetic parameters U^* and K_g were also determined, respectively, by the Hoffman-Lauritzen theory.     

STUDIES OF THE CRYSTALLIZATION BEHAVIOR IN THE CRYSTALLINE/AMORPHOUS POLYMER BLENDS: POLY(ETHYLENE OXIDE)/POLY(METHYL METHACRYLATE) AND POLY(ETHYLENE OXIDE)/POLY(VINYL ACETATE)

The crystallization process of poly(ethylene oxide) (PEO)/poly(methyl methacrylate) (PMMA)and PEO/poly(vinyl acetate) (PVAc) blends has been characterized by Fourier Transform Infrared(FTIR) spectra in conjunction with Differential Scanning Calorimeter (DSC) measurements. Thecrystallinity of PEO varies consistently with PEO content in PEO/PVAc blends and the PEO/PMMAblends containing 50 wt% or less PMMA. For the PEO/PMMA blends containing 60 wt% ormore PMMA, the crystallinity of PEO decreases more than PEO content but develops with crystal-lization time. These results can be explained in terms of difference between the crystallization tem-perature (T_c) and glass transition temperature (T_g) of the blends as a function of content of amorphouscomponent.     

Polymer electrolyte membranes by in situ polymerization of poly(ethylene carbonate‐co‐ethylene oxide) macromonomers in blends with poly(vinylidene fluoride‐co‐hexafluoropropylene)

Salt‐containing membranes based on polymethacrylates having poly(ethylene carbonate‐co‐ethylene oxide) side chains, as well as their blends with poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP), have been studied. Self‐supportive ion conductive membranes were prepared by casting films of methacrylate functional poly(ethylene carbonate‐co‐ethylene oxide) macromonomers containing lithium bis(trifluorosulfonyl)imide (LiTFSI) salt, followed by irradiation with UV‐light to polymerize the methacrylate units in situ. Homogenous electrolyte membranes based on the polymerized macromonomers showed a conductivity of 6.3 × 10^?6 S cm^?1 at 20 °C. The preparation of polymer blends, by the addition of PVDF‐HFP to the electrolytes, was found to greatly improve the mechanical properties. However, the addition led to an increase of the glass transition temperature (T_g) of the ion conductive phase by ～5 °C. The conductivity of the blend membranes was thus lower in relation to the corresponding homogeneous polymer electrolytes, and 2.5 × 10^?6 S cm^?1 was recorded for a membrane containing 10 wt % PVDF‐HFP at 20 °C. Increasing the salt concentration in the blend membranes was found to increase the T_g of the ion conductive component and decrease the propensity for the crystallization of the PVDF‐HFP component. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 79–90, 2007     

PEO／PVP共混体系结晶行为

本文用WAXD、PLM、DSC方法研究了聚氧化乙烯(PEO)/聚乙烯基吡咯烷酮(PVP)共混体系的结晶行为,探索了两组分聚合物间相互作用及体系结晶度与非晶组分含量的关系。DSC研究表明PEO/PVP共混体系具有两个玻璃化转变温度,分别是纯组分的T_g,无相容性。应用Avrami和LH方程对其动力学参数进行了研究。偏光显微镜观察了共混物结构形态。     

Investigation at the chain segmental level of the miscibility of poly(vinyl chloride)/atactic poly(methyl methacrylate) blends

We employed high‐resolution ¹³C cross‐polarization/magic‐angle‐spinning/dipolar‐decoupling NMR spectroscopy to investigate the miscibility and phase behavior of poly(vinyl chloride) (PVC)/poly(methyl methacrylate) (PMMA) blends. The spin–lattice relaxation times of protons in both the laboratory and rotating frames [T₁(H) and T_1ρ(H), respectively] were indirectly measured through ¹³C resonances. The T₁(H) results indicate that the blends are homogeneous, at least on a scale of 200–300 Å, confirming the miscibility of the system from a differential scanning calorimetry study in terms of the replacement of the glass‐transition‐temperature feature. The single decay and composition‐dependent T_1ρ(H) values for each blend further demonstrate that the spin diffusion among all protons in the blends averages out the whole relaxation process; therefore, the blends are homogeneous on a scale of 18–20 Å. The microcrystallinity of PVC disappears upon blending with PMMA, indicating intimate mixing of the two polymers. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2390–2396, 2001     

Nonlinear Effects on the Ionic Conductivity of Polyethylene Oxide)/Uthium Perchlorate Complexes Caused by the Blending of Polyvinyl Acetate)

Poly(ethylene oxide) (PEO)/LiClO₄/poly(vinyl acetate) (PVAc) and PEO/LiClO₄/poly(vinyl pyrrolidone) (PVP) complexes were prepared with various weight ratios of PVAc and PVP to PEO. The conductivity (σ) of the PEO/LiClO₄ complex was increased in a nonlinear fashion by the presence of up to 60 wt% PVAc. PEO/LiClO₄/PVAc complexes with weight percents of PVAc greater than 60 had σ's less than that of PEO/LiClO₄. The σ of PEO/LiClO₄ was decreased by the presence of any PVP.     

Melt‐processable blends of ionic poly(p‐phenylene terephthalamide) and poly(4‐vinylpyridine): Relaxation behavior

Melt‐processable blends were prepared from rigid molecules of an ionically modified poly(p‐phenylene terephthalamide) (PPTA) and flexible‐coil molecules of poly(4‐vinylpyridine) (PVP). Dynamic mechanical analyses of blends with 50% or more of the ionic PPTA component revealed the presence of two distinct phases. The glass‐transition temperature of the more stable, ionic PPTA‐rich phase increased linearly with the ionic PPTA content. The second phase present in these blends was an ionic PPTA‐poor, or a PVP‐rich, phase. For this phase, a reasonably good fit of the data, showing the glass‐transition temperature as a function of the ionic PPTA content, was achieved between the results of this study and the reported results of previous investigation of molecular composites of the same two components with ionic PPTA contents of 15 wt % or less. The possible influence of annealing on the blend structure of a 90/10 blend of ionic PPTA and PVP was examined. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1468–1475, 2003     

Ion conductivity studies of blends of poly(methyl methacrylate)-g-poly(ethylene glycol) and poly(ethylene glycol) complexed with LiCF3 SO3

Polymer electrolytes which are adhesive, transparent, and stable to atmospheric moisture have been prepared by blending poly(methyl methacrylate)-g-poly(ethylene glycol) with poly(ethylene glycol)/LiCF₃ SO₃ complexes. The maximum ionic conductivities at room temperature were measured to be in the range of 10⁻⁴ to 10⁻⁵ s cm⁻¹. The clarity of the sample was improved as the graft degree increased for all the samples studied. The graft degree of poly(methyl methacrylate)-g-poly(ethylene glycol) was found to be important for the compatibility between the poly(methyl methacrylate) segments in poly(methyl methacrylate)-g-poly(ethylene glycol) and the added poly(ethylene glycol), and consequently, for the ion conductivity of the polymer electrolyte. These properties make them promising candidates for polymer electrolytes in electrochromic devices. © 1996 John Wiley & Sons, Inc.