Study of polyurethane/sulfonated dimethyl fumarate complex

In this study linear polyether polyurethanes (PU) and sulfonated dimethyl fumarate (SDMF) were successfully synthesized and a series of novel solid polymer electrolytes, based on the complexes of PU and SDMF, were prepared. Fourier transform–Raman spectroscopy (FT‐Raman), ¹H‐NMR, differential scanning calorimetry (DSC), atomic force microscopy (AFM), and complex impedance analysis were utilized to investigate the chemical structure, microscale morphology, and ionic conductive property of this system. Results show that the ionic conductivity of the PU/SDMF series increases with increasing temperature. In the salt concentration range investigated, there is a maximum ionic conductivity for the PU/SDMF system. When the molar ratio of the ether oxygen and sodium cation is about 24, the optimum compatibility between the hard and soft segments is realized and the highest soft‐segment T_g is reached. A further increase in salt concentration causes the aggregation and precipitation of SDMF, and the decrease of the soft‐segment T_g. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 67–74, 2002; DOI 10.1002/app.10205     

The effect of the length of the oxyethylene chain on the conductivity of the polyurethaneurea electrolyte

Polyurethaneureas (PUU), which were synthesized from 4,4′-diphenylmethane diisocyanate (MDI), poly(ethylene glycol) (PEG), and 3,5-diaminobanzoic acid (DABA), were used as polyelectrolytes in this study. Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR) were used to monitor the effect of the various kinds of PEG on the changes in morphology of PUU electrolytes corresponding to the concentration of lithium perchlorate (LiClO₄) dopants. The results of DSC and FT-IR indicate the Li⁺ ions coordinate with the soft and hard segments. Additionally, the crystallinity of the PEG soft segment and the ordered hydrogen-bonded urea carbonyl groups decreased with increasing salt concentration. Impedance spectroscopy (IS) measurements show that the PUU electrolyte with the high phase separation degree has the high ionic conductivity. The hard-segment T_g and the soft-segment T_m influence the conductivity behavior of polyelectrolytes with increasing measurement temperature.     

Soft segmental effect of methylene bis(p‐cyclohexyl isocyanate) based thermoplastic polyurethane impregnated with lithium perchlorate/propylene carbonate on ionic conductivity

Thermoplastic polyurethane (TPU) was employed as the polymer matrix for ion conduction as gelled electrolytes with lithium perchlorate (LiClO₄) in propylene carbonate (PC) solution. The TPU was prepared by methylene bis(p‐cyclohexyl isocyanate) as the hard segment while employing both poly(ethylene glycol) (PEG) and poly(tetramethylene glycol) (PTMG) as the soft segments. The copolymer comprising both PEG and PTMG was prepared such that it possessed the combined characteristics of good conductivity from the former and good mechanical properties from the latter. All the polymers were characterized by gel permeation chromatography, differential scanning calorimetry, and Fourier transform IR spectroscopy. The conductivity data were obtained from alternating current impedance experiments. The results revealed that the copolymer containing both PEG and PTMG as the soft segments showed better performance than TPU containing either PEG or PTMG. The copolymer TPU(PEG/PTMG) proved to be a good gelled electrolyte from 5 to 85°C. This copolymer, impregnated with 150% LiClO₄/PC, possessed good mechanical strength and conductivity as high as 10^?3 S/cm. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 935–942, 2001     

Physical and electrochemical properties of low molecular weight poly(ethylene glycol)‐bridged polysilsesquioxane organic–inorganic composite electrolytes via sol–gel process

A new class of ionic conducting organic/inorganic hybrid composite electrolyte with high conductivity, better electrochemical stability and mechanical behavior was prepared through the sol–gel processing between ethylene‐bridged polysilsesquioxane and poly(ethylene glycol) (PEG). The composite electrolyte with 0.05 LiClO₄ per PEG repeat unit has the best conductivity up to 10^?4 S/cm at room temperature with the transference number up to 0.48 and an electrochemical stability window as high as 5.5 V versus Li/Li⁺. Moreover, the effect of the PEG chain length on the properties of the composite electrolyte has also been studied. The interactions between ions and polymer have also been investigated for the composite electrolyte in the presence of LiClO₄ by means of FTIR, DSC, and TGA. The results indicated the interaction of Li⁺ ions with the ether oxygen of the PEG, and the formation of transient crosslinking with LiClO₄, resulting in an increase of the T_g of the composite electrolyte. The VTF‐type behavior of the ionic conductivity implied that the diffusion of the charge carriers was assisted by the segmental motions of the polymer chains. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2752–2758, 2007     

The effect of EPIDA units on the conductivity of poly(ethylene glycol)-4,4′-diphenylmethane diisocyanate-EPIDA polyurethane electrolytes

Novel thermoplastic polyurethanes with chelating groups were synthesized from 4,4′-diphenylmethane diisocyanate (MDI), poly(ethylene glycol) (PEG), and EP-IDA. Differential scanning calorimetry (DSC), fourier transform infrared spectroscopy (FT-IR), and impedance spectroscopy (IS) were used to monitor changes in the morphology of these polyurethanes with the concentration of lithium perchlorate (LiClO₄) dopants. Adding the salt significantly changes the FTIR spectrum of the polyurethane, indicating an interaction between the lithium cation within the urethane group and the chelating group. The soft segment T_g increases with LiClO₄ concentration, as determined by DSC, indicating that solubility of the lithium cation in the host polyurethane increases with the chelating groups. IS shows that the bulk conductivity reaches a maximum as the salt concentration is increased. One of the investigated polyurethane electrolytes has an ionic conductivity as high as ∼10⁻⁶ S cm⁻¹ at room temperature.     

Effects on the structure and properties of membranes formed by blending polydimethylsiloxane polyurethane into different soft‐segment waterborne polyurethanes

Polydimethylsiloxane polyurethane (PDMS‐PU), which was synthesized from PDMS as the soft segment, was blended into a variety of ester‐ or ether‐based soft‐segment waterborne polyurethanes with different concentrations to investigate the crystallization, thermal, and physical properties of the membrane formations. According to X‐ray analysis, the ether‐based PUs, synthesized from soft segments of poly(propylene glycol) (PPG1000) or poly(ethylene glycol) (PEG2000), were found to have maximum crystallinity at a 5% blending ratio of PDMS‐PU, but the ester‐based PU, synthesized from soft segments of polycaprolactone (PCL1250), had decreased crystallinity at a 5% blending ratio. Differential scanning calorimetric analysis revealed that the T_g,s values of PUs were highest when the blending ratio of PDMS‐PU was 5%–10%, except for PU from PCL1250. Moreover, ether‐based PUs showed maximum T_m,h values, but the T_m,h of the ester‐based PU was greatly reduced when PU with PCL1250 was blended with PDMS‐PU. In addition, the PU from PEG2000 had the highest melting entropy. Mechanical property analysis showed that the stress of ether‐based PUs would be increased when PUs were blended with a small amount of PDMS‐PU and that the stress of PU from poly(tetramethylene glycol) (PTMG1000) increased to its greatest value (20–30 MPa). On the other hand, the ester‐based PU, from PCL1250 blended with PDMS‐PU, would have reduced stress. On the whole, the stress and strain of PU from PEG1000 had excellent balance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 210–221, 2006     

Synthesis of polyurethane–imide (PU–imide) copolymers with different dianhydrides and their properties

This study reports the synthesis of polyurethane–imide (PU–imide) copolymers using 4,4′-diphenylmethane diisocyanate (MDI) polytetramethylene glycols (PTMGs) and different aromatic dianhydrides. Differential scanning calorimetry (DSC) results indicate that PU–imide copolymers had two phase structures containing four transition temperatures (T_gs, T_ms, T_gh and T_mh). However, only PU–imide copolymers were formed by soft PTMG(2000) segments possessing a T_ms (melting point of soft segment). When different aromatic dianhydrides were introduced into the backbone chain of the polyurethane, although the T_gs (glass transition temperature of the soft segment) of some of PU–imide copolymers did not change, the copolymers with long soft segments had low T_gs values. The T_gh (glass transition temperature of hard segment) values of PU–imide copolymers were higher than that of polyurethane (PU). In addition, the high hard segment content of PU–imide copolymer series also had an obvious T_mh (melting point of hard segment). According to thermogravimetric analysis (TGA) and differential thermogravimetric analysis (DTGA), the PU–imide copolymers had at least two stages of degradation. Although the T_di (initial temperature of degradation) depended on the hard segment content and the composition of hard segment, the different soft segment lengths did not obviously influence the T_di. However, PU–imide copolymers with a longer soft segment had a higher thermal stability in the degradation temperature range of middle weight loss (about T_d 5%–50%). However, beyond T_d 50% (50% weight loss at temperature of degradation), the temperature of degradation of PU–imide copolymers increased with increasing hard segment content. Mechanical properties revealed that the modulus and tensile strength of PU–imide copolymers surpassed those of PU. Wide angle X-ray diffraction patterns demonstrated that PU–imide copolymers are crystallizable. © 1999 Society of Chemical Industry     

Solid polymer electrolytes VIII: effect of LiClO4-doped level on the microstructure and ionic conductivity of a chemical-covalently polyether-siloxane hybrid electrolyte

A new hybrid polymer electrolyte system based on chemical-covalently polyether and siloxane phases is designed and prepared in the presence of lithium perchlorate (LiClO₄) which acted as both ionic source and the epoxide ring-opening catalyst. The effect of salt-doped level on the microstructure and ionic conductivity of these composite electrolytes were investigated by means of Fourier transform infra-red spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis, a.c. impedance and multinuclear solid-state nuclear magnetic resonance measurements. DSC results indicate that the formation of transient cross-links between Li⁺ ions and the ether oxygens on complexation with LiClO₄ results in an increase in polyether segment T_g. However, the polyether segment T_g decreases at the highest salt concentration (5.0 mmol LiClO₄/g PEGDE), ascribing to the plasticizing effect. The behavior of ion transport is coupled with the segmental motions of polymer chains and also correlated with the interactions between ions and polymer host.     

Effects of reaction and cure temperatures on morphology and properties of poly(ester‐urethane)

Poly(ester‐urethane) was synthesized from poly(ethylene glycol adipate) (PEG) and 2,4‐toluene diisocyanate (TDI) to study the effects of reaction temperature and cure temperature on the crystallization behavior, morphology, and mechanical properties of the semicrystalline polyurethane (PU). PEG as soft segment was first reacted with TDI as hard segment at 90, 100, and 110°C, respectively, to obtain three kinds of PU prepolymers, coded as PEPU‐90, PEPU‐100, and PEPU‐110. Then the PU prepolymers were crosslinked by 1,1,1‐tris (hydroxylmethyl) propane (TMP) and were cured at 18, 25, 40, 60, and 80°C. Their structure and properties were characterized by attenuated total reflection Fourier transform infrared, wide‐angle X‐ray diffraction, scanning electron microscopy, dynamic mechanical analysis, and tensile testing. With an increase of the reaction temperature from 90 to 100°C, the crystallinity degree of soft segment decreased, but interaction between soft and hard segments enhanced, leading to the increase of the glass transition temperature (T_g) of soft domain and tensile strength. When the cure temperature was above 60°C, miscibility between soft and hard segments of the PEPU films was improved, resulting in relatively low crystallinity and elongation at break, but high soft segment T_g and tensile strength. On the whole, all of the PEPU‐90, PEPU‐100, and PEPU‐110 films cured above 60°C possessed higher tensile strength and elongation at break than that of the films cured at other temperatures. The results revealed that the reaction temperature and cure temperature play an important role in the improvement of the crosslinking structure and mechanical properties of the semicrystalline PU. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 708–714, 2006     

Polymer electrolytes based on poly(ethylene glycol) and cyanoresin

Polymer electrolytes based on a mixed polymer matrix consisting of poly(ethylene glycol) (PEG) and cyanoresins with lithium salt and plasticizer were prepared with an in situ blending process to improve both the mechanical properties and the ionic conductivity (σ). The PEG/lithium perchlorate (LiClO₄) complexes, including blends of cyanoethyl pullulan (CRS) and cyanoethyl poly(vinyl alcohol) (CRV), exhibited higher σ's than a simple PEG/LiClO₄ complex when the blend compositions of CRS/CRV were 5 : 5 or 3 : 7 or than CRV alone. When the CRS/CRV blend was compared with a copolymer of cyanoethyl pullulan and cyanoethyl poly(vinyl alcohol) (CRM) in the same molar ratio, the σ values of the polymer electrolytes containing the CRM copolymer series were slightly higher than those of the CRS/CRV blends containing PEG/LiClO₄ complexes. Moreover, the addition of cyanoresin to PEG/LiClO₄/(ethylene carbonate–propylene carbonate) polymer electrolytes provided better thermal stability and dynamic mechanical properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2402–2408, 2007     

Physical and potentiometric properties of polyurethane‐based cation‐selective membranes

Lipophilic salts based on tetraphenylborate derivatives [e.g., potassium tetrakis(p‐chlorophenyl)borate (KTpClPB), sodium tetraphenylborate (NaTPB), and cesium tetrakis(3‐methylphenyl)borate are essential ingredients used in the preparation of solvent polymeric cation‐selective membranes. The effects of such lipophilic salts on the physical properties of a polyurethane (PU) matrix comprising 4,4′‐diphenylmethane diisocyanate, 1,4‐butanediol, and poly(tetramethylene ether glycol) were examined. Differential scanning calorimetry measurements revealed that the sodium and potassium salts doped in PU increased the glass‐transition temperatures (T_g) of the matrix, while the film containing cesium salt exhibited slightly decreased T_g. The temperature dependence of the ionic conductivity for PU60 films doped with KTpClPB is well described by the Arrhenius‐type equation, and that doped with NaTPB is described by the Vogel–Tammann–Fulcher (VTF)‐type equation. The temperature dependence of the ionic conductivity on the VTF‐type equation suggests that the transport of sodium ions in the PU60 matrix is more strongly coupled to the soft segmental motion, and potassium ions are decoupled from the polymer host and transported by activated hopping. The effect of added salt on the internal structure of PU membranes was investigated by measuring the ratio between the free and hydrogen‐bonded CO bands at 1703 and 1730 cm⁻¹, respectively. The results showed that the ether oxygens in the soft segment chains are strongly coupled to the potassium or sodium, but much less to cesium. The potentiometric properties of these lipophilic additive doped PU membranes were characterized by incorporating valinomycin and 4‐tert‐butylcalix[4]arene‐tetraacetic acid tetraethylester as potassium‐ and sodium‐selective ionophores, respectively. Their response behavior could be explained by the observed physical characteristics. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 618–625, 2001     

Preparation and performance analysis of barium titanate incorporated in corn starch‐based polymer electrolytes for electric double layer capacitor application

Polymer electrolyte membranes composing of corn starch as host polymer, lithium perchlorate (LiClO₄) as salt, and barium titanate (BaTiO₃) as composite filler are prepared using solution casting technique. Ionic conductivity is enhanced on addition of BaTiO₃ by reducing the crystallinity and increasing the amorphous phase content of the polymer electrolyte. The highest ionic conductivity of 1.28 × 10^?2 S cm^?1 is obtained for 10 wt % BaTiO₃ filler in corn starch‐LiClO₄ polymer electrolytes at 75°C. Glass transition temperature (T_g) of polymer electrolytes decreases as the amount of BaTiO₃ filler is increased, as observed in differential scanning calorimetry analysis. Scanning electron microscopy and thermogravimetric analysis are employed to characterize surface morphological and thermal properties of BaTiO₃‐based composite polymer electrolytes. The electrochemical properties of the electric double‐layer capacitor fabricating using the highest ionic conductivity polymer electrolytes is investigated using cyclic voltammetry and charge‐discharge analysis. The discharge capacitance obtained is 16.22 F g^?1. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43275.     

Lithium ionic conductivity in poly(ether urethanes) derived from poly(ethylene glycol) and lysine ethyl ester

Poly(ether urethanes) obtained by the copolymerization of poly(ethylene glycol) (PEG) and lysine ethyl ester (LysOEt) are elastomeric materials that can be processed readily to form flexible, soft films. In view of these desirable physicomechanical properties, the potential use of these new materials as solid polymer electrolytes was explored. Solid polymer electrolytes were prepared with copolymers containing PEG blocks of different lengths and with different concentrations of lithium triflate (LiCF₃SO₃). Correlations between the length of the PEG block, the concentration of lithium triflate in the formulation, and the observed Li⁺ ion conductivity were investigated. Solid electrolyte formulations were characterized by differential scanning calorimetry for glass transition temperatures (T_g), melting points (T_m), and crystallinity. Ionic conductivity measurements were carried out on thin films of the polymer electrolytes that had been cast on a microelectrode assembly using conventional ac-impedance spectroscopy. These polymer electrolytes showed inherently high ionic conductivity at room temperature. The optimum concentration of lithium triflate was about 25–30% (w/w), resulting at room temperature in an ionic conductivity of about 10⁻⁵ S cm⁻¹. For poly(PEG₂₀₀₀-LysOEt) containing 30% of LiCF₃SO₃, the activation energy was ∼ 1.1 eV. Our results indicate that block copolymers of PEG and lysine ethyl ester are promising candidates for the development of polymeric, solvent-free electrolytes. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1449–1456, 1997     

Blending poly(methyl methacrylate) and poly(styrene‐co‐acrylonitrile) as composite polymer electrolyte

A blend of poly(methyl methacrylate) (PMMA) and poly(styrene‐co‐acrylonitrile) (PSAN) has been evaluated as a composite polymer electrolyte by means of differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, ac impedance measurements, and linear sweep voltammetry (LSV). The blends show an interaction with the Li⁺ ions when complexed with lithium perchlorate (LiClO₄), which results in an increase in the glass‐transition temperature (T_g) of the blends. The purpose of using PSAN as another component of the blend is to improve the poor mechanical properties of PMMA‐based plasticized electrolytes. The mechanical property is further improved by introducing fumed silica as inert filler, and hence the liquid electrolyte uptake and ionic conductivity of the composite systems are increased. Room‐temperature conductivity of the order of 10^?4 S/cm has been achieved for one of the composite electrolytes made from a 1/1 blend of PSAN and PMMA containing 120% liquid electrolyte [1M LiClO₄/propylene carbonate (PC)] and 10% fumed silica. These systems also showed good compatibility with Li electrodes and sufficient electrochemical stability for safe operation in Li batteries. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1319–1328, 2001     

Mechanical,thermal, and electric properties of polyurethaneimide elastomers

Linear polyurethaneimide elastomers (PUI) were obtained from polyether- or polyester-diols, diphenylmethane diisocyanate or bitolylene diisocyanate and pyromellitic acid dianhydride. It was found that these polymers have considerably better mechanical properties than typical linear polyurethanes (PU). The elastic modulus and stress at break increase with contents of the hard polyimide segments. The softening temperatures and thermal stability of the PUI at 500°C were higher than the ones of PU with similar hard segment contents. Electric properties of PUI were close to the ones of conventional PU. It was shown that cellular PUI had considerably lower dielectric constant. T_g's of the soft segments PUI were less than T_g's corresponding to PU. It is connected with greater phase separation of the hard imide segments from the soft polyether– or polyester–urethane matrix.     

The effects of soft segments on the physical properties and water vapor permeability of H12MDI-PU cast films

This research was based on the study of the effects of H₁₂MDI-1, 4BD PU soft segments on the physical properties and water vapor permeability of films cast from solvent evaporation or wet coagulation method. The soft segments studied included polyether, polyester, and polycaprolactone polydiols. The NCO/OH mol ratios of prepolymer were prepared by 2, 3, 4, 5, and 8, respectively. The chain lengths of the soft segments used were: PTMG of molecular weights 650, 1000, 2000, and 2900; PBA of 1000, 2000, and 3000. The results revealed that the polyether-based PU cast films had lower T_gs than the polyester-based PU films. In general, the polyether-based PU films shows the characters of higher water vapor permeability, lower breaking elongation, and higher breaking strength. Films with higher molecular weight soft segments in the polymer chains exhibited lower T_gs, lower breaking strength, higher breaking elongation, and higher water vapor permeability. As the hard segment contents were increased, the films exhibited higher T_gs. Films with higher hard-segment ratios had the highest breaking strength but the water vapor permeability, on the other hand, became lower. Films cast from the solvent evaporation method had higher breaking strength and higher breaking elongation but lower water vapor permeability than films cast from the wet coagulation method. © 1994 John Wiley & Sons, Inc.     

Characteristics of PPG-based thermoplastic polyurethane doped with lithium perchlorate

Segmented thermoplastic polyurethane (TPU) was synthesized from methylene bis(cyclohexyl isocyanate) (H₁₂MDI), ethylenediamine (EDA), and poly(propylene glycol) (PPG) with a molecular weight of 1000. The ratio of hard segment to soft segment (NCO/OH) is changed to test the chemical and physical properties. Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and impedance spectroscopy (IS) were utilized to monitor the phase change of these TPU samples with various lithium perchlorate (LiClO₄) concentrations. Significant changes occur in the FTIR spectrum of the TPU with LiClO₄ concentration above 0.5 mmol/g TPU, indicating that an interaction existed between the lithium cation and the hard segment or soft phase. The soft-segment T_g increased with increasing LiClO₄ concentration through the examination of DSC. IS results indicate an increase in bulk conductivity as the salt concentration is increased. Electrochemical stability of the TPU sample was studied by cyclic votammetry (CV). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 389–399, 2001     

Influence of ionic charge placement on performance of poly(ethylene glycol)-based sulfonated polyurethanes

Poly(ethylene glycol) (PEG)-based sulfonated polyurethanes bearing either sulfonated soft segments (SSSPU) or sulfonated hard segments (SHSPU) were synthesized using sulfonated monomers. Differential scanning calorimetry (DSC) revealed that sulfonate anions either in the soft segments or hard segments both increased the glass transition temperatures (T_g’s) of the soft segments and suppressed their crystallization. Moreover, dynamic mechanical analysis (DMA) and tensile analysis demonstrated that SSSPU possessed a higher modulus and tensile strength relative to SHSPU. Fourier transform infrared (FTIR) spectroscopy revealed that hydrogen bonding interactions in SHSPU were suppressed compared to SSSPU and noncharged PU. This observation suggested a high level of phase-mixing for SHSPU. In addition, atomic force microscopy (AFM) phase images revealed that both SSSPU and noncharged PU formed well-defined microphase-separated morphologies, where the hard segments phase-separated into needle-like hard domains at the nanoscale. However, SHSPU showed a phase-mixed morphology, which was attributed to increased compatibility of polar PEG soft segments with sulfonated ionic hard segments and disruption of hydrogen bonds in the hard segment. The phase-mixed morphology of SHSPU was further demonstrated using small angle X-ray scattering (SAXS), which showed a featureless X-ray scattering profile. In contrast, SAXS profiles of SSSPU and noncharged PU demonstrated microphase-separated morphologies. Moreover, SSSPU also displayed a broad ionomer peak ranging in q = 1–2 nm^?1, which resulted from the sodium sulfonate ion pair association in the polar PEG soft phase. Morphologies of sulfonated polyurethanes correlated well with thermal and mechanical properties.     

Effect of reaction kinetics of polymer electrolyte on the ion‐conductive behavior for poly(oligo oxyethylene methacrylate)–LiTFSI mixtures

The effect of the reaction kinetics on the ionic conductivity for a comblike‐type polyether (MEO) electrolyte with lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) was characterized by DSC, complex impedance measurements, and ¹H pulse NMR spectroscopy. The ionic conductivity of these electrolytes was affected by the reaction condition of the methacrylate monomer and revealed by the glass transition temperature (T_g), spin–spin relaxation time (T₂), steric effects of the terminal groups, and the number of charge carriers indicated by the VTF kinetic parameter. In this system, the electrolytes prepared by the reaction heating rate of 10°C/min of MEO–H and 15°C/min of MEO–CH₃ showed maximum ionic conductivity, σ_i, two to three times higher in magnitude than that of the σ_i of the others at room temperature. As experimental results, the reaction kinetic rate affected the degree of conversion, the ionic conductivity, and the relaxation behaviors of polyether electrolytes. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2149–2156, 2003     

Differential scanning calorimetry analysis of silicon‐containing and phosphorus‐containing segmented polyurethane. I—Thermal behaviors and morphology

This article investigated thermal transition and morphology utilizing differential scanning calorimetry (DSC), which was performed on silicon‐containing and phosphorus‐containing segmented polyurethane (Si‐PU and P‐PU). The hard segments of those Si‐PU and P‐PU polymers investigated consisted of 4,4′‐diphenylmethane diisocyanate (MDI) and diphenylsilanediol (DSiD), MDI, and methylphosponic (MPA), respectively. The soft segment of those polymers comprised polytetramethylene ether glycol, with an average molecular weight of 1000 or 2000 (PTMG 1000 and PTMG 2000, respectively). Several thermal transitions appeared for on the Si‐PU and P‐PU polymers, reflecting both the soft‐segment and hard‐segment phases. The Si‐PU and P‐PU polymers with a lower hard‐segment content exhibited a high degree of phase separating as indicated by the constancy of both the soft‐segment glass transition temperature (T_gs) and the breadth of transition zone (ΔB). The polymers in which PTMG 2000 was used as the soft segment generally exhibited a crystalline melting endotherm about 10°C, while crystallization usually disappeared upon melt quenching. The hard segments of the Si‐PU and P‐PU polymers displayed multiple endotherms. The first endotherm was related to a short‐range ordering of the hard segment domain (Region I), and the second endotherm was ascribed to a long‐range ordering of the domain (Region II). The wide‐angle X‐ray demonstrated that the structure in Region I and Region II was almost completely amorphous. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3489–3501, 2001