The ionic conductive property of sulfonated polyethylene oxide polyurethane ionomers

A series of lithium and sodium salts of sulfonated polyethylene oxide (PEO) polyurethane ionomers in different levels of ionization were prepared. It has been found that this material is a new type of ionic conductive polymer, characterized by a single-ion transport mechanism and good mechanical properties. The ionization level significantly influences the ionic conductivity of the samples. When the mole ratio of the metal ion and ether oxygen atom is about 0.05, the ionomers exhibit maximum cationic conductivity. An optimal cationic conductivity of 1.0 × 10^?5 S/cm is obtained at about 70°C without any addition of organic plasticizer. The conductivity increases apparently when propylene carbonate and low MW PEO are added to the polyurethane ionomer. © 1995 John Wiley & Sons, Inc.     

Synthesis and optical properties of new polyurethane cationomers with anchored stilbene chromophores

An ionic diol bearing a one‐sided urethane‐stilbene group located on the ammonium quaternary structure was prepared and proposed as an intermediate for polyurethane ionomer synthesis. Polyurethane cationomers with stilbene ionic groups based on poly(tetramethylene oxide) diols, 4,4′‐diphenylmethane diisocyanate and the aforementioned ionic diol, were synthesized and characterized. Some aspects of the trans–cis photoisomerism and fluorescent emission of the stilbene chromophore in polyurethane cationomers were studied comparatively with the urethane‐stilbene diol. The stilbene polycations absorbed at λ_A = 316 nm and emitted violet‐blue light with an emission maxima at λ_F = 444 nm (dimethylformamide solution) and λ_F = 465 nm (film). These polymers are known for their elastomeric properties and are assumed to be of great interest for some future applications. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1918–1928, 2002     

UV curable waterborne polyurethane acrylate dispersions based on hyperbranched aliphatic polyester: effect of molecular structure on physical and thermal properties

A novel waterborne hyperbranched polyurethane acrylate for aqueous dispersions (WHPUDs) based on hydroxy‐functionalized hyperbranched aliphatic polyester Boltorn? H20 was investigated. The effects of structural composition and crosslinking density have been studied in terms of swellability by water, thermal degradation, viscosity changes as well as transmission electron microscopy (TEM) morphology. The swell ratio showed an increasing trend with the higher concentration of ionic group, which is due to the increased total surface area of particles. The results of thermogravimetric analysis (TGA) for cured WHPUD films indicated good thermal stability with no appreciable weight loss until 200°C. The activation energies were evaluated and were found in the range 154–186 kJ mol^?1. It was observed that an increase in hard segment content provoked the increases in thermal degradation temperature and activation energy of waterborne dispersions. The transmission electron photographs revealed that the average particle sizes of aqueous dispersions were in the range 30–125 nm. Owing to the enlargement of the stabilization site, the particle size decreased as the content of carboxyl group and degree of neutralization increased. The viscosity of WHPUDs increased rapidly with increasing the degree of neutralization. Moreover, water showed a favorable viscosity reduction effect. Copyright © 2004 John Wiley & Sons, Ltd.     

Preparation and ionic conductivities of the plasticized polymer electrolytes based on poly(methyl methacrylate-co-alkali metal methacrylate)

Ionic conductivities of the polymer electrolytes prepared from the ionomer (poly(methyl methacrylate-co-alkali metal methacrylate)), lithium perchlorate, and ethylene carbonate as a plasticizer, were studied as a function of the ion content and the alkali-metal cation of the ionomer. It was possible to obtain tough films with room-temperature ionic conductivities of ∼ 10^-3 S/cm. The maximum ion conductivities of the polymer electrolytes were obtained at the ion content of 5 mol % for both Li and Na ionomer. The effects of the ion content of the ionomer on the ionic conductivities of the polymer electrolytes were mainly interpreted in terms of the characteristics of the ion aggregate formed in the polymer electrolytes. The thermal dependence of the ionic conductivity was shown to be a non-VTF pattern in some of the polymer electrolytes investigated, which is expected to be due to the presence of the ion aggregate. © John Wiley & Sons, Inc.     

Synthesis, characterization and mechanical properties of polyester-based aliphatic polyurethane elastomers containing hyperbranched polyester segments

Aliphatic polyester-based polyurethane (PU) elastomers with hyperbranched polyester segments were synthesized from polyester diol, hydroxyl-terminated hyperbranched polyester (HB-20), isophorone diisocyanate (PDI) and 1,4-butanediol. The crosslinking density of the PU elastomer was calculated by using Flory-Rehner equation. The degree of hydrogen bonding, the microstructure and the morphologies of these PU materials were characterized by means of FT-IR, WAXD and DSC, respectively. The experimental results showed that the PU elastomers containing small amount of HB-20 exhibited the enhanced hydrogen bonding and mechanical properties. As compared with the comparable PU specimen, the tensile strength of the polyester-based aliphatic PU containing 6 wt% HB-20 increased by 71.2 times, up to 36.1 MPa, and the elongation at break was still as high as 333.1%, resulting from the dual effects of the hydrogen bonding and the crosslinking density in the PU system.     

Physical characteristics and properties of waterborne polyurethane materials reinforced with silk fibroin powder

Degummed silk filament was pulverized with a home‐made machine to obtain silk fibroin (SF) powder, and the structure, morphology, and particle size of the SF powder were investigated. The individual spherical particles and aggregates with different morphology of silk fibroin coexisted in water. A waterborne polyurethane (WPU) aqueous dispersion was blended with the SF powder to prepare novel blended materials with improved physical properties. The average particle size and zeta potential of the WPU/SF aqueous dispersions were characterized. The result showed that the WPU/SF dispersion with higher SF content exhibited a less negative zeta potential and a larger average particle size. Furthermore, the effect of SF content on the morphology, miscibility, and mechanical properties of the resulting blended films was studied by scanning electron microscopy, wide‐angle X‐ray diffraction, dynamic mechanical thermal analysis, and tensile testing. The films showed an improved Young's modulus and tensile strength from 0.3 to 33.8 MPa, and 0.6 to 5.2 MPa, respectively, with the increasing of SF up to a content of 26 wt %. The negative charges in the periphery and the small particle size made a good effort on dispersing SF powder into the WPU matrix as small aggregates, and the SF powder led to the efficient strengthening of WPU materials. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 940–950, 2010     

Optimization of anionic conductivity through the coexistence of ionomer cluster and backbone-backbone morphologies in anion exchange membranes

Random copolymers of poly(4-vinylpyridine) and polyisoprene were synthesized, and subsequently quaternized with 1-alkylbromides. The number of carbons on the pendant side-chain of the resultant comb-shaped polymer, n, ranged from 2–8. The comb-shaped polymers were crosslinked employing thiol-ene chemistry to give mechanically robust ion conducting membranes. Analysis by wide and medium-angle X-ray scattering show three morphology regimes that are dependent on the number of carbons on the pendant side-chains. When n = 2, ionomer cluster morphology was dominant, when n = 8 backbone-backbone morphology was dominant, and when n = 3–6, the membrane showed a coexistence of both ionomer cluster and backbone-backbone morphologies. Evaluation of the water uptake of the membranes showed a maximum water uptake per cation of 9.5 when n = 5 at 95% relative humidity (RH) and 60°C. Conductivity of the samples characterized by electrochemical impedance spectroscopy showed bromide conductivity as high as 110 mS/cm when n = 3 at 95% RH and 90°C.     

Exploring preferential association of laponite and cloisite with soft and hard segments in TPU‐clay nanocomposite prepared by solution mixing technique

Thermoplastic polyurethane (TPU) is a versatile polymer exhibiting many engineering applications. In this article, two varieties of clay (Cloisite and Laponite RD) have been used to prepare TPU‐based nanocomposites. They differ in, chemical composition, hydrophobicity, aggregation tendency, and dispersibility in a particular solvent. A detailed investigation of the thermal, morphological, and rheological behavior reflects the affinity of Cloisite towards the soft segment, whereas it is the hard segment for modified Laponite. The maximum improvement in onset degradation temperature has been observed to be 17.5 and 8.3 °C for Cloisite and Laponite, respectively. Five percent Cloisite‐filled sample shows optimum storage modulus in the glassy region where as it is the 10% filled sample at the rubbery region. However, the trend remains indifferent both in rubbery and glassy regions for Laponite, and properties have been found optimum for 3% filled sample. To explore the behavior in the terminal and flow regions, dynamic rheological experiments were performed in low shear rate. Variation in dynamic rheological properties can be explained well on the basis of the combination of partly exfoliated, intercalated, and aggregated structures of the nano clay inside the TPU matrix, depending on their nature and preferential association with different segments. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2341–2354, 2008     

Electrical conductivity in solid solutions and in two-phase regions of the silver halide-bivalent metal (cadmium,cobalt, zinc) halide systems

Electrical conductivity of solid systems AgX-MX₂ (where M=Cd, Co, Zn and X=Cl, Br) were measured in a large range of temperature and compositions. Activation energies and conductivity values vs. composition are presented and discussed in relation to phase equilibria in the respective systems. Maximum of the conductivity value and stabilization of the activation energy have been found for silver halides doped heavily with divalent cation e.g. in the systems forming solid solutions on the silver halide side. Disorder in AgBr on the approach to melting, expected to be higher than in AgCl, has been shown by means of original DSC curves presented for both halides.     

Synthesis and morphology of rigid polyurethane foams with POSS as pendant groups or chemical crosslinks

This work reports on the preparation of polyurethane foams (PUFs) chemically modified by functionalized 1,2‐propanediolisobutyl polyhedral oligosilsesquioxane (PHI‐POSS) as pendant groups and octa(3‐hydroxy‐3‐methylbutyldimethylsiloxy) POSS (OCTA‐POSS) as chemical crosslinks. The resulting foams, which contain 0 to 15 wt% POSS (versus polyol), were characterized in terms of their structure, morphology, density, thermal conductivity, compressive strength, and water absorption. Fourier transform infrared‐attenuated total reflectance revealed good reaction rate between POSS and PUF. PHI‐POSS suppresses the formation of the hydrogen bonds in the soft phase. The composite foams with OCTA‐POSS showed a reduced number of cells and increased average area of foam cells in comparison with the PUF, while the addition of PHI‐POSS causes an increase in the number of cells of the foam as compared with the reference, and thus a reduction in the average area of cells. Scanning electron microscopy–energy‐dispersive X‐ray spectroscopy analysis revealed that POSS moieties form lamellae‐shaped crystals of different sizes, distributed homogeneously in the bulk (PHI‐POSS) or close to the self surfaces (OCTA‐POSS). The compressive strength of PUF/POSS hybrids in the direction parallel and perpendicular to the direction of foam rise is greater than the strength of the reference foam. PHI‐POSS improves monotonically the compressive strength in the studied loading range. About 5 wt% OCTA‐POSS also provides reinforcement, but further loading reverses the phenomenon. PUF/POSS hybrids absorb less water than the pristine foam because of an increase of foam density. Copyright © 2015 John Wiley & Sons, Ltd.     

高陶瓷含量复合固态电解质

全固态锂二次电池兼具高能量密度和高安全性特点.高陶瓷含量的陶瓷-聚合物复合固态电解质综合了聚合物电解质的柔韧性和陶瓷电解质的高机械强度与高锂离子迁移数等优点,有望优先其他形式固态电解质应用于全固态锂二次电池.本文在简要介绍固态复合电解质后,重点从复合电解质膜的性能特点与制备方法、陶瓷-聚合物界面相互作用以及由此导致的新...     

Nanocomposites of polyurethane with various organoclays: Thermomechanical properties,morphology, and gas permeability*

The properties of polyurethane (PU) nanocomposites with three different organoclays were compared in terms of their thermal stabilities, mechanical properties, morphologies, and gas permeabilities. Hexadecylamine–montmorillonite, dodecyltrimethyl ammonium–montmorillonite, and Cloisite 25A were used as organoclays for making PU hybrid films. The properties were examined as a function of the organoclay content in a matrix polymer. Transmission electron microscopy photographs showed that most clay layers were dispersed homogeneously into the matrix polymer on the nanoscale, although some particles of clay were agglomerated. Moreover, the addition of only a small amount of organoclay was enough to improve the thermal stabilities and mechanical properties of PU hybrid films, whereas gas permeability was reduced. Even polymers with low organoclay contents (3–4 wt %) showed much higher strength and modulus values than pure PU. Gas permeability was reduced linearly with an increasing amount of organoclay in the PU matrix. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 670–677, 2002; DOI 10.1002/polb.10124     

Photopolymerization of waterborne polyurethane acrylate dispersions based on hyperbranched aliphatic polyester and properties of the cured films

A series of novel waterborne hyperbranched polyurethane acrylates for aqueous dispersions (WHPUD) based on hydroxy-functionalized hyperbranched aliphatic polyester Boltorn H20 were investigated and used as UV curable oligomers. The aqueous dispersions were electrostatically stabilized with carboxyl groups incorporated into their structures, which were neutralized by triethylamine. The photopolymerization kinetics of these WHPUDs was studied with respect to polymerization rates and unsaturation conversions in the presence of a photoinitiator using differential scanning calorimetry. The polymerization rates of the resins under UV irradiation and the gel contents in the cured films showed an increasing trend with higher concentration of acrylate functionality, which is in favor of the theory of radical chain polymerization. The mechanical and thermal behaviors of UV cured films of aqueous dispersions were evaluated by tensile testing and dynamic mechanical thermal analysis (DMTA). The results of DMTA investigations indicated that the glass transition temperature shifted to higher temperature as the content of the hard segment consisting of IPDI-HEA increased. Moreover, the storage modulus and pendulum hardness also increased with increasing the hard segment content. As the degree of neutralization increased, the T_g and tensile strength decreased, whereas, the elongation at break increased.     

Synthesis and properties of sulfonated multiblock copoly(ether sulfone)s by a chain extender

A new series of sulfonated multiblock copoly(ether sulfone)s applicable to proton exchange membrane fuel cells was synthesized. The multiblock copolymers were synthesized by the nucleophilic aromatic substitution of hydroxyl‐terminated oligomers in the presence of highly reactive decafluorobiphenyl (DFB) as a chain extender. Because of the high reactivity of DFB, the ether–ether interchange reaction, which could lead to a randomized polymer architecture, was prevented, and multiblock copolymers with high molecular weights were easily produced. The multiblock copolymers gave tough, flexible, and transparent membranes by solution casting. The ion exchange capacity values could be easily controlled by changing the sulfonated block ratios in the copolymers. The resulting membranes demonstrated good oxidative and dimensional stability and significantly higher proton conductivity than sulfonated random poly(ether sulfone) copolymers. The morphologies of the membranes were investigated by tapping mode atomic force microscopy, which showed that the multiblock membranes had a clear hydrophilic/hydrophobic separated structure. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3947–3957, 2008     

Synthesis and properties of organic-silica nanocomposites with perhydropolysilazane

The synthesis and properties of the organic polymer-silica nanocomposites by blending perhydropolysilazane with organic polymer having hydroxyl groups have been described. Poly(methyl methacrylate) (PMMA)-silica nanocomposites with a PMMA/silica lamellar structure and spherical silica domains in a PMMA matrix were obtained with random copolymers and block copolymers. The effect of the architecture of the random and block copolymers on the morphology of composites has been summarized. The thermal stability, electrical properties, such as field break down, leakage current, etc., and surface hardness of the composites have been discussed. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5174–5181, 2006     

Synthesis and characterization of novel fluorinated thermoplastic polyurethane with high transmittance and superior physical properties

Three novel series of transparent fluorinated thermoplastic polyurethane (FTPU) elastomers based on 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI), polytetramethylene glycol (PTMG), polycaprolactone (PCL) and 4,4′-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene] bisphenol (BPAF) were synthesized by two-step solution polymerization. The FTPU were characterized by Fourier transform infrared spectrometry (FTIR), UV-Visible spectrometry (UV-Vis), wide angle X-ray diffraction (WAXD), atomic force microscopy (AFM), thermogravimetric analysis (TGA), and mechanical tests. The FTIR results indicate that the micro-phase separation and hydrogen bonding strength increase with increasing fluorine content, which are proved by the results of AFM and WAXD. The UV-Vis tests show high transmittance of FTPU films which is affected by crystallization easily. The TGA and mechanical tests indicate that thermal stability and mechanical properties of FTPU are improved significantly with the introduction of BPAF.     

Study of phase separation in polyurethane using paramagnetic labels. Effect of soft segment molecular weight,structure, and thermal history

The morphology of segmented polyurethane (PU) elastomers was studied by means of ESR at various temperatures ranging from 100K-450K. The PU's were based on 4,4'-diphenylmethane diisocyanate (MDI), poly (oxytetramethylene) glycols (PTMO) and hydroxyl-terminated random compolymers of tetrahydrofuran and 3-methyl-tetrahydrofuran (THF/Me-THF). Purified 1,4-butanediol (BD) was used as a chain extender. The nitroxide probe, 4-hydroxy-2-2',6-6'-tetramethylpiperidine-1-oxyl (TEMPOL), was used to label the polyurethanes by reaction with an NCO group of MDI. Analysis of the electron spin resonance (ESR) spectra suggested that the label situates at heterogeneous sites, which means that a two-phase domain is present. The morphologies at 300K and 400K were compared. It was found from ESR spectra that polyurethanes made from soft segments having higher MW exhibited greater phase separation at 300K than their corresponding elastomers made from lower MW soft segments. However, at 400K the more isotropic ESR spectra for the PUs containing higher MW soft segments suggested that the PUs were more mobile than their analogs having lower MW soft segments. The introduction of 3-methyl side groups decreased the phase mixing at 400K due to steric hindrance.     

Properties of fire agent integrated with molecular sieve and tetrafluoroborate ionic liquid in thermoplastic polyurethane elastomer

Thermoplastic polyurethane (TPU) elastomer has a widely application because of its perfect physical and chemical properties. However, it was limited by its low reliability in fire safety. In this paper, a new fire agent integrated with molecular sieve and tetrafluoroborate ionic liquid ([EOOEMIm][BF₄]) was used to improve fire safety of TPU. The fire safety of TPU composites was investigated by cone calorimeter test, smoke density test, and thermogravimetric/infrared spectroscopy, respectively. The results showed that modified molecular sieve (MMS) can improve fire safety of TPU effectively. The luminous flux increased to 10.10%, total smoke release decreased by 58%, and heat release rate declined of 65% than pure TPU when the addition of MMS was 0.5 wt%. In addition, MMS can improve thermal stability of TPU even in nitrogen according to thermogravimetric/infrared spectroscopy test. These proved that MMS has a satisfactory application prospect in fire safe polymer materials.     

Use of blowing catalysts for integral skin polyurethane applications in a controlled molecular architectural environment: Synthesis and impact on ultimate physical properties

Polyurethane elastomers of a controlled molecular architecture were synthesized using a two‐step polymerization technique. The building blocks of the elastomeric materials included urea–urethane prepolymers end‐capped with diisocyanate groups and had an exact number of urea groups at both ends. Two‐dimensional bifurcated hydrogen‐bonding networks incorporating the urea groups were, with differential scanning calorimetric and dynamic mechanical thermal analyzer techniques, responsible for the increase in the glass‐transition temperature (T_g) of the hard block and sharp interface morphology between the pure “hard” domains and pure “soft” domains. The higher extent of the phase separation between the two phases contributed to higher elastic moduli for the hard blocks and higher tensile strength for the elastomeric samples. Higher elongation values were attributed to the liberation of the elastomeric chain ends that otherwise would have been constrained in the interface region. The higher T_g values of the hard blocks corresponded to an increase in the hardness values and a decrease in the tear‐strength values. The increase in the amount of urea groups within the hard segments, as a result of the increased amount of water and blowing catalyst, resulted in elastomeric foams with higher open‐cell content. This resulted in lower resilience values as measured using the pendulum rebound test and was attributed to the ability of the open cells to absorb and dissipate energy. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2526–2536, 2002     

Synthesis and characterization of mixing soft-segmented waterborne polyurethane polymer electrolyte with room temperature ionic liquid

Composite polymer electrolytes based on mixing soft-segment waterborne polyurethane(WPU)and 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide(BMImTFSI)have been prepared and characterized.The addition of BMImTFSI results in an increase of the ionic conductivity.At high BMImTFSI concentration(BMImTFSI/WPU=3 in weight ratio),the ionic conductivity reaches 4.27×10~(-3)S/cm at 30℃.These composite polymer electrolytes exhibit good thermal and electrochemical stability,which are high enough to be...