Characterization of the stable and metastable poly(ethylene oxide)–urea complexes in electrospun fibers

Solution electrospinning was used for the first time to prepare nanofibers of the stable (α) and metastable (β) complexes between poly(ethylene oxide) (PEO) and urea. Both types of fibers were highly crystalline and presented a large level of molecular orientation. Detailed characterization of the ill‐studied β complex was performed using wide angle X‐ray diffraction (WAXD), infrared spectroscopy, and differential scanning calorimetry (DSC). Results reveal that it possesses a 3:2 PEO:urea stoichiometry and suggest that it belongs to the orthorhombic system with a = 1.907 nm, b = 0.862 nm, and c = 0.773 nm. The PEO chains are oriented along the fiber axis and present a conformation significantly affected by strong hydrogen bonding with urea when compared with the pure polymer and the stable complex. A layered structure model is suggested for the metastable complex, in which the urea molecules would be arranged into a ribbon‐like structure intercalated between two PEO layers. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1903–1913, 2008     

Controlled preparation of nanometer‐sized supramolecular cylinders of poly(ethylene oxide) embedded in methacrylate matrices

Semi‐interpenetrating networks of poly(ethylene oxide) (PEO) and highly crosslinked poly(methacrylate)s were generated from solutions of PEO in mixtures of methacrylate monomers and dimethacrylate crosslinkers. The deep quenching of the solutions into the unstable region resulted in microphase separation via a spinodal decomposition mechanism. Through the crystallization of the PEO inside the polymer‐rich phase, the domain size was reduced below the Cahn–Hilliard limit. The microstructure was permanently preserved by subsequent UV‐initiated polymerization of the monomers well below the PEO melting temperature. The semi‐interpenetrating networks were characterized by differential scanning calorimetry, small‐angle X‐ray scattering, NMR spin‐diffusion measurements, and electron microscopy. Morphologies based on networks of cylindrical PEO aggregates with diameters of 10 ± 2 nm were observed, nearly independent of the molecular weight of the used PEO. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2041–2056, 2000     

Effect of aging on fractional crystallization of poly(ethylene oxide) component in poly(ethylene oxide)/poly(3‐hydroxybutyrate) blends

The effect of aging on the fractional crystallization of the poly(ethylene oxide) (PEO) component in the PEO/poly(3‐hydroxybutyrate) (PHB) blend has been investigated. The partial miscibility of the PEO/PHB blends with high PEO molecular weight (M_v = 2.0 × 10⁵ g/mol) was confirmed by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis. The fractional crystallization behavior of the PEO component in the PEO/PHB blends with low PEO content (not more than 30 wt% of PEO), before and after aging under vacuum at 25 °C for 6 months, were compared by DSC, fourier transform infrared microscopic spectroscopy, small angle X‐ray diffraction, and scanning electron microscopy. It was confirmed that nearly all the PEO components remain trapped within interlamellar regions of PHB for the PEO/PHB blends before aging. Under this condition, the crystallization of PEO is basically induced by much less active heterogeneities or homogeneous nucleation at high supercoolings. While, after the same PEO/PHB samples were stored at 25 °C in vacuum for 6 months, a part of the PEO component was expelled from the interlamellar region of PHB. Under this condition, the expelled PEO forms many separate domains with bigger size and crystallizes at low supercoolings by active heterogeneous nucleation, whereas the crystallization of PEO in the interlamellar region is still mainly induced by less active heterogeneities or homogeneous nucleation at extreme supercoolings. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2665–2676, 2005     

Effect of incorporated CdS nanoparticles on the crystallinity and morphology of poly(styrene‐b‐ethylene oxide) diblock copolymers

Surface‐modified CdS nanoparticles selectively dispersed in hexagonally packed poly(ethylene oxide) (PEO) cylinders of poly(styrene‐b‐ethylene oxide) (PSEO) block copolymers were prepared. The photoluminescence and ultraviolet–visible characteristics of the presynthesized CdS nanoparticles in N,N‐dimethylformamide and in PEO domains of the PSEO block copolymers were determined. Because of strong interactions between the CdS nanoparticles and PEO chains, as shown by Fourier transform infrared spectroscopy, the incorporation of the CdS nanoparticles prevented the PEO cylinders from properly crystallizing; this was confirmed by differential scanning calorimetry and wide‐angle X‐ray diffraction measurements. The intercylinder distance between the swollen and reduced‐crystallinity CdS/PEO cylinders in turn increased, as confirmed by small‐angle X‐ray scattering and transmission electron microscopy. At a high CdS concentration (43 wt % or 8.3 vol % with respect to PEO), however, the hexagonally packed cylindrical nanostructure of the PSEO diblock copolymers was destroyed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1220–1229, 2005     

Synthesis and characterization of poly(ethylene oxide)/polylactide/poly(ethylene oxide) triblock copolymer

Poly(ethylene oxide/polylactide/poly(ethylene oxide) (PEO/PL/PEO) triblock copolymers, in which each block is connected by an ester bond, were synthesized by a coupling reaction between PL and PEO. Hydroxyl‐terminated PLs with various molecular weights were synthesized and used as hard segments. Hydroxyl‐terminated PEOs were converted to the corresponding acid halides via their acid group and used as a soft segment. Triblock copolymers were identified by Fourier transform infrared spectroscopy, ¹H NMR, and gel permeation chromatography. Differential scanning calorimetry (DSC) and X‐ray diffractometry of PEO/PL/PEO triblock copolymers suggested that PL and PEO blocks were phase‐separated and that the crystallization behavior of the PL block was markedly affected by the presence of the PEO block. PEO/PL/PEO triblock copolymers with PEO 0.75k had two exothermic peaks (by DSC), and both peaks were related to the crystallization of PL. According to thermogravimetric analysis, PEO/PL/PEO triblock copolymer showed a higher thermal stability than PL or PEO. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2545–2555, 2002     

Nanostructured thermoset epoxy resin templated by an amphiphilic poly(ethylene oxide)‐block‐poly(dimethylsiloxane) diblock copolymer

An amphiphilic poly(ethylene oxide)‐block‐poly(dimethylsiloxane) (PEO–PDMS) diblock copolymer was used to template a bisphenol A type epoxy resin (ER); nanostructured thermoset blends of ER and PEO–PDMS were prepared with 4,4′‐methylenedianiline (MDA) as the curing agent. The phase behavior, crystallization, hydrogen‐bonding interactions, and nanoscale structures were investigated with differential scanning calorimetry, Fourier transform infrared spectroscopy, transmission electron microscopy, and small‐angle X‐ray scattering. The uncured ER was miscible with the poly(ethylene oxide) block of PEO–PDMS, and the uncured blends were not macroscopically phase‐separated. Macroscopic phase separation took place in the MDA‐cured ER/PEO–PDMS blends containing 60–80 wt % PEO–PDMS diblock copolymer. However, the composition‐dependent nanostructures were formed in the cured blends with 10–50 wt % PEO–PDMS, which did not show macroscopic phase separation. The poly(dimethylsiloxane) microdomains with sizes of 10–20 nm were dispersed in a continuous ER‐rich phase; the average distance between the neighboring microdomains was in the range of 20–50 nm. The miscibility between the cured ER and the poly(ethylene oxide) block of PEO–PDMS was ascribed to the favorable hydrogen‐bonding interaction. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3042–3052, 2006     

Conformational changes of poly(ethylene oxide) in poly(ethylene oxide)/poly(methyl methacrylate) blends by supercritical carbon dioxide

The effects of supercritical carbon dioxide (SC CO₂) fluids on the morphology and/or conformation of poly(ethylene oxide) (PEO) in PEO/poly(methyl methacrylate) (PMMA) blends were investigated by means of differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction (WAXD), and Fourier transform infrared (FTIR). According to DSC data for a given blend, the melting enthalpy and, therefore, degree of crystallinity of PEO were increased, whereas the melting temperature of PEO was decreased, with SC CO₂ treatment. The enhancement of PEO crystallization with SC CO₂ treatment, as demonstrated by DSC data, was supported by WAXD data. According to FTIR quantitative analyses, before SC CO₂ treatments, the conformation of PEO was transformed from helix to trans planar zigzag via blending with PMMA. This helix‐to‐trans transformation of PEO increased proportionally with increasing PMMA content, with around 0.7% helix‐to‐trans transformation per 1% PMMA incorporation into the blend. For a given blend upon SC CO₂ treatments, the conformation of PEO was transformed from trans to helix. This trans‐to‐helix transformation of PEO decreased with increasing PMMA contents in the blends because of the presence of interactions between the two polymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2479–2489, 2004     

Poly(ethylene imine)‐graft‐poly(ethylene oxide) brush‐like copolymers: Preparation,thermal properties,and selective supramolecular inclusion complexation with α‐cyclodextrin

Poly(ethylene imine)‐graft‐poly(ethylene oxide) (PEI‐g‐PEO) copolymers were synthesized via Michael addition reaction between acryl‐terminated poly(ethylene oxide) methyl ether (PEO) and poly(ethylene imine) (PEI). The brush‐like copolymers were characterized by means of Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. It is found that the crystallinity of the PEO side chains in the copolymers remained unaffected by the PEI backbone whereas the crystal structure of PEO side chains was altered to some extent by the PEI backbone. The crystallization behavior of PEO blocks in the copolymers suggests that the bush‐shaped copolymers are microphase‐separated in the molten state. The PEO side chains of the copolymers were selectively complexed with α‐cyclodextrin (α‐CD) to afford hydrophobic side chains (i.e., PEO/α‐CD inclusion complexes). The X‐ray diffraction (XRD) shows that the inclusion complexes (ICs) of the PEO side chains displayed a channel‐type crystalline structure. It is identified that the stoichiometry of the inclusion complexation of the PEI‐g‐PEO with α‐CD is close to that of the control PEO with α‐CD. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2296–2306, 2008     

Synthesis and characterization of crystalline graft polymer poly(ethylene oxide)‐g‐poly(ɛ‐caprolactone)2 with modulated grafting sites

The graft polymer poly(ethylene oxide)‐g‐poly(?‐caprolactone)₂ (PEO‐g‐PCL₂) with modulated grafting sites was synthesized by the combination of ring‐opening polymerization (ROP) mechanism, efficient Williamson reaction, with thiol–ene addition reaction. First, the precursor of PEO‐Allyl‐PEO with two terminal hydroxyl groups and one middle allyl group was prepared by ROP of EO monomers. Then, the macroinitiator [PEO‐(OH)₂‐PEO]_s was synthesized by sequential Williamson reaction between terminal hydroxyl groups and thiol–ene addition reaction on pendant allyl groups. Finally, the graft polymer PEO‐g‐PCL₂ was obtained by ROP of ?‐CL monomers using [PEO‐(OH)₂‐PEO]_s as macroinitiator. The target graft polymer and all intermediates were well characterized by the measurements of gel permeation chromatography, ¹H NMR, and thermal gravimetric analysis. The crystallization behavior was investigated by the measurements of differential scanning calorimetry, wide‐angle X‐ray diffraction and polarized optical microscope. The results showed that when the PCL content of side chains reached 59.2%, the crystalline structure had been dominated by PCL part and the crystalline structure formed by PEO part can be almost neglected. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2239–2247     

Phase behavior and crystallization of a poly(ethylene oxide)/cellulose acetate butyrate blend

The phase behavior of a partially miscible blend of poly(ethylene oxide) (PEO) and cellulose acetate butyrate (CAB) and the crystalline microstructure of PEO in the blend were studied with differential scanning calorimetry (DSC), optical microscopy, and synchrotron small‐angle X‐ray scattering (SAXS) methods. PEO/CAB showed a lower critical solution temperature (LCST) of 168 °C at the critical composition of PEO of 60 wt %. All blend compositions showed a single glass‐transition temperature (T_g) when they were prepared at temperatures lower than the LCST. However, with increasing CAB content, T_g of the blend changed abruptly at 70 wt % CAB; that is, a cusp existed. Below 70 wt % CAB, the change in T_g with blend composition was predicted by the Brau–Kovacs equation, whereas this change was predicted by the Fox equation at higher CAB contents. A gradual but small depression of the melting point of PEO in the blend with an increasing amount of CAB suggested that the PEO/CAB blends exhibited a weak intermolecular interaction. From DSC and SAXS experiments, it was found that amorphous CAB was incorporated into the interlamellar region of PEO for blends with less than 20 wt % CAB, whereas it was segregated to exist in the interfibrillar region in PEO for other blends with larger amounts of CAB. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1673–1681, 2002     

熔融法制备聚氧化乙烯/蒙脱土杂化材料及其结晶行为

聚氧化乙烯;熔融插入;纳米杂化;熔融法制备聚氧化乙烯/蒙脱土杂化材料及其结晶行为     

Micro‐phase‐separation behavior of amphiphilic polyurethanes involving poly(ethylene oxide) and poly(tetramethylene oxide)

The temperature dependence of thermal, morphological, and rheological properties of amphiphilic polyurethanes was examined with differential scanning calorimetry (DSC), wide‐angle X‐ray scattering (WAXS), small‐angle X‐ray scattering (SAXS), rheological measurements, and Fourier transform infrared spectroscopy. Multiblock (MPU) and triblock (TPU) polyurethanes were synthesized with two crystallizable segments—poly(ethylene oxide) (PEO) as a hydrophilic block and poly(tetramethylene oxide) (PTMO) as a hydrophobic block. DSC and WAXS measurements demonstrated that the microphase of MPUs in the solid state is dominantly affected by the PEO crystalline phase. However, high‐order peaks were not observed in the SAXS measurements because the crystallization of the PEO segments in MPUs was retarded by poor sequence regularity. The microphase in the melt state was induced by the hydrogen bonding between the N? H group of hexamethylene diisocyanate linkers and the ether oxygen of PEO or PTMO blocks. As the temperature increased, the smaller micro‐phase‐separated domains were merged into the larger domains, and the liquidlike ordering was eventually disrupted because of the weakening hydrogen bonding. However, the fully homogeneous state of an MPU with a molar ratio of 5/5 PEO/PTMO (MPU55) was not confirmed even at much higher temperatures with both SAXS and rheological measurements. However, the SAXS patterns of TPU showed weak but broad second‐order peaks below the melting temperature of the PEO block. Compared with MPU55, the ordering of the TPU crystalline lamellar stacks was enhanced because of the high sequence regularity and the low hydrogen‐bonding density. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2365–2374, 2003     

Crystallization and melting of poly(glycerol adipate)‐based graft copolymers with single and double crystallizable side chains

The crystallization and melting behavior of a series of poly(glycerol adipate) (PGA) based graft copolymers with either poly(ε‐caprolactone) (PCL), poly(ethylene oxide) (PEO), or PCL‐b‐PEO diblock copolymer side chains (i.e., PGA‐g‐PCL, PGA‐g‐PEO, and PGA‐g‐(PCL‐b‐PEO)) was studied using polarized light optical microscopy (POM), differential scanning calorimetry (DSC), small‐angle X‐ray scattering (SAXS), and wide‐angle X‐ray diffraction (WAXD). These results were compared with the behavior of the corresponding linear analogs (PEO, PCL, and PCL‐b‐PEO). POM revealed that spherulitic morphology was retained after grafting. However, spherulite radius as well as radial growth rate was significantly smaller in the graft copolymers. Evaluation of isothermal crystallization kinetics by means of the Avrami theory revealed that the nucleation density was much higher in the graft copolymers. The DSC results indicated that the degree of crystallinity decreased strongly upon grafting while the melting temperatures of PGA‐g‐PCL and PGA‐g‐PEO were found to be close to the values of neat PCL and PEO, respectively. This was attributed to the absence of specific thermodynamic interactions, and, additionally, to lamella thicknesses being similar to those of the homopolymers. The latter point was confirmed by SAXS measurements. In case of PCL‐b‐PEO diblock copolymers and PGA‐g‐(PCL‐b‐PEO) graft copolymers, the crystallization behavior and thus the resulting lamellar morphology is more complex, and a suitable model was developed based on a combination of DSC, WAXD, and SAXS data. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 1581–1591     

Effect of poly(ethylene oxide) on the structure and properties of poly(vinyl alcohol)

To improve the drawability of poly(vinyl alcohol) (PVA) thermal products, poly(ethylene oxide) (PEO), a special resin with good flexibility, excellent lubricity, and compatibility with many resins, was applied, and the Fourier transform infrared spectroscopy, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and wide‐angle X‐ray diffraction (WXRD) were adopted to study the hydrogen bonds, water states, thermal properties, crystal structure, and nonisothermal crystallization of modified PVA. It was found that PEO formed strong hydrogen bonds with water and PVA, thus weakened the intra‐ and inter‐hydrogen bonds of PVA, changed the aggregation states of PVA chains, and decreased its melting point and crystallinity. Moreover, the interactions among PVA, water, and PEO retarded the water evaporation and made more water remain in the system to plasticize PVA. The existence of PEO also slowed down the melt crystallization process of PVA, however, increased the nucleation points of system, thus made more and smaller spherulites formed. The weakened crystallization capability of PVA and the lubrication of PEO made PVA chains to have more mobility under the outside force and obtain high mechanical properties. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1946–1954, 2010     

Synthesis,characterization, and properties of new sequenced poly(ether amide)s based on 2‐(4‐aminophenyl)‐5‐aminobenzimidazole and 2‐(3‐aminophenyl)‐5‐aminobenzimidazole

A set of new aromatic poly(ether amide)s containing benzimidazole groups and ethylene oxide sequences of different lengths were synthesized and characterized. The new polymers were prepared from two benzimidazole diamines, 2‐(4‐aminophenyl)‐5‐aminobenzimidazole and 2‐(3‐aminophenyl)‐5‐aminobenzimidazole, and various oligo(ethylene oxide)dibenzoyl chlorides. They exhibited good solubility in polar aprotic solvents and glass‐transition temperatures in the range of 125–300 °C (the longer the ethylene oxide spacer was, the lower the glass‐transition temperature was). The new polyamides were essentially amorphous, as observed by X‐ray diffraction measurements and confirmed by differential scanning calorimetry measurements, by means of which no melting endotherm was observed in any case. The decomposition temperatures, as revealed by thermogravimetric analysis in nitrogen, were about 400 °C for all of them, regardless of the length of the ethylene oxide content or the phenylene ring orientation (meta or para) of the diamine moiety. The number of ethylene oxide linkages per repeat unit also determined the water uptake. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1414–1423, 2006     

Clicked (AB)2C‐type miktoarm terpolymers: Synthesis,thermal and self‐assembly properties,and preparation of nanoporous materials

A well‐defined (PEO‐PS)₂‐PLA miktoarm terpolymer ( 1 ) was synthesized by stepwise click reactions of individually prepared poly(ethylene oxide) (PEO), polystyrene (PS, polymerized by atom transfer radical polymerization), and polylactide (PLA, polymerized by ring‐opening polymerization) blocks. As characterized by differential scanning calorimetry and small‐angle X‐ray scattering techniques, the terpolymer self‐assembled into a hexagonal columnar structure consisting of PLA/PEO cylindrical cores surrounded by PS chains. In contrast, the ion‐doped sample ( 1‐Li⁺ ) with lithium concentration per ethylene oxide = 0.2 exhibited a three‐phase lamellar structure, which was attributed to the microphase separation between PEO and PLA blocks and to the conformational stabilization of the longest PLA chain. The two‐phase columnar morphology before the ion doping was used to prepare a nanoporous material. PLA chains in the cylindrical core region were hydrolyzed by sodium hydroxide, producing nanopores with a pore diameter of about 14 nm. The resulted nanoporous material sank to the bottom in water, because of water‐compatible PEO chains on the walls. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Hydrophilic segmented block copolymers based on poly(ethylene oxide) and monodisperse amide segments

Segmented block copolymers based on poly(ethylene oxide) (PEO) flexible segments and monodisperse crystallizable bisester tetra‐amide segments were made via a polycondensation reaction. The molecular weight of the PEO segments varied from 600 to 4600 g/mol and a bisester tetra‐amide segment (T6T6T) based on dimethyl terephthalate (T) and hexamethylenediamine (6) was used. The resulting copolymers were melt‐processable and transparent. The crystallinity of the copolymers was investigated by differential scanning calorimetry (DSC) and Fourier Transform infrared (FTIR). The thermal properties were studied by DSC, temperature modulated synchrotron small angle X‐ray scattering (SAXS), and dynamic mechanical analysis (DMA). The elastic properties were evaluated by compression set (CS) test. The crystallinity of the T6T6T segments in the copolymers was high (>84%) and the crystallization fast due to the use of monodisperse tetra‐amide segments. DMA experiments showed that the materials had a low T_g, a broad and almost temperature independent rubbery plateau and a sharp flow temperature. With increasing PEO length both the PEO melting temperature and the PEO crystallinity increased. When the PEO segment length was longer than 2000 g/mol the PEO melting temperature was above room temperature and this resulted in a higher modulus and in higher compression set values at room temperature. The properties of PEO‐T6T6T copolymers were compared with similar poly(propylene oxide) and poly(tetramethylene oxide) copolymers. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4522–4535, 2007     

Relationship between morphology structure and composition of polycaprolactone/Poly(ethylene oxide)/Polylactide copolymeric microspheres

A novel tri‐component copolymer, polycaprolactone/poly(ethylene oxide)/polylactide (PCEL) was synthesized. The effect of the chemical composition on physical properties was investigated by using NMR, differential scanning calorimetry (DSC) and X‐ray diffraction. Both the soft segment poly(ethylene oxide) (PEO) and polycaprolactone (PCL) could enhance the mobility of polymer chains and decrease the crystallizability of the copolymers. The polymeric microspheres, which are of interest for drug delivery systems, were prepared using an emulsification‐solvent evaporation technique. By scanning electron microscopy (SEM) and atomic force microscopy (AFM), the surface morphology of the microspheres was studied. It was found that the presence of PEO segment could improve the hydrophilicity of the copolymers and the morphology of the polymeric microspheres could be altered by adjusting the chemical composition. The accumulation of PEO segments on the outer surface of the polymeric microspheres was proven by X‐ray photoelectron spectroscopy (XPS). It had also been proven that the PCL segment could facilitate the movement of PEO segment to the outer surface. Copyright © 2002 John Wiley & Sons, Ltd.     

Homopolymer and block copolymer brushes on gold by living anionic surface‐initiated polymerization in a polar solvent

Living anionic surface‐initiated polymerization on flat gold substrates has been conducted to create uniform homopolymer and diblock copolymer brushes. A 1,1‐diphenylethylene (DPE) self‐assembled monolayer was used as the immobilized precursor initiator. n‐BuLi was used to activate the DPE in tetrahydrofuran at –78 °C to initiate the polymerization of different monomers (styrene, isoprene, ethylene oxide, and methyl methacrylate). Poly(styrene) (PS) and poly(ethylene oxide) (PEO) in particular were first investigated as grafted homopolymers, followed by their copolymers, including poly(isoprene)‐b‐poly(methylmethacrylate) (PI‐b‐PMMA). A combined approach of spectroscopic (Fourier transform infrared spectroscopy, surface plasmon spectroscopy, ellipsometry, X‐ray photoelectron spectroscopy) and microscopic (atomic force microscopy) surface analysis was used to investigate the formation of the polymer brushes in polar solvent media. The chemical nature of the outermost layer of these brushes was studied by water contact angle measurements. The effect of the experimental conditions (solvent, temperature, initiator concentration) on the surface properties of the polymer brushes was also investigated. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 769–782, 2006     

Influence of DC electric field on both crystalline structure and conductivity of poly(ethylene oxide)10:LiClO4 electrolyte

The dynamic ionic conductivity and polarizing morphology of poly(ethylene oxide)₁₀:LiClO₄ (PEO₁₀:LiClO₄) electrolyte membranes under different direct current electric fields (EFs) were simultaneously investigated. PEO molecular chains were found to rearrange during the migration of charge carriers, and the rearrangement of PEO molecular chains dramatically affected the conductivity of the electrolyte membrane. No noticeable differences of conductivity and polarizing morphology between the heating and cooling process were observed when the EF was absent. However, the conductivity of the membrane was remarkably enhanced after applying an EF and after carrying out a heating–cooling loop. Differential scanning calorimetry and wide‐angle X‐ray diffraction of the sample with different treatments of both EFs and heating–cooling loops showed that the conductivity enhancement or reduction after loading special EFs and heating–cooling loops were attributed to the change of both the crystallite size of certain diffraction planes and the thickness of PEO lamellae. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012