bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on calcium‐containing poly(urethane ether)s
Authors: Jayakumar R. , Lee Y.‐S. , Nanjundan S. 
Published: August 2003

AbstractThe calcium salt of mono(hydroxyethoxyethyl)phthalate [Ca(HEEP)2] was synthesized by the reaction of diethylene glycol, phthalic anhydride, and calcium acetate. Calcium‐containing poly(urethane ether)s (PUEs) were synthesized by the reaction of hexamethylene diisocyanate (HMDI) or tolylene 2,4‐diisocyanate (TDI) with a mixture of Ca(HEEP)2 and poly(ethylene glycol) (PEG300 or PEG400) with di‐n‐butyltin dilaurate as a catalyst. A series of calcium‐containing PUEs of different compositions were synthesized with Ca(HEEP)2/PEG300 (or PEG400)/diisocyanate (HMDI or TDI) molar ratios of 2:2:4, 3:1:4, and 1:3:4 so that the coating properties of the PUEs could be studied. Blank PUEs without calcium‐containing ionic diols were also prepared by the reaction of PEG300 or PEG400 with HMDI or TDI. The PUEs were well characterized by Fourier transform infrared, 1H and 13C NMR, solid‐state cross‐polarity/magic‐angle‐spinning 13C NMR, viscosity, solubility, and X‐ray diffraction studies. The thermal properties of the polymers were also studied with thermogravimetric analysis and differential scanning calorimetry. The PUEs were applied as top coats on acrylic‐coated leather, and their physicomechanical properties were also studied. The coating properties of PUEs, such as the tensile strength, elongation at break, tear strength, water vapor permeability, flexing endurance, cold crack resistance, abrasion resistance, color fastness, and adhesive strength, were better than the standard values. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2865–2878, 2003
Synthesis and enzymatic degradation of 2‐methylene‐1,3‐dioxepane and methyl acrylate copolymers
Authors: Sun L. F. , Zhuo R. X. , Liu Z. L. 
Published: August 2003

AbstractCopolymers of 2‐methylene‐1,3‐dioxepane (MDO) and methyl acrylate (MA) containing ester units both in the backbone and as pendant groups were synthesized by free‐radical copolymerization. The influence of reaction conditions such as the polymerization time, temperature, initiator concentration, and comonomer feed ratio on the yield, molecular weight, and copolymer composition was investigated. The structure of the copolymers was confirmed by 1H NMR, 13C NMR, and IR spectroscopy. Differential scanning calorimetry indicated that the copolymers had a random structure. An NMR study showed that hydrogen transfer occurred during the copolymerization. The reactivity ratios of the comonomers were rMDO = 0.0235 and rMA = 26.535. The enzymatic degradation of the copolymers obtained was carried out in the presence of proteinase K or a crude enzyme extracted from earthworms. The experimental results showed that the higher ester molar percentage in the backbone caused a faster degradation rate. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2898–2904, 2003
Synthesis of amphiphilic poly(para‐phenylene)s by Suzuki polycondensation
Authors: Zhang Changmei , Schlaad Helmut , Schlüter A. Dieter 
Published: August 2003

Abstract1,4‐Dibromobenzenes carrying nonpolar hexoxy and polar oligo(ethylene glycol) side chains were subjected to Suzuki polycondensation with a benzene‐1,4‐bisboronic acid ester to produce high‐molar‐mass poly(para‐phenylene)s. The molar masses were determined with size exclusion chromatography with conventional polystyrene and universal calibration. These novel amphiphilically equipped rigid‐rod polymers have the potential to segregate lengthwise into polar and nonpolar domains, a property that has only rarely been described, and promise to exhibit novel interesting supramolecular properties. The oligo(ethylene gylcol) side chains terminate with a silyl‐protected alcohol group, and its deprotection on the polymer was proven to proceed quantitatively. This not only led to a further polarity increase but allows us to attach even more polar (e.g., charged) units in future projects. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2879–2889, 2003
Synthesis of side‐chain liquid‐crystalline homopolymers and triblock copolymers with p‐methoxyazobenzene moieties and poly(ethylene glycol) as coil segments by atom transfer radical polymerization and their thermotropic phase behavior
Authors: He Xiaohua , Zhang Hailiang , Yan Deyue , Wang Xiayu 
Published: August 2003

AbstractA series of side‐chain liquid‐crystalline (LC) homopolymers of poly[6‐(4‐methoxy‐4′‐oxy‐azobenzene) hexyl methacrylate] with different degrees of polymerization were synthesized by atom transfer radical polymerization (ATRP), which were prepared with a wide range of number‐average molecular weights from 5.1 × 103 to 20.6 × 103 with narrow polydispersities of around 1.17. Thermal investigation showed that the homopolymers exhibit two mesophases, a smectic phase, and a nematic phase, and the phase‐transition temperatures of the homopolymers increase clearly with increasing molecular weights. A series of novel LC coil triblock copolymers with narrow polydispersities was synthesized by ATRP, and their thermotropic phase behavior was investigated with differential scanning calorimetry and polarized optical microscopy. The LC coil triblocks were designed to have an LC conformation of poly[6‐(4‐methoxy‐4′‐oxy‐azobenzene) hexyl methacrylate] with a wide range of molecular weights from 3.5 × 103 to 1.7 × 104 and the coil conformation of poly(ethylene glycol) (PEG) (number‐average molecular weight: 6000 or 12,000) segment. Their characterization was investigated with 1H NMR, Fourier transform infrared spectra, and gel permeation chromatography. Triblock copolymers exhibited a crystalline phase, a smectic phase, and a nematic phase. The phase‐transition temperatures from the smectic to nematic phase and from the nematic to isotropic phase increased, and the crystallization of PEG depressed with increasing molecular weight of the LC block. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2854–2864, 2003
Design and synthesis of a thermally stable second‐order nonlinear optical chromophore and its poled polymers
Authors: Qin Anjun , Yang Zhou , Bai Fenglian , Ye Cheng 
Published: August 2003

AbstractA multiple charge‐transfer second‐order nonlinear optical (NLO) chromophore 2,3‐bis(4‐aminophenyl)‐5,6‐dicyanopyrazine (BAPDCP) was successfully designed and synthesized. It was characterized by 1H NMR, mass spectrometry, Fourier transform infrared spectroscopy, and elemental analysis. The first hyperpolarizability β of BAPDCP was measured with the Hyper–Rayleigh scattering technique, which was 123.5 × 10−30 esu. The donor‐embedded prepolyimide and prepolyurea were also synthesized by a polyaddition reaction. Thermogravimetric analysis and differential scanning calorimetry demonstrated that either the chromophore or the polymers have fine thermal stability. The thin films of prepolymers were prepared by coating on ITO glass substrate and poled by corona poling at elevating temperature. The second‐order NLO coefficients d33 of the films were measured by in situ second‐harmonic generation measurements. The d33 were deduced as 27.7 and 16.5 pm/V for polyurea and polyimide at 1064 nm fundamental wavelength, respectively. The onset depoling temperature of the polyimide and polyurea were both as high as 200 °C. To understand the temperature effect to the orientation thermal stability of polyimide, two films were treated at different final poling temperatures. The depoling experimental results showed that the orientation stability is higher, as raising the final treated temperature but the d33 value are almost similar. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2846–2853, 2003
Fluorinated vinyl ethers as new surface agents in the photocationic polymerization of vinyl ether resins
Authors: Bongiovanni R. , Sangermano M. , Malucelli G. , Priola A. , Leonardi A. , Ameduri B. , Pollicino A. , Recca A. 
Published: August 2003

AbstractThe syntheses of fluorinated vinyl ethers (H2CCHOCH2CH2CnF2n+1, n = 6 or 8) and their copolymerizations with bis(4‐vinyloxybutyl) isophthalate are reported. The fluorinated monomers were prepared by the transetherification of ethyl vinyl ether and fluorinated alcohols in a 75% yield. Added in low concentrations (0.1–3.0 wt %) to formulations containing bis(4‐vinyloxybutyl) isophthalate, they did not affect the kinetics of the cationic photopolymerization. The cured films were transparent and showed interesting properties in terms of wettability, hardness, cross‐cut adhesion, and chemical inertness. The fluoromonomers increased the hydrophobicity of the film surface, whereas the adhesion on various substrates such as glass and wood was unchanged. An increase in the methyl ethyl ketone resistance was also observed. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2890–2897, 2003
Heterogeneous nucleation on the crystallization poly(ethylene terephthalate)
Authors: Bian Jie , Ye Sheng‐Rong , Feng Lin‐Xian 
Published: August 2003

AbstractThe crystallization behavior of poly(ethylene terephthalate) (PET) with disodium terephthalate (DST) as nucleating agent was investigated. A detailed analysis of the crystallization course from the melt was made with the Avrami expression. The results demonstrated that DST additive can promote the PET crystallization rate in its entire crystallizable temperature range, and the acceleration degree of DST decreases with increasing temperature after a temperature higher than 180 °C. The values of the Avrami exponent indicated that the crystallization mode in Avrami theory is not suitable for the crystallization of these polymers, and the mechanism of the heterogeneous nucleation on PET crystallization is discussed. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2135–2144, 2003
Effects of plasticizers on novel electromechanical actuations with different poly(vinyl chloride) gels
Authors: Uddin Md. Zulhash , Watanabe Masashi , Shirai Hirofusa , Hirai Toshihiro 
Published: August 2003

AbstractFour different plasticizers were applied to make different poly(vinyl chloride) (PVC) gels, poly(vinyl chloride)‐bis(2‐ethylhexyl)phthalate (PVC‐DOP), poly(vinyl chloride)‐di‐n‐butylphthalate, poly(vinyl chloride)‐bis(2‐ethylhexyl)adipate, and poly(vinyl chloride)‐tris(2‐ethylhexyl)trimellitate. In our previous work, we reported that PVC‐DOP gel exhibits novel and reversible deformations of creeping and jointlike bending induced by direct current electric fields. In this article, we scrutinize the effects of plasticizers on electromechanical actuations, that is, reversible creeping and bending actuation with four of the different aforementioned gels. We measured the relative creeping distance, creeping area, creeping velocity, current observed, and bending angle as a function of applied electric fields for different PVC gels and found significant differences among them. To explain these variations, we compared the utility of plasticizers on the basis of the properties of different PVC gels, such as plasticizer‐retention ability, bending modulus, elongation at break, and the dielectric constant. The mentioned properties of the PVC gels played vital roles on their electromechanical actuations. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2119–2127, 2003
Numerical simulation of coupled‐stress case II diffusion in one dimension
Authors: Vijalapura Prashanth K. , Govindjee Sanjay 
Published: August 2003

AbstractThis article is concerned with the robust and efficient numerical simulation of case II diffusion, which constitutes an important regime of solvent diffusion into glassy polymers. Even in the one‐dimensional case considered here, the numerical simulation of case II diffusion is made difficult by the extreme nonlinearities and coupling in the governing model equations due to a nonlinear flux law needed to produce sharp solvent fronts, a concentration‐dependent relaxation time of the polymer used to model the glass‐rubber transition, and coupling between the diffusion and deformation phenomena. Having an efficient and accurate solution to such equations is central to advancing a clear understanding of the meaning of such models. The difficulties due to coupling and nonlinearities are highlighted by the consideration of a specific, normalized, one‐dimensional case II diffusion model laid out in a general framework of balance laws. Issues such as the stiffness of the spatially discrete differential algebraic equations obtained from the finite element discretization of the governing equations and their bearing on the choice of time‐stepping schemes are discussed. The key requirements of numerical schemes, namely, robustness and efficiency, are addressed by the use of an implicit, adaptive, second‐order backward differentiation formula with error control for time discretization. Error control is used to maximize the step size to satisfy a target error and the radius of convergence requirements while nonlinear algebraic equations are solved at each time step. An example of an initial boundary value problem is solved numerically to show that the chosen model reproduces case II behavior and to validate that the stated objectives for the numerical simulation are met. Finally, the features and numerical implementation of this model are compared with those of a closely related case II diffusion model due to Wu and Peppas. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2091–2108, 2003
Glassy polymer‐sorption phenomena measured with a quartz crystal microbalance technique
Authors: Zhang C. , Cappleman B. P. , Defibaugh‐Chavez M. , Weinkauf D. H. 
Published: August 2003

AbstractThe quartz crystal microbalance (QCM) method is applied to the measurement of CO2 sorption in glassy poly(ethylene terephthalate) (PET), poly(methyl methacrylate), and polysulfone. Polymer thin films in the thickness range of 350–550 nm are prepared by spin‐casting onto the quartz crystal devices. Sorption isotherms at temperatures below the glass transition are analyzed with the dual‐mode sorption model. As‐cast, quenched, and slow‐cooled thermal‐conditioning protocols yield consistent trends in the sorption level, namely, as‐cast > quenched > slow‐cooled. The sorption levels and model results for the quenched‐conditioned samples measured with QCM compare favorably with those reported from the pressure‐decay and gravimetric methods on thick films. With extended analysis of PET, the QCM technique is also useful for the exploration of the temperature dependence associated with gas sorption in glassy polymer systems. Measured heats of sorption and the collapse of the Langmuir component near the PET glass‐transition temperature agree with those reported previously. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2109–2118, 2003
Terraces on banded spherulites of polyhydroxyalkanoates
Authors: Xu Jun , Guo Bao‐Hua , Chen Guo‐Qiang , Zhang Zeng‐Min 
Published: August 2003

AbstractOn banded spherulites of poly(3‐hydroxybutyrate) and its copolymers, fine circles were observed between either cross‐polarizers or without polarizers. Atomic force microscopy was applied to confirm that these circles are terraces with heights up to several hundred nanometers rather than cracks. Real‐time observation demonstrated that the terrace forms at the front of the growing spherulites just before or exactly when two spherulites impinge on each other. Terraces were observed on the spherulites crystallized from melt confined between glass or polyimide slides rather than poly(ethylene terephthalate) slides. The formation of the terraces may have resulted from instability of the moving boundary of the melt film confined between the spherulite surface and cover slide. Wettability of the substrate played an important role in the formation of the terraces. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2128–2134, 2003
Properties of poly(dimethylsiloxane)/hydrogel multicomponent systems
Authors: Abbasi F. , Mirzadeh H. 
Published: August 2003

AbstractThe properties of surface‐ and bulk‐modified poly(dimethylsiloxane) (PDMS) were examined. Laser‐induced surface grafting of poly(2‐hydroxyethyl methacrylate) (PHEMA) on PDMS and a sequential method for preparation of interpenetrating polymer networks of PDMS/PHEMA were, respectively, used for surface and bulk modifications. The hydrogel content and water‐uptake capability of the modified samples were also investigated. The modified PDMS samples were examined by performing attenuated total reflection/Fourier transform infrared spectroscopy, dynamic mechanical thermal analysis, scanning electron microscopy, and water contact‐angle measurements. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2145–2156, 2003
Effects of several lanthanide trichloride hydrates on the melting behavior and spherulitic superstructure of poly(ethylene oxide)
Authors: Tang Jianguo , Lee Cynthia K. S. , Belfiore Laurence A. 
Published: August 2003

AbstractBinary mixtures of poly(ethylene oxide) (PEO) with the trichloride hydrates of lanthanum, cerium, europium, terbium, and ytterbium have been studied with calorimetry, polarized optical microscopy, and infrared spectroscopy. Melting‐point depression of the PEO‐rich phase occurs in all cases. At sufficiently high concentrations of the low molecular weight lanthanide complex, crystallization of the polymer is absent. The lighter lanthanides with larger ionic radii, such as lanthanum and cerium, are more effective in suppressing PEO crystallization from solution or the molten state because they are more oxophilic. The spherulitic superstructure of PEO disappears at rather low concentrations of the lanthanide salts, between 2 and 8 mol % Ln3+. Lanthanum and terbium are most efficient at disrupting the formation of PEO spherulites, and europium is least efficient. Infrared spectroscopy identifies twisting and wagging vibrational absorptions of CH2 groups in the polymer that are sensitive to the morphologies of these mixtures. Modifications of the PEO infrared absorbances in the presence of these five lanthanide salts correlate more closely with the presence or absence of major PEO melting, not the formation of a spherulitic superstructure. The phase behavior is rather simple, with no evidence of eutectic solidification upon cooling from the molten state. Multiple melting endotherms are observed in the differential scanning calorimetry heating traces of binary mixtures containing 8 mol % Yb3+ and between 10 and 20 mol % Eu3+, but the concentration dependence of these first‐order endothermic transitions is not characteristic of eutectic phase behavior. The presence of trivalent cations, such as Eu3+ or Yb3+, in these complexes perturbs the crystallization kinetics of PEO upon cooling from the molten state, as well as the melting behavior upon heating. Ion–dipole or electrostatic interactions between the lanthanide cation and the ether oxygen of PEO might alter the surface free energy at the periphery of the crystalline lamellae and perturb the chain‐folding characteristics of PEO. Consequently, coupling between the amorphous matrix and the PEO crystallites is strengthened, and this provides stability for the existence of multiple‐chain‐folded crystals composed of rather thin lamellae that could be responsible for multiple melting behavior. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2200–2213, 2003
Specific reversible melting of polyethylene
Authors: Androsch R. , Wunderlich B. 
Published: August 2003

AbstractThe specific reversibility of the crystallization and melting of linear and branched polyethylene has been determined as function of temperature by temperature‐modulated differential scanning calorimetry. The specific reversibility of crystallization and melting is defined as the ratio of the reversible enthalpy to the total enthalpy of the transition, both measured at the same temperature. This definition emphasizes a close connection between the reversible and irreversible parts of the transition. As one would expect, the crystal‐to‐melt transition of a given portion of a sample can only be reversible at a temperature close to its own temperature of irreversible melting. Reversible melting is absent at temperatures far from irreversible melting, and this is usually seen by experimentation as its zero‐entropy production melting temperature. The reversible change in the fold length, in contrast, is observed far from the melting temperature of the crystal involved. The specific reversibility of the crystallization and melting of polyethylene crystals may exceed 50% outside the temperature range of the main crystallization and melting. The specific reversibility seems rather independent of the branch concentration, and this points to similar mechanisms of the reversible transition in linear polyethylene of high crystallinity and in branched polyethylene of low crystallinity. The reversible transition is due to a local equilibrium at the crystal surface and is, therefore, largely independent of the overall morphology of the sample. In this study, a model is developed that is based on partial molecular melting, which avoids the need of molecular nucleation and permits, therefore, reversible melting as seen for small molecules in the presence of crystal nuclei. It provides an explanation of the rather large number of the crystals that may participate in reversible melting and allows a connection to the fully reversible crystallization of paraffins and the fully irreversible crystallization of extended‐chain crystals of high crystallinity. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2157–2173, 2003
Impact of average free‐volume element size on transport in stereoisomers of polynorbornene. I. Properties at 35 °C
Authors: Wilks Broderick R. , Chung Won J. , Ludovice Peter J. , Rezac Mary R. , Meakin Pavla , Hill Anita J. 
Published: August 2003

AbstractThis article demonstrates that transport of gases through glassy polymers is significantly influenced not only by the absolute amount but also by the distribution of free volume. Two stereoisomers of polynorbornene with nearly equivalent total free volume, but markedly different average free‐volume sizes, were evaluated. The free‐volume element size was probed with positron annihilation lifetime spectroscopy, wide‐angle X‐ray scattering, gas sorption, and molecular modeling. The permeation, sorption, and diffusion of light gases were measured in each stereoisomer at 35 °C. All analytical techniques indicated that one isomer (labeled as Architecture II) had a larger average free‐volume element size but fewer elements. This isomer also had a very slightly higher bulk density (1.000 vs 0.992 g/cm3 for the other stereoisomer). Architecture II also had gas sorption and diffusion coefficients that were two to three times those of the less dense counterpart. These differences have been attributed to differences in the free‐volume element size available within the polymer matrix. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2185–2199, 2003