bluuebunny/crossref_metadata_2025_split huggingface dataset:
A novel route to poly(α‐hydroxyacrylic acid) derivatives by the hydrolysis of polymers containing 1,3‐dioxolan‐4‐one moiety
Authors: Miyagawa Toyoharu , Sanda Fumio , Endo Takeshi 
Published: August 2002

AbstractThe alkali hydrolysis of poly(2,2‐dimethyl‐5‐methylene‐1,3‐dioxolan‐4‐one) and poly(2,2‐dimethyl‐5‐methylene‐1,3‐dioxolan‐4‐one‐co‐styrene) was carried out with a sodium hydroxide solution (40%) in tetrahydrofuran at room temperature to obtain poly(α‐hydroxyacrylic acid) or poly(α‐hydroxyacrylic acid‐co‐styrene) with number‐average molecular weights of 39,000–73,000 in 41–86% yields. The styrene unit in the hydrolyzed copolymer hindered the formation of a lactone ring. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1629–1633, 2001
Promoted random orientation of the phenyl substituent of phenylhydroquinone–terephthalic acid polyesters prepared with a diphenyl chlorophosphate/pyridine condensing agent
Authors: Higashi Fukuji , Watabiki Mamoru , Kim Ji‐Hong 
Published: August 2002

AbstractThe reaction of sterically hindered hydroxyl groups at the 2‐position of methylhydroquinone and phenylhydroquinone (PhHQ) to form esters was largely promoted by their slow addition to benzoic acid activated by diphenyl chlorophosphate in pyridine. A modification of this reaction was applied to the preparation of thermotropic terephthalic acid/PhHQ and 2,5‐dichloroterephthalic acid/PhHQ polymers with randomly oriented phenyl substituents, and the properties of the polymers were studied in terms of their transition temperatures, which were determined by differential scanning calorimetry and microscopic observation. The melting points were lowered by about 30–50 °C by the dropwise addition of PhHQ over 10–30 min. The molecular structures of the 2,5‐dichloroterephthalic acid/PhHQ polymers were studied by 13C NMR. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1726–1732, 2001
Tertiary amine‐functionalized polymers by atom transfer radical polymerization
Authors: Summers Gabriel J. , Ndawuni M. Patrick , Summers Carol A. 
Published: August 2002

AbstractThe quantitative synthesis of tertiary amine‐functionalized polymers by atom transfer radical polymerization is reported. Tertiary amine‐functionalized polystyrene was prepared with the adduct of 1‐(bromoethyl)benzene with 1‐(4‐dimethyl‐aminophenyl)‐1‐phenylethylene as an initiator in the atom transfer radical polymerization of styrene in the presence of a copper (I) bromide/2,2′‐bipyridyl catalyst system. The polymerization proceeded via a controlled free‐radical polymerization process to afford quantitative yields of the corresponding tertiary amine‐functionalized polystyrene with predictable number‐average molecular weights (1600–4400), narrow molecular weight distributions (1.09–1.31), and an initiator efficiency of 0.95. The polymerization process was monitored by gas chromatographic analysis. The tertiary amine‐functionalized polymers were characterized by thin‐layer chromatography, size exclusion chromatography, potentiometry, and spectroscopy. All experimental evidence was consistent with quantitative functionalization via the 1,1‐diphenylethylene derivative. Polymerization kinetic measurements showed that the polymerization reaction followed first‐order‐rate kinetics with respect to monomer consumption and that the number‐average molecular weight increased linearly with monomer conversion. © 2001 John Wiley & Sons, Inc. J Polym Sci A Part A: Polym Chem 39: 2058–2067, 2001
Effect of pressure on the luminescence of a series of methoxy phenylacetylene dendrimers neat and in dilute solution in solid poly(tert‐butyl methacrylate)
Authors: Zhu A. , Bharathi P. , Drickamer H. G. , Moore J. S. 
Published: August 2002

AbstractThe effect of pressure up to 60 kbar was measured on the luminescence peak location and efficiency for a series of methoxy phenylacetylene dendrimers (MeO). Dendrimers MeO‐3, MeO‐7, MeO‐15, MeO‐31, MeO‐63, and MeO‐127 were studied as neat polymers. MeO‐3, MeO‐15, MeO‐63, and MeO‐127 were also investigated in dilute solutions in poly(tert‐butyl methacrylate). According to measurements of the dilute solutions, there is a charge‐transfer (CT) state that, for the smaller dendrimers, lies well above the π* state; for the larger dendrimers, it is the emitting state at 1 atm. With increasing pressure, the intramolecular CT state is rapidly stabilized, so that at high pressure the emission is from this state for all dendrimers. For the neat polymers, there is an initial redshift that reverses direction at a pressure that is higher for smaller dendrimers. This reversal is attributed to intermolecular CT. There may be changes in the molecular geometry and/or relative orientation of adjacent dendrimers that tend to stabilize the intermolecular CT in the solid state. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2859–2865, 2001
Chain‐extended, hydroxyterminated‐polybutadiene‐based polyurethaneureas: Synthesis, reaction kinetics, and properties
Authors: Gupta Tarakranjan , Adhikari Basudam 
Published: August 2002

AbstractHydroxyterminated‐polybutadiene‐based prepolyurethanes were prepared with two different catalysts, dibutyltindilaurate (DBTDL) and triethylamine (TEA); chain extension of the prepolyurethanes followed with two different aromatic diamines, oxydianiline and 4,4′‐diaminodiphenylsulfone, in various concentrations. The prepolyurethane synthesis followed second‐order kinetics, with the DBTDL catalyst showing better efficiency for urethane formation than TEA. TEA‐catalyzed synthesis suffered from the self‐association of isocyanates as a major side reaction, following second‐order kinetics with respect to isocyanate concentration. Although there was a gradual increase in the intrinsic viscosity during prepolyurethane synthesis in the presence of DBTDL, the intrinsic viscosity remained almost constant with the progress of the reaction in the presence of TEA. The tensile properties of prepolyurethane and polyurethaneureas synthesized in DBTDL‐catalyzed reactions were higher than the properties of those synthesized in TEA‐catalyzed reactions. The variation of the tensile strength with the diamine concentration was correlated with the crosslink density and sol fraction. The solubility of the hard segment of polyurethaneurea in the reaction medium appeared to be important in influencing the tensile properties. The effects of the diamine concentration (chain extender) on the diffusion coefficient and activation energy of diffusion of toluene in polyurethaneureas were studied. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2978–2992, 2001
Synthesis of a new polymer surface bearing grafted azo polymer chains
Authors: Poncin‐Epaillard Fabienne , Beunet Johann , Bulou A. , Bardeau Jean‐François 
Published: August 2002

AbstractAzobenzene, a photosensitive chromophore that undergoes photoinduced and thermal cis–trans isomerization, can be applied in a nonlinear optical field. {4′‐[(Hydroxy)ethyl]amino}‐4‐nitroazobenzene (disperse red 1) corresponds to one of these azo compounds, which can be grafted to a polymer chain as a part of the main chain, as a dangling group, or onto the polymer surface. In the last case, disperse red 1 is transformed into an acrylic monomer and then grafted onto a polypropylene surface modified with a cold carbon dioxide‐plasma treatment. A method is proposed for quantifying the radicals formed during the plasma treatment and, consequently, for optimizing the grafting reaction. The best conditions (the nature of the solvent, temperature, monomer concentration, and duration) are given. Both IR and Raman spectroscopies were used as efficient techniques for grafting characterization. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3052–3061, 2001
Phase behavior of low molecular weight polyethylenes from homogeneous and heterogeneous solutions
Authors: Chatterjee Jhunu , Alamo Rufina G. 
Published: August 2002

AbstractThe pseudophase diagrams of solutions of low molecular weight polyethylene (PE) (number‐average molecular weight < 1500 g/mol) in octamethyl cyclotetrasiloxane (OCTS) and isododecane (IS) were determined by direct observation of cloud points and optical microscopy. In addition, melting temperatures were also determined by differential scanning calorimetry. In the range of single liquid–solid transitions, the data conformed to the classical melting temperature composition relation as a result of the formation of extended crystallites. The melting data were used to determine the interaction parameter of the PE in OCTS (1.4 ± 0.1) and IS (0.22 ± 0.05). The structural and thermal properties of the gels formed by a competing liquid–liquid and liquid–solid phase separation, under nonequilibrium conditions, contrast with the properties of the crystals formed from a single liquid–solid transition. Coarsening within the liquid phases was evidenced by optical microscopy, and insights about the mechanism of the kinetics of the coarsening process are given. The temporal changes of the melting temperature of crystallites formed from the heterogeneous phase (OCTS) reveal dynamics within a nonequilibrium state. In contrast, the crystallites formed from a homogeneous solution (IS) showed negligible melting‐temperature changes with time. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 878–889, 2002
Sphere‐to‐cylinder transition in dilute solutions of diblock copolymers
Authors: Termonia Yves 
Published: August 2002

AbstractAB diblock copolymers dissolved in a selective solvent for block B spontaneously self‐assemble into spherical or cylindrical micelles with an A core surrounded by a corona of the B block. Using a Monte Carlo lattice model, we find that the sphere‐to‐cylinder transition can be fully described in terms of a packing parameter that depends on the relative cross sections of the two blocks. The latter can be varied either by a block length being changed or by the B block being allowed to adopt an ordered conformation (e.g., helical). The model results are in good agreement with experimental observation. They also shed some light onto the molecular origins of the ease of processing and exceptional mechanical properties of spider dragline. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 890–895, 2002
Unified analysis of thermodynamic and rheological properties of high polymer solutions. II. Ternary systems
Authors: Irurzun Isabel M. , Grigera Tomás S. , Cortizo M. Susana , Figini Rubén V. , Marx‐Figini Marianne 
Published: August 2002

AbstractWe extend to ternary solutions our previous study of conformational, thermodynamic, and rheological properties of semidilute polymer solutions in good solvent. Osmotic pressure and viscosity measurements were performed in several mixtures of two compatible polymers in a common solvent. Renormalization group results were used to analyze the data, using de Gennes's blobs model to connect dynamic and conformational properties. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1071–1079, 2002
Revisiting some phenomena in polyelectrolyte solutions
Authors: Morawetz Herbert 
Published: August 2002

AbstractThis review deals with the counterion distribution around rod‐shaped polyions, the reaction kinetics in polyelectrolyte solutions, the anomalous behavior of poly(methacrylic acid), and the formation of pearl‐necklace‐like structures of polyelectrolytes in poor solvent media. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1080–1086, 2002
Electrorheological properties of suspensions of monodispersed micron‐sized polyaniline composite particles
Authors: Jun Jung‐Bae , Lee Chung‐Hyuk , Kim Jin‐Woong , Suh Kyung‐Do 
Published: August 2002

AbstractMonodispersed micron‐sized polyaniline (PANi) composite particles were synthesized by chemically oxidative polymerization of aniline in the presence of functional porous polymer particles. The formation of the PANi‐coated composite particles was confirmed by scanning electron microscopy. Electrorheological (ER) properties of the monosized composite particle suspensions were then investigated under different DC electric fields by altering the particle characteristics. The ER effect of the PANi composite suspensions was largely dependent on the composition ratio (PANi loading), the particle conductivity, and the particle concentration. Dynamic oscillation measurements revealed that the applied electric field induced the viscoelastic property of the ER suspensions by generating the chain structures of the suspended particles. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1163–1170, 2002
Temperature dependence of the phase separation in ethyl cyanoethyl cellulose/poly(acrylic acid)/4′‐n‐pentyl‐4‐cyano‐biphenyl composite films
Authors: Zhou Xuesong , Huang Yong 
Published: August 2002

AbstractA novel polymer‐dispersed liquid‐crystal film consisting of micrometer‐scale liquid‐crystal droplets in ultraviolet‐cured polymer composite matrices with cholesteric order was prepared and the influence of cure temperature on the phase separation was studied. The existence and pitch of the ethyl cyanoethyl cellulose cholesteric liquid‐crystalline phase were influenced by the existence of low molecular weight liquid crystals. The macromolecular cholesteric phase disappeared when the 4′‐n‐pentyl‐4‐cyano‐biphenyl concentration was over 40 wt %, and 4′‐n‐pentyl‐4‐cyano‐biphenyl domains were dispersed in the isotropic matrix of the polymer composite. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1334–1341, 2002
Sorption and partial molar volumes of C2 and C3 hydrocarbons in polypropylene copolymers
Authors: Tsuboi Akio , Kolář Petr , Ishikawa Takeshi , Kamiya Yoshinori , Masuoka Hirokatsu 
Published: August 2002

AbstractThe sorption of C2 and C3 hydrocarbons in two ethylene–propylene copolymers and a propylene homopolymer and the simultaneous dilation of the polymers were measured at temperatures of 287–363 K and pressures up to 4 MPa. The sorption isotherms were well described by the Flory–Huggins theory of dissolution. Dilation isotherms in the form of elongation versus pressure were similar in shape to the corresponding sorption isotherms. Solubility coefficients, partial molar volumes, and Flory–Huggins interaction parameters were determined from these isotherms. The thermal expansivities of the hydrocarbons dissolved in the polymers were 0.002–0.005 K−1, and the Flory–Huggins interaction parameters depended not only on temperature but also on concentration. At 323 K, the calculated solubilities of propylene in the ethylene–propylene‐rubber regions of the copolymers were 1.8 times higher than in the amorphous regions of the propylene homopolymer. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1255–1262, 2001
Origin of miscibility‐induced sequential reordering and crystallization‐induced sequential reordering in binary copolyesters: a Monte Carlo simulation
Authors: Youk Ji Ho , Jo Won Ho 
Published: August 2002

AbstractThe effect of the repulsive interaction between the components of binary copolyesters on their sequence order was investigated with the Monte Carlo simulation method. The phase separation and ester‐interchange reactions were implemented simultaneously with a kind of one‐site bond fluctuation model. When the repulsive interaction energy was applied to the binary copolyesters, miscibility‐induced sequential reordering (MISR) was induced. The more repulsive the pair interaction was, the higher the sequence order was. During the MISR process, homoester‐interchange reactions became more favorable because of the repulsive interaction, accompanying the decrease of the interactional free energy. The sequence order resulting from MISR was independent of the relative trial ratio of phase separation to ester‐interchange reaction at a given value of interaction energy. Restoration of the sequence distribution was also simulated with and without the repulsive interaction between the components of the binary copolyesters to investigate the effect of MISR on the crystallization‐induced sequential reordering (CISR) process in binary copolyesters, where sequences with lengths longer than 6 were assumed to crystallize and could not take part in ester‐interchange reactions. The sequence distribution in the amorphous phase was restored via ester‐interchange reactions. When the repulsive interaction was applied to binary copolyesters during the CISR process, restoration of the sequence distribution was accelerated, indicating that MISR can accelerate the CISR process when a polyester blend shows upper critical solution temperature behavior. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1337–1347, 2001
Application of a model‐free isoconversional method to the cure of phenolic systems
Authors: Li Shuyan , Järvelä Pentti 
Published: August 2002

AbstractThe curing process of a phenolic resole was monitored with differential scanning calorimetry under nonisothermal and isothermal conditions, the curing kinetics were analyzed with a model‐fitting approach and a model‐free isoconversional method, and the activation energy of this phenolic system was found to be close to 46 ± 4 kJ mol−1. For complicated cures, the model‐free isoconversional method was found to be a simpler and more reliable approach. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1525–1528, 2001
Poly(ethylene terephthalate) copolymers containing 5‐nitroisophthalic units. II. Crystallization studies
Authors: Kint Darwin P. R. , De Ilarduya Antxon Martínez , Muñoz‐Guerra Sebastián 
Published: August 2002

AbstractThe microstructure and crystallization behavior of a set of poly(ethylene terephthalate‐co‐5‐nitroisophthalate) copolymers (PETNI) containing 5‐nitroisophthalic units in the 10–50 mol % range were examined and compared to those of poly(ethylene terephthalate) (PET) and poly(ethylene terephthalate‐co‐isophthalate) (PETI) copolymers. A 13C NMR analysis of PETNI copolymers in a trifluoroacetic acid solution indicates that they are random copolymers with average sequence lengths in accordance with ideal polycondensation statistics. Differential scanning calorimetry (DSC) studies show that PETNI containing 5‐nitroisophthalic units up to 20 mol % are able to crystallize and that crystallization takes place in these copolymers at much slower rates than in PET. Wide‐angle X‐ray diffraction from powder and fibers reveals that crystallizable PETNI adopts the same triclinic crystal structure as PET, with the nitroisophthalate units being excluded from crystallites. Fourier transform infrared in combination with cross‐polarization/magic‐angle spinning 13C NMR spectroscopy demonstrates the occurrence of a gauche–trans conversion encompassing the crystallization process. A correlation between DSC and spectroscopic data leads us to conclude that the content of trans conformer in the noncrystallized phase of PETNI is higher than in both PET and PETI copolymers and suggests that secondary crystallization in the homopolymer must proceed by a mechanism different than that in copolymers. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1553–1564, 2001
Resonance raman spectra of poly‐(p‐phenylenebenzobisoxazole), poly‐(p‐phenylenebenzobisthiazole), and poly(pyridobisimidazole)
Authors: Takahashi Yasuhiro 
Published: August 2002

AbstractResonance Raman spectra of poly(p‐phenylenebenzobisoxazole) (PBO), poly(p‐phenylenebenzobisthazole) (PBZT), and poly(pyridobisimidazole) (PIPD) were measured. In the case of PBO, no large dependence on wavelength of excited laser can be observed, whereas in the cases of PBZT and PIPD, the spectra depends on wavelength of excited laser. This difference may be attributed to the colors of the samples: PBO is gold, and PBZT and PIPD are metallic blue, which show the different conjugated states. The spectra of PBO are rather simpler than those of PBZT and PIPD. This is considered to be reflected by the fact that only a chain passes through the unit cell of PBO, while two chains pass through the unit cell of PBZT and PIPD. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1791–1793, 2001
Differential scanning calorimetry, small‐angle X‐ray scattering, and wide‐angle X‐ray scattering on homogeneous and heterogeneous ethylene‐α‐copolymers
Authors: Jokela K. , Väänänen A. , Torkkeli M. , Starck P. , Serimaa R. , Löfgren B. , Seppälä J. 
Published: August 2002

AbstractThe objective of this work was to use both X‐ray and differential scanning calorimetry techniques in a comparative study of the lamellar and crystalline structures of heterogeneous and homogeneous ethylene‐α‐copolymers. The samples differed in the comonomer type (1‐butene, 1‐hexene, 1‐octene, and hexadecene), comonomer content, and catalyst used in the polymerizations. Step crystallizations were performed with differential scanning calorimetry, and the crystallinity and lamellar thicknesses of the different crystal populations were determined. Wide‐angle X‐ray scattering was used to determine crystallinities, average sizes of the crystallites, and dimensions of the orthorhombic unit cell. The average thickness, separation of the lamellae, and volume fractions of the crystalline phase were determined by small‐angle X‐ray scattering (SAXS). The results revealed that at densities below 900 kg/m3, polymers were organized as poorly organized crystal bundles. The lamellar distances were smaller and the lamellar thickness distributions were narrower for the homogeneous ethylene copolymers than for the heterogeneous ones. Step‐crystallization experiments by SAXS demonstrated that the long period increased after annealing. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1860–1875, 2001
Transcrystallization kinetics of poly(vinylidene fluoride)
Authors: Benkhati Hassan , That Ton , Tan Minh , Jungnickel Bernd‐J. 
Published: August 2002

AbstractWe report the transcrystallinity of poly(vinylidene fluoride) on several different types of substrate materials. The supermolecular structure and its development were characterized with polarization microscopy, whereas differential scanning calorimetry was used for monitoring the isothermal and nonisothermal crystallization kinetics. Although only approximately applicable, an Avrami–Ozawa analysis of the latter yielded reliable exponents, which characterized the transcrystalline nucleation conditions, the related dimensionality of growth, and the resulting texture. The results complemented and agreed quantitatively with those of light microscopy. Several polymers, including poly(ethylene terephthalate), polytetrafluoroethylene, and polyimide, induced distinct transcrystallinity, but only a spherulitic supermolecular structure developed on glass and metallic substrates. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2130–2139, 2001