bluuebunny/crossref_metadata_2025_split huggingface dataset:
Counter‐ion‐specific helix formation of poly(γ‐methyl L‐glutamate) derivatives containing sulfonate group in aqueous alcohols
Authors: Ando Akihiro , Satoh Mitsuru 
Published: August 2002

AbstractCharged polypeptides containing sulfonate groups were prepared by transesterification of poly(γ‐methyl L‐glutamate) with isethionic acid. The coil–helix transition of the sulfonated polypeptides was investigated in aqueous alcohols. Marked counter‐ion specificity was observed for helix formation: Li+ < Na+ < Cs+ ≦ Rb+ ≦ K+; this was different to that for poly(L‐glutamate) (PLG): Cs+ ≪ K+ < Li+ < Na+. Specific helix stabilization by counter‐ion mixing, which has been found for the PLG system, was not observed for the sulfonated polypeptides. The counter‐ion‐ and solvent‐specific helix formation is discussed and compared with that in PLG.© 2001 Society of Chemical Industry
Influence of molecular interactions on spherulite morphology in miscible poly(ethylene oxide)/epoxy network versus poly(ethylene oxide)/poly(4‐vinyl phenol) blend
Authors: Huang Yin Ping , Kuo Jen‐Fen , Woo E M 
Published: August 2002

AbstractRelationships between the spherulite morphology and changes in hydrogen‐bonding interactions between the linear poly(ethylene oxide) (PEO) polymer and a crosslinking epoxy system (diglycidylether of bisphenol‐A resin with 4,4′‐diaminodiphenylsulfone) (DGEBA/DDS) before and after cure have been explored The hydrogen‐bonding interaction is more significant before cure because of the interactions between the ether group of PEO and the amine group of DDS. The interaction between PEO and epoxy/DDS becomes less in the cured network. The morphology of the PEO crystals is, in turn, affected by the contents and chemical structures (functional groups, molecular weights, crosslinks, etc) of crosslinking epoxy/DDS. PEO/poly(4‐vinyl phenol) (PVPh), a thermoplastic non‐curing miscible system with the hydrogen bonding between the ether group of PEO and the OH group of PVPh, is also compared. In comparison with the PEO/epoxy/DDS system, the spherulite morphology of PEO/PVPh becomes more extensively spread out, with the extents increasing with the PVPh contents in the PEO/PVPh blend.© 2001 Society of Chemical Industry
Effect of multifunctional comonomers on the properties of poly(ethylene terephthalate) copolymers
Authors: Yoon Kwan Han , Min Byung Ghyl , Park O Ok 
Published: August 2002

AbstractThe properties of poly(ethylene terephthalate) (PET) and its copolymers containing 0.04–0.15 mol% of pentaerythritol and trimethylolethane (TME) have been investigated. The molecular weight of the copolymers increased with comonomer content, and this effect was observed significantly with pentaerythritol copolymers, resulting in broad molecular weight distribution. The comonomer effect on the mechanical properties was small. The shear viscosity of the copolymers showed shear thinning within the experimental shear rate range. The crystallization rate and birefringence of the fibres containing 0.103 mol% pentaerythritol increased with the spin draw ratio, whereas they decreased with comonomer content.© 2002 Society of Chemical Industry
Emotional/behavioral disabilities and gifted and talented behaviors: Paradoxical or semantic differences in characteristics?
Authors: Morrison William F. 
Published: August 2002

AbstractThe identification of gifted and talented behaviors within students who have an identified exceptionality has resulted in the questioning of traditional profiles of individuals qualifying for services within gifted and special education. Much of this reflection to date has been focused on the characteristics of gifted and talented behaviors exhibited by students with high incidence disabilities (learning disabilities and attention deficit/hyperactivity disorders). Absent from the literature has been an examination of the learning and personal characteristics of students identified as having an emotional/behavioral disability who concurrently exhibit gifted and talented behaviors. An exploration of the growing body of literature in the fields of gifted and special education has revealed a number of similar or common characteristics in these two populations that warrant investigation. The purpose of this article is to develop a profile in the aforementioned population to aid in the identification of, and programming for, individuals with an emotional/behavioral disability who exhibit gifted and talented behaviors. © 2001 John Wiley & Sons, Inc.
Polyether‐bridged cyclophanes incorporating bisphenol A units as neutral receptors for quats: synthesis, molecular structure and binding properties
Authors: Cort Antonella Dalla , Nissinen Maija , Mancinetti Daniele , Nicoletti Elena , Mandolini Luigi , Rissanen Kari 
Published: August 2002

AbstractTwo novel neutral polyoxyethylene bridged cyclophanes (2a and 2b) incorporating bisphenol A units were synthesized and characterized by means of x‐ray crystal structure determination. The binding properties of 2a and 2b toward tetramethylammonium, N‐methylpyridinium, and acetylcholine cations were evaluated by means of 1H NMR spectroscopy. Consistent with indications provided by the molecular structure, the cavity in the basket‐like cyclophanes is large enough to accommodate the given guest cations conveniently. Circumstantial evidence was obtained that 1,1,2,2‐tetrachloroethane is too large to enter the cavity of the smaller cyclophane 2a, but can be included in the cavity of the larger cyclophane 2b. Copyright © 2001 John Wiley & Sons, Ltd.
Synthesis and hydrogel formation of fluorine‐containing amphiphilic ABA triblock copolymers
Authors: Matsumoto Kozo , Nishimura Ryuji , Mazaki Hiroaki , Matsuoka Hideki , Yamaoka Hitoshi 
Published: August 2002

AbstractFluorine‐containing amphiphilic ABA triblock copolymers, poly(2‐hydroxyethyl vinyl ether)‐block‐poly[2‐(2,2,3,3,3‐pentafluoropropoxy)ethyl vinyl ether]‐block‐poly(2‐hydroxyethyl vinyl ether) [poly(HOVE‐b‐PFPOVE‐b‐HOVE)] (HFH), poly[2‐(2,2,3,3,3‐pentafluoropropoxy)ethyl vinyl ether]‐block‐poly(2‐hydroxyethyl vinyl ether)‐block‐poly[2‐(2,2,3,3,3‐pentafluoropropoxy)ethyl vinyl ether] [poly(PFPOVE‐b‐HOVE‐b‐PFPOVE)] (FHF), and poly(n‐butyl vinyl ether)‐block‐poly(2‐hydroxyethyl vinyl ether)‐block‐poly(n‐butyl vinyl ether) [poly(NBVE‐b‐HOVE‐b‐NBVE)] (LHL), were synthesized, and their behavior in water was investigated. The aforementioned polymers were prepared by sequential living cationic polymerization of 2‐acetoxyethyl vinyl ether (AcOVE) and PFPOVE or NBVE, followed by hydrolysis of acetyl groups in polyAcOVE. FHF and LHL formed a hydrogel in water, whereas HFH gave a homogeneous aqueous solution. In addition, the gel‐forming concentration of FHF was much lower than that of corresponding LHL. Surface‐tension measurements of the aqueous polymer solutions revealed that all the triblock copolymers synthesized formed micelles or aggregates above about 1.0 × 10−4 mol/L. The surface tensions of HFH and FHF solutions above the critical micelle concentration were lower than those of LHL, indicating high surface activity of fluorine‐containing triblock copolymers. Small‐angle X‐ray scattering measurements revealed that HFH formed a core‐shell sperical micelle in 1 wt % aqueous solutions, whereas the other block copolymers caused more conplicated assembly in the solutions. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3751–3760, 2001
Biodegradation of copolymers composed of optically active L‐lactide and (R)‐ or (S)‐1‐methyltrimethylene carbonate
Authors: Tsutsumi Chikara , Yasuda Hajime 
Published: August 2002

AbstractRandom copolymerizations of L‐lactide with (R)‐, (S)‐, or rac‐1‐methyltrimethylene carbonate with bis(pentamethylcyclopentadienyl) samarium‐methyl tetrahydrofuranate [(C5Me5)2SmMe(THF)] as a novel initiator provided high molecular weight polymers with low polydispersities. Biodegradation of the resulting polymers with tricine and {N‐[tris(hydroxymethyl)methyl]‐2‐aminoethane sulfonic acid (TES) buffers as well as activated sludge showed only a small weight loss, whereas the polymer with proteinase K revealed high biodegradability independent of the optical activity of 1‐methyltrimethylene carbonate. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3916–3927, 2001
Atom transfer radical copolymerization of N‐phenylmaleimide and styrene initiated with dendritic polyarylether 2‐bromoisobutyrate
Authors: Zhao You‐Liang , Jiang Jing , Liu Hong‐Wei , Chen Chuan‐Fu , Xi Fu 
Published: August 2002

AbstractDendritic polyarylether 2‐bromoisobutyrates with different generations (Gn‐Br, n = 1–3) were prepared by reaction of the Fréchet‐type hydroxyl‐terminated polyarylether with 2‐bromoisobutyryl bromide and triethylamine. Gn‐Br as a macroinitiator for the controlled free‐radical polymerization of N‐phenylmaleimide (PhMI, M1) and styrene (St, M2) was investigated. The copolymerization carried out in anisole with CuBr/bpy catalyst afforded polymers with well‐defined molecular weights and low polydispersities (1.12 < Mw/Mn < 1.35). When the molar fraction of PhMI was 0.50, the apparent activation enthalpy of copolymerization was 38.2 kJ/mol. The effects of monomer feed on the apparent activation enthalpy and copolymer composition were also studied. The monomer reactivity ratios were determined to be r1 = 0.0325 and r2 = 0.0524 according to the Kelen–Tüdős method. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3960–3966, 2001
Physicochemical and thermal studies of viscose rayon borate fiber and its carbon fiber
Authors: Ko Young Gun , Choi Ung Su , Ahn Dong June , Kim Jeong Su , Kim Tae Young 
Published: August 2002

AbstractNonhalogen compounds have been studied for improvements in the flameproofing property and toxicity of flame retardants. Borate compounds have properties of multifunctional smoke suppressants, flame retardants, and afterglow suppressants. In this study, borate was coupled onto the surface of viscose rayon felt. Coupling and carbonization were confirmed by attenuated total reflectance Fourier transform infrared (ATR FTIR). The initial carbonization temperature was certified with ATR FTIR, elemental analysis of carbon, and thermogravimetric analysis. In the carbonization step, all chemical groups of the surface of the viscose rayon felt degraded to the various gases. Moreover, the weight percentage of the carbon element increased with increasing carbonization temperature. Initial rapid thermal degradation temperatures of viscose rayon prepared at various temperatures increased with the increasing reaction temperature. The activation energy was calculated with the Freeman and Carroll method. The activation energy of borate‐coupled viscose rayon decreased much more than before coupling. However, the activation energy increased with the increasing carbonization temperature in the carbonization step. Viscose rayon borates showed higher limiting oxygen index (LOI) values and volumetric resistance rate values than viscose rayon phosphates. In this article, the relationship between the activation energy and LOI is studied. The synthesized viscose rayon borate is found to be highly effective as a flame retardant and electrically resistant. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3875–3883, 2001
Lanthanocene amide complexes as single‐component initiators for the polymerization of (dimethylamino)ethyl methacrylate
Authors: Shen Qi , Wang Yaorong , Zhang Keda , Yao Yingming 
Published: August 2002

AbstractPolymerization of (dimethylamino)ethyl methacrylate (DMAEMA) by lanthanocene amide complexes was investigated. The results show that (MeC5H4)2LnN(i‐Pr)2[tetrahydrofuran (THF)] (Ln = Y, Er, Yb), (MeC5H4)2YbNC5H10(HNC5H10) (HNC5H10 = piperidine), (MeC5H4)2YbNPh2(THF), and (t‐BuC5H4)2YbNPh2(THF) are effective initiators for the polymerization of DMAEMA, and the molecular weights of the polymers obtained exceed 100 × 103. The polymerization reactions can be varied over quite a broad range of temperatures from −78 to 40 °C. The central metals and amido groups had a significant effect on the polymerization activity. The increasing activity of central metals and amido groups was Yb < Er < Y and NPh2 < N(i‐Pr)2 < NC5H10, respectively. © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 612–616, 2002; DOI 10.1002/pola.10141
Synthesis of star‐shaped copolymers with methyl methacrylate and n‐butyl methacrylate by metal‐catalyzed living radical polymerization: Block and random copolymer arms and microgel cores
Authors: Baek Kyung‐Youl , Kamigaito Masami , Sawamoto Mitsuo 
Published: August 2002

AbstractVarious star‐shaped copolymers of methyl methacrylate (MMA) and n‐butyl methacrylate (nBMA) were synthesized in one pot with RuCl2(PPh3)3‐catalyzed living radical polymerization and subsequent polymer linking reactions with divinyl compounds. Sequential living radical polymerization of nBMA and MMA in that order and vice versa, followed by linking reactions of the living block copolymers with appropriate divinyl compounds, afforded star block copolymers consisting of AB‐ or BA‐type block copolymer arms with controlled lengths and comonomer compositions in high yields (≥90%). The lengths and compositions of each unit varied with the amount of each monomer feed. Star copolymers with random copolymer arms were prepared by the living radical random copolymerization of MMA and nBMA followed by linking reactions. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 633–641, 2002; DOI 10.1002/pola.10145
Synthesis of novel nitrogen‐ and sulfur‐containing conjugated polymers used as hole‐transporting materials for organic light‐emitting diodes
Authors: Zhu Kaizheng , Xie Zhiyuan , Wang Lixiang , Jing Xiabin , Wang Fosong 
Published: August 2002

AbstractTwo series of highly soluble novel nitrogen‐ and sulfur‐containing conjugated polymers were synthesized via an acid‐induced self‐polycondensation of functional monomers with methyl sulfinyl and aromatic groups. The well‐defined structures of synthesized polymers were confirmed by their NMR and IR spectra. The highest occupied molecular orbital energy values for these materials, estimated by cyclic voltammetry, showed a broad range of values from about 5.0 to 5.2 eV used as hole‐transport layers (HTL) in two‐layer light‐emitting diodes ITO/HTL/Alq3/Mg:Ag [ITO = indium tin oxide, and Alq3 = tris(8‐quinolinato) aluminum]. The typical turn‐on voltage of these diodes was about 4–5 V. The maximum brightness of the device was about 3440 cd/m2 at 20 V. The maximum efficiency was estimated to be 0.15 lm/W at 10 V. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1321–1333, 2002
Functionalization of polyethylene with silane comonomers
Authors: Lipponen S. , Seppälä J. 
Published: August 2002

AbstractWe synthesized a new weakly interacting monomer with a reactive phenylsilane group that is an intermediate for many functional groups. The synthesis was performed in two steps: the hydrosilylation of 1,7‐octadiene with dimethylchlorosilane and a Grignard reaction with phenyl magnesium bromide. The new monomer, 7‐octenyldimethylphenylsilane, was isolated and copolymerized with ethylene via metallocene catalysts (Me2Si(Me‐2‐Ind)2ZrCl2 and Et(Ind)2ZrCl2) and methylaluminoxane (MAO) as a cocatalyst. Electropositive silicon had no negative effect on the copolymerization reaction. The polymerization activity increased, and the molar mass of the product remained at a high level. The comonomer incorporation reached a significant 11.8 wt % (2.6 mol %). © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1303–1308, 2002
Styrylpyridinium borate salts as dye photoinitiators of free‐radical polymerization
Authors: Jędrzejewska Beata , Kabatc Janina , Pietrzak Marek , Pączkowski Jerzy 
Published: August 2002

AbstractStyrylpyridinium borate salts photoinitiate free‐radical polymerization. The rate of photopolymerization depends on the ΔGo of electron transfer between a borate anion and a styrypyridinium cation. This latter value was estimated for a series of styrylpyridinium borate salts, and the relationship between the rate of polymerization and the free energy of activation gives the dependence predicted by the classical theory of electron transfer. This relation was independently observed for the two series of styrylpyridinium borate salts tested—one for the photoredox pair with an iodine atom and the second without. Styrylpyridinium borate salts were stable at ambient temperature in the formulations prepared for the photopolymerization experiments. Photopolymerization initiated by the photoredox pairs tested proceeded by the conventional mechanism in which bimolecular termination occurs by a reaction between two macroradicals. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1433–1440, 2002
Kinetics of alpha‐methylstyrene oligomerization by catalytic chain transfer
Authors: Gridnev A. A. 
Published: August 2002

AbstractAlpha‐methylstyrene (AMS) can be effectively dimerized by a free‐radical mechanism mediated by the catalytic chain transfer (CCT). Above the ceiling temperature of AMS, 61 °C, the dimer may become almost an exclusive product with only a small percentage of impurity of AMS trimer and tetramer. Kinetics of the AMS oligomerization has two characteristic features. First, the rate of the oligomerization increases with concentration of the CCT catalyst. Second, conversion reaches a plateau at 60–70%. A kinetic scheme explained both effects. Besides AMS, para‐ and methasubstituted AMS can also be dimerized. Orthosubstituted AMS's do not oligomerize. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1366–1376, 2002
Fluoride‐terminated hyperbranched poly(arylene ether phosphine oxide)s via nucleophilic aromatic substitution
Authors: Bernal David P. , Bankey Nathaniel , Cockayne Robert C. , Fossum Eric 
Published: August 2002

AbstractA series of ABx‐type triarylphosphine oxide monomers, bis‐(4‐fluorophenyl)‐(4‐hydroxyphenyl)phosphine oxide (4a), bis‐(3,4‐difluorophenyl)‐(4‐hydroxyphenyl)phosphine oxide (4b), and 4‐hydroxyphenyl‐bis‐(3,4,5‐trifluorophenyl)phosphine oxide (4c) were prepared, characterized, and polymerized under nucleophilic aromatic substitution conditions [N‐methylpyrrolidone (NMP), K2CO3] to provide the corresponding hyperbranched poly(arylene ether phosphine oxide)s with number‐average molecular weights ranging from 9200 to 14,600 Da. NMR spectroscopic analysis indicated the presence of highly branched products with an approximate degree of branching of 0.57. The polymers were soluble in a variety of typical organic solvents and displayed excellent thermal stability. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1456–1467, 2002
Cationic ring‐opening polymerization of monothiocarbonate with a norbornene group
Authors: Nemoto Nobukatsu , Kakimoto Keiichiro , Endo Takeshi 
Published: August 2002

AbstractThis work deals with the cationic ring‐opening polymerization of cyclic thiocarbonates with a norbornene or norbornane moiety, that is, 5,5‐(bicyclo[2.2.1]hept‐2‐ene‐5,5‐ylidene)‐1,3‐dioxane‐2‐thione (TC1) or 5,5‐(bicyclo[2.2.1]heptane‐5,5‐ylidene)‐1,3‐dioxane‐2‐thione (TC2), respectively. The reaction of TC1 initiated by trifluoromethanesulfonic acid (TfOH), methyl trifluoromethanesulfonate (TfOMe), boron trifluoride etherate (BF3OEt2), or triethyloxonium tetrafluoroborate (Et3OBF4) afforded unidentified products; however, TC1 underwent cationic ring‐opening polymerization with methyl iodide as an initiator to afford polythiocarbonate because the propagating end was stabilized by the covalent‐bonding property. The polymerization of TC2 initiated by TfOH, TfOMe, BF3OEt2, or Et3OBF4 afforded polythiocarbonate with good solubility in common organic solvents and a narrow molecular weight distribution because of the absence of a double‐bond moiety. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1698–1705, 2002
Synthesis and properties of novel polyurethanes containing 3,4‐dioxybenzylidenecyanoacetate group as a nonlinear optical chromophore
Authors: Lee Ju‐Yeon , Park Eun‐Ju 
Published: August 2002

AbstractMethyl 3,4‐di‐(2′‐hydroxyethoxy)benzylidenecyanoacetate (3) was prepared by hydrolysis of methyl 3,4‐di‐(2′‐vinyloxyethoxy)benzylidenecyanoacetate (2). Diol 3 was condensed with 2,4‐toluenediisocyanate, 3,3′‐dimethoxy‐4,4′‐biphenylenediisocyanate, and 1,6‐hexamethylenediisocyanate to yield polyurethanes 4–6 containing the nonlinear optical chromophore 3,4‐dioxybenzylidenecyanoacetate. The resulting polyurethanes 4–6 were soluble in common organic solvents such as acetone and dimethylformamide. Polymers 4–6 indicated thermal stability up to 300 °C in thermogravimetric thermograms with glass‐transition temperature values obtained from differential scanning calorimetric thermograms in the range of 78–102 °C. The second‐harmonic generation coefficients (d33) of the poled polymer films were around 6.9 × 10−9 esu. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1742–1748, 2002
Preparation of the thermotropic copoly(amide ester) of p‐aminobenzoic acid and m‐hydroxybenzoic acid with diphenyl chlorophosphate/pyridine
Authors: Higashi Fukuji , Komatsu Masao , Takizawa Junko 
Published: August 2002

AbstractA thermotropic copoly(amide ester) exhibiting a nematic mesophase within the range of 240–360 °C was prepared by the solution copolycondensation of p‐aminobenzoic acid (40–70 mol %) and m‐hydroxybenzoic acid with diphenyl chlorophosphate in pyridine in the presence of LiCl. For control of the sequence distribution of p‐aminobenzoic acid, the amount of LiCl and the dropwise addition of the phosphate were examined. The transition temperatures (from a solid phase to a nematic mesophase) of the resultant copolymers were affected by the period of addition and the amounts of the aminobenzoic acid and LiCl and were investigated in terms of the distributions of the monomers determined by 1H NMR. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1775–1780, 2002
An efficient route for the synthesis of hyperbranched polymers and dendritic building blocks based on urea linkages
Authors: Ambade Ashootosh V. , Kumar Anil 
Published: August 2002

AbstractA highly efficient synthetic route, based on the quantitative reaction between amine and isocyanate functionalities, was used successfully for the synthesis of hyperbranched polymers and dendritic building blocks based on urea linkages. The thermal decomposition of 3,5‐diamino benzoyl azide or 5‐amino isophthaloyl azide generated in situ the corresponding phenyl isocyanates, which were then polymerized to give wholly aromatic hyperbranched polyureas. Hyperbranched polyurea with amine chain ends was soluble in common organic solvents. The degree of branching, as calculated with 1H NMR, was 0.55. Diethyl 5‐amino isophthalate and Boc‐protected 5‐amino isophthaloyl azide were used for the successful stepwise synthesis of dendritic wedges based on urea linkages. The thermal generation of the isocyanate functionality with gaseous nitrogen as the side product and its quantitative reaction with amine groups were the salient features of this convergent synthesis. This eliminated the use of chromatographic purification, an inherent part of other convergent growth approaches, and made it a very efficient synthetic route for the synthesis of dendritic wedges. The products were characterized by 1H NMR, 13C NMR, and electron spray mass spectroscopy (ESMS) techniques. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1295–1304, 2001