bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and Micellization of Star‐Shaped Poly(ethylene glycol)‐block‐Poly(ε‐caprolactone)
Authors: Kim Keon Hyeong , Cui Guo Hua , Lim Hyung Jun , Huh June , Ahn Cheol‐Hee , Jo Won Ho 
Published: August 2004

AbstractSummary: The relationship between the architecture of block copolymers and their micellar properties was investigated. Diblock, 3‐arm star‐shaped and 4‐arm star‐shaped block copolymers based on poly(ethylene glycol) and poly(ε‐caprolactone) were synthesized. Micelles of star‐shaped block copolymer in an aqueous solution were then prepared by a solvent evaporation method. The critical micelle concentration and the size of the micelles were measured by the steady‐state pyrene fluorescence method and dynamic light scattering, respectively. The CMC decreased in the order di‐, 3‐arm star‐shaped and 4‐arm star‐shaped block copolymer. The size of the micelles increased in the same order as the CMC. Theory also predicts that the formation of micelles becomes easier for 4‐arm star‐shaped block copolymers than for di‐ and 3‐arm star‐shaped block copolymers, which qualitatively agrees with the experiments.
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Effect of Ethanol on the Rheological Properties of Water‐Rich Gels of Diblock Copolymer E43B11
Authors: Kelarakis Antonis , Havredaki Vasiliki , Booth Colin 
Published: August 2004

AbstractSummary: The effect of added ethanol on the rheological behaviour of aqueous solutions of diblock copolymer E43B11 (E = oxyethylene unit, B = oxybutylene unit) has been investigated. Thermally reversible sol‐gel transitions were observed for concentrated solutions of the copolymer in solutions containing 0–30 wt.‐% ethanol. Storage (G′) and loss (G″) moduli and yield stress (σy) were used to define hard and soft gel phases. The introduction of 10 wt.‐% ethanol did not alter the phase behaviour greatly, whereas higher ethanol concentrations had a large effect, which differed in kind from that reported for triblock copolymers of ethylene oxide and propylene oxide, type EPE.Temperature dependence of the logarithm of (•) storage and (○) loss modulus for 20 wt.‐% copolymer in 10 wt.‐% ethanol.magnified imageTemperature dependence of the logarithm of (•) storage and (○) loss modulus for 20 wt.‐% copolymer in 10 wt.‐% ethanol.
Cationic Polymerization of 2‐Vinylthiophene by Chloroarylmethanes as Surface Initiators on Silica and Consecutive Hydride Abstraction by Acceptors
Authors: Höhne Susanne , Seifert Andreas , Friedrich Manfred , Holze Rudolf , Spange Stefan 
Published: August 2004

AbstractSummary: 2‐Vinylthiophene (2‐VT) has been cationically polymerized using chloroarylmethane derivatives as the surface polymerization initiator on silica. By applying this procedure a soluble fraction of poly(vinylthiophene) (PVT) and PVT/silica composites can be simultaneously synthesized. The mass balance of the products (soluble fraction and hybrid particle fraction) depends significantly on temperature and 2‐VT/silica ratio. The hydride abstraction reaction of PVT both in solution and immobilized on silica particle surface has been studied using 2,3‐dichloro‐5,6‐dicyano‐1,4‐quinone (DDQ), tetrachloro‐1,4‐quinone (chloranile = ClA) and triphenylmethylium as reagents. The transformation process of PVT towards conjugated polymers has been studied with UV‐vis spectroscopy and ESR spectroscopy. Cyclic voltammetry shows that chloranil is complexated with the formed polymer. Radical formation increases with increasing degree of conversion. The soluble fraction of the conjugated PVT sections formed is capable of reacting with each other as evidenced by GPC data. Structure of PVT/silica and resulting hybrid materials have been investigated by solid state 13C {1H} CP MAS NMR‐spectroscopy showing a reaction of methine and methylene hydrogen atoms after treatment with DDQ or chloranil as hydride acceptors. For all poly‐(2‐vinylthiophene)/hydride acceptor systems studied, chloranil has been found to be the best reagent for the transformation of PVT towards conjugated polymers.Transformation of PVT in poly(2‐ethinylthiophene) (PET) and PVT‐PET copolymers.magnified imageTransformation of PVT in poly(2‐ethinylthiophene) (PET) and PVT‐PET copolymers.
Block Copolymers Build‐up of Electron and Hole Transport Materials
Authors: Behl Marc , Zentel Rudolf 
Published: August 2004

AbstractSummary: In this article we describe the synthesis of various monomers modified with triphenyl‐1,3,5‐triazine side groups as electron transport moieties. By nitroxide‐mediated polymerization with a TEMPO unimer it was possible to obtain polymers with a narrow polydispersity. Furthermore, by living radical polymerization block copolymers were obtained from these monomers. Therefore, microphase separated structures are accessible which possess hole conducting moieties in one phase and electron conducting moieties in the other phase.General build‐up of the copolymers consisting of hole and electron conductor.magnified imageGeneral build‐up of the copolymers consisting of hole and electron conductor.
Demonstration of the Existence of Long‐Lived Species in the Cationic Polymerization of 1,3‐Pentadiene Initiated by Aluminium Trichloride in Non Polar Solvent
Authors: Bennevault‐Celton Véronique , Delfour Marilyn , Cheradame Hervé 
Published: August 2004

AbstractSummary: A kinetic study of the polymerization of a mixture of 1,3‐pentadiene isomers initiated by AlCl3 was carried out in pentane at −10 and 20 °C. A second apparent monomer order was found mainly at room temperature and was explained by a complexation of propagating active centers by the polymer, the true monomer order being first. This apparent order did not result from the presence of the two isomers in the monomer mixture. Kinetic simulations confirmed this interpretation and pointed out the fact that the interaction between the polymer and the active centers was stronger at −10 °C, thus limiting the polymer conversion at this temperature. The novelty of these findings lies in the fact that the inactive complexed centers can be activated by reaction with the monomer, providing active species when necessary. The existence of active centers even after a long reaction time at room temperature, and the reactivation of the complexed centers, was evidenced by incremental monomer addition and by the formation of sulfonium ions after quenching the polymerization by an excess of dimethyl sulfide. The latter were characterized by 1H NMR spectroscopy.Complexation of propagating active centers by the polymer giving dormant species (C+/P), with following reactivation by a new monomer charge.magnified imageComplexation of propagating active centers by the polymer giving dormant species (C+/P), with following reactivation by a new monomer charge.
Effect of Macrocycles on the Temperature‐Responsiveness of Poly[(methoxy diethylene glycol methacrylate)‐graft‐PEG]
Authors: Kitano Hiromi , Hirabayashi Tadashi , Gemmei‐Ide Makoto , Kyogoku Mayumi 
Published: August 2004

AbstractSummary: A homopolymer of 2‐(2′‐methoxyethoxy)ethyl methacrylate (DM) dissolved in pure water demonstrated an abrupt increase in its turbidity at a critical temperature (LCST). Meanwhile, the LCST for a copolymer of DM and ω‐methoxy(oligoethyleneoxy)ethyl methacrylate (PaM) (PDMPaM) significantly increased with increasing content of PaM residue. Furthermore, the addition of macrocycles such as hexasodium calix[6]arenehexasulfonic acid (SCX6), α‐cyclodextrin (α‐CD) and 2,6‐di‐O‐methyl‐β‐cyclodextrin (DM‐β‐CD) changed the LCST. SCX6 raised the LCST significantly, DM‐β‐CD slightly raised the LCST and α‐CD slightly lowered it. These phenomena could be attributed to the formation of an inclusion complex (polypseudorotaxane) at the grafted PEG chain of the copolymer. ROESY, fluorescence measurements and the viscosity behavior of the SCX6‐PEG dimethylether (PEG‐DME) mixture supported the theory of the complexation of SCX6 with the PEG chain. The apparent association constants (Kapp) of PEG‐DME or grafted PEG with SCX6 and α‐CD were determined using fluorescence and UV‐vis absorption measurements, respectively. The complexation of the SCX6‐polymer conjugate with PDMPaM was also examined by time‐evolution measurements of the turbidity. The effect of the structure of guest and host molecules on the LCST for the copolymer was discussed in detail.Schematic representation of the formation of polypseudorotaxane of PDMPaM with SCX6.magnified imageSchematic representation of the formation of polypseudorotaxane of PDMPaM with SCX6.
Preparation of Scratch and Abrasion Resistant Polymeric Nanocomposites by Monomer Grafting onto Nanoparticles, 5
Authors: Bauer Frank , Ernst Horst , Hirsch Dietmar , Naumov Sergej , Pelzing Mathias , Sauerland Volker , Mehnert Reiner 
Published: August 2004

AbstractSummary: Reinforced clear coats were prepared using nanosized silica and alumina particles in UV/EB curable acrylate formulations. For a firm embedding of the oxide nanofillers via covalent bonds to the network acrylates their surfaces were modified by polymerization‐active trialkoxysilanes, e.g., methacryloxypropyltrimethoxysilane and vinyltrimethoxysilane. The cured nanocomposite clear coats showed improved scratch and abrasion resistance. However, oxide modifications accomplished by silanes having polymerization‐inactive methyl, propyl, and isobutyl functionalities yield coatings with similar scratch and abrasion resistance. To explain these findings, infrared and multinuclear MAS NMR experiments, MALDI‐TOF and ESI‐MSn mass spectroscopy, and atomic force microscopy results were used to reveal the structure of surface‐anchored organosilanes and their interaction with the acrylate matrix. Ladder‐like polysiloxane chains chemically grafted onto the filler particles have been proposed. These ladder‐like structures build a short range interpenetrating network with the polyacrylates. This results in a durable link between the organic and inorganic phase.Proposed ladder‐like arrangement of T3 structure of silicon atoms in MEMO polysiloxanes grafted on silica surface.magnified imageProposed ladder‐like arrangement of T3 structure of silicon atoms in MEMO polysiloxanes grafted on silica surface.
Effects of Residual Nuclei on Crystals and Equilibrium Melting Points of Dual Crystals in Poly(ethylene 2,6‐naphthalene‐dicarboxylate)
Authors: Woo Eamor , Huang Doan‐Ho , Wu Ming‐Chien 
Published: August 2004

AbstractSummary: The crystal structures and possible transformations in poly(ethylene naphthalate) (PEN) were examined using differential scanning calorimetry (DSC) and wide‐angle X‐ray diffraction (WAXD). The crystal cells (α‐ and β‐form) were dependent on several factors related to their thermal histories. For PEN subjected to Tmax = 280 °C (where Tmax is the maximum melt temperature at which the samples were treated before crystallization), only the α‐form developed regardless of the temperature of crystallization or cooling rate. However, for PEN subjected to Tmax = 300 °C, PEN developed mixed dual crystals, with greater fractions of the α‐form at low temperatures of crystallization (220 °C or lower) or higher cooling rates, but higher β‐form fractions at higher crystallization temperatures (>230 °C). The difference in the relative stability of these two crystals was utilized to prepare PEN containing only the α‐form or only the β‐form. The equilibrium melting temperatures of these two crystal forms in PEN were then measured separately. For PEN containing only the β‐form, T (289.3 °C) was found by using the Hoffman‐Weeks technique, while for PEN containing only the α‐form, T was determined using the same technique but was found to be lower (282.6 °C).Comparison of Hoffman‐Weeks extrapolations for the α‐crystal and β‐crystal, respectively, in PEN.magnified imageComparison of Hoffman‐Weeks extrapolations for the α‐crystal and β‐crystal, respectively, in PEN.
Unexpected Formation of Atactic Blocks in Propylene/1‐Pentene Copolymers from rac‐Me2Si(2‐MeBenz[e]Ind)2ZrCl2
Authors: Sacchi Maria Carmela , Forlini Fabrizio , Tritto Incoronata , Stagnaro Paola 
Published: August 2004

AbstractSummary: Supplementary experimental findings are reported in addition to those presented in a previous paper dealing with the microstructure of propylene/1‐pentene copolymers prepared with rac‐Me2Si(2‐MeBenz[e]Ind)2ZrCl2. The fractionation results which demonstrate that the atactic part of the copolymer can not be separated from the isotactic one confute the hypothesis suggested by other authors according to which the catalyst used could contain a percent of impurities of the meso (aspecific) form. This evidence is in agreement with the observed narrow polydispersities and the almost random distribution of the comonomers (rP · rCm ≈ 1) which are typical of single site catalysts.13C NMR methyl region of pentane‐soluble (a) and pentane‐insoluble (b) fractions of copolymer prepared with MBI.magnified image13C NMR methyl region of pentane‐soluble (a) and pentane‐insoluble (b) fractions of copolymer prepared with MBI.
Cover Picture: Macromol. Chem. Phys. 12/2004
Authors: Woo Eamor , Huang Doan‐Ho , Wu Ming‐Chien 
Published: August 2004

Back Cover: The Figure on the cover shows a comparison of Hoffman‐Weeks extrapolations for poly(ethylene 2,6‐naphthalene‐dicarboxylate) (PEN) specimens containing only α‐crystal and β‐crystal, respectively. The insets show x‐ray diffraction patterns of PEN melt crystallized in two steps with different maximum melt temperatures before crystallization. The thermal history is an important factor which influences the formation of the crystal cells.Further details can be found in the Full Paper by E.‐M. Woo,* D.‐H. Huang, and M.‐C. Wu on page 1644.
Synthesis and Characterization of New Aromatic Polyamides with N,N′‐Di(4‐n‐alkylphenyl)benzodiimide Unit on the Main Chain
Authors: Choi Kyung Ho , Jung Jin Chul 
Published: August 2004

AbstractSummary: New aromatic polyamides containing two n‐alkylphenylimide units fused to the main chain were prepared by the activated polyamidation of 3,6‐di(4‐carboxyphenyl)‐N,N′‐di(4‐n‐alkylphenyl)pyromellitimides (CmDA, m = 0, 8, 12, 16) with oxy‐4,4′‐dianiline in a mixture of N‐methylpyrrolidone and pyridine (Py) in the presence of triphenyl phosphite and CaCl2. The imide‐containing dicarboxylic acid monomers were synthesized by the imidization of 3,6‐di(4‐carboxyphenyl)pyromellitic dianhydride with 4‐n‐alkylanilines. The polymers showed both enhanced thermal stability and excellent solubility due to the presence of thermally stable pendent imido groups and internally plasticizing n‐alkyl chains. Their glass transition temperatures were between 225 and 285 °C and decreased with increasing side chain length. Wide‐angle X‐ray diffraction investigations revealed that all the polymers are amorphous and have typical layered structures formed by n‐alkyl side chains.
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Structure and Properties of Compatible PPSF‐Rich Blends with PET
Authors: Retolaza Aritz , Eguiazábal José I. , Nazábal Jon 
Published: August 2004

AbstractSummary: New PPSF/PET (poly(phenyl sulfone)/poly(ethylene terephthalate)) blends rich in PPSF were obtained by direct injection molding. Biphasic morphologies with a very large interface area/dispersed phase volume ratio were obtained and were attributed to a low interfacial tension in the melt state, a consequence of the reactions observed between the components of the blends. This favorable morphology led to small strain mechanical properties close or slightly above those predicted by the direct rule of mixtures, and more significantly, to elongations at break of the blends higher than that of the PPSF matrix.Morphology of the cryogenically‐broken etched surface of a PPSF/PET 75/25 blend.magnified imageMorphology of the cryogenically‐broken etched surface of a PPSF/PET 75/25 blend.
On Toughness and Stiffness of Poly(butylene terephthalate) with Epoxide‐Containing Elastomer by Reactive Extrusion
Authors: Yu Zhong‐Zhen , Yan Cheng , Dasari Aravind , Dai Shaocong , Mai Yiu‐Wing , Yang Mingshu 
Published: August 2004

AbstractSummary: To obtain a balance between toughness (as measured by notched impact strength) and elastic stiffness of poly(butylene terephthalate) (PBT), a small amount of tetra‐functional epoxy monomer was incorporated into PBT/[ethylene/methyl acrylate/glycidyl methacrylate terpolymer (E‐MA‐GMA)] blends during the reactive extrusion process. The effectiveness of toughening by E‐MA‐GMA and the effect of the epoxy monomer were investigated. It was found that E‐MA‐GMA was finely dispersed in PBT matrix, whose toughness was significantly enhanced, but the stiffness decreased linearly, with increasing E‐MA‐GMA content. Addition of 0.2 phr epoxy monomer was noted to further improve the dispersion of E‐MA‐GMA particles by increasing the viscosity of the PBT matrix. While use of epoxy monomer had little influence on the notched impact strength of the blends, there was a distinct increase in the elastic stiffness. SEM micrographs of impact‐fracture surfaces indicated that extensive matrix shear yielding was the main impact energy dissipation mechanism in both types of blends, with or without epoxy monomer, and containing 20 wt.‐% or more elastomer.SEM micrographs of freeze‐fractured surfaces of PBT/E‐MA‐GMA blend illustrating the finer dispersion of E‐MA‐GMA in the presence of epoxy monomer.magnified imageSEM micrographs of freeze‐fractured surfaces of PBT/E‐MA‐GMA blend illustrating the finer dispersion of E‐MA‐GMA in the presence of epoxy monomer.
Compatibilization of Poly(propylene)/Polyamide 6 Blends with Functionalized Poly(propylene)s Prepared with Metallocene Catalyst
Authors: Hippi Ulla , Korhonen Maija , Paavola Santeri , Seppälä Jukka 
Published: August 2004

AbstractSummary: Propylene was copolymerized with 10‐undecen‐1‐ol using dimethylsilanylbis(2‐methyl‐4‐phenyl‐1‐indenyl)zirconium dichloride as catalyst and MAO and TIBA as cocatalysts. Comonomer incorporations from 0.1 to 0.9 mol‐% (0.5 to 3.6 wt.‐%) were obtained. These hydroxyl functionalized copolymers were applied as compatibilizers to PP/PA6 blend with a composition of 70/30. For comparison, hydroxyl functionalized polyethylene prepared with metallocene catalyst and commercial MAH grafted ethylene butyl acrylate (E/BA/MAH) and poly(propylene) (PP‐g‐MAH) were also used as compatibilizers. Effects of the compatibilizers on morphology and mechanical and thermal properties of the blends were studied. Enhanced adhesion between the blend components was observed in morphology and dynamic mechanical studies. Although improvement in toughness was not as pronounced as expected, there were indications that the hydroxyl functionalized propylene copolymers prepared with metallocene catalysts could serve as a new type of compatibilizer in polymer blends.SEM micrograph (5 000×) of an PP/PA6/PP‐co‐OH4 blend.magnified imageSEM micrograph (5 000×) of an PP/PA6/PP‐co‐OH4 blend.
A Novel Phosphorus‐Containing Polymer as a Highly Effective Flame Retardant
Authors: Chang Yu‐Long , Wang Yu‐Zhong , Ban Da‐Ming , Yang Bing , Zhao Guo‐Ming 
Published: August 2004

AbstractSummary: A novel phosphorus‐containing polymeric retardant, WLA‐3, was synthesized from phenylphosphonic dichloride (PPD) and 2‐(6‐oxido‐6H‐dibenz〈c,e〉〈1,2〉oxaphosphorin‐6‐yl) 1, 4‐benzenediol (ODOPB). The flame‐retardant element, phosphorus, was bonded both in the main chains and in the pendant chains of flame‐retardant polymer molecules, and reached a content of 13.8%. The high phosphorus content and rich aryl group structures of WLA‐3 contribute an excellent flame retardancy to poly(ethylene terephthalate) (PET) without a considerable decrease of mechanical properties. WLA‐3 is also very effective in improving flame retardancy of epoxy resin and unsaturated polyester.
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Reaction Calorimetry in Supercritical Carbon Dioxide
Authors: Fortini Sophie , Lavanchy Frédéric , Meyer Thierry 
Published: August 2004

AbstractSummary: Reaction calorimetry is an efficient tool used to obtain kinetic, thermodynamic and safety data. A reaction calorimeter, RC1e‐HP350, developed in collaboration with Mettler‐Toledo GmbH, allows investigating chemical reactions under supercritical conditions. The main technical difference, compared with a classical liquid system, is that the whole reactor volume is occupied by the media. Heat transfer analysis in supercritical carbon dioxide (scCO2) by the Wilson plot method shows that the behavior of the internal heat transfer coefficient in scCO2 is the opposite of the one observed for classical liquid. In scCO2 the lower the temperature (above the critical point) the better the internal heat transfer coefficient. The evolution of scCO2 thermodynamical and transport properties near the critical point are responsible for this behavior. The dispersion polymerization of methyl methacrylate in scCO2, with the polydimethylsiloxane monomethacrylate as stabilizer, is used as a model reaction. A polymerization reaction enthalpy of −56.9 ± 2.2 kJ · mol−1 is determined, being in good agreement with previously reported data. The results presented illustrate the accuracy of the heat balance model used and emphasize the potential of reaction calorimetry for the promotion of supercritical fluids technologies.Technical comparison between liquid and supercritical reaction calorimetry.magnified imageTechnical comparison between liquid and supercritical reaction calorimetry.
Fluorinated Hyperbranched Polymers as Additives in Cationic Photopolymerization
Authors: Sangermano Marco , Malucelli Giulio , Bongiovanni Roberta , Vescovo Lorenzo , Priola Aldo , Thomas Richard R. , Kim Yongsin , Kausch Charles M. 
Published: August 2004

AbstractSummary: Different fluorinated hyperbranched polymers (HBP) were synthesized starting from fluorinated oxetanes and employed as additives in cationic photopolymerization of epoxy monomers. As previously observed for other hydroxyl containing HBP, they interact with the polymeric carbocation through a chain transfer mechanism inducing an increase in the final epoxy conversion. High gel content values (>96%) for the photocured films confirm that the HBP additive is tightly crosslinked to the polymeric network. In the presence of this fluorine‐containing HBP it is possible to influence the bulk properties, as well as, the surface properties. The fluorinated HBP tends to migrate to the surface inducing an increase of hydrophobicity.The hyperbranched polymer used in this work.magnified imageThe hyperbranched polymer used in this work.
Preparation of Poly(3,4‐ethylenedioxythiophene) in a Chiral Nematic Liquid‐Crystal Field
Authors: Goto Hiromasa , Akagi Kazuo 
Published: August 2004

AbstractSummary: The 3,4‐ethylenedioxythiophene (EDOT) monomer in a chiral nematic liquid‐crystal electrolyte was polymerized by application of a voltage to yield a thin film. Circular dichroism measurements indicated a Cotton effect for the film. Optical texture suggests that the polymer shows a finger‐print texture and a spiral texture similar to that of the chiral nematic phase. This simple method provides a new technique for preparing chiral conducting films in a thermotropic chiral liquid‐crystal field.Optical micrograph of (R)‐PEDOT* (no polarizer).imageOptical micrograph of (R)‐PEDOT* (no polarizer).
Stability of Nanoporous Materials
Authors: Muralidharan Vijayanand , Hui Chung‐Yuen 
Published: August 2004

AbstractSummary: The stability of nanoporous materials as a result of surface interaction forces has been considered in this paper. We show that cylindrical pores in linear elastic materials will collapse if α = γ/μA > 2. As one would expect physically, smaller cavities tend to be more unstable for the same surface energy and material properties as a result of the high internal Laplace pressure. Extensions to account for large deformation and strain‐hardening effects and for viscoelastic materials are discussed.Normalized potential energy versus cavity stretch for the well‐known Neo–Hookean material model. The equilibrium solution shifts to the left as the parameter α increases, implying a greater cavity shrinkage.imageNormalized potential energy versus cavity stretch for the well‐known Neo–Hookean material model. The equilibrium solution shifts to the left as the parameter α increases, implying a greater cavity shrinkage.