bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stable Free‐Radical Copolymerization of Styrene with Acrylates Using OH‐TEMPO
Authors: Appelt Mathias , Schmidt‐Naake Gudrun 
Published: March 2004

AbstractSummary: Stable free‐radical copolymerizations (SFRP) of styrene with N‐acryloyl morpholine (AMo), 2‐ethoxyethyl acrylate (EOEA) and isobornyl acrylate (iBoA), respectively, were carried out under control of the stable nitroxide radical 4‐hydroxy‐2,2,6,6‐tetramethylpiperidine‐N‐oxyl (OH‐TEMPO). The polymerizations were initiated by a polystyrene macroinitiator (PS‐MI). No accelerating agents were used. In contrast to the experiences made with methacrylates there was no decrease in the polymerization rates up to 50 mol‐% of AMo or EOEA in the monomer mixture. This behavior was ascribed to a compensation of the lack of thermal initiation by the high propagation rate constants of the acrylates. The produced AB diblock polymers were successfully employed in block extension reactions in styrene yielding ABA triblock polymers. Copolymerization reactivity ratios (r‐values) and glass transition temperatures have been estimated.Monomer structures.magnified imageMonomer structures.
Synthesis of Norbornene Derivatives by Diels‐Alder Cycloaddition and Subsequent Copolymerization with Maleic Anhydride
Authors: Pasquale Anthony J. , Fornof Ann R. , Long Timothy E. 
Published: March 2004

AbstractSummary: Several norbornene (Nb) derivatives were synthesized by facile Diels‐Alder cycloaddition reactions of cyclopentadiene with α‐olefins containing electron‐withdrawing groups such as nitrile (CN), phosphonate, and ester. The Diels‐Alder adducts were subsequently copolymerized with maleic anhydride (MAH) using free radical polymerization conditions previously determined for MAH/Nb copolymerizations. Further functionality was introduced into the copolymers through acid‐catalyzed hydrolysis of poly(Nb‐alt‐MAH) and poly(NbCN‐alt‐MAH) copolymers. FTIR confirmed hydrolysis of the anhydrides to carboxylic acid‐functionalities and indicated no appreciable hydrolysis of the nitrile functionality. Observed copolymerization rates (kobs) were measured using in situ FTIR. A dramatic decrease in the rate of copolymerization was observed for the Nb derivatives that contained a strong electron‐withdrawing functionality. This observation suggested a significant electronic influence on the free radical copolymerization rate with maleic anhydride due to the electron‐withdrawing nature of the Nb substituents.Vinylene region of in situ FTIR “waterfall” plot for 50/50 Nb/MAH alternating copolymerization.magnified imageVinylene region of in situ FTIR “waterfall” plot for 50/50 Nb/MAH alternating copolymerization.
Synthesis and ATRP Activity of New TREN‐Based Ligands
Authors: Gromada Jérôme , Spanswick James , Matyjaszewski Krzysztof 
Published: March 2004

AbstractSummary: Ligands suitable for atom transfer radical polymerization (ATRP) were prepared by the Michael addition of several acrylates (allyl, benzyl, butyl, 2‐ethylhexyl, and 3‐(dimethoxymethylsilyl)propyl acrylates) with tris(2‐aminoethyl)amine (TREN). These ligands, readily prepared from inexpensive precursors, were used for the preparation of catalyst complexes suitable for polymerization of (meth)acrylates and styrene, providing activity comparable to catalysts currently used for these monomers. Catalysts containing ligands with a dimethoxymethylsilyl substituent were examined for copper removal after the reaction mixture was contacted with silica gel.magnified image
Synthesis of Structurally‐Controlled AIDS Vaccine Model with Glyco‐Peptide Dendrimer Scaffolds
Authors: Baigude Huricha , Katsuraya Kaname , Okuyama Kohsaku , Uryu Toshiyuki 
Published: March 2004

AbstractSummary: A novel glyco‐peptide dendrimer‐type AIDS vaccine model with a well‐defined structure was synthesized. A low‐substituted, monodispersed, glyco‐peptide dendrimer was prepared by binding maltose to a proline‐poly(lysine) dendrimer with monofunctional prolyl amino groups on the periphery. To the hemispherical maltose‐proline‐poly(lysine) dendrimer, succinic anhydride was reacted to provide succinylated dendrimer with an average of 13 succinyl carboxyl groups per dendrimer. The reactivity of succinyl‐maltose‐proline‐poly(lysine) dendrimer was investigated by coupling a tripeptide to the carboxyl group in water using 1‐ethyl‐3‐(3‐dimethylaminopropyl)carbodiimide hydrochloride (EDC) as a condensing agent. By binding two kinds of peptide sequences included in the envelope glycoprotein of HIV to the dendrimer, AIDS vaccine models with glyco‐peptide dendrimer scaffold were synthesized. The structure of the vaccine models was determined by NMR and MALDI‐TOF mass analyses.Leu‐Pro‐Gly‐succinyl‐maltose‐proline‐poly(lysine) dendrimer generation 3.magnified imageLeu‐Pro‐Gly‐succinyl‐maltose‐proline‐poly(lysine) dendrimer generation 3.
Atom Transfer Radical Polymerization Using Multidentate Amine Ligands Supported on Soluble Hyperbranched Polyglycidol
Authors: Kumar Kainthan Rajesh , Kizhakkedathu Jayachandran N. , Brooks Donald E. 
Published: March 2004

AbstractSummary: Controlled polymerization of styrene in toluene was achieved by atom transfer radical polymerization (ATRP) using hyperbranched polyglycidol‐supported multidentate amine ligands/CuIBr catalyst systems. These catalyst systems with nanoscopic dimensions were more active than the corresponding low‐molecular‐weight ligands. The controlled/living nature of the polymerization is supported by linear first order plots (ln[M]o/[M] versus time) and a linear increase of $\overline M _{\rm n}$ versus conversion as well as low polydispersity. Similar controlled polymerization of methyl methacrylate was possible in acetonitrile. Up to 97% of total copper used for polymerization could be removed from the polymer by simple precipitation in methanol and filtration.Molecular weight characteristics for styrene polymerization using PG‐triamine as a ligand.magnified imageMolecular weight characteristics for styrene polymerization using PG‐triamine as a ligand.
Synthesis of a New Macromonomer from 2‐(Dimethylamino)ethyl Methacrylate Bearing 1‐(Isopropenylphenyl)‐1,1‐dimethylmethyl Isocyanate Group
Authors: Boyer Cyril , Boutevin Gilles , Robin Jean‐Jacques , Boutevin Bernard 
Published: March 2004

AbstractSummary: The telomerization of 2‐(dimethylamino)ethyl methacrylate (DMAEMA) with 2‐mercaptoethanol in acetonitrile shows that the telogen can react with the monomer by nucleophilic addition. It is to say that the tertiary amino group leads to nucleophilic addition rather than telomerization. The oligomers thus obtained were functionalized with 1‐(isopropenylphenyl)‐1,1‐dimethylmethyl isocyanate (TMI) in anhydrous toluene to afford macromonomers. These macromonomers were copolymerized with styrene and the r1, r2 ratio was determined according to Jaacks and Macret's methods. It was thereby demonstrated that the r1 value for this type of monomer is close to zero.Structure of the model molecule.magnified imageStructure of the model molecule.
A Model System for the Thermodynamic Analysis of Reaction‐Induced Phase Separation: Solutions of Polystyrene in Bifunctional Epoxy/Amine Monomers
Authors: Zucchi Ileana A. , Galante María J. , Borrajo Julio , Williams Roberto J. J. 
Published: March 2004

AbstractSummary: A model system, consisting of a linear polymer dissolved in a bifunctional monomer/co‐monomer solvent, was selected to test the applicability of the Flory‐Huggins (FH) theory in the absence of the usual assumptions present in the analysis of modified thermosetting polymers. Solutions of two almost monodisperse polystyrenes (PS, $\overline M _{\rm n}$ = 83 000 or 217 000), in diglycidyl ether of bisphenol A (DGEBA) and in stoichiometric DGEBA/BA (benzylamine) solutions, exhibited an upper critical solution temperature (UCST) behavior. Cloud‐point curves (CPC) were fitted with the FH model using an interaction parameter depending on both temperature and concentration, χ = (a + b/T)/(1 − cϕ2), where ϕ2 represents the volume fraction of PS. A group‐contribution method provided a reasonable explanation of the observed trends. Cloud‐point times in the course of the DGEBA/BA stepwise polymerization, carried out at 70 °C and 80 °C, were determined for solutions containing 2.5 to 15 wt.‐% PS ($\overline M _{\rm n}$ = 83 000). Times were transformed to conversions using kinetic curves determined by Fourier Transform Infrared Spectroscopy (FT‐IR) and Size Exclusion Chromatography (SEC). The analysis of cloud‐point conversions with the FH model was performed considering the (ideal) distribution of epoxy/amine species generated as a function of conversion. An empirical fitting of cloud‐point curves was possible with the use of an interaction parameter decreasing with conversion. Possibilities of improving the thermodynamic description of a polymerization‐induced phase separation are discussed.Cloud‐point curves for PS‐DGEBA binary solutions.magnified imageCloud‐point curves for PS‐DGEBA binary solutions.
Solid Polymer Electrolytes, 9
Authors: Liang Wuu‐Jyh , Kao Hsien‐Ming , Kuo Ping‐Lin 
Published: March 2004

AbstractSummary: A new hybrid polymer electrolyte system containing polysiloxane and polyether segments has been designed and prepared by epoxide crosslinking. The thermal behavior, structure and ionic conductivity of the hybrid materials were investigated and characterized by differential scanning calorimetry (DSC), 13C solid‐state NMR spectroscopy and alternating current (AC) impedance measurements. Two glass transition temperatures were observed, showing a dependence on the composition and LiClO4/PC content. The miscibility of the polymer components in the hybrid was studied by examining the 1H spin relaxation times in the laboratory frame (T1(H)) and in the rotating frame (T1ρ(H)) with various compositions. Multi‐relaxation T1ρ(H) behavior has been observed, indicative of the presence of structural heterogeneity on the timescale of T1ρ(H). These results are correlated and used to interpret the phenomenon of the conductivity of the lithium ion in the matrix of hybrid networks.Schematic structure of polysiloxane/polyether networks.magnified imageSchematic structure of polysiloxane/polyether networks.
Retarded Anionic Polymerization: Copolymerization of Butadiene and Styrene in the Presence of Alkyllithium and n,s‐Dibutylmagnesium or Triisobutylaluminium Derivatives
Authors: Carlotti Stéphane , Ménoret Stéphane , Barabanova Anna , Desbois Philippe , Deffieux Alain 
Published: March 2004

AbstractSummary: The influence of Lewis acid additives on the anionic butadiene polymerization using lithium as a counter ion in non‐polar solvent is investigated. A decrease of the polymerization rate was always observed. In the presence of n,s‐Bu2Mg the percentage of 1,2‐vinyl units increases with the [Mg]/[Li] ratio. This evolution can be explained by further complexation of lithium with free dialkylmagnesium modifying the nature of the propagating species and/or possible 1,4 to 1,2 isomerization during chain exchanges between lithium and magnesium derivatives. As a result of the transmetallation process, 0.5 to 1 supplementary chains are formed by magnesium depending on the [Mg]/[Li] ratio. In contrast, the iBu3Al/RLi system does not yield any modification of polybutadiene microstructure, which remains close to the one observed with s‐BuLi alone. The determination of the reactivity ratios in styrene‐butadiene copolymerization shows that tapered‐like copolymers are obtained in the presence of both n,s‐Bu2Mg and iBu3Al. However the magnesium derivative induces a lesser increase of styrene incorporation in the copolymer than the aluminium additive. The observed microstructure and reactivity ratios support that the monomer insertion proceeds directly into heterocomplexes.magnified image
Non‐Isothermal Crystallization of Poly(trimethylene terephthalate) (PTT)/Clay Nanocomposites
Authors: Hu Xianbo , Lesser Alan J. 
Published: March 2004

AbstractSummary: The non‐isothermal crystallization of intercalated poly(trimethylene terephthalate) (PTT)/clay nanocomposites was investigated quantitatively by different methods. Non‐isothermal crystallization of pure PTT can be described by the Ozawa equation, but the Ozawa theory is not valid for PTT/clay nanocomposites. The addition of clay into PTT decreases the crystallization half‐time while increasing the crystallinity and crystallization rate. The PTT/modified clay nanocomposites, in turn, have a higher crystallization rate parameter, k1/n, and a lower crystallization half‐time compared to unmodified clay/PTT composites. The crystallization activation energy, calculated from Kissinger equation, of PTT, PTT/unmodified clay, and PTT/modified clay composites are 100, 180, and 198–230 kJ · mol−1, respectively. Similarly, the nucleating activities of the unmodified clay and modified clays are 0.73 and 0.51–0.58, respectively. Although the addition of clay increases the crystallization activation energy, the clay still acts as an effective nucleating agent and increases the crystallization rate and crystallinity of PTT. Further, the modified nanoscale clays are more effective nucleating agents than the unmodified counterparts, and the most effective nucleating concentration of nano‐clay is between 1.0–3.0 wt.‐%.The crystallization half‐time, t1/2, decreases as a function of cooling rate, Q, and decreases with an increase in clay concentration.magnified imageThe crystallization half‐time, t1/2, decreases as a function of cooling rate, Q, and decreases with an increase in clay concentration.
Cholesteric Liquid‐Crystalline Side‐on Polysiloxanes: Effects of Biaxiality on the Cholesteric Structure
Authors: Ogawa Hiroshi , Stibal‐Fischer Elke , Finkelmann Heino 
Published: March 2004

AbstractSummary: Biaxial side‐on cholesteric copolysiloxanes with laterally attached mesogenic groups were investigated in mixtures with a low molar mass liquid crystal. While mixtures with a low concentration of the polymer exhibit the conventional fingerprint texture, for concentrations above about 60 mol‐% characteristic irregularities appear in the cholesteric structure that are obviously due to phase biaxiality. Besides the absence of pseudo‐isotropic lines, irregular patterns perpendicular to the helix axis emerge and the periodic distance of regions with similar optical properties along the helix axis is strongly disturbed. This suggests that the photonic band gap width of a uniaxial cholesteric phase becomes strongly affected when a phase transformation into a biaxial cholesteric phase occurs.Cholesteric fingerprint texture of a mixture of uniaxial nematic monomer and biaxial cholesteric polymer.magnified imageCholesteric fingerprint texture of a mixture of uniaxial nematic monomer and biaxial cholesteric polymer.
Golden‐age gambling: Psychological benefits and self‐concept dynamics in aging consumers' consumption experiences
Authors: Loroz Peggy Sue 
Published: March 2004

AbstractPhenomenological investigation of casino gambling among older consumers yields the identification of the psychological benefits of this consumption experience for this population. Control, Lift, and Escape emerge as central themes as older consumers' gambling experiences unfold, and the elements and psychological outcomes of each of these themes are discussed. Through interpretive analysis, a conceptual framework is developed in which these factors serve an intermediary role between the more shallow hedonic responses of “fantasies, feelings, and fun” (Holbrook & Hirschman, 1982) and deeper aspects of the self. It is proposed that the psychological benefits of gambling and other forms of experiential consumption may ultimately reinforce and enhance seniors' self‐concepts. © 2004 Wiley Periodicals, Inc.
Hope, hopelessness, and coping: A framework for class‐distinctive cognitive capital
Authors: Henry Paul 
Published: March 2004

AbstractEvidence that a variety of psychological dispositions vary systematically with social class has been reported in the marketing literature over the last 50 years. However, recent work has been extremely limited. Research progress has been stifled because of poor conceptual specification and lack of an integrative framework capable of grounding these dispositions in theory. This article draws upon the psychology of coping—specifically harnessing hope/hopelessness theories—to develop a much‐needed framework. This will facilitate clear conceptual specification of the psychological dispositions where social class distinctions have been proposed, and specify the relations between each of the dispositions. The term cognitive capital is introduced to capture the idea that one's mix of psychological dispositions operates as a system that can be thought of as an important type of resource that is gradationally distributed with social class level. This cognitive‐capital system impacts life chances and quality‐of‐life outcomes via the predominant pattern of coping responses that are employed in dealing with the many adversities, threats, and challenges that life typically presents. The framework provides academics with a vehicle to progress understanding of these psychological phenomena, marketing communicators with an enriched picture of class‐based distinctions, and public policy makers with an understanding of levers that contribute to social inequality. © 2004 Wiley Periodicals, Inc.
Plasma‐Initiated Controlled/Living Radical Polymerization of Methyl Methacrylate in the Presence of 2‐Cyanoprop‐2‐yl 1‐dithionaphthalate (CPDN)
Authors: Chen Gaojian , Zhu Xiulin , Zhu Jian , Cheng Zhenping 
Published: March 2004

AbstractSummary: Plasma‐initiated controlled/living radical polymerization of methyl methacrylate (MMA) was carried out in the presence of 2‐cyanoprop‐2‐yl 1‐dithionaphthalate. Well‐defined poly(methyl methacrylate) (PMMA), with a narrow polydispersity, could be synthesized. The polymerization is proposed to occur via a RAFT mechanism. Chain‐extension reactions were also successfully carried out to obtain higher molecular weight PMMA and PMMA‐block‐PSt copolymer.Dependence of ln([M]0/[M]) on post‐polymerization time (above), and \overline M _{\rm n} and PDI against conversion (below) for plasma initiated RAFT polymerization of MMA at 25 °C.magnified imageDependence of ln([M]0/[M]) on post‐polymerization time (above), and \overline M _{\rm n} and PDI against conversion (below) for plasma initiated RAFT polymerization of MMA at 25 °C.
New Method of Synthesis of Poly(ester amide)s Derived from the Incorporation of Glycolic Acid Residues into Aliphatic Polyamides
Authors: Vera Montserrat , Rodríguez‐Galán Alfonso , Puiggalí Jordi 
Published: March 2004

AbstractSummary: A new method for the preparation of poly(ester amide)s derived from glycolic acid units has been developed. Glycolic acid units can be incorporated with a high yield into a nylon‐n or a nylon‐n,m. The synthesis is based on a final thermal polycondensation with the formation of a metal halide salt as a driving force. New poly(ester amide)s have high molecular weights, good mechanical behaviour, and variable thermal properties, giving rise to a group of materials with potential interest as biodegradable materials in applications like surgical sutures.Results of the differential scanning calorimeter heating runs for the sodium (a) and potassium (b) salts of N‐chloroacetyl‐6‐aminohexanoic acid.magnified imageResults of the differential scanning calorimeter heating runs for the sodium (a) and potassium (b) salts of N‐chloroacetyl‐6‐aminohexanoic acid.
Synthesis and Characterization of a Novel Calix[4]arene‐Based Periodic Mesoporous Organosilica
Authors: Liu Chunqing , Fu Lei , Economy James 
Published: March 2004

AbstractSummary: A new calix[4]arene‐based periodic mesoporous organosilica has been synthesized using tetraethoxysilane (TEOS) and a calix[4]arene‐based silane monomer as the precursors and cetyltrimethylammonium bromide (CTAB) surfactant as the structure‐directing template, and is shown to be capable of visual detection and entrapment of NO2.Synthesis of the novel mesoporous organosilica material containing covalently bound tetra‐O‐alkylated calix[4]arene hosts.magnified imageSynthesis of the novel mesoporous organosilica material containing covalently bound tetra‐O‐alkylated calix[4]arene hosts.
Narrowly Distributed Dendronized Polymethacrylates by Reversible Addition‐Fragmentation Chain Transfer (RAFT) Polymerization
Authors: Zhang Afang , Wei Liuhe , Schlüter A. Dieter 
Published: March 2004

AbstractSummary: RAFT is applied to the dendronized macromonomers of the first and second generation, 1 and 2, respectively. Good results are obtained in the presence of AIBN as radical initiator, with compound 6 as mediator and at mediator to monomer ratios of 2:200 for monomer 1 ($\overline M _{\rm n}$ = 320 000, PDI = 1.24) and monomer 2 ($\overline M _{\rm n}$ = 178 000, PDI = 1.20). The common characteristics of a controlled polymerization are reasonably met. The more sterically demanding G2 monomer 2 requires higher polymerization temperatures.
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A Mixed Ruthenium Polypyridyl Complex Containing a PEG‐Bipyridine Macroligand
Authors: Marin Veronica , Holder Elisabeth , Meier Michael A. R. , Hoogenboom Richard , Schubert Ulrich S. 
Published: March 2004

AbstractSummary: An amino‐functionalized bipyridine ligand was prepared in order to serve as a bridging unit to an activated low‐molecular‐weight monomethyl ether of poly(ethylene glycol) (PEG). Coordination of a ruthenium(II) phenantroline precursor onto the formed PEG‐containing bipyridine ligand yielded a metal‐containing polymer which shows interesting properties for solar cell applications.A schematic of the described polymeric ruthenium(II) complex and its absorption and emission properties.magnified imageA schematic of the described polymeric ruthenium(II) complex and its absorption and emission properties.
Effects of the Bead‐Solvent Interaction on the Dynamics of Macromolecules, 1
Authors: Uvarov Alexander , Fritzsche Stephan 
Published: March 2004

AbstractSummary: Hamiltonian dynamics and a chain model are used to study the dynamics of macromolecules immersed in a solution. From the Hamiltonian of the overall system, “macromolecule + solvent,” a master and a Fokker‐Planck equation are then derived for the phase‐space distribution of the macromolecule. In the Fokker‐Planck equation, all the information about the interaction among the beads of the macromolecule as well as the effects of the surrounding solvent is described by friction tensors, which are expressed in terms of the bead‐solvent interaction and the dynamic structure factor of the solvent. To explore the influence of the bead‐solvent potential on the dynamics of macromolecules, the friction tensors are calculated for a dumbbell molecule and for three choices of the interaction (Yukawa, Born‐Mayer, and Lennard‐Jones). Expressions are derived, in particular, for the friction tensor coefficients of the center‐of‐mass and the relative coordinates of the dumbbell. For the long‐term behaviour of the internal momentum autocorrelation function, moreover, an “algebraic decay” is found, in contrast to the (unphysical) exponential decay as known from phenomenological theory.Yukawa, Born‐Mayer and Lennard‐Jones bead‐solvent interaction potentials.imageYukawa, Born‐Mayer and Lennard‐Jones bead‐solvent interaction potentials.