bluuebunny/crossref_metadata_2025_split huggingface dataset:
Etude de la réaction de télomérisation d'un monomère tensioactif anionique
Authors: Boutevin Bernard , Robin Jean‐Jaques , Boyer Bernard , Roque Jean‐Pierre , Senhaji Omar 
Published: April 2003

AbstractThe synthesis of a new anionic polymerizable surfactant is described. It is obtained by reaction between methacryloyl chloride and 5‐phenyl‐1‐pentanol. In a last step, the aromatic group is alkylated with succinic anhydride in order to obtain an ionic group. All products were characterized by 1H nuclear magnetic resonance and the transfer constant CT with C8H17C2H4SH and the ratio kp2/kt were determined. CT is in agreement with that of classical acrylates whereas kp2/kt is lower because of the long methacryloyl chain which reduces the propagation rate.
Living cationic polymerization of styrene by the bifunctional initiating system 1,4‐bis(1‐chloroethyl)benzene/SnCl4 in the presence of 2,6‐di‐tert‐butylpyridine
Authors: Kwon Oh‐Sig , Gho Chang Gi , Choi Byong‐Seok , Choi Sam‐Kwon 
Published: April 2003

AbstractThe polymerization of styrene was studied by using a bifunctional initiator, 1,4‐bis(1‐chloroethyl)benzene (1). It was demonstrated that living polymerization can be achieved in the styrene/1/SnCl4 system in chloroform at −15°C in the presence of 2,6‐di‐tert‐butylpyridine. The number‐average molecular weight of the obtained polymers increases with monomer conversion and with addition of a fresh feed of monomer at the end of the first‐stage polymerization. The molecular weight distribution (MWD) of the obtained polymers is narrow ratio of weight‐ to number‐average molecular weights (Mw/Mn < 1,2) throughout the polymerization. In the absence of 2,6‐di‐tert‐butylpyridine, the initiating system results polystyrene with a bimodal MWD. Also a bimodal MWD was obtained with H2O/SnCl4 as initiating system. 2,6‐Di‐tert‐butylpyridine in conjunction with H2O/SnCl4 does not lead to polymerization.
Phase transformation on heating of undercooled melt of poly(ethylene oxide)‐urea molecular complex
Authors: Bogdanov Bogdan , Michailov Marin , Uzov Christo , Gavrailova Girka 
Published: April 2003

AbstractX‐ray and calorimetric investigations of the structure and transformations on heating of quenched (undercooled) samples of poly(ethylene oxide)‐urea molecular complexes are discussed. It was established that at room temperature the undercooled melt of the molecular complex contains free urea in a tetragonal crystal modification and a high‐temperature poly(ethylene oxide)‐urea molecular complex whose crystal modification does not coincide with the known hexagonal crystal structure of the molecular complex obtained from solution or by slow cooling from the melt. It was shown that on heating this molecular complex to a temperature between 87,5 and 90°C, the hexagonal crystal modification, stable at room temperature, is obtained.
Preparation and photochemical properties of 4‐propenoylbenzil polymers
Authors: Lukáč Ivan , Hrdlovič Pavol , Schnabel Wolfram 
Published: April 2003

Abstract4‐Propenoylbenzil (PCOCO) obtained by dehydrochlorination of 4‐(3‐chloropropanoyl)benzil (CICOCO) was homo‐ and copolymerized with styrene (St) and methyl methacrylate (MMA). The polymers strongly absorb UV light at wavelengths between 300 and 400 nm. The triplet‐triplet absorption spectra of the homo‐ and copolymers and of CICOCO are bathochromically shifted relative to the spectrum of unsubstituted benzil triplets. The triplets of the homopolymer have a lifetime shorter than that of CICOCO and the copolymers, which is attributed to self‐quenching. Similar conclusions were arrived at from emission measurements. Irradiation of the copolymer PCOCO/St in dilute solution at λinc = 366 nm results in simultaneous crosslinking and mainchain degradation. Crosslinking is accomplished via combination of ketyl radicals formed by hydrogen abstraction of 1,2‐dicarbonyl groups in side chains. Therefore, crosslinking is the predominant process in solutions of hydrogen‐donating liquids such as tetrahydrofuran. Main‐chain scission is a secondary photoreaction. It primarily affords the photooxidative decomposition of 1,2‐dicarbonyl groups. Main‐chain scission predominates over crosslinking in solvents not acting as hydrogen donors such as benzene. Generally, O2 retards crosslinking and enhances main‐chain degradation.
Synthesis and thermal behavior of liquid‐crystalline block copolymers containing both main‐chain and side‐chain mesomorphic blocks
Authors: Galli Giancarlo , Chiellini Emo , Laus Michele , Bignozzi Maria Chiara , Angeloni Annino Sante , Francescangeli Oriano 
Published: April 2003

AbstractA novel type of block copolymers comprising both side‐chain and main‐chain liquid‐crystalline (LC) blocks in the same macromolecular structure was synthesized and studied. The former block was either one of two LC polymethacrylates containing an azobenzene mesogen with different substituents (block A), and the latter was a semiflexible LC polyester block (block B). Thermal, dynamic‐mechanical, and X‐ray diffraction data indicated that the two structurally different blocks were at least partly phase‐separated within the glassy and LC states. The thermodynamic phase transition parameters of block A were not affected by copolymer composition. However, significant deviations of the thermodynamic parameters of block B were observed relative to those of the corresponding homopolymers. In particular, the normalized transition enthalpies of block B were much lower, suggesting the occurrence of a more or less diffuse interphase. An increase in the nematic‐isotropic temperature was found at variance with previous results on most of the LC block copolymers, in which only one block was an LC component.
Liquid‐crystalline main‐chain polymers with a poly(p‐phenylene terephthalate) backbone, 9. Dynamic mechanical and dielectric behaviour of the polyester with 6‐(pentyloxy)hexyloxy side chains
Authors: Damman Sebastian B. , Buijs Jan A. H. M. 
Published: April 2003

AbstractIn the liquid‐crystalline polymer poly(p‐phenylene terephthalate) with dodecyloxy side chains the various possible crystalline structures of the side chain layers determine the mechanical and dielectric behaviour in the solid state. In this investigation the influence of replacement of the methylene unit at the centre of the side chain by an oxygen atom is studied by means of dynamic mechanical and dielectric measurements. It turns out that the oxygen replacement results in an obstruction of crystallization within the side‐chain layers, as is clearly manifested by the enhancement of the β‐relaxation (attributed to the amorphous side‐chain regions) and the nearly complete disappearance of the β*‐relaxation (crystalline side‐chain regions).
Synthesis of poly(9‐hexyl‐3,6‐carbazolyleneethynylene) and its model compounds
Authors: Beginn Christine , Gražulevičius Juozas V. , Strohriegl Peter , Simmerer Jürgen , Haarer Dietrich 
Published: April 2003

AbstractThe novel conjugated polymer poly(9‐hexyl‐3,6‐carbazoylyleneethylene) (16) was prepared by palladium‐catalyzed polycondensation of 3,6‐diiodo‐9‐hexylcarbazole and 3,6‐diethynyl‐9‐hexylcarbazole. The polymer has a number‐average molecular weight (M̄n) of 3 100. By fractionation a polymer with M̄n of 6 400 was obtained. Besides polycondensation, a palladium‐catalyzed bond‐opening polymerization of the triple bonds occurs as a side reaction which can be partially suppressed by lowering the reaction temperature to 60°C. Two well‐defined model compounds of the title polymer, a dimer and a trimer, were synthesized by stepwise reaction. The mass spectra of both model compounds demonstrate the remarkably high stability of the radical cations of the dimer and trimer. Since the trimer forms a stable glass it is ideally suited for the investigation of its photoconductive properties. First experiments carried out by the Time‐of‐Flight technique showed remarkably high carrier mobilities up to 2 · 10−4 cm2/(V · s) for the trimer.
Functional metallomacrocycles and their polymers, 26. Synthesis of 2‐acryloylamino‐9,16,23‐tri‐tert‐butylphthalocyanine and autoxidation of thiol with water‐soluble polymers containing cobalt(II) phthalocyaninate complex
Authors: Kimura Mutsumi , Dakeno Tomohiro , Adachi Etsuko , Koyama Toshiki , Hanabusa Kenji , Shirai Hirofusa 
Published: April 2003

AbstractThe catalytic autoxidation of 2‐mercaptoethanol was studied by using new water‐soluble polymers containing a cobalt(II) phthalocyaninate complex as a catalyst. The phthalocyanine vinyl‐monomer, 2‐acryloylamino‐9,16,23‐tri‐tert‐butylphthalocyanine (APc(t‐Bu)3), was synthesized and copolymerized with three kinds of water‐soluble monomers to result in a favorite electrostatic environment as a catalyst. The resulting cationic polymer containing a cobalt(II) phthalocyaninate complex has high activity as a catalyst for autoxidation of 2‐mercaptoethanol independent of pH. The catalystic system obeys Michaelis‐Menten kinetics with respect to substrate concentration. The rate constant k5 of the rate‐controlling step and the apparent Michaelis constant K were obtained from a Lineweaver‐Burk plot. The cationic environment on the polymeric catalyst enhances enzyme‐like activity in the neutral pH region for autoxidation of 2‐mercaptoethanol, because of the promotion of substrate dissociation and the accumulation of thiolate anions.
Bulk crystallization of solution epoxidized trans‐1,4‐polyisoprene
Authors: Vasanthan Nadarajah , Corrigan Joseph P. , Woodward Arthur E. 
Published: April 2003

AbstractCopolymers of trans‐1,4‐polyisoprene containing 2,2 mol‐%, 5,0 mol‐% and 9,8 mol‐% epoxidized units were crystallized from the melt at temperatures (Tc) of 25 to 36°C. The progress of the crystallization was monitored, and final crystallinities at Tc and after cooling to 25°C were measured using Fourier‐transform infrared spectroscopy. The morphology of samples, treated with OsO4 at 25°C after crystallization was complete, was observed using scanning electron microscopy. The crystallinity decreases linearly with increasing epoxy content at Tc = 25°C and 30°C and shows marked deviations from linearity at Tc = 36°C. Differences in morphology with epoxy content and Tc were observed. The differences in crystallinity between solution and melt crystallized samples are discussed.
Anomalies in the temperature dependence of the electrical conductivity of polypyrrole
Authors: Skákalová Viera , Fedorko Pavol , Plocharski Janusz 
Published: April 2003

AbstractAnomalies in the temperature dependence of the conductivity of BF4− doped polypyrrole were observed in cyclic measurements at temperatures between 250 K and 310 K. The anomalies were accompanied by endothermic effects in differential scanning calorimetry and are interpreted as being due to conformational changes (creation and disappearance of conformational defects) in the polymer chains. The conformational defects are supposed to influence the energy and the concentration of bipolarons and, consequently, the transport in the polymer.
A study of chain dynamics in water‐swollen gels of poly(ethylene oxide) dialkyl ethers using NMR and differential scanning calorimetry
Authors: Knowles Paul R. , Barlow Raymond J. , Heatley Frank , Booth Colin , Price Colin 
Published: April 2003

AbstractWater swollen gels of (unbranched) dialkyl ethers (n = 16, 17, 18, 20 and 21) of poly(ethylene oxide) (M̄n = 10000, 20000 and 30000) have been investigated using NMR spectroscopy and differential scanning calorimetry (DSC). Aggregates of the alkyl segments were found to undergo a ‘solid/liquid’ transition at a temperature approximating the melting point of an unbranched hydrocarbon about three to four carbon atoms shorter than the alkyl chain. Below the transition temperature, the alkyl component gave a broad NMR line whose second moment was approximately one‐quarter that of a crystalline alkane of similar length. The enthalpy of the transition was approximately one‐third that of the corresponding unbranched alkane. These results indicate a partially crystalline structure for the ‘solid’ aggregates.
Synthesis of poly(chalcone)s by polycondensation of aromatic dialdehydes with aromatic diacetyl compounds
Authors: Ueda Mitsuru , Yokoo Takayoshi , Oda Mitsuo 
Published: April 2003

AbstractPoly(chalcone)s were prepared by polycondensation of aromatic dialdehydes with aromatic diacetyl compounds in methanesulfonic acid (MSA) or phosphorus pentoxide/methanesulfonic acid (PPMA). Polycondensations proceed smoothly at room temperature and produced poly(chalcone)s with inherent viscosities up to 0,97 dL · g−1. The reaction of acetophenone with aromatic aldehydes in MSA or PPMA was studied in detail to demonstrate the feasibility for polymer formation. Poly(chalcone)s are only soluble in concentrated sulfuric acid and methanesulfonic acid at room temperature. Thermogravimetry of poly(chalcone)s showed 10% weight loss around 380 and 420°C in air and under nitrogen, respectively.
New type of polyvinylsaccharides with N,N‐dimethylbarbituric acid as a linker between sugar and styrene residue
Authors: Wulff Günter , Clarkson Guy 
Published: April 2003

AbstractA new type of polyvinylsaccharide with a CC bond between the pendent sugar and the backbone was prepared. Without use of protecting groups N,N‐dimethylbarbituric acid was used to link sugars directly to a polymerizable group. Homo‐ as well as copolymers were prepared by radical initiation. The barbiturate ring of the polymer undergoes a specific base‐catalyzed ring cleavage to give highly water‐soluble polymers. Also in copolymers with less than 32 mol‐% styrene residues water solubility is attained due to the newly formed diamide groups.
Ring‐opening metathesis polymerization of 11‐alkylidenebenzonorbornadienes
Authors: Schimetta Michael , Stelzer Franz 
Published: April 2003

Abstract11‐(α‐Phenylbenzylidene)benzonorbornadiene (3) and other similar monomers were synthesized by cycloaddition of dehydrobenzene with different fulvenes. Ring‐opening metathesis polymerization of the resulting monomers using Mo‐carbene initiators gave highly stereoregular polymers. Variation of the substituents allows control of the stereoregularity of these polymers. Poly[11‐(α‐phenylbenzylidene)benzonorbornadiene] is completely cis connected, whereas poly[11‐(α‐methylbenzylidene)benzonorbornadiene] is completely trans linked. The polymers contain two very reactive carbon‐hydrogen bonds that are both allylic and benzylic. Elimination of these bridgehead hydrogens gives a fully conjugated polymer that can be described as having “fulvenoid” or “quinoid” geometry.
The crystal and molecular structure of an asymmetric diacetylene monomer, 6‐(2‐methyl‐4‐nitroanilino)‐2,4‐hexadiyn‐1‐ol
Authors: Vlasse Marcus , Paley Mark S. 
Published: April 2003

AbstractThe crystal and molecular structure of an asymmetric diacetylene monomer has been determined from x‐ray diffraction data. The crystals, obtained from an acetone/pentane solution, are orthorhombic, Fdd2 with Z = 16 in a unit cell having dimensions of a = 42,815(6) Å, b = 22,224(5) Å, c = 4,996(1) Å. The structure was solved by direct methods and refined by leastsquares techniques to an RF of 6,4% for 988 reflections and 171 variables. The diacetylene chains are disposed in the unit cell in a complex manner in order to satisfy the hydrogen‐bonding, crystal packing, and symmetry requirements of the system. The solid state polymerization mechanism is discussed with respect to the geometric disposition of the diacetylene chains. These chains are far apart and incorrectly oriented with respect to each other to permit polymerization in the crystal by means of 1,4‐addition, consistent with the Baughman mechanistic model.
Graft copolymerization of methyl methacrylate by lithium diisopropylamide‐treated poly(vinyl propionate)
Authors: Inoki Mari , Akutsu Fumihiko , Yamaguchi Hideki , Naruchi Kiyoshi , Miura Masatoshi 
Published: April 2003

AbstractThe anionic grafting of methyl methacrylate (MMA) onto poly(vinyl propionate) (PVPr) was achieved after treatment of the latter with lithium diisopropylamide (LDA). The percentage of grafting of the polymer was between 120 and 730%, no homopolymers being obtained. The degree of lithiation was determined to be 26 mol‐% with respect to monomer units by means of deuterolysis. The hydrolysis of the graft copolymers results in the side‐chain polymers (PMMA) and poly(vinyl alcohol) (PVA). The average number of branches in the graft copolymer increases from 1 to 7 with increasing percentage of grafting. M̄w/M̄n of the side chain poymer is between 2,0 and 6,7. The low reactivity of the lithium sites may be caused by aggregation of enolates, leading of the broadening of the molecular weight distribution.
Reduction of bis(η5‐cyclopentadienyl)zirconium dichloride in the presence of methylalumoxane
Authors: Cam Darinn , Sartori Franco , Maldotti Andrea 
Published: April 2003

AbstractThe reaction occurring between bis(η5‐C5H5)ZrCl2 (C5H5 = cyclopentadienyl) and methylalumoxane (MAO) has been studied by means of electron paramagnetic resonance (EPR) spectroscopy at different zirconium concentrations and Al/Zr mole ratios. The toluene solution of bis(η5‐C5H5)ZrCl2/methylalumoxane, in the absence of ethylene, was verified to be more stable than the catalytic system based on bis(η5‐C5H5)TiCl2/AIR3 (R = alkyl). Zr(IV) was reduced to Zr(III) in small amounts with a Landé factor g = 1,998 and a hyperfine interaction splitting constant α (91Zr) = 7 G. The presence of ethylene strongly increased the efficiency of the Zr(IV) to Zr(III) reduction. Simultaneously it modified the chemical electronic surrounding of the Zr nucleus as revealed by the sharp increase of α(91Zr) = 12 G.
Enhancement of miscibility between hemicellulose and lignin by addition of their copolymer, the lignin‐carbohydrate complex
Authors: Shigematsu Mikiji , Morita Mitsuhiro , Sakata Isao , Tanahashi Mitsuhiko 
Published: April 2003

AbstractThe miscibility between hemicellulose and lignin from beech wood was investigated from observation of their glass transition temperature, along with the effect of addition of their copolymer, the lignin‐carbohydrate complex (LCC). The binary and ternary blend systems of hemicellulose, lignin and LCC change from immiscible to miscible by increasing the temperature. This behavior shows that this blend system has an upper critical solution temperature (UCST). The binodal temperature decreases with increasing amount of LCC added. This behavior was analyzed by the temperature and composition dependence of the Flory polymer‐polymer interaction parameter (χ12). The value of χ12 estimated from the phase diagrams indicates that χ12 decreases with an increase in both the lignin content and the temperature.
Synthesis of 6‐O‐carboxymethylchitin immobilizing doxorubicins through tetrapeptide spacer groups and its enzymatic release behavior of doxorubicin in vitro
Authors: Ohya Yuichi , Nonomura Koji , Hirai Keiichi , Ouchi Tatsuro 
Published: April 2003

AbstractChitin is a non‐toxic biodegradable polysaccharide. 6‐O‐Carboxymethylchitin (CM‐chitin) is a water‐soluble chitin derivative. In order to provide a water‐soluble macromolecular prodrug of doxorubicin (DXR) reducing the side‐effects and exhibiting high antitumor activity, the fixation of DXRs to CM‐chitin through covalent bonds was carried out. Especially, a lysosomally digestible tetrapeptide (Gly‐Phe‐Leu‐Gly) was used as spacer groups between CM‐chitin and DXRs. In this paper, two kinds of conjugates, CM‐chitin/Gly‐Phe‐Leu‐Gly/DXR conjugate 5 having lysosomally digestible tetrapeptide spacer groups and CM‐chitin/C5/DXR conjugate 6 having pentamethylene spacer groups, were synthesized. The effect of introduction of the spacer groups on the release behavior of DXR from the conjugate was investigated. The conjugate 5 having tetrapeptide spacer groups showed a distinct increase in the release rate of DXR in the presence of the lysosomal enzyme cathepsin B at 37°C in vitro; however, the conjugate 6 did not show such specific release behavior.
Poly(phenylene oxide) macromonomers for graft copolymer synthesis via ring‐opening olefin metathesis polymerization
Authors: Grutke Stefan , Hurley James H. , Risse Wilhelm 
Published: April 2003

AbstractPoly(oxy‐2,6‐dimethyl‐1,4‐phenylene) samples with bicyclic olefin end groups were obtained by esterification of the hydroxyl end group of the poly(phenylene oxide) with bicyclo[2.2.1]hept‐5‐ene‐2‐carbonyl chloride. Mixtures of these macromonomers with bicyclo[2.2.1]hept‐5‐ene‐2‐carboxylic acid 2‐(2‐(2‐methoxyethoxy)ethoxy)ethyl ester were copolymerized by ring‐opening olefin metathesis polymerization (ROMP) to produce graft copolymers with poly(phenylene oxide) side chains. The catalyst used for the metathesis polymerization was RuCl3(hydrate). Molecular weights of the graft copolymers were in the range of 130 000 to 250 000. Macromonomers containing exclusively exo‐linked bicyclic end groups were found to be more reactive than macromonomers with 55% exo‐ and 45% endo‐substituted end groups.
Degradation of a branched perfluoropolyalkylether fluid with anhydrous aluminium chloride
Authors: Eapen Kalathil C. , John Peter J. , Liang Jim C. 
Published: April 2003

AbstractThe degradation of a branched perfluoropolyalkylether (PFPAE) fluid with anhydrous AlCl3, in the absence of oxygen, has been re‐examined with emphasis on understanding the nature of the volatile products formed. GC/FTIR and GC/MS have been employed for identification of a number of compounds in the complex mixture of volatile products obtained. Hexafluoroacetone was a major component of this mixture. In addition, a number of chlorofluoro compounds and shorter chain oligomers without and with reactive functional groups such as ketone, acyl fluoride, and acyl chloride were formed. While successive losses of end units appear to be the predominant mode of degradation, the possibility of internal bond fission cannot be completely ruled out. There is strong evidence to suggest that carbonyl functional groups are not restricted to the leaving monomer units. They are present to a smaller extent in the residual fluid also. More than one mode of degradation, beginning either at the perfluoropropoxy end‐group or perfluoroethoxy end‐group which involves migration of a chlorine atom or fluorine atom from the end‐group to internal site or vice versa, can explain the formation of the volatile compounds identified. The mechanism of degradation involved in the initial loss of a terminal unit need not be operational in further degradation of the polymer chain, as a carbonyl functionality generated in the end‐group of the degrading polymer chain can alter the course of further reactions. While such a change in the mechanism of degradation is possible due to carbonyl functionality generated, it remains speculative in the absence of experimental support.
Effects of axial ligands on the electron transfer catalyzed by manganese tatrakis(pentafluorophenyl)porphyrin in poly(γ‐methyl L‐glutamate) membrane
Authors: Dewa Takehisa , Satoh Mitsuru , Komiyama Jiro , Nango Mamoru , Tsuda Kazuichi 
Published: April 2003

AbstractPoly(γ‐methyl L‐glutamate) (PMLG) membrane containing manganese tetrakis(pentafluorophenyl)porphyrinSystematic name: Tetrakis(pentafluorophenyl)porphyrinatomanganese.
(MnPFPP) has been studied for the transmembrane redox reaction between dithionite and ferricyanide in separated solutions. The effects of the ligand species, namely, OH−, Cl−, imidazole (Im), pyrazine (Pyz), triethylamine (TEA), and pyridine (Py), on the electron transfer rate in the membrane were examined. UV/VIS spectroscopy and sorption measurements confirm that these ligands are sorbed by the membrane from the external buffer solution and coordinate to MnPFPP. With the membrane containing 160 μmol · g−1 of MnPFPP, the apparent rate factor, estimated as the pseudo‐first‐order rate constant of the bleach of ferricyanide times membrane thickness, follows the order Im ≫ Cl− > Pyz > TEA, OH−, Py > 0, suggesting that Im, Cl− and Pyz are effective ligands for the electron transfer. Such a ligand‐specific transfer stems from the electron‐transferability of the ligands between MnPFPP's.