bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vinylpolymerisation mit reduzierenden Übergangsmetallverbindungen, 3. Polymerisation in gegenwart von initiatorsystemen aus vanadium(II)‐ und vanadium (III)‐chlorid sowie organischen halogenverbindungen
Authors: Moszner Norbert , Hartmann Manfred 
Published: April 2003

AbstractThe polymerization of methyl methacrylate initiated by the redox system vanadium(III) chloride/carbon tetrachloride was studied. The rate of polymerization can be described by the equation Rp = k · [VCl3]0,5·[CCl4]0,5·[MMA]1,0. The overall activation energies were estimated to be 74,5 kJ·mol−1 for VCl3/CCl4 and 59,5 kJ·mol−1 for VCl2/CCl4. Vanadium (II) chloride acts as a retarder in the polymerization of styrene initiated by 2,2′‐azoisobutyronitrile (AIBN). The polymerization of acrylonitrile and methyl methacrylate is inhibited by vanadium (II) chloride. The polymerization of acrylonitrile initiated by AIBN is retarded by vanadium (III) chloride.
Über enzymanalog gebaute polymer, 16. Über den Einfluß der flexibilität der haftgruppen auf die racemattrennungsfähigkeit
Authors: Wulff Günter , Gimpel Jürgen 
Published: April 2003

AbstractThe influence of the binding group flexibility on the ability for racemic resolution was investigated for binding groups situated in chiral cavities of enzyme‐analogously built polymers. D‐Glyceric acid was used as a template to introduce dihydroxyborylphenyl‐, 4‐(2‐hydroxyborylethyl)phenyl‐, or 5‐dihydroxyhoryl‐1,2‐indanediyl groups into chiral cavities of macroporous polymers. Investigations on the ability for racemic resolution revealed a lower specificity with higher binding group flexibility. On increasing the rigidity compared to the dihydroxyborylphenyl group the specificity is diminished to some extent. This may be attributable to a hindrance of the embedding of the substrate.
Ionic conductivity of polyether‐polyurethane networks containing NaBPh4: A free volume analysis
Authors: Killis Andreas , LeNest Jean‐François , Cheradame Hervé , Gandini Alessandro 
Published: April 2003

AbstractThe ionic conductivity of polyoxyethylene‐ and polyoxypropylene‐polyurethane networks containing sodium tetraphenylborate was studied as a function of temperature and salt concentration. The results can be rationalised in terms of free volume considerations. The fact that the WLF equation applies to the conductivity of these materials demonstrates that there exists a direct relationship between the ion conduction process and the viscoelastic properties of the networks.
Contribution à l'étude de la métallation de structures polyisoprène, . Etude sur polymères
Authors: Brosse Jean‐Claude , Abdin Bin Maidunny Zainul , Soutif Jean‐Claude 
Published: April 2003

AbstractMetalation of polyisoprene by the complex sec‐butyllithium‐N,N,N′,N′‐tetramethylethylenediamine (secBuLi‐TMEDA) is strongly affected by the conditions of reaction. In certain cases, a first order rate constant with respect to each reagent is observed. The mole ratio secBuLi/TMEDA has a preponderant effect on the rate of metalation. A maximum yield is observed when the mole ratio secBuLi/TMEDA is 1/0,5. Addition of a cocomplexing reagent, potassium tert‐butoxide (tertBuOK), to the complex secBuLi‐TMEDA yields a higher rate of metalation. A good yield can be obtained when polysioprene is treated with the metalating complex secBuLi‐TMEDA‐tertBuOK in a mole ratio of 1/0,5/1.
Processable heat‐resistant polymers, 10. Synthesis and characterization of an unsaturated polyesterimide containing 1,5‐dioxoisoindoline‐2,5‐diyl units
Authors: Maiti Sukumar , Ray Atanu , Maiti Manoranjan 
Published: April 2003

AbstractA new polyesterimide containg CC‐double bonds was prepared by reacting an unsaturated diacid chloride containing a cyclic imido group with ethylene glycol at low temperature. The solubility, thermal, electrical and cross‐linking properties of the polymer were studied. The polymer was found to be thermostable and soluble in highly polar solvents. X‐ray diffraction data revealed that the polymer is crystalline. The unsaturation sites of the polymer chain could be exploited for crosslinking reactions. The swelling behavior of the crosslinked polymer was studied as well as the thermal and electrical properties. The overall thermal stability of the crosslinked polymer was found to be higher than that of the uncrosslinked polymer.
Télomères monofonctionnels du chlorure de vinyle, 2. Cinétique par amorçage radicalaire
Authors: Boutevin Bernard , Piétrasanta Yves , Taha Mohamed 
Published: April 2003

AbstractRadical telomerizations of vinyl chloride with telogens RCCl3, containing alcohol and acid functions in the R group, were carried out. The molecular weights of the obtained products are between 1000 and 10 000. Transfer constants (CT) were calculated for each case by studying the DPn (10 to 50) variation as a function of the mole ratio (R) of telogen to monomer. In addition, the functionality of the resulting poly(vinyl chloride) was evaluated from the values of CT and R.
Photolytisch induzierte umsetzungen chlorhaltiger systeme in lösungen mit polystyrol
Authors: Woliński Leszek , Turzyński Zbigniew , Zaleska Wiesława 
Published: April 2003

AbstractUV spectroscopic measurements to identify the products of photolysis in polystyrene solutions of CCl4 and CHCl3 as a function of the atmospheric oxygen concentration are conducted. In polystyrene chains CC bonds are formed, thus changing the absorption properties in the long wave length range. The concentration of induced CC bonds is higher in CCl4 solution than in CHCl3 solution. The effect of O2 is observable for pressures p ≥ 2 · 10−1 mmHg; it is of minor importance for the formation of CC bonds, however. On the low‐molecular‐weight side COCl2, Cl2, and HCl are the photolysis products in the presence of O2. Observable changes in the absorption of the solvent at 280 nm were attributed to the electronic n ← π* transition of the carbonyl groups of COCl2, whereas the newly created broad band in the UV spectrum of the solvent was attributed to the electronic 1 Π1u ←1Σ g+ and 3Π+ou ← 1Σg+ transitions in Cl2. The first of these transitions is responsible for the dissociation of Cl2 molecules. A hypothesis has been set forth that molecular oxygen affects the probability density of the electronic 3Πou+ ← 1Σg+ transition. The concentration of O2 has a substantial effect on the concentration of the COCl2 photoproducts, which is best displayed by the molar absorption coefficient of this compound.
Biomimetic approach to the design of a pyridoxal enzyme model, 3. Synthesis of 4‐formyl‐3‐hydroxy‐5‐methacryloylaminomethyl‐2‐methylpyridine and its 5′‐N‐methylated analogue
Authors: Belokon' Yuri N. , Tararov Vitali I. , Bakhmutov Vladimir I. , Belikov Vasili M. 
Published: April 2003

AbstractThe synthesis of 4‐formyl‐3‐hydroxy‐5‐methacryloylaminomethyl‐2‐methylpyridine (7a) and 4‐formyl‐3‐hydroxy‐5‐(N‐methacryloyl‐N‐methyl)aminomethyl‐2‐methylpyridine (7b) is reported. The intermediate products 5‐aminomethyl‐2,2,8‐trimethyl‐2H,4H‐[1,3]‐dioxino[4,5‐c]‐pyridine hydrochloride (3a), 2,2,8‐trimethyl‐5‐methylaminomethyl‐2H,4H‐[1,3]‐dioxino[4,5‐c]‐pyridine hydrochloride (3b), 5‐methacryloylaminomethyl‐2,2,8‐trimethyl‐2H,4H‐[1,3]‐dioxino‐[4,5‐c]pyridine hydrochloride (5a), 5‐(N‐methacryloyl‐N‐methyl)aminomethyl‐2,2,8‐trimethyl‐2H,4H‐[1,3]‐dioxino‐[4,5‐c]pyridine hydrochloride (5b), 3‐hydroxy‐4‐hydroxymethyl‐5‐metha‐cryloylaminomethyl‐2‐methylpyridine (6a) and 3‐hydroxy‐4‐hydroxymethyl‐5‐(N‐methacryloyl‐N‐methyl)aminomethyl‐2‐methylpyridine (6b) were isolated and identified.
Hydrolyse énantiosélective d'α‐aminoesters catalysée par des complexes chiraux de métaux de transition immobilisés sur supports macromoléculaires
Authors: Spassky Nicolas , Reix Michel , Sepulchre Marie‐Odile , Guetté Jean‐Paul 
Published: April 2003

AbstractThe kinetics of hydrolysis of D‐ and L‐histidine methyl ester were studied in the presence of crosslinked hydrophilic polymeric supports bearing L‐histidine moieties complexed with Ni2+ salt. The selectivity of hydrolysis (kD/kL ratio) rises with the increase of the hydrophilic character (content of monomeric units of 2‐hydroxyethyl methacrylate) of the resin. It varies with the ratio ester / catalytic moiety, the best result being obtained when the latter is close to 1. The selectivity depends on the temperature and an inversion of this selectivity is observed at 31°C. The optimization of all the parameters studied allowed to reach the same enantioselectivity and comparable rates of hydrolysis as observed in a model reaction carried out under homogeneous conditions.
Effect of zinc chloride on the radical polymerization of cyclohexyl acrylate
Authors: Liaw Der‐Jang , Chung Kwang‐Chih 
Published: April 2003

AbstractThe paper presents a study of the radical polymerization of cyclohexyl acrylate (CHA) in the presence of ZnCl2. It was found by IR, 1H NMR, and 13C NMR spectroscopy that a complex of ZnCl2 with CHA is formed. For copolymerization of CHA with vinylidene chloride, both the Q‐ and e‐value of CHA increased with the ZnCl2 concentration. The initiation rate and k/kt were determined using DPPH as an inhibitor. It was found that ZnCl2 did not affect the initiation rate. The kp value of CHA was determined to be about 2720 1 · mol−1 · s−1 in the absence and 4710 1 · mol−1 · s−1 in the presence of ZnCl2 by the rotating sector method. The enhanced polymerization rate of CHA in the presence of ZnCl2 can be ascribed to the large kp value. The termination rate constant is not significantly affected by the presence of ZnCl2.
Polymerisationsauslösung mit substituierten ethanen, 5. Polymerisation von verschiedenen methacrylmonomeren
Authors: Błedzki Andrzej , Braun Dietrich , Menzel Wolfgang , Titzschkau Klaus 
Published: April 2003

AbstractMethyl methacrylate, benzyl methacrylate, butyl methacrylate, and methacrylic acid can be polymerized by 1,1,2,2‐tetraphenyl‐1,2‐diphenoxyethane and 1,1,2,2‐tetraphenyl‐1,2‐dicyanoethane. In the first period of the polymerization with both initiators oligomers are formed which can initiate the polymerization of other vinyl monomers yielding block‐copolymers besides the resp. homopolymers.
Hydrodynamic constants and frictional properties of polystyrene in dilute solution
Authors: Bohdanecký Miloslav , Petrus Vladimír , Porsch Bedřich , Sundelöf Lars‐Olof 
Published: April 2003

AbstractExperimental data from hydrodynamic measurements on eleven standard polystyrene samples in a poor and a good solvent (cyclohexane at theta‐temperature 34,5°C, toluene at 25°C) are analyzed in terms of the two‐parameter theory of the hydrodynamic properties of random coils. The discussion is focussed on the expansion factors of hydrodynamic radii αf and αμ, evaluated from the translation friction coefficients and the intrinsic viscosity, and on the hydrodynamic‐interaction parameters P and Φ. The expansion factors αf and αη are shown to assume nearly equal values (at 1,15 ≤αη ≤ 1,5). That implies that the dependences on coil expansion must be very similar for P and Φ1/3. The value of the P parameter in the unperturbed state (i.e. P0) is shown to be close to that recently calculated by Zimm and to be significantly higher than the results of previous theoretical calculations.
Study of step‐growth polymerizations using epoxy‐carboxy reaction, 2. Study of the epoxy‐carboxy reaction on models in nitrobenzene
Authors: Madec Pierre‐Jean , Maréchal Ernest 
Published: April 2003

AbstractIn the first part of this series devoted to epoxy‐carboxy polycondensation, we showed that the overall mechanism of the amine catalyzed epoxy‐carboxy reaction is complex. The present article studies the reaction of benzoic acid with 1‐phenoxy‐2,3‐epoxypropane carried out in nitrobenzene and in the presence of N,N‐dimethyldodecylamine as catalyst. In contrast to the results obtained in low polar solvents, where two equivalent reactions take place, the studies carried out in nitrobenzene show that, in this solvent, one of these two reactions is largely predominant. Its rate equation is: υ = k [epoxy][amine]. However, in the last steps of the reaction (conversion above 75% ), the system behaves as in low polar solvents. These results were obtained from studies carried out under stoichiometric and non‐stoichiometric conditions. The overall rate constant depends only very slightly on the stoichiometric balance. This is in agreement with a major contribution of one of two competitive reactions.
Study of step‐growth polymerizations using epoxy‐carboxy reaction, 4. Study of the epoxy‐carboxy reaction carried out in the melt on high molecular weight models
Authors: Madec Pierre‐Jean , Maréchal Ernest 
Published: April 2003

AbstractEpoxy‐Carboxy polycondensation is studied in the melt by use of the octadecanoic acid/1‐dodecyloxy‐2,3‐epoxypropane reaction as a model. The catalyst is N,N‐dimethyldodecylamine. The results obtained from these high molecular weight models show that, as for the studies performed in a solvent, two main reactions take place. The experiments are carried out under stoichiometric and non‐stoichiometric conditions. It appers that, due to the strong interaction between epoxy compound and amine, a polymerization of oxirane takes place to a small extent, being a side reaction of the system. As a consequence, epoxy groups are consumed more rapidly than acid groups. Nevertheless, an approximation allowed the determination of the rate constants relative to the two main reactions. Activation parameters of these reactions are reported.
Synthèse par voie radicalaire de polymères à extrémités hydroxylées, 11. Etude de la copolymérisation du méthacrylate de méthyle avec divers acrylates et méthacrylates. Détermination des rapports de réactivité
Authors: Brosse Jean‐Claude , Gauthier Jean‐Marie , Lenain Jean‐Claude 
Published: April 2003

AbstractMethylmethacrylate (MMA) was polymerized in an oxygen or argon atmosphere with butyl or isobutyl acrylates, and butyl, isobutyl, or 2,3‐epoxypropyl methacrylates, by hydrogen peroxyde in the presence of ethanol under UV irradiation (254 nm) at room temperature. The reactivity ratios were determined. MMA shows a higher reactivity than its comonomers, in good agreement with the results of the literature, except for isobutyl and 2,3‐epoxypropyl methacry‐lates.
Molmassenverteilung und lösungszustand von linearen polyethylenen, 1. Lichtstreuungs‐, viskositäts‐ und GPC‐messungen
Authors: Böhm L. L. , Lanver U. , Lechner M. D. 
Published: April 2003

AbstractLight scattering, viscosity and GPC measurements were performed on a homologous series of linear polyethylenes with viscosity average molar masses in decahydronaphthalene at 135°C between 1,0 · 105 and 2,7 · 106 g · mol−1 and relatively broad molar mass distributions. 1,2,4‐Trichlorobenzene, α‐chloronaphthalene, decahydronaphthalene (decalin) and decane were used as solvents. In the case of linear polyethylene in decahydronaphthalene and decane relationships between intrinsic viscosity and weight average molar mass were established. The values of the weight average molar masses obtained by light scattering are considerably higher than those obtained by viscosity and GPC measurements. These discrepancies are explained by molecular aggregation of the polyethylene macromolecules.
Über polyarylenalkenylene und polyheteroarylenalkenylene, 14. Synthesen und charakterisierung von poly(thieno[2′,3′:1,2]benzo[4,5‐b]thiophen‐2,6‐diylvinylenarylenvinylen)en, poly(4,8‐dimethoxythieno[2′,3′:1,2]benzo[4,5‐b]thiophen‐2,6‐diylvinylenarylenvinylen)en und einigen modellverbindungen
Authors: Koßmehl Gerhard , Beimling Peter , Manecke Georg 
Published: April 2003

AbstractWittig‐reactions of thieno[2′,3′:1,2]benzo[4,5‐b]thiophene‐2,6‐dicarboxaldehyde (8a) with “mono‐ and bis‐Wittig‐salts” 12a–c and 9a–c poly(thieno[2′,3′:1,2]benzo[4,5‐b]thiophene‐2,6‐diylvinylenearylenevinylene)s 10a–c and some model compounds 13a–c were obtained. Analogous reactions of 4,8‐dimethoxythieno[2′,3′:1,2]benzo[4,5‐b]thiophene‐2,6‐dicarboxaldehyde (8b) gave the corresponding poly(4,8‐dimethoxythieno[2′,3′:1,2]benzol[4,5‐b]thiophene‐2,6‐diylvinylenearylenevinylene)s 11a–c and their model compounds 14a–c. Wittig‐reactions of benzo[b]thiophene‐2‐carboxaldehyde (15) with “mono‐ and bis‐Wittig‐salts” gave model compounds 16a–c and 17a, c. A new synthesis of thieno[2′,3′:1,2]benzo[4,5‐b]thio‐phene (4) was worked out. 4,8‐Dimethoxythieno[2′,3′:1,2]benzo[4,5‐b]thiophene (7) and dicarboxaldehydes 8a and 8b were synthesized for the first time. The structures of all compounds were confirmed by elemental analyses, IR and electronic spectra, those of the model compounds additionally by mass spectra, and in case of sufficient solubility by 1H NMR spectra. The electrical conductivities of all polymers and their model compounds were investigated.
Main features of hydrolysis of polymeric enaminones based on a water‐soluble copolymer from N‐vinyl‐2‐pyrrolidone and 5‐methyl‐5‐hexene‐2,4‐dione
Authors: Panarin Evgenii F. , Kopeikin Victor V. 
Published: April 2003

AbstractWater‐soluble polymeric enaminones (2) were obtained by condensation of a copolymer (1) from N‐vinyl‐2‐pyrrolidone and 5‐methyl‐5‐hexene‐2,4‐dione with amines. It was found first that polymers 2 undergo hydrolysis by water much more slowly than low molecular weight enaminones of similar structure and, secondly, their hydrolysis does not obey the pseudo‐first‐order rate law. These differences in the kinetic behaviour of polymers and model compounds are due, respectively, first to a steric hindrance of the attack of water at the polymer chains and, secondly, to the association of low molecular reaction products with the monomeric units of N‐vinylpyrrolidone in the copolymers. A detailed study of the hydrolysis of polymeric enaminones of amino acids, characterized by extraordinary high hydrolysis rates confirmed the existence of the intramolecular base catalysis of the attack of water at the protonated enaminone by their own carboxylate groups.
Reactive microgels by the self‐emulsifying copolymerization of unsaturated polyester resins with acrylic and methacrylic esters
Authors: Miyata Mikiyi , Funke Werner 
Published: April 2003

AbstractThe self‐emulsifying copolymerization of unsaturated polyesters (UP) with various acrylic and methacrylic esters was studied. The structure of comonomers significantly influences the character of microgels obtained. Among these monomers the copolymerization of UP with methyl methacrylate (MMA) was investigated in detail in order to make clear the behavior of this polymerization as compared with that of styrene. The water/monomer and UP/MMA ratios were found to be the most important factors controlling the molecular weight and solution viscosity of the microgels. The relationship between M̄w and intrinsic viscosity of microgels suggests that the microgels from MMA have less compact structure than those from styrene.
The measurement of the tacticity of poly(vinyl chloride) by 13C nuclear magnetic resonance spectroscopy
Authors: King Janice , Bower David I. , Maddams William F. , Pyszora Henryk 
Published: April 2003

AbstractFourier transform 1H‐decoupled 13C NMR spectra were obtained on seven poly(vinyl chloride), (PVC), samples in solution in o‐dichlorobenzene. Four of the polymers were of the commercial type and the others were prepared by suspension polymerisation at +90°C, +5°C, and ‐30°C. Measurements of the spectra were used to assess the precision and accuracy with which information about the tacticity of PVC can be obtained from such spectra. The results show that the well‐resolved α‐carbon triad and β‐carbon tetrad spectra obtained may be reliably analysed to give values of the probability of syndiotactic placement with a precision of about 0,005 for measurements on a single run on a single sample. The simplest and probably the most reliable method of measuring the areas under the peaks which correspond to specific triads ot tetrads is to use the spectrometer integrator, although results of slightly lower precision may be obtained by the use of a curve resolver. Consideration of possible systematic errors due to different T1 relaxation times, unequal nuclear Overhauser enhancement (NOE) factors, and incomplete dissolution of the polymer has shown that the only one of these which is possibly significant is that due to NOE, which is almost certainly less than 0,008, so that the absolute accuracies of the Pr values should be better than that. A more detailed study of the data shows that the polymers made at 5°C and ‐30°C are almost certainly non‐Bernoullian and that firstoder Markov statistics can adequately describe the observed departures from Bernoullian statistics. These departures may have significant consequences for the physical properties of the polymers.
Low temperature elastomeric polyamides containing perfluorinated polyether building blocks
Authors: Caporiccio Gerardo , Strepparola Ezio , Bargigia Gianangelo , Novaira Giuseppe , Peveri Glauco 
Published: April 2003

AbstractReductive cleavage of derivatives from tetrafluoroethylene photooxidation resulted in perfluorinated polyethers with α,ω‐carboxylic ester groups B. Their condensation with suitable aliphatic and aromatic diamines gave a new class of elastomers, crosslinkable by organic peroxides. A good balance of low temperature elasticity, resistance to solvents, and thermostability was particularly found for aromatic polyamides.
Polyurethanes containing poly(oxyethylene) block units and their properties as polychelatogenes
Authors: Bayer Ernst , Grathwohl Paul‐Anton , Geckeler Kurt 
Published: April 2003

AbstractPolyurethanes 6 and 7 based on poly(oxyethylene) (5) were synthesized and investigated for the application as macromolecular chelating agents. 4,4′‐Diaminobenzil (3c) and 4,4′‐diaminobenzil monoxime (4a) were prepared as monomer precursors in 70 and 80% yield. Copolymers were obtained in yields between 40 and 60% by polyaddition of the corresponding diisocyanates 3d and 4b to poly(oxyethylene) (5) of different chain length and characterized by IR and 13C NMR spectroscopy. The application of the resulting polyurethanes containing functional aromatic block units as polychelatogenes was studied in homogeneous phase by membrane filtration. The metal content was determined in both the filtrate and the retentate and in the case of Ni2+ at different pH values. At pH 2, for example, the molar binding capacity of a polyurethane sample of 6 was 3 times as high as that of 5.
Caractérisation physico‐chimique d'un polymère phosphore
Authors: Chakra Taher Abou , De Jaeger Roger , Baillet Christiane , Delfosse Lucien , Cavrot Jean‐Paul , Rietsch François 
Published: April 2003

AbstractA mixture, probably composed of a poly(chlorotrimethylsilyloxy)phosphazene and a compound with the general formula H2Cl2NOP (inactive toward THF) was used to initiate the polymerization of tetrahydrofuran. The resulting polymer (PTHFP) contains phosphorus associated with nitrogen, as assessed by IR, 31P and 1H NMR spectroscopy. The thermal stability of PTHFP, observed by thermogravimetry, was found to be much higher than that of polytetrahydrofuran (PTHF). At the end of its decomposition a solid residue remains, which was identified as a poly(phosphazene oxide) (PNO)n. The combustion behaviour is also modified in that the cool flame combustion area is raised up in the pressure‐temperature coordinates. In addition, the disappearance of the so‐called secondary cool flame (SCF) phenomenon is in favour of the heterogeneous action of the phosphorus derivatives during the inhibition of combustion at higher temperatures. The thermochemical analysis (DSC‐Rheovibron) shows the existence of a semi‐cristalline structure proportional to the amount of phosphorus introduced into the PTHF chain. The glass transition temperature of PTHFP was found to be slightly higher than that of PTHF without any apparent relation to their structures. The same conclusion arises from the viscoelastic measurements.