bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transesterification of poly(methyl acrylate) with optically active alcohols
Authors: Yamaguchi Hidemasa , Fujiwara Yoshiaki , Minoura Yuji 
Published: April 2003

AbstractTransesterifications of atactic and isotactic poly(methyl acrylate) with optically active alcohols such as (S)‐2‐methyl‐butanol, D‐borneol and L‐menthol were carried out in toluene at 100°C using p‐toluenesulfonic acid as catalyst to obtain optically active polymers. In addition a relationship between the conformation and the optical behaviour of the transesterified poly(methyl acrylate) was investigated. The specific rotation of the transesterified atactic poly(methyl acrylate) increased linearly with increasing introduced optically active groups at the lateral chain, in contrast to that of the isotactic poly(methyl acrylate) which increased nonlinearly with increasing introduced asymmetric groups. Since the specific rotations of the transesterified polymers depend on these tacticities the conclusion was drawn that the optical activity is caused not only by the asymmetric group in the lateral chain but also by molecular dissymmetry in the principal chain.
Poly(2‐vinylquinoline 1‐oxide) and some methyl derivatives: Synthesis and viscometric studies
Authors: Bonsall Colin , Holt Paul 
Published: April 2003

AbstractThe syntheses of poly[1‐(1‐oxy‐2‐quinolyl)ethylene] [poly(2‐vinylquinoline 1‐oxide)] (1a) and of a number of methyl derivatives (1b—f) are described. Some of the polymers are insoluble in water but soluble in aqueous acetone at several pH values. Those polymers that have a methyl substituent in position 4 are soluble in aqueous acetone below pH < 4 and the viscosity rises steeply with decreasing pH. Polymers with no methyl substituent in position 4 are soluble in aqueous acetone at pH > 6 and the viscosity varies but little with the pH.
On the properties and thermal conversion of ladder polymers with conjugated bonds
Authors: Salaurov V. N. , Kryazhev Yu. G. , Yushmanova T. I. , Vakul'Skaya T. I. , Voronkov M. G. 
Published: April 2003

AbstractThe cationic polymerization of vinylacetylenes can be implemented using an excess of catalysts, such as BF3O(C2H5)2, SnCl4, H2SO4, CCl3COOH, CF3COOH (20–50 mol per 100 mol monomer). This is due to the formation of a charge‐transfer complex between the catalyst and the polymer obtained, which was confirmed by UV, ESR and IR spectra.Polymers with conjugated ladder sequences in the chain (LP) (4) were prepared using vinylacetylene (1a), 1‐hexen‐3‐yne (1b), 2‐methyl‐1,5‐hexadiene‐3‐yne (3a), 2‐methyl‐5‐hexen‐3‐yn‐2‐ol (3b) or 5‐methoxy‐5‐methyl‐1‐hexen‐3‐yne (3c). The polymers obtained (molar mass = 2000–7000) are pale yellow to pale brown powders which display properties characteristic of polymers with conjugated bonds, i.e. thermal stability in vacuum and air, continuous absorption in UV and near visible regions, broad fluorescence spectra, electric conductivity and ESR signals.The effect of heat treatment in vacuum and air on the structure and some electrophysical properties of LPs was studied by IR, luminescence, ESR and mass‐spectroscopy and also by TGA, DTA, and X‐ray diffraction analyses.The heat treatment in the temperature range of 150–400°C gives rise to a complete cyclization accompanied by a partial degradation and leads to the formation of polycondensed aromatic structures and to a sharp increase of electroconductivity up to 1.10−5Ω−1cm−1 and to an increase of the concentration of paramagnetic particles up to 1.1020 spin/g at an ESR signal width in vacuum of 0,4 gauss (0,4.10−4 tesla).
Polyélectrolytes optiquement actifs à hydrophobie variable, 1. Copolymères amide‐acide acryliques obtenus par hydrolyse contrǒlée des (±), (+) et (−) poly[N‐(sec‐butyl)‐N‐méthyl‐acrylamides]
Authors: Braud Christian , Vert Michel , Sélégny Eric 
Published: April 2003

AbstractOn hydrolyse progressivement en milieu acide (CH3COOH + HCl) les (±), (+) et (−) poly‐[N‐(sec‐butyl)‐N‐méthylacrylamide] (1) obtenus par polymérisation radicalaire des (±), (−) et (+) N‐(sec‐butyl)‐N‐méthylacrylamides (AAM). On obtient une série de copolymeères (2) consititués de motifs hydrophobes dérivés de AAM et de motifs hydrophiles dérivés de l'acide acrylique (AA) répartis statistiquement et en proportion variable selon le temps d'hydrolyse. La viscosité, le pouvoir rotatoire dans le méthanol, la solubilité dans divers solvants, les spectres IR à l'état solide et la dispersion de la rotation optique (ORD) sont étudiés en fonction du taux d'hydrolyse. Pour interpréter l'évolution de l'ORD et des spectres IR on a supprimé les interactions H entre groupes amide et acide par méthylation de ces derniers au diazométhane. Au cours de la neutralisation des différents copolymères 2 par KOH, on constate que l'augmentation de la proportion des parties hydrophobes par rapport aux parties hydrophiles modifie fortement l'ionisation des groupes COOH des motifs monomères dérivés de l'acide acrylique.
Solution properties and unperturbed dimensions of poly(5‐p‐methyl methacrylate) and poly(2‐tert‐butylphenyl methacrylate)
Authors: Tricot Michel , Bleus Joseph P. , Riga Jean‐Pierre , Desreux Victor 
Published: April 2003

AbstractThe solution properties of poly(5‐p‐menthyl methacrylate) and poly(2‐tert‐butylphenyl methacrylate) are determined by several methods in good and ideal solvents. The flexibilities σ calculated on the basis of the unperturbed dimensions are 3,1 and 2,6, resp. These values are compared with those found for other polymethacrylates with bulky substituents. The influence of a large group in ortho position at the cyclohexyl and the phenyl rings is discussed in terms of steric hindrance and specific interactions.
Crystallinity and polymorphism of 6‐polyamide
Authors: Gurato Giorgio , Fichera Annamaria , Grandi Francesco Zilio , Zannetti Roberto , Canal Pietro 
Published: April 2003

AbstractBy X‐ray diffraction and by density measurements as well as by differential scanning calorimetry, the crystallization phenomena of 6‐polyamide(nylon‐6) samples, obtained under different conditions were investigated.Particularly we have analyzed a method for the quantitative determination of the α, γ, and δ (amorphous) phases. This was based on the decomposition of the areas of the X‐ray diffraction patterns. These data were related with density and calorimetric measurements and finally gave a good picture of the transitions involving the different phases.We have used this method for the characterization of nylon‐6 of low and medium viscosity and we have considered the differences of behaviour between the various series of samples.
Approaches towards a comprehensive theory of the cationic polymerisation of olefins
Authors: Plesch Peter H. 
Published: April 2003

AbstractSome of the factors which influence, or must be contained in, a Comprehensive Theory of the cationic polymerisation of olefins are discussed from new points of view, starting from the author's new theory concerning initiation by metal halides. Alleged determinations of the rate constant k are criticised because they ignored two equilibria which make the concentration of growing polymer chains [P] in general less than the nominal concentration, c0, of initiator. One of them is a binary ionogenic equilibrium involving metal halide MtXn and polymer halide PnX. The other is between metal halide and olefin. An equation relating [P] to c0 is deduced which takes account of these equilibria. The importance of the second equilibrium is illustrated by the way in which it provides simple explanations of hitherto obscure phenomena. Some of these arise during the interaction of aluminium halides with olefins in different circumstances, others concern the different interactions which can take place between titanium tetrachloride and 1,1‐diphenylethylene. The fact that titanium tetrachloride appears to be able to initiate without co‐initiator in some systems, but requires one in others is explained by the self‐ionisation of the metal halide and the effects of impurities.
Über polymere mit phenyltropylium‐ und styryltropyliumsalzgruppierungen
Authors: Manecke Georg , Steudle Ernst 
Published: April 2003

AbstractAnionaustauscherharze mit der Tropyliumgruppe wurden dargestellt. Poly{1‐[4‐(1,3,5‐cycloheptatrien‐7‐yl)phenyl]äthylen} (3) wurde durch thermische Polymerisation von 7‐(p‐Vinylphenyl)‐1,3,5‐cycloheptatrien (2) erhalten. Das schwach gelbgrün gefärbte, lösliche Polymere 3 (rel. mol. Masse=4330) wurde durch sein IR‐Spektrum charakterisiert. Die Dehydrierung von 3 lieferte ein Poly[1‐(4‐tropyliumylphenyl)äthylenperchlorat] (4) in dem 78% der 1,3,5‐Cycloheptatrien‐Reste dehydriert waren. Das polymere Tropyliumsalz 4 tauschte beim alternierenden Behandeln mit 0,1 N NaOH und 25proz. Perchlorsäure reversibel 2,0–2,5 mVal/g Perchlorationen gegen Hydroxylionen aus. Bei der Kondensation von Poly[1‐(4‐formylphenyl)äthylen] (5) mit Methyltropyliumperchlorat (6) wurden schwarze Polymere mit 1‐[4‐(2‐Tropyliumylvinyl)phenyl]äthylen‐Gruppierungen (7) erhalten, die unter den obigen Bedingungen reversibel 1,0–1,5 mVal/g austauschten.Die polymeren Tropyliumsalze 4 und 7 wurden durch ihre IR‐Spektren charakterisiert.
Modell‐untersuchungen zur struktur eines polyimids aus pyromellithsäuredianhydrid und benzidin
Authors: Brune Hans‐Albert , Horvath Andreas , Vollmert Bruno 
Published: April 2003

AbstractAnhand geeigneter Modellverbindungen konnte 1H‐NMR‐spektroskopisch nachgewiesen werden, daß sich auch am isolierten, gelösten Molekül des N‐Phenylphthalimids eine zeitlich stationäre sp2‐Hybridisierung mit ebener Anordnung der drei vom Stickstoff ausgehenden σ‐Bindungen einstellt. Diese Bindungsverhältnisse haben für das Polyimid der Pyromellithsäure, Poly(pyromellithdiimido‐4,4′‐biphenylylen) (4), eine streng lineare, stäbchenförmige Struktur des Makromoleküls zur Folge.
Cationic polymerization of cyclic sulfides, 5 Polymerization of propylene sulfide with triethyloxonium tetrafluoroborate
Authors: Van Ooteghem Daniël R. , Goethals Eric J. 
Published: April 2003

AbstractTime‐conversion curves show that the polymerization of propylene sulfide (1) by triethyloxonium tetrafluoroborate (TEFB) in methylene chloride consists of an initial very fast, non‐stationary stage A and a much slower subsequent stage B which leads to quantitative conversion. The termination reaction of stage A is of first order with respect to initiator concentration and is independent of monomer concentration. The proposed mechanism for this termination is the formation of a (mainly) 12‐membered cyclic sulfonium salt at the end of the polymer chain. The ratio of the rate constant of propagation to the rate constant of termination at 0°C in CH2Cl2 is 9 dm3 mol−1. From the kinetics, it is concluded that stage B is initiated by slow formation of a three‐membered cyclic sulfonium salt by an intramolecular nucleophilic attack of the last sulfide function of the polymer chain on the α‐carbon next to the sulfonium salt. Further evidence for this kind of re‐initiation is obtained from the observation that simple trialkylsulfonium salts are very poor initiators or completely incapable of initiating the polymerization, whereas under identical conditions 2‐thia‐alkylsulfonium salts give polymerizations without stage A which are similar to the stage B of the TEFB‐initiated reactions. A backbiting reaction, similar to the termination reaction, is responsible for the degradation of polymer (mainly) into cyclic tetramer. The molecular weights of the polymers, measured by gel permeation chromatography, are in reasonable agreement with the proposed mechanism.
Étude de la microstructure de polyéthylènes de basse densité chlorés en solution et en suspension
Authors: Humbert Gerard , Quenum Bienvenu M. , Pham Quang T. , Berticat Philippe , Vallet Georges 
Published: April 2003

AbstractL'analyse par R.M.N. haute résolution de la microstructure de polyéthylènes basse densité chlorés soit en suspension soit en solution est entreprise et fait apparaître une différence fondamentale de constitution entre ces deux catégories de produits.Les produits préparés en suspension peuvent schématiquement être considérés jusqu'à 65% de chlore comme des copolymères semi‐cristallins séquencés polyéthylène–polychlorure de vinyle et, au‐delà, comme des copolyméres amorphes de chlorure de vinyle, dichloro‐1,1 éthylène, dichloro‐1,2 éthylène et trichloro‐1,1,2 éthylène.Les produits préparés en solution sont pratiquement chlorés de façon statistique et deviennent très rapidement amorphes. Au début de leur chloration la formation de groupement dichlorométhylène domine. Pour des teneurs en chlore plus élevées apparaissent des séquences polychlorure de vinyle qui deviennent prédominantes à 60% de chlore. Au‐delà de 60% de chlore se forment des unités dichloro‐1,2 éthylène.
Chemische synthese eines phagenspezifischen DNA‐fragments
Authors: Schott Herbert 
Published: April 2003

AbstractDie Synthese eines Decadesoxyribonukleotids wird beschrieben, dessen Basensequenz dA‐G‐A‐A‐A‐T‐A‐A‐A‐A im Minus‐Strang der DNA des Phagen ϕX 174 vorkommt. Mit Hilfe dieses synthetischen Primers sollen weitere Bereiche der DNA des Phagen ϕX 174 sequenziert werden. Das Decanukleotid wird nach der Methode von Khorana et al. aus den geschützten Nukleotidblöckend(MeOTr)bzA‐ibuG, dpbzA‐bzA(Ac), dpbzA‐T(Ac) und dpbzA‐bzA‐bzA‐bzA(Ac) unter Verwendung von TPS als Kondensationsmittel in drei Kondensationsschritten aufgebaut.
Cationic polymerization of 3‐methylenecyclohexene and 2‐methyl‐1,3‐pentadiene
Authors: Imanishi Yukio , Kanagawa Shuichi , Higashimura Toshinobu 
Published: April 2003

AbstractTo investigate the effect of a cyclic structure on the reactivity of conjugated dienes in cationic polymerization, a cyclic diene 3‐methylenecyclohexene (1) and the corresponding linear diene 2‐methyl‐1,3‐pentadiene (2) were synthesized and polymerized. Cationic polymerizations and copolymerizations showed that 1 was more reactive than 2. The conjugated double bonds in 1 were proved to be less resonance‐stabilized than that in 2. However, the conjugate cation 1 was found to be more stable than that of 2. The combination of these two factors made the cyclic diene more reactive than the linear d+. Cationic polymerizations of 2 were fast and non‐stationary, giving low molecular weight polymers. The polymerizations proceeded mainly by the 1,4 route and to a smaller extent by the 1,2 route. A brief discussion on the stereochemistry in some electrophilic addition reactions of methyl‐substituted butadienes is also given.
Redoxharze auf der basis von 5,6‐dichlor‐3‐vinyl‐4,7‐dihydro‐1H‐4,7‐indazoldion
Authors: Acosta Francisco , Storck Winfried , Manecke Georg 
Published: April 2003

AbstractEs wurde der Inhibierungseffekt von 5,6‐Dichlor‐3‐vinyl‐4,7‐dihydro‐1H‐4,7‐indazoldion (1a) auf die thermische Styrolpolymerisation, die Homopolymerisation von 1‐Acetyl‐4,7‐diacetoxy‐5,6‐dichlor‐3‐vinylindazol (2a) und von 4,7‐Diacetoxy‐5,6‐dichlor‐1‐vinylindazol (2c) sowie die vernetzende Copolymerisation von 2a mit 4,7‐Diacetoxy‐5,6‐dichlor‐1,3‐divinylindazol (2b) untersucht. Durch Verseifung und Propansulfonierung der vernetzten Polymeren wurden stabile Redoxharze dargestellt. Ihre Austausch‐ (1,8–2,2 mäq/g) und Redoxkapazität (2,5–4,0 mäq/g) sowie ihre Mittelpunktspotentiale (467–475 mV bei pH 1,66) wurden ermittelt.
Preparation of vinyl polymers as pH indicator
Authors: Hatanaka Hideo , Sugiyama Kazuo , Nakaya Tadao , Imoto Minoru 
Published: April 2003

Abstract4‐(p‐Aminophenylazo)phenyl methacrylate (1a) and 4‐(p‐dimethylaminophenylazo)‐phenyl methacrylate (1b) were synthesized and characterized. These monomers were polymerized with 2,2′‐azoisobutyronitrile. The properties of these monomers and polymers as pH indicators are described.
Some anomalies in the kinetics of heterogeneous oxidative condensation reactions
Authors: Brooks Brian W. , Smith Roy M. 
Published: April 2003

AbstractThe rate of thiophenol oxidation in a catalysed gas‐liquid reaction is found to depend on the initial concentration of thiophenol but is independent of the changes in thiophenol concentration which occur during the course of the oxidation. The reaction rates have been used to construct a Lineweaver‐Burk plot. These results are compared with those which have previously been obtained in the oxidative condensation of 2,6‐dimethylphenol. The kinetic similarities between catalysed oxidative condensation reactions and enzyme reactions are discussed. It is shown that the linearity of the Lineweaver‐Burk plots does not ensure that the absorption of oxygen is chemically controlled. It is suggested that deductions which previous workers have made from the use of Lineweaver‐Burk plots must be treated with caution.
Polymerization of acrylonitrile by a ternary catalyst: FeCl3/2,2′‐dipyridyl/epoxypropane
Authors: Ikeda Masanori , Hirano Tsuneo , Uchida Akira , Tsuruta Teiji 
Published: April 2003

AbstractThe ternary system FeCl3/2,2′‐dipyridyl (1) (Dip)/epoxypropane (2) was found to be active as catalyst for the polymerization of acrylonitrile (4). The lack of one of the catalyst components makes the system inactive for polymerization. The active species is concluded to be partially alkoxylated ferric chloride complexed with 1, and the polymerization might be initiated by the alkoxy group of the complex. Copolymerization of 4 and styrene indicates that the polymerization is anionic at 30°C. At 50 and 80°C, however, both anionic and radical polymerizations seem to take place.
Vinyl polymerization by metal complexes, 14. Synthesis of 2‐substituted and 2,4‐disubstituted imidazole‐copper(II) complexes as initiator systems for vinyl polymerization
Authors: Shirai Hirofusa , Inaki Yoshiaki , Takemoto Kiichi 
Published: April 2003

AbstractA series of the copper(II) complexes of the type CuL4X2 (L: ligand, X: anion) was prepared with the following substituted imidazoles as ligands 2‐ethyl‐ (1a), 2‐ethyl‐4‐methyl‐ (1b), 2‐phenyl‐ (1c), 2‐undecyl‐ (1d), and 2‐heptadecylimidazole (1e). The structures of these complexes were confirmed by elemental analysis, reflection spectra of the crystals as well as IR‐spectroscopy. Polymerization of acrylonitrile was tested in the presence of each imidazole‐copper(II) complex in dimethyl sulfoxide solution.
Étude des systèmes ternaires polymère/mélange de solvants en équilibre thermodynamique avec le solvant binaire correspondant
Authors: Hert Marius , Strazielle Claude 
Published: April 2003

AbstractNous avons obtenu l'équilibre thermodynamique entre les solutions ternaires de polymères en mélanges de solvants et les solvants binaires, en réalisant une dialyse de la solution ternaire par rapport au mélange de solvants. La solvatation préférentielle du polymère par un des deux solvants, qui se manifeste par des variations de composition du solvant binaire de part et d'autre de la membrane imperméable aux macromolécules, a été mise en évidence par réfractométrie différentielle et par mesures de densités, pour des solutions diluées et modéremment concentrées en polymère. Nous avons étudié un certain nombre de systèmes, ce qui nous a permis de discuter des avantages de ces moyens d'étude et de confronter les résultats aux prévisions théoriques.
Structural and thermodynamic characteristics of chlorinated polyethylenes, 2
Authors: Erä Väinö A. 
Published: April 2003

AbstractA series of suspension chlorinated and chlorosulfonated polyethylenes (CPE and CSPE resp.) of varying chlorine contents were investigated. The ß‐ and γ‐relaxation processes are related to motions of CH2CHClCH2 and CH2 units in the chains of CPE and CSPE polymers, respectively. In isothermal crystallization, the fine structures of the polymers change gradually, as is shown by the variation in the pattern of the DSC curve and the shift of the melting peak.
Steric and electrostatic factors on the formation and the structure of polymeric cobalt(III) complexes
Authors: Tsuchida Eishun , Nishide Hiroyuki , Takeshita Michitaka 
Published: April 2003

AbstractPolymeric cobalt(III)‐complexes (2a, b, c, e, f, g, h, i, j) were prepared by a substitution reaction between a polymeric ligand (1a or 1b) and a Co(III)‐chelate. They were characterized by elemental and spectroscopic analyses. The complexation rates of the Co(III)‐en‐ and Co(III)‐trien‐chelates were found to be smaller than those of the non‐charged Co(III)‐chelates. This retardation effect was explained by an electrostatic repulsion of the cationic polymeric complexes 2a, b or 2c. The degree of coordination (x) was found to reach a constant level of about 0,65 under the reaction conditions. This experimental x‐value of saturation was nearly equal to the value which was calculated statistically.
Kinetics of polymerization of 1,3‐dioxepane with the Al(C2H5)3/H2O catalyst system
Authors: Donescu Dan 
Published: April 2003

AbstractThe kinetics of the polymerization of 1,3‐dioxepane (DH) with the catalytic system Al(C2H5)3/H2O was studied. The dependence of the polymerization rate R0 of the monomer DH(M) may be represented by the equation:

The kinetic scheme which verifies the obtained results is that which takes into consideration in the starting period of the polymerization the existence of chain transfer to the monomer. The decrease of the polymerization rate and the diminishing of the intrinsic viscosity at high conversions points to the existence of chain transfer to the polymer in this stage of the reaction. The reaction rate constants of the chain transfer to the monomer are one order of magnitude higher than those of the transfer reaction to the polymer.
Untersuchungen von polymeren im massenspektrometer, 3. Fragmentierungsreaktionen oligomerer benzyle
Authors: Lüderwald Ingo , Montaudo Giorgio , Przybylski Michael , Ringsdorf Helmut 
Published: April 2003

AbstractBeim thermischen Abbau von Polybenzylen im Massenspektrometer werden oligomere Benzylbruchstücke mit gesättigten (Phenyl‐, Alkyl‐) und ungesättigten (Chinonmethid)‐Endgruppen gebildet. Zur Differenzierung der thermischen und elektronenstoßinduzierten Abbaureaktionen wurden die Fragmentierungsreaktionen oligomere Benzyle vom Typ1a, bim Massenspektrometer untersucht. Bei Anwendung niedriger Elektronenstoßenergien wurden als Hauptfragmentierungsreaktionen Alkyl‐, α‐Benzyl‐ und β‐Benzylspaltung sowie die für 1,2‐disubstituierte Benzyle strukturspezifischeortho‐Umalgerung gefunden, die eine Differenzierung stellungsisomerer Oligobenzyle ermöglicht. Die genannten Reaktionen wurden durch Hochauflösungsmessungen und Registrierung zahlreicher metastabiler Zerfälle mit der “Defocusing”‐Technik nachgewiesen. Der Einfluß unterschiedlicher Substitution der Phenylringe und Methylengruppen auf das Fragmentierungsverhalten der oligomeren Benzyle wird diskutiert.
Cationic copolymerisation of 1,3‐dioxolane with 5‐methyl‐2,3‐dihydro‐2‐furanone initiated with triethyloxonium tetrafluoroborate
Authors: Yokoyama Yasuaki , Okada Masahiko , Sumitomo Hiroshi 
Published: April 2003

AbstractThe copolymerization of 1,3‐dioxolane (1) with 5‐methyl‐2,3‐dihydro‐2‐furanone (2) which has two functional groups, a CC double bond and a γ‐lactone ring, was carried out in nitrobenzene, dichloromethane, and toluene at 0 C with triethyloxonium tetrafluoroborate as initiator. NMR analysis of the microstructure of the copolymer disclosed that a random copolymer was formed in this system, and that the exclusive addition of the growing chain end of 1 to the CC double bond occurred in the cross‐propagation from 1 to 2. The highly selective reactivity of the growing species of 1 was discussed.Homopolymerizability of 2 was also studied by using various cationic and radical initiators.