bluuebunny/crossref_metadata_2025_split huggingface dataset:
Acrylonitrile polymerization in aqueous solution
Authors: Morris Carolyn E. M. , Parts Adolf G. 
Published: April 2003

AbstractThe polymerization of acrylonitrile in aqueous solution in the presence of an anionic soap was examined, particular attention being paid to the size of the latex particles as a function of the extent of the reaction. It was found that in some systems the rate of polymerization became irreproducible at conversions higher than about 25%. A tendency to gel formation in systems of quite low solids content was also noted.For one system the size of the latex particles at various conversions was determined by light scattering using the dissymmetry method. The average particle size was found to be essentially constant up to about 20% conversion and to increase slowly at higher conversions.A mechanism of particle formation and growth is proposed to account for these observations.
Calculation of the characteristic ratio of polypropylene containing chemical inversions (head‐to‐head and tail‐to‐tail units)
Authors: Asakura Tetsuo , Ando Isao , Nishioka Atsuo 
Published: April 2003

AbstractThe characteristic ratio (CR, i.e., a measure for the end‐to‐end distance) of polypropylene was calculated taking into account the chemical inversions such as head‐to‐head and tail‐to‐tail units in the chain and compared with the values calculated previously as a function of the tacticity.
Reactivity of polystyrene and model compounds toward tert‐butoxy radicals
Authors: Dulog Lothar , David Karl‐Heinz 
Published: April 2003

Abstracttert‐Butoxy radicals were generated by decomposing di‐tert‐butyl hyponitrite. The relative reactivities of substrates were measured from the ratio of tert‐butanol and acetone formed. Polystyrene was found to be less reactive than model compounds. Activation parameters for the hydrogen abstraction reaction for cumene, 3‐phenylpentane, and 2,4‐diphenylpentane are reported and show small differences for the enthalpy of activation; large negative values for the entropy of activation demonstrate the importance of steric hindrance in the hydrogen abstracting step. 2,3‐Diphenylbutane as model compound for head to head links in polystyrene exhibits low reactivity, whereas 2,5‐diphenylhexane, a model for tail to tail links, is more reactive than the dimer head to tail model. Still more reactive is 2,4‐diphenyl‐2‐pentene as model for an unsaturated unit in polystyrene.
Schlangenkäfig‐polymere, 2.N‐chlorierung verschiedener schlangenkäfig‐polyelektrolyte auf der basis von polyacrylamiden und einem anionenaustauscher
Authors: Kaczmar B. Ulrich , Traser Sigrid 
Published: April 2003

AbstractSchlangenkäfig‐Polyelektrolyte auf der Basis von Polyacrylamiden und einem Anionenaustauscher wurden, soweit sie sekundäre Amidgruppen enthalten, N‐chloriert. Die Geschwindigkeit und das Ausmaß der N‐Chlorierung sowie die Stabilität der Polyacrylamide wurden untersucht und diskutiert. Schließlich wurde die Chloraufnahme des Anionenaustauschers zeitlich verfolgt und interpretiert.
Interpretation of monomer‐polymer equilibria in the polymerization of alkyl substituted 1,3‐dioxolanes
Authors: Okada Masahiko , Mita Koji , Sumitomo Hiroshi 
Published: April 2003

AbstractThe thermodynamic parameters for the monomer‐polymer equilibria in the polymerization of 4‐methyl‐, 4‐ethyl‐, 4‐isopropyl‐, 4,4‐dimethyl‐, and cis‐ and trans‐4,5‐dimethyl‐1,3‐dioxolanes were calculated from the number of conformational isomers. The number of conformational isomers and the gauche interactions involved were enumerated for the monomeric unit of each polymer, whilst the number of conformational isomers and their energies due to the gauche interactions, bond opposition strain (“Pitzer strain”) between the cis neighbouring bonds of the ethylene part of the 1,3‐dioxolane ring, and 1,3‐nonbonded interaction were estimated for each monomer. On the basis of these enumerations, the enthalpy and entropy values for the polymerization of the alkyl substituted 1,3‐dioxolanes were computed by using the observed values for 1,3‐dioxolane as the standard for the calculation. From the comparison of the calculated values with the experimental results, it is concluded that the effects of alkyl substituents on the monomer‐polymer equilibria can arise principally from the various conformational isomers in the monomeric and polymeric states.
Homo‐ und copolymerisation von N,N‐disubstituierten carbamoyloxyalkylacrylaten und ‐methacrylaten
Authors: Probst Joachim , Kolb Günter 
Published: April 2003

AbstractEs wurden Methacrylate und Acrylate (3a–i) von N,N‐disubstituierten 2‐Hydroxyalkyl‐carbamaten (2) dargestellt und radikalisch homo‐ und copolymerisiert. Dabei wurde gefunden, daß die Homopolymerisation nach den üblichen kinetischen Gesetzmäßigkeiten verläuft. Die physikalisch‐chemischen Eigenschaften der Polymeren werden durch die sperrigen und polaren Seitengruppen bestimmt, was sich bei Viskositäts‐, GPC‐, Röntgen‐, DTA‐ und Kernresonanzmessungen bemerkbar machte. Das Verhalten der Methacrylate bei der radikalischen Copolymerisation mit einer Reihe von Comonomeren zeigte Ähnlichkeit mit dem des Methylmethacrylats, jedoch wiesen die neu dargestellten Methacrylate cine geringere Einbautendenz in die Copolymeren auf als das Methylmethacrylat, was wohl wiederum auf die unterschiedlichen sterischen Effekte zurückzuführen ist.
Vinyl polymerisation of acrylonitrile by the vanadium(V)‐glycerol redox system
Authors: Rout Anuradha , Singh Baishnab C. , Santappa M. 
Published: April 2003

AbstractA kinetic study of the thermal polymerisation of acrylonitrile initiated by the redox system V5+ ‐glycerol in sulfuric acid and perchloric acid was made in the temperature range 35–45°C. The rates of polymerisation and V5+ disappearance wee measured with respect to their dependence on time, monomer, metal ion, glycerol, acid, and ionic strength. Experimental evidences provide support to a mechanism involving initiation by a free radical produced by the decomposition of the acyclic complex between V5+ and glycerol. The kinetics are consistent with a linear termination of polymerisation (1st order in respect of growing radicals) at higher concentration of V5+. The various rate and activation parameters were evaluated and an appropriate reaction scheme is proposed. The induction period and the polymerisation rate of the V5+ ‐glycerol system were compared with those involving polyhydroxy alcohol systems such as sorbitol and mannitol.
Synthèse par polymérisation anionique de copolymères biséquencés polybutadiène‐poly(vinyl‐2 naphtalène). Étude de leur structure en solution concentrée avant et après polymérisation du solvant
Authors: Douy André , Jouan Gilbert , Gallot Bernard 
Published: April 2003

AbstractNous avons préparé par polymérisation anionique sous vide des copolymères biséquencés polybutadiène‐poly(vinyl‐2 naphtalène) (BVN) et nous discutons les conditions de polymérisation qui conduisent à des copolymères isomoléculaires. En utilisant la diffraction des rayons X aux petits angles et la microscopie électronique nous avons déterminé structure des mésophases obtenues par dissolution des copolymères BVN dans un vant préférentiel des séquences poly(vinyl‐2 naphtalène) et des copolymères organisés des préparés par polymérisation du solvant de la mésophase. Nous avons montré que les copolymères BVN présentent en fonction de la composition du copolymère les mêmes types de structure que les copolymères bi‐ et triséquencés polystyrène‐polybutadiène. Nous décrirons en détail les structures lamellaire et hexagonale inversée des polymères BVN et l'influence de la concentration, de la nature et de la polymérisation solvant sur leurs paramètres géométriques.
Verschiedenartige Additionsreaktionen von 2‐Cyano‐2‐propylradikalen an p‐Tolylmethacrylat und 4‐Cyclohexylphenylmethacrylat
Authors: Kämmerer Hermann , Pachta Jiri 
Published: April 2003

AbstractDurch Umsetzung von p‐Tolylmethacrylat oder 4‐Cyclohexylphenylmethacrylat in stark verdünnter, siedender Benzollösung mit einem sehr großen Überschuß an 2,2′‐Azoisobutyronitril wurden die erwarteten Additionsprodukte mit 2‐Cyano‐2‐propylradikalen (1) erhalten, nämlich p‐Tolyl‐ bzw. 4‐Cyclohexylphenyl‐[4‐cyano‐2‐(2‐cyano‐2‐propyl)‐2,4‐dimethyl]valerianat (3a bzw. 3b) mit rund 50% Ausbeute. Daneben wurden p‐Tolyl‐ bzw. 4‐Cyclohexylphenyl‐(4‐cyano‐4‐methyl‐2‐methylen)valerianat (4a bzw. 4b), p‐Tolyl‐ bzw. 4‐Cyclohexylphenyl‐[4‐cyano‐2(2‐cyano‐2‐methyl‐1‐propyl)‐4‐methyl]valerianat (5a bzw. 5b), p‐Tolyl‐ bzw. 4‐Cyclohexylphenyl‐(4‐cyano‐2,4‐dimethyl)valerianat (6a bzw. 6b) und p‐Tolyl‐ bzw. 4‐Cyclohexylphenyl‐(4‐cyano‐2,4‐dimethyl)‐2‐pentenoat (7a bzw. 7b) isoliert. Ihre Strukturen wurden durch Massenspektrometrie, Elementaranalysen, Mikrohydrierungen, IR‐ und UV‐Spektren bestimmt. Es konnten, bezogen auf die eingesetzten Monomeren, 95 bzw. 100% in ihrer Struktur aufgeklärte Reaktionsprodukte gefaßt werden. Die Entstehung der Verbindungen kann durch ein Zusammenspiel von Additionen der 2‐Cyano‐2‐propylradikale (1), Abspalten von Wasserstoff bzw. Disproportionierungen erklärt werden.
New catalysts for the oxidative polymerization of 2,6‐dimethylphenol, 2. Copper complexes containing the dicyanoethenedithiolatocuprate structure as the ligand
Authors: Yoshimura Tamotsu , Storck Winfried , Manecke Georg 
Published: April 2003

AbstractIt was found that the reaction of 1,2‐dicyano‐1,2‐ethenedithiolate, resp. of bis(1,2‐dicyano‐1,2‐ethenedithiolato)cuprate(2‐), with Cu2+ does not lead to copper bis(1,2‐dicyano‐1,2‐ethenedithiolato)cuprate(2‐) dihydrate (1a) as described in the literature but to a reaction product which has a complex structure containing mainly Cu+. This compound as well as complexes with the same ligand, but with Cu+, Cu2+ or Cu3+ as the central atom, were synthesized and tested with and without added cuprous chloride as catalysts for the oxidative polymerization of 2,6‐dimethylphenol. Included in this investigation were some copper complexes with the isomeric ligand 2,2‐dicyano‐1,1‐ethenedithiolate.
Coenzyme models, 5. Addition reaction of cyanide ion to monomeric and polymeric nicotinamides. Correlation between equilibria and reaction rates
Authors: Shinkai Seiji , Tamaki Kiyoshi , Kunitake Toyoki 
Published: April 2003

AbstractRate and equilibrium constants (kf and K, respectively) for the addition of cyanideion to poly[1‐(4‐vinylbenzyl)nicotinamide chloride] (poly{1‐[4‐(3‐aminocarbonylpyridiniomethyl)phenyl]ethylene chloride}) (poly(1)) and a corresponding monomeric derivative of nicotinamide, 3‐aminocarbonyl‐1‐benzylpyridinium chloride (2), were evaluated at 30°C, in an aqueous system. The rate constant for the reaction of poly(1) with CN− at μ = 0,1 mol 1−1 was found to be higher by a factor of 22 and the association constant by a factor of about 65, compared with those for the reaction of 2 with CN−. At a lower ionic strength (μ = 0,008 mol 1−1), the reaction parameters were markedly enhanced (108‐fold and 218‐fold, respectively). The rate enhancements in the polymeric system are attributable to the increase in the ΔS term. This favorable entropy term caused the deviation from the linear log K‐log Kf relationship which holds strictly for monomeric compounds.
Asymmetric synthesis catalyzed by (S)‐alanine‐N‐propylamide as a terminal model of poly[(S)‐alanine]
Authors: Ueyanagi Kaoru , Inoue Shohei 
Published: April 2003

AbstractThe asymmetric addition of 1‐dodecanethiol (1) to isopropenyl methyl ketone (2) catalyzed by (S)‐alanine‐N‐propylamide (5) as a terminal model of poly[(S)‐alanine] (3c) was studied. When the asymmetric addition reaction was carried out in chloroform, it was accompanied with a slow competitive racemization of the product by the catalyst. On the other hand, when ethanol was added to the reaction system, the racemization was much depressed.
Branching and unsaturated structures in radically polymerized poly(vinyl chloride)s studied by high‐resolution proton magnetic resonance
Authors: Pétiaud Roger , Pham Quand‐Tho 
Published: April 2003

AbstractRadically polymerized PVC obtained in bulk was fractionated and examined by high resolution NMR using spectrum accumulation. The main unsaturation found consists of 1‐chloro‐2‐pentene structures, and the saturated chain end should be a 1,2‐dichloroethyl group. Owing to the semi‐quantitative determinations, there are, independently of molecular weight, two or three double bonds per 1000 monomer units, while the number of branches was found to increase with increasing molecular weight.
Über einige besonderheiten der polymerisation von 2,3‐dimethylbutadien in durch lithiumorganische verbindungen initiierten prozessen
Authors: Smirnowa Natalia , Sgonnik Vladimir , Kalninsch Karl , Erussalimsky Boris 
Published: April 2003

AbstractThe polymerization of 2,3‐dimethylbutadiene (DMB) induced by butyllithium (BuLi), oligo‐2,3‐dimethylbutadienyllithium (ODMBL), and by the system ODMBL/N,N,N′,N′‐tetramethylethylenediamine (TMD) was investigated in heptane at 60°C. The reaction order with respect to the organolithium compound was found to be for these cases −0,32, 0,28, and 0,56 respectively. The negative reaction order for BuLi is caused by the existence of the mixed associates (BuLi)x. (MnLi)y which follows from the negative influence of BuLi on the propagation reaction rate in the system DMB/ODMBL. Contrary to butadiene and isoprene, catalytic amounts of TMD decrease the propagation rate of DMB. This phenomenon is ascribed to a weak tendency of the complexes of the DMB‐living chains to dissociate into the monomeric form MnLi. TMD. The UV‐ and IR‐spectra of the living DMB‐chains and their complexes with TMD are studied.
Anionic polymerization of siloxanes, 2. Internal multifunctional assistance of siloxane system to the siloxane bond cleavage by alcali metal silanolates
Authors: Mazurek Mieczysław , Chojnowski Julian 
Published: April 2003

AbstractThe kinetics of the reaction of potassium phenyldimethylsilanolate (1) with the series of linear trimethylsilyl‐end‐blocked dimethylsiloxane oligomers and with the series of cyclic dimethylsiloxane oligomers was studied to clear some mechanistic problems of anionic polymerization of siloxanes.The results indicate that the high reactivity of the siloxane bond in linear and higher cyclic oligomers—responsible for the large scope of chain redistribution and cyclization processes in the siloxane anionic polymerization system—is due to a mechanism involving multifunctional interaction of siloxane with silanolate, which gives assistance to the siloxane bond cleavage. This mechanism is impeded when strong cation solvating agents are present in the system.
Die Bestimmung der Molekulargewichtsverteilung von nichtkristallisierenden Polymeren mit dem Elektronenmikroskop, 4. Weiterentwicklung der Präparationsmethode durch Gefriertrocknung
Authors: Koszterszitz G. , Barnikol W. K. R. , Schulz G. V. 
Published: April 2003

AbstractMolecular weigth distribution curves determined by electron microscopy exhibit a deviation when approaching a molecular weight of 106. Picturing of single molecules therefore was improved by the introduction of shadowing by electron beam. Techniques of preparation (by freeze‐drying) and shadowing are described in detail. The scanning size of the electron beam shadowing is in between 15 and 20 Å and is given by the structure of the supporting film. By double shadowing from different sides it is demonstrated, that there is no “decoration effect” in electron beam shadowing. The lower limit of an exact determination of the dimensions is a molecular weight of ca. 105. It is shown with latex particles that there is a change of shape with time of the particles after sedimentation on the support which is dependent on the kind of polymer and of the conditions. Their volume though remains constant within the limits of error.
Structural study of polybutadiene‐poly(ethylene oxide) block copolymers. Influence of the nature of the amorphous block on the refolding of the poly(ethylene oxide) chains
Authors: Gervais Monique , Gallot Bernard 
Published: April 2003

AbstractOur earlier studies on block copolymers polystyrene‐poly(ethylene oxide) has allowed to state the influence of the molecular weight of the copolymer and of its composition on the refolding of the crystallized poly(ethylene oxide) chains. To precise the effect of the nature of the amorphous block, we have studied by X‐ray diffraction and differential scanning calorimetry, the lamellar crystalline structures exhibited by block copolymers polybutadiene‐poly(ethylene oxide) (BEO) in the presence of a preferential solvent of one block: xylene for polybutadiene (PB), acetic acid or acrylic acid for poly(ethylene oxide) (PEO). In systems BEO copolymer/preferential solvent of PEO, the lamellar structure with crystallized PEO chains (LCC) exists at temperatures below about 45°C and for solvent concentrations ranging from 0 to a value characteristic of the copolymer. In the LCC structure, the chains of PEO crystallize in two layers; the solvent forms a third layer located between the PEO layers. We have studied the influence of the nature of the amorphous block on the variation of the structural parameters with the solvent concentration. In systems BEO copolymer/preferential solvent of PB, the lamellar structure with crystallized PEO chains (LC) appears at temperatures below about 50°C and for all solvent concentrations where the mesophase exists. In the LC structure, the chains of PEO crystallize folding in two superposed layers. We have established the influence of the solvent concentration and the nature of the amorphous block on the number of folds and the crystallinity of the PEO chains.
Über die möglichkeiten zur bestimmung von mischungsenthalpien und ‐volumina aus der molekulargewichtsabhängigkeit der kritischen entmischungstemperaturen und ‐drücke am beispiel des systems trans‐decahydronaphthalin/polystyrol
Authors: Wolf B. A. , Jend R. 
Published: April 2003

AbstractCloud‐point curves and critical curves (Tc = f(p)) have been measured for the system trans‐decahydronaphthalene/polystyrene and three different molecular weights of the polystyrene component (2,5 · 106; 3,9 · 105; 1,1 · 105). It turned out that by variation of the pressure the metastable region can be investigated up to the spinodal curve.A comparison of the theta‐temperatures and the enthalpy contributions χH (to the Flory‐Huggins interaction parameter χ) resulting from the measured critical temperatures according to Shultz‐Flory, with the corresponding directly obtained literature data, demonstrates that, although the extrapolation of Tc to infinite molecular weight is feasible, χH obtained in this way is greater by a factor of approximately three, due to the concentration dependence of χ. The same is true for the determination of χV (the contribution of the work in change of volume to χ) from the molecular weight dependence of the critical pressure. The determination of χV from the slope of the critical curves and known χH is, however, possible; the results are in good agreement with direct measurements.The shape of the critical curves calculated theoretically according to Prigogine and Patterson, turns out to be very sensitive to the precise values chosen for the mechanical data of the pure components. By adjustment of the system‐specific parameters the measured critical curves can be well represented analytically.
Terpolymerization of polar vinyl monomers with butadiene and styrene in the presence of Lewis acids
Authors: Kuran Witold , Pasynkiewicz Stanisław , Nadir Riad 
Published: April 2003

AbstractTerpolymerizations of polar vinyl monomers, acrylonitrile, methyl acrylate, or methyl methacrylate with butadiene and styrene in the presence of ethylaluminium dichloride, zinc chloride, or other Lewis acids were carried out. The yield and the contents in monomer units of the terpolymer and the yields of the polar vinyl monomer/butadiene 1,4‐cycloaddition byproduct formed in these systems were determined. Butadiene conversions in the above terpolymerizations and 1,4‐cycloaddition side reactions were related to those in the copolymerization and 1,4‐cycloaddition proceeding in corresponding binary systems without styrene. The results are discussed in terms of a radical polymerization and a polar 1,4‐cycloaddition mechanisms.
Mechanism of the NCA‐polymerization, 5. Catalysis by secondary amines
Authors: Kricheldorf Hans R. 
Published: April 2003

AbstractL‐Phenylalanine NCA and glycine NCA react with excess diisopropylamine or dicyclohexylamine to give only polymeric products. In contrast, excess morpholine or diethylamine produces no polymerization but instead yield amino acid amides (2) and hydantoic acids (6), which indicate the intermediate formation of NCA anions 4, which are in equilibrium with the isomeric α‐isocyanatocarboxylates (5). Diisopropylamine and dicyclohexylamine in the presence of N‐acetylglycine NCA (13) yield also quantitative polymerization of glycine NCA, from which oligomers 14 with acetyl and NCA end groups may be isolated. Under the same conditions morpholine and diethyl amine yield no polymerization, since these amines are acylated by excess N‐acetylglycine NCA. These results show that secondary amines with small substituents react preferentially as nucleophiles so that the NCA‐polymerization proceeds, as with initiation by primary amines, through propagation by nucleophilic end groups. Secondary amines with bulky substituents, in analogy with the tertiary amines, produce only NCA anions which polymerize according to the “activated monomer mechanism”, i.e., through reaction with the electrophilic NCA chain end. Apparently contradictory experiments of Seeney and Harwood were reinvestigated and the results are discussed.
Microstructure of 1,5‐cyclooctadiene oligomers
Authors: Sato Hisaya , Tanaka Yasuyuki , Taketomi Takanao 
Published: April 2003

Abstract1H and 13C NMR spectra of 1,5‐cyclooctadiene oligomers were investigated and compared with those of 1,4‐polybutadiene. The oligomers were prepared with Rh2O7 as catalyst and fractionated by vacuum distillation or gel‐permeation chromatography. It was found that each fraction consists of a mixture of steric isomers possessing cis and trans structures in different ratios. The 13C NMR spectra of oligomers with less than 24 carbons vary with ring size, which is explained in terms of ring strain effects. The 13C NMR spectra of oligomers with more than 28 carbons are identical with the spectrum of 1,4‐polybutadiene. It resulted that the ratio of cis to trans structure in the oligomers decreases with increasing molecular weight from 70:30 (C16) to that in the cyclooctadiene polymer (40:60).
Elektrokinetische untersuchungen an fasern, 1. Theoretische zusammenhänge
Authors: Aichele Wilfried , Schollmeyer Eckhard , Herlinger Heinz 
Published: April 2003

AbstractSome relations between electrokinetic properties are shown. First by means of phenomenological equations, the electroviscose effect is explained to be due to the electroosmotic backstreaming. It is shown that in principle the equivalence of streaming‐current‐and streaming‐potential‐methods to get zetapotentials is included in these equations. This equivalence was used first by Smoluchowski to derive his equation for the zeta‐potential for the special case of a single capillary. The equation he found concerning the relations between both zeta‐potential and streaming‐potential and streaming current between the ends of a capillary was extended by different authors to bundles of capillaries and then to plugs. It is discussed, which of the extensions are correct and which properties should be included in a so‐called “porosity factor”.From a mathematical treatment of the surface conductivity in case of capillaries it is shown that zeta‐potentials can be obtained in principle by measuring the conductivity of the system plug‐electrolyte. For this system a procedure is deduced to calculate approximately the porosity factor from measurements of the electrical resistance.