bluuebunny/crossref_metadata_2025 huggingface dataset:
Gel permeation chromatography with crosslinked polystyrene gels and poor and theta solvents for polystyrene, 2. Separation mechanism
Authors: Dawkins John V. , Hemming Malcolm
Published: April 2003

For separations performed with crosslinked polystyrene gels, an interpretation is proposed for the displacement to high retention volume of plots of log hydrodynamic volume versus retention volume for polystyrene (PS) in poor and theta solvents, e.g. cyclohexane, trans‐decalin, and N,N‐dimethylformamide, with respect to plots for other polymers for which these same eluents are good solvents. PS separates by steric exclusion and by solute‐gel interaction effects giving rise to partition and adsorption mechanisms. The retention volume VR is given by

where V0 is the interstitial volume, Vi is the solvent volume within the gel, KD is the distribution coefficient for steric exclusion, and Kp is the distribution coefficient for solute‐gel interaction effects. For polymers in good solvent media separating solely by steric exclusion, Kp is unity. For PS in poor and theta solvents, network‐limited partition and network‐limited adsorption mechanisms are proposed in which Kp is greater than unity. The hydrodynamic volume universal calibration method is applicable when Kp is greater than unity, provided the retention parameter is changed from VR to (VR–V0)/Kp. From the network‐limited adsorption mechanism, a plot of log[(VR–V0)/Kp] versus polymer hydrodynamic radius yields the average pore size of the crosslinked polystyrene gel. Experiments are reported showing the dependence of Kp on gel porosity and on solvent power by varying the temperature of the eluent.
Gel permeation chromatography with crosslinked polystyrene gels and poor and theta solvents for polystyrene, 3. Temperature dependence of universal calibration for trans‐decalin
Authors: Dawkins John V. , Hemming Malcolm
Published: April 2003

Gel permeation chromatography calibrations for polystyrene (PS) standards and poly(dimethylsiloxane) (PDS) fractions have been obtained with crosslinked polystyrene gels using trans‐decalin as eluent at 25, 60, 100, and 138°C. At these temperatures, the Mark‐Houwink exponent for PS in trans‐decalin is 0,52, 0,64, 0,67, and 0,67, respectively. The eluent is a good solvent for PDS at all four temperatures. At 25 and 60°C, the plot of log hydrodynamic volume versus retention volume for PS is displaced to high retention volumes with respect to the plot for PDS, the displacement increasing as the retention volume increases. The deviation between the two plots decreases as the temperature is raised, becoming almost negligible at 100°C. trans‐Decalin gives rise to broadened gel permeation chromatograms, because of the high viscosity of the cluent. However, additional broadening occurs for PS at 25 and 60°C, the broadening increasing as retention volume increases, and as temperature falls. Both the additional retention and broadening for PS are explained by solute‐gel interactions. The calibration results are plotted according to equations representing network‐limited partition and network‐limited adsorption mechanisms. The distribution coefficient for solute‐gel interaction effects. Kp, falls as the temperature is raised. When Kp is greater than unity, it is shown that the hydrodynamic volume universal calibration method is applicable, if the retention parameter is changed from VR to (VR–V0)/Kp, where V0 is the interstitial volume.
Mechanical relaxation in polystyrene/poly(ethylene oxide) block copolymers
Authors: Shimura Yukio , Hatakeyama Tatsuko
Published: April 2003

Mechanical relaxation behaviors were investigated for twelve samples of polystyrene/poly(ethylene oxide) multiblock copolymers and two ABA‐type copolymers using a torsion pendulum type viscometer. Logarithmic decrements of damped oscillations and shear moduli of polymer‐impregnated glass braids were plotted in the temperature range between –130 and 130°C. The temperature for the maximum logarithmic decrement decreased with the molecular weight of the poly(ethylene oxide) blocks showing increased relaxation of the polystyrene blocks. Relative modulus values are also discussed in relation to the amounts of poly(ethylene oxide) blocks.
Tetraaza[14]annulen‐derivate und ihre vorstufen, 1. Niedermolekulare modellverbindungen
Authors: Müller Reinhardt , Wöhrle Dieter
Published: April 2003

Aromatische o‐Diamine (1) und Propinal reagieren im Molverhältnis 1:2 zu 3,3′‐(1,2‐Arylen‐1,2‐diimino)dipropenalen (2). Die Umsetzung der Diamine 1 mit Propinal im Mengenverhältnis 1:1 nach verschiedenen Methoden führt zu niedermolekularen symmetrischen und asymmetrischen Tetraaza[14]annulen‐Derivaten (4). Zahlreiche Metallkomplexe (3 und 5) wurden aus den Verbindungen 2 bzw. 4, dargestellt. Die Produkte wurden durch IR‐, Elektronen‐ und Massenspektren charakterisiert.
Stereoregularity of polystyrene and mechanism of polymerization
Authors: Matsuzaki Kei , Uryu Toshiyuki , Seki Toshiyuki , Osada Kiyoshi , Kawamura Tokiji
Published: April 2003

The Stereoregularity of polystyrenes prepared with radical, anionic, and cationic initiators was determined by means of 13C‐NMR spectroscopy. Aromatic C1 carbon spectra measured on o‐dichlorobenzene solutions consisted of about six peaks and the peak at the highest magnetic field (at 146,3 ppm) was assigned to an rrrr pentad. The proportion of racemic dyads Pr, was directly calculated from the proportion of the rrrr pentad peak assuming that the Bernoullian statistics holds for the polymerization of styrene. The Pr values of polystyrenes prepared with radical initiators at temperatures from 80° to 0°C were 0,72–0,73, while the cationic polymerizations gave Pr values ranging from 0,54 to 0,68. The Pr values of the same polystyrenes were also calculated by use of a p‐xylene/chloroform mixture as solvent for the 13C‐NMR measurements. For anionically obtained polystyrenes, considerably different Pr values were found using both solvent systems. From this, it was considered that the anionic polymerization of styrene with butyllithium as catalyst does not obey the Bernoullian statistics.
Dynamic cooling and isothermal crystallizations of poly(vinylidene fluoride) from the melt
Authors: Nakamura Shigeo , Sasaki Toshio , Funamoto Jun , Matsuzaki Kei
Published: April 2003

The dynamic cooling and the isothermal crystallizations of poly(vinylidene fluoride) from the melt were investigated using a differential scanning calorimeter. In both the dynamic cooling and isothermal crystallizations, the kinetic treatments indicated that during the crystallization of poly(vinylidene fluoride) the nucleation proceeds homogeneously and the growth occurs three dimensionally. The melting curves were recorded at various stages of the isothermal crystallization, and the thickening of lamellar crystals was observed, which can be explained more reasonably by the annealing theory than by the molecular fractionation theory.
Preparation of poly[N‐(3‐acryloylaminopropyl)carbazole] and its charge transfer complex with 2,4,7‐trinitrofluorenone
Authors: Ito Hiroshi , Tazuke Shigeo , Okawara Makoto
Published: April 2003

A new carbazole polymer, poly{1‐[3‐(9‐carbazolyl)propylaminocarbonyl]ethylene} {poly[N‐(3‐acryloylaminopropyl)carbazole]} (6) was prepared by radical polymerization ofN‐(3‐acryloylaminopropyl)carbazole (5). Copolymerization of5(M1) with styrene (M2) provided the monomer reactivity ratiosr1= 0,13±0,08 andr2= 3,47±0,12. TheQ‐evalues of5were calculated asQ1= 0,18 ande1= +0,10. Fluorescence spectra of6andN‐(3‐isobutyrylaminopropyl)carbazole (2), prepared as a monomer model compound, were nearly identical, indicating the absence of intramolecular excimer formation for6. The stability constants (K) of the charge transfer complexes of6and2with 2,4,7‐trinitrofluorenone (TNF) were determined in 1,2‐dichloroethane at 20°C under the conditions of both [6] or [2]≫[TNF] and [6] or [2]≪[TNF]. The values ofKwere 4,9 and 5,2dm3mol−1for2when [2]≫[TNF] and [2]≪[TNF], respectively, and 16dm3mol−1for6when [6]≫[TNF]. The polymer6precipitated, however, when [6]≪[TNF]. As a reference, charge transfer complex formation of poly[1‐(9‐carbazolyl)‐ethylene] [poly(N‐vinylcarbazole)] [1] with TNF was studied under the same conditions. The values ofKfor1were identical when [1]≫[TNF] and [TNF]. These results were explained by assuming a sandwich‐type charge transfer complex for6, but not for1. The space between the carbazolyl groups in1would be too small to accomodate a TNF molecule between the chromophores.
Study of the mechanism of propagation and transfer reactions in the polymerization of olefins by Ziegler‐Natta catalysts, 1. Determination of the number of propagation centers and the rate constant
Authors: Chumaevskii Nikolay B. , Zakharov Vladimir A. , Bukatov Gennadii D. , Kuznetzova Galina I. , Yermakov Yurii I.
Published: April 2003

The number of propagation centers (Cp) and the propagation rate constant (Kp) in the polymerization of ethylene and propene in the presence of heterogeneous TiCl3 derived Ziegler‐Natta catalysts of different composition were determined using the method of quenching the polymerization by radioactive carbon monoxide (14CO). The values of Kp, (1,2±0,3)·104 l mol−1 s−1 at 75°C for ethylene and (90±20) l mol−1 s−1 at 70°C for propene polymerization, significantly exceed those ones obtained by use of tritium tagged alcohols as quenching agents. Further, for the polymerization of olefins in the presence of TiCl3 based catalysts, the influence of catalyst composition, polymerization conditions, and monomer nature on Cp and Kp was studied.
ESR measurements during γ‐radiation induced solid‐state polymerization of 1,3,5‐trithiane
Authors: Gearhart Richard C. , Schultz Jerold M.
Published: April 2003

The time‐dependences of ESR spectra were measured during the γ‐radiation induced solid‐state polymerization of 1,3,5‐trithiane to polythiomethylene. The reaction was carried out at several temperatures, both under air and under N2. The initial reaction kinetics are second order, but become of lower order at the highest temperatures under air. Mass spectrographic results indicate spontaneous degradation under these high temperature conditions. It is concluded that an observed peak in reaction rate with temperature derives from the onset of spontaneous chain termination.
Untersuchungen einiger gesetzmäßigkeiten der polykondensation von tetracarbonsäure‐tetranitrilen mit diaminen sowie der eigenschaften der entstehenden polymere
Authors: Winogradowa Swetlana V. , Siling Swetlana A. , Solowjöw Wladimir N.
Published: April 2003

Polyhexazocyclane sind ein neuer Typ von Polymeren mit stickstoffhaltigen Makroheterocyclen in der Kette, die durch Polykondensation von Tetracarbonsäuretetranitrilen mit Diaminen unter Ammoniakentwicklung dargestellt werden können.

Die Untersuchung einer Modellreaktion von Phthalodinitril mit p‐Phenylendiamin in verschiedenen Hydroxyl‐Gruppen enthaltenden Medien hat gezeigt, daß die Kondensation in Phenol und Kresolen im Unterschied zur Kondensation in aliphatischen Alkoholen die Darstellung von makroheterocyclischen Verbindungen mit hoher Ausbeute ermöglicht. Bei der Durchführung solcher Kondensationen in Phenolen mit elektronenanziehenden Substituenten werden keine Makroheterocyclen gebildet.

Die Umsetzung von Ammoniak mit einem Modell‐Makroheterocyclus führt zur Bildung einer Reihe von Substanzen, die Zwischenprodukte seiner Synthese sind. Dies gestattet die Annahme, daß die Bildung des Makroheterocyclus und folglich die Polykondensation der Tetracarbonsäure‐tetranitrile mit Diaminen ein Gleichgewichtsprozeß ist.

Die Polyhexazocyclane sind thermobeständige Polymere. Der Zersetzungspunkt an der Luft liegt über 400°C. Bei der Erhitzung über 250°C werden die Polymere vernetzt. Sie erweichen nicht vor ihrer Zersetzung.
Selective adsorption of metal ions on poly(4‐vinylpyridine) resins in which the ligand chain is immobilized by crosslinking
Authors: Nishide Hiroyuki , Tsuchida Eishun
Published: April 2003

Chelate forming resins (3) were prepared by crosslinking poly(4‐vinylpyridine) (1) with 1,4‐dibromobutane (2) and their complexation with metal ions was studied. Stability constants (K) were found to be much higher for the Cu‐3 system than for the Cu‐1 system, which indicates that 3 uptakes Cu ions with high efficiency. K and the adsorption capacity of Cu decrease largely with increasing degree of crosslinking. Visible and ESR spectra of Cu‐3 show that the structure of the Cu complex within 3 is the same as that of the monomeric Cu‐pyridine complex. However, the ligand‐chain is immobilized in the highly crosslinked 3c and 3d, so that the square planar structure of a stable Cu complex is distorted. The amount of adsorption of Cu, Fe, Cr, Ni, and Zn ions on 3 decreases with the crosslinking, but the adsorption of Hg ions is independent; i.e. 3d selectively adsorbs Hg ions. Metal complexed 1 was crosslinked according to Scheme 1 and the metal ion which was used as template is well adsorbed by the obtained 3. It is considered, therefore, that the ligand chain is maintained at the best conformation for the template ion.
Über Polyarylenalkenylene und Polyheteroarylenalkenylene, 7. Die Anwendung von HMO‐Rechnungen auf elektronenspektroskopische und struckturanalytische Probleme oligomerer und polymerer Polyarylenalkenylene und Polyheteroarylenalkenylene
Authors: Koßmehl Gerhard , Bohn Bodo , Broser Waldemar
Published: April 2003

Für die homologen Reihen der Di‐2‐thienyl‐ und Diphenylalkapolyene mit 1—6 olefinischen Doppelbindungen sowie die oligomeren Arylen‐ bzw. 2,5‐Thienylenvinylene und 2,5‐Thienylen‐1,3‐butadienylene wurden nach der HMO‐Methode die Energiewerte für den π → π* Übergang (Δxj‐Werte) berechnet, die mit den λmax‐Werten (π → π*‐Übergänge) gut übereinstimmen. Für die genannten Verbindungen wurden auch die Bindungsordnungen für die Kohlenstoff‐Kohlenstoff‐Bindungen berechnet. Aus den berechneten Bindungsordungen für die π‐Elektronensysteme ergibt sich, daß der Bindungsangleich schon bei den Tetrameren bis Pentameren weitgehend erreicht ist. Für 5 einfache Verbindungen läßt sich anhand der röntgenographisch ermittelten Bindungslängen eine gute Übereinstimmung über die Bindungsangleichung dieser konjugierten π‐Elektronesysteme mit den Aussagen aus den Bindungsordnungen feststellen.
Characterization of the urinary polymer‐related material from rats given poly[biguanide‐1,5‐diylhexamethylene hydrochloride]
Authors: Bratt Harold , Hathway David E.
Published: April 2003

Gastro‐intestinal absorption in rats of poly[biguanide‐1,5‐diylhexamethylene hydrochloride] (1) amounts to only 5,6% of a single oral dose, and after chronic administration, tissue concentrations do not exceed 0,3 μg g−1. It has been shown by simple chromatographic and spectroscopic methods that urinary polymer‐related material consists of small amounts of 1‐oligomers, with two cyanoguanidino end groups, as well as the trace constituents, 3,3′‐dicyano‐1,1′‐hexamethylenediguanidine (8a) and a compound which is considered to be 1‐(6‐aminohexyl)‐3‐cyanoguanidine (2) that is formed during the synthesis of 1. Hence, the constituents of 1 are unmetabolized in rats.
Osmotic coefficients of aqueous polyelectrolyte solutions at low concentrations, 3. Dependence on macroion molecular weight
Authors: Oman Srečko
Published: April 2003

Eight sodium salts of polystyrenesulfonic acid (poly[1‐(sulfophenyl)ethylene]) of different molecular weights were prepared similarly and purified in the same way. Their aqueous solutions were thus chemically equivalent, and differed only in their molecular weights, which were determined viscosimetrically.

The osmotic coefficients (Φ) of the acid and its sodium, thallium, calcium and cadmium salt solutions were measured by a membrane osmometer for counterion molalities mc = 10−2 to 5·10−4mol/kg, at 25°C. In the same concentration range, the activity coefficients of hydrogen counterions (γH) of acid solutions were calculated from electromotive force measurements and the osmotic coefficients of the acid solutions were determined by the cryoscopic method for two different molecular weights. The values obtained are presented graphically as functions of the measured average molecular weight for mc = 10−3 and 10−2 mol/kg and are in good mutual agreement within experimental error.

This agreement of results could be assumed to verify experimentally that the colligative properties of polystyrene‐sulfonate polyelectrolytes at low concentrations are dependent on the molecular weight of the polyion.

The obtained results together with some literature data, allow us to evaluate very approximately the activity coefficients of monovalent counterions (γc) for mc = 10−2 mol/kg as a function of the degree of polymerization (n) of linear oligoions or polyions, for values of n up to 104.
Radical reactions initiated by chelate complexes of transition metals, 14. Copper(II) 2‐aminoethanolate – a selective initiator for polymerization of vinyl monomers
Authors: Bartoň Jaroslav , Mapunda‐VlčKová Jana
Published: April 2003

It was found that copper(II) 2‐aminoethanolate (Cumea) initiates the polymerization of methyl methacrylate but not that of styrene and acrylonitrile. The selectivity of Cumea with respect to initiation of vinyl monomers is caused by formation of monomer radicals which originate from the decay of the complex Cumea‐monomer. By adding free aminoalcohol and/or carbon tetrachloride to the system Cumea‐MMA, the complex Cumea‐MMA is not formed and the initiating radicals arise from consecutive reactions between Cumea and aminoalcohol or carbon tetrachloride. In this case formation of the initiating radicals is not dependent on the complex Cumea‐monomer; consequently, a loss of selectivity of Cumea during initiation of the polymerization of unsaturated monomers occurs.
The dimerization of 1‐alkynes by rhodium(I) catalysts. Effect of phosphorus ligands on regioselectivity
Authors: Yoshikawa Susumu , Kiji Jitsuo , Furukawa Junji
Published: April 2003

The dimerization of 1‐alkynes by rhodium(I) complexes in the presence of phosphorus ligands is described. The products are linear and branched dimers, the ratio of which is correlated with the electronic parameters, vCO of Ni(CO)3L, of the ligands L, but no simple correlation is apparent between their steric parameter and the selectivity. Electron‐donating ligands promote the formation of the linear dimer. The substituents of the 1‐alkynes also affect the distribution of linear and branched dimers. Electron‐donating substituents prefer linear isomer to branched one. The reactivity of the substituted 1‐alkynes (RCCH) increased with substituent R in the order
The proton chemical shifts of α‐helical poly‐L‐alanine
Authors: Asakura Tetsuo , Ando Isao , Nishioka Atsuo
Published: April 2003

The proton chemical shifts of NH, α‐CH, and CH3 groups in α‐helical poly‐L‐alanine (PLA) were calculated by taking account of diamagnetic shielding effect, electric‐field effect, and magnetic anisotropy effect. The first and second terms were obtained from the electron density distributions in the model compounds of PLA hydrogen‐bonded with formamide, and the last term was evaluated from the magnetic anisotropy effect due to the CO, (O)CN, and α‐CHN bonds, where the two kinds of bond anisotropy of the CN bond were estimated semi‐empirically on the basis of the experimental data about six kinds of amides. The calculated chemical shifts agreed fairly well with the observed values.
Catalyses by polymer complexes, 2. Enhanced esterolytic reactivity of complexes of polymeric soaps and dodecanethiol towards 4‐nitrophenyl acetate
Authors: Shinkai Seiji , Kunitake Toyoki
Published: April 2003

The reaction of dodecanethiol with 4‐nitrophenyl acetate in the presence of dodecyl derivatives of poly(4‐vinylpyridine) and poly(1‐vinyl‐2‐ethylimidazole) was studied at 30°C. It was found that at pH 9,48 the reaction is completed after a few seconds in the presence of polymeric micelles with a content of dodecyl groups > 22 mole‐%, and that the second‐order rate constant amounts to 3,2·103 l mol−1 s−1, which is ca. 150 times higher than that obtained in the absence of the polymer. The reaction rate increases with the content of dodecyl groups in the polymer and the maxima appear at 20 to 30 mole‐%. Polymers substituted with hexyl or ethyl groups instead of dodecyl groups, showed to be virtually ineffective. Obviously, the hydrophobic environment of the polymer activates the bound thiol anion.
Interaction between dyes and polyelectrolytes, 5. Effect of organic and inorganic salts on metachromasy of methylene blue
Authors: Shirai Masamitsu , Nagaoka Yoshihiro , Tanaka Makoto
Published: April 2003

The effect of alkali metal chlorides and 1‐substituted 3‐carbamoylpyridinium bromides (2a–d) on the metachromatic behavior of methylene blue (1) induced by poly(potassium styrenesulfonate) (PSS) and poly(potassium vinyl sulfate) (PVS) was investigated spectrophotometrically. The size of hydrated ion and the hydrophobicity of substituent were significant factors for inorganic and organic salts, respectively. Effect of these salts on the metachromasy was characteristic of each polyanion used. A peculiar phenomenon that the metachromasy of the PSS‐1 system was enhanced on addition of small amounts of 1‐dodecyl‐3‐carbamoylpyridinium bromide (2d) was observed.
Application of spin trapping technique to radical polymerization, 15. Photo‐decomposition of dibenzoyl disulfide and evaluation of relative reactivities of vinyl monomers toward the benzoylthiyl radical
Authors: Sato Tsuneyuki , Abe Masao , Otsu Takayuki
Published: April 2003

The mechanism of photo‐decomposition of dibenzoyl disulfide (DBDS) in benzene or in monomers, and the evaluation of relative reactivities of various vinyl monomers toward the benzoylthiyl radical (4) were investigated by means of the spin trapping technique using 2‐methyl‐2‐nitrosopropane (BNO). When DBDS photo‐decomposed in benzene at 22±2°C in the presence of BNO, both 4 and benzoyl radicals were trapped as their nitroxyl radicals, indicating that both SS and CS bonds in DBDS were decomposed during its photolysis. However, when the photo‐decompositions were performed in the monomers, propagating radicals (7) were trapped, but no allyl‐type radicals (11). The coupling constants of the nitroxyl radicals of various propagating radicals were determined. From the ESR spectra of the systems DBDS/vinyl monomers/methyl methacrylate (as reference)/BNO the relative concentrations of the nitroxyls, [8]/[10, X = COOCH3], were determined by computer simulation, and the relative reactivities of the vinyl monomers toward 4 were estimated. It was found that the relative reactivities of these monomers are correlated with their e values to give a linear relationship with a negative slope, similar to those toward the tert‐butoxyl radical found in the previous paper.
Reactive copolymers of N‐(2‐hydroxypropyl)methacrylamide with N‐methacryloylated derivatives of L‐leucine and L‐phenylalanine, 1. Preparation, characterization, and reactions with diamines
Authors: Kopeček J.
Published: April 2003

Reactive copolymers of N‐(2‐hydroxypropyl)methacrylamide (1) with p‐nitrophenyl esters of N‐methacryloylglycyl‐L‐leucine (3a), N‐methacryloylglycyl‐L‐phenylalanine (3b), N‐methacryloyl‐ε‐aminocaproyl‐L‐leucine (7a), and N‐methacryloyl‐ε‐aminocaproyl‐L‐phenylalanine (7b) (i.e. copolymers 8–11) were synthesized. The polymers thus obtained were characterized by the content of active groups, by intrinsic viscosity [η], and by the rate constant of aminolysis with tert‐butylamine in dimethyl sulfoxide. Polymers containing free NH2 groups were prepared by a polymeranalogous reaction with diamines, predominantly 1,6‐hexanediamine. The effect of the copolymer structure, of diamine, and of the reaction conditions on the course of the polymeranalogous reaction was studied.
1H NMR study of random and alternating styrene/n‐alkyl methacrylate copolymers
Authors: Podešva J. , Doskočilová D.
Published: April 2003

The 1H NMR spectra of random and alternating copolymers of styrene and methyl methacrylate, ethyl methacrylate, butyl methacrylate, and octyl methacrylate were analyzed. In the first approximation, the one‐parameter statistics suggested for the interpretation of these spectra is in agreement with the experimental data. The way in which the copolymer is synthesized and the copolymerization mechanism following therefrom markedly affect the magnitude of the parameter of coisotacticity σ: for all comonomer pairs under study, σ is higher if an organometallic catalyst is used (alternating copolymerization) than in the case of a radical initiator (statistical copolymerization). With increasing number of carbon atoms in the n‐alkyl alcohol residue, σ decreases to a limiting value.
Das Verhalten von isotaktischen Polyacrylsäuren im Organismus. Verteilung und Ausscheidung bei Mäusen
Authors: Mück Karl‐Friedrich , Christ Othmar , Kellner Hans‐Martin
Published: April 2003

Isopropyl acrylate‐2,3‐14C and isopropyl acrylate‐2,3‐3H were polymerized using anionic initiators. The isotactic polymers were fractionated by fractional precipitation and characterized. The polymer fractions were hydrolysed to polyacrylic acids by trifluoroacetic acid. Aqueous solutions of these radioactive labelled polyacrylic acids were injected intravenously to mice in amounts of 40 to 100mg/kg. Distribution in organs and the excretion were studied. About two thirds of the dose were excreted within the first two days with a half‐life of about 0,5 days. Further excretion took place with a half‐life of about six weeks. Distribution in the organism was not uniform; the highest concentrations were found in spleen, bones, and liver, i.e. organs being parts of the reticuloendothelial system. A relationship between organ concentration and molecular weight of the polyacrylic acid was only observed in the spleen. Nine weeks after injection about 10% of the dose were still retained in the organism, mainly in the skeleton.
Cationic polymerization of cyclic amines, 5. Polymerization of N‐tert‐butylaziridine
Authors: Bossaer Piet K. , Goethals Eric J.
Published: April 2003

The polymerization of N‐tert‐butylaziridine (TBA) in dichloromethane with different cationic initiators leads to quantitative conversion. With triethyloxonium tetrafluoroborate (TEFB), initiation is rapid and the molecular weights of the polymers increase with increasing [TBA]/[TEFB] ratios. In contrast with other polymerizations of N‐substituted aziridines, termination reactions are absent. This is ascribed to the high steric hindrance of the tert‐butyl group which makes a nucleophilic attack of a polymeric amino function on the growing species (aziridinium ion) impossible. Poly(TBA) obtained by precipitation from its solution shows a high degree of crystallinity as is shown by its mp of 142°C (DSC) and by its well resolved X‐ray diffraction diagram. The viscosities of aqueous solutions of the hydrochloride of poly(TBA) show typical polyelectrolyte behaviour.
Zur Taktizität von Poly(α‐methylstyrol), 4. Das 1H‐ und 13C‐NMR‐Spektrum des 1,3,3‐Trimethyl‐1‐phenylbutyllithium
Authors: Wicke Reinhard , Elgert Karl‐Friedrich
Published: April 2003

The structure of 1,3,3‐trimethyl‐1‐phenylbutyllithium (1b), which is a model compound for the active chain end in the polymerisation of α‐methylstyrene with butyllithium, was investigated with 1H and 13C NMR spectroscopy. The carbon‐13 chemical shift of the αC‐atom in benzene and tetrahydrofuran as solvent suggests a substantial sp2 hybridisation. The rotation of the aromatic ring around the bond (C6H5)αC is hindered at room temperature. In benzene as solvent the carbon‐13 resonances of the αC‐atom and the aromatic C‐atoms are strongly broadened. This broadening, caused by exchange reactions or 13C‐7Li‐coupling, can be interpreted by an interaction of the lithium atom with the aromatic ring. This interpretation of the 13C NMR spectra leads to a structure, in which the lithium is not located at the αC‐atom but in the space over the bond (C6H5)αC.
Zur Taktizität von Poly(α‐methylstyrol), 6. Zum stereoregulierenden Mechanismus der Polyreaktion des α‐Methylstyrols mit Butyllithium in Tetrahydrofuran
Authors: Wicke Reinhard , Elgert Karl‐Friedrich
Published: April 2003

Some models of the stereoregulating mechanism of the polymerisation of α‐methylstyrene with butyllithium in tetrahydrofuran are discussed. A mechanism is proposed, in which the depolymerisation of the polymer chain and an isomerisation reaction of the active site change the tacticity generated by each propagation step. The isomerisation reaction is interpreted as a dissociation of the active lithiumorganic compound occurring with racemisation. The quantitative calculation of the tacticity based on the mechanism without depolymerisation using kinetic data agrees well with the experimental dependence of the tacticity on reaction temperature and initial monomer concentration. The activation parameters of the isomerisation reaction used in this treatment are (index r = racemic, m = meso):
The thermal behavior of cycloalkanes
Authors: Höcker Hartwig , Riebel Klaus
Published: April 2003

The thermal behavior of cycloalkanes (CH2)n with 12 ≤ n ≤ 84 prepared by metathesis reaction of cyclododecene, GPC separation of the oligomers, and hydrogenation has been investigated. The molar enthalpies of fusion being lower by a certain amount than those of the corresponding n‐alkanes are a linear function of the chain length n. The entropy of fusion per CH2 increases with chain length in a not‐linear mode (when plotted vs. 1/n). The melting points of the cycloalkanes are lower than those of the corresponding n‐alkanes, the difference becoming smaller with increasing chain length.
Synthesis and condensation polymerization of N‐(3‐carboxy‐2‐hydroxypropyl) derivatives of purine bases
Authors: Hattori Masahira , Takai Hiroshi , Kinoshita Masayoshi
Published: April 2003

4‐(1,3‐Dimethyl‐2,6‐dioxo‐2,6‐dihydropurin‐7‐yl)‐3‐hydroxybutyric acid (4a) and 4‐(6‐amino‐9‐purinyl)‐3‐hydroxybutyric acid (4b) were synthesized through the addition reaction of theophylline or adenine, respectively, to 1‐chloro‐2,3‐epoxypropane followed by cyanization and acidic hydrolysis. Condensation polymerization of 4a was carried out using dicyclohexylcarbodiimide, 2,4,6‐triisopropylbenzenesulfonyl chloride or p‐toluenesulfonyl chloride as dehydrating agents in dimethylformamide or pyridine. The oligoester of 4a was obtained as a white powder with a molecular weight > 700, according to gel filtration measurement.
Interaction between dyes and polyelectrolytes, 8. Effect of polyanions on the mixed dimer formation of cationic dyes
Authors: Shirai Masamitsu , Nagatsuka Tatsuki , Tanaka Makoto
Published: April 2003

The effect of polyanions on the formation of mixed dimers of methylene blue (1) and trypaflavine (2), methylene blue (1) and phenosafranine (3), and methylene blue (1) and pyronine G (4) was investigated spectrophotometrically. The following polyanions were used: poly(potassium styrenesulfonate) (PSS), poly(potassium vinyl sulfate) (PVS), and poly(sodium acrylate) (PAA). On addition of polyanions, the formation of mixed dimers was enhanced largely. Thermodynamic parameters inferred that the enhancement of the formation of mixed dimers in the presence of polyanions resulted from an entropic factor.
Polymerization of lactams, 24. Effect of impurities on the non‐activated polymerization of 2‐pyrrolidone initiated with potassium tert‐butoxide
Authors: Roda Jan , Kmínek Ivan , Králíček Jaroslav
Published: April 2003

The effect of tert‐butyl alcohol, lower alcohols, and water on the non‐activated polymerization of 2‐pyrrolidone initiated with potassium tert‐butoxide at 40°C was investigated. It was proved that the alcoholytic activity of alcohols decreased with the steric hindrance of the hydroxyl group; the effect of water is distinctly more pronounced.
Stereosequencing in poly(leucine) obtained from stereoselective polymerization of racemic leucine N‐carboxy anhydride
Authors: Semen John , Elias Hans‐Georg
Published: April 2003

Polymerization of mixtures of D‐ and L‐isomers of α‐amino acid N‐carboxy anhydrides follow normal copolymerization behavior, and sometimes even ideal copolymerization, which is conventionally interpreted as leading to a random distribution of monomer units along the polymer chains. Equations are dereived which relate the fraction of isotactic L‐diads to experimental data from the previously reported methods involving sequential and stereospecific cleavage with enzymes. The application of these equations to poly(D,L‐leucines), which were prepared by polymerization of racemic leucine N‐carboxy anhydride with chiral and achiral primary amines as initiators, indicated that the polymers contain between 94 and 98% isotactic diads. The poly(leucines) thus consist of long stereoblocks despite the observed ideal copolymerization behavior.
A bifunctional anionic initiator soluble in non‐polar solvents
Authors: Beinert Gérard , Lutz Pierre , Franta Emile , Rempp Paul
Published: April 2003

Addition of two molecules of sec‐butyllithium to one molecule of m‐diisopropenylbenzene produces a bifunctional initiator which is soluble in non‐polar solvents. This initiator is quite efficient for the polymerization of isoprene and butadiene and allows the preparation of samples of particular interest: bifunctional polydienes with high 1,4‐cis and 1,4 contents, respectively, and by using a cross‐linking agent elastomeric gels even after removal of the solvent.
Advances in etherification reaction mechanism of poly(oxymethylene)diol[α‐hydro‐ω‐hydroxypoly(oxymethylene)] with triethyl orthoformate
Authors: Colombo Paolo , Custro Sergio , Ermoni Mario , Radici Pierino
Published: April 2003

The etherification of poly(oxymethylene)diol[α‐hydro‐ω‐hydroxypoly(oxymethylene)] with orthoesters in the presence of Lewis acids leads to the simultaneous formation of various types of end groups: orthoformyl [bis(alkoxy)methoxy] groups (A), formyl (oxyformyl)(B), and ether (alkoxy) groups (C). It was elucidated theoretically and experimentally that the orthoformyl end groups are intermediates of formyl end groups, and partially of ether end groups. The kinetics of the reactions was also evaluated at various temperatures.
Copolymerization of carbon dioxide with propylene oxide catalyzed by poly(p‐hydroxystyrene)/diethylzinc system
Authors: Nishimura Masatoshi , Kasai Masanori , Tsuchida Eishun
Published: April 2003

A polymeric catalyst prepared from poly[1‐(4‐hydroxyphenyl)etylene] (1), and Zn(C2H5)2 was found to be effective for the copolymerization of carbon dioxide and 1,2‐epoxypropane. The highest activity was observed when a mole ratio of phenolic hydrogen in 1 to Zn(C2H5)2 equal to unity was applied in contrast to the catalysts so far reported. The structure of the catalyst after the copolymerization was determined by IR and H1 NMR spectroscopy. A Zn—C2H5 bond in this system was confirmed to be the active center. A possible inactivation process of the catalyst is proposed.
13C NMR spectra of poly(alkyl α‐chloroacrylate)s
Authors: Hatada Koichi , Kitayama Tatsuki , Lenz Robert W.
Published: April 2003

13C NMR spectra of isotactic and syndiotactic poly(ethyl α‐chloroacrylate)s and poly(isopropyl α‐chloroacrylate)s were measured in toluene‐d8 at 25 MHz. The spectra were analyzed for triad, tetrad and pentad tacticities comparing the spectra with the results previously obtained by 1H NMR spectroscopy. Tetrad tacticities of the polymers were measured from the resonance of the backbone methylene carbon and favorably compared with tetrad values obtained by 1H NMR. The resonance of the carbonyl carbon showed the peaks corresponding to the tactic triad with a pentad splitting in mm resonance. The triad values obtained from the carbonyl carbon resonance were in good agreement with those calculated from the tetrad values as well as the triad tacticities obtained by 1H NMR. The quaternary carbon reconances were very complicated because the chemical shift differences for the different tactic triads were of the comparable magnitude with those for the pentads, and a tentative peak assignment was made with the aid of the statistical calculation of pentad values assuming first‐order Markovian statistics for the isotactic polymer and Bernoullian statistics for the syndiotactic polymer.
Macroion‐pairs and macroions in the kinetics of polymerization of hexamethylene oxide (oxepane)
Authors: Brzezińska Krystyna , Matyjaszewski Krzysztof , Penczek Stanisław
Published: April 2003

Cationic polymerization of oxepane (hexamethylene oxide) (1) in CH2Cl2 and C6H5NO2 as solvents was initiated with 1,3‐dioxolan‐2‐ylium hexafluoroantimonate (2). Dissociation constants (KD) of the ion‐pairs of polyoxepane into ions were measured: KD (in CH2Cl2, T = 25°C) = 2,8·10−5 mol·l−1 [ΔHD = −3,8 kJ·mol−1 (−0,9 kcal·mol−1), ΔSD = −98 J·mol−1·K−1 (−23,4 cal·mol−1·K−1)]; KD (in C6H5NO2, T = 25°C) = 1,6·10−3 mol·l−1 [ΔHD = −7,1 kJ·mol−1 (−1,7 kcal·mol−1), ΔSD = −78 J·mol−1·K−1 (−18,7 cal·mol−1·K−1)]; these values are close to those of the ion‐pairs of polytetrahydrofuran. Rate constants kp+ and kp±, determined from the kinetic measurements for degrees of dissociation of macroion‐paris ranging from 0,02 to 0,21 (in CH2Cl2) and from 0,09 to 0,7 (in C6H5NO2), were found to be identical within an experimental error of kinetic measurements. The activation parameters of propagation were measured and their dependences on the polarity of the polymerization mixtures are discussed.
Streulichtmessungen an polymerlösungen zur bestimmung der verteilungsbreite des molekulargewichtes
Authors: Hack Hrabanus , Meyerhoff Günther
Published: April 2003

By increasing the experimental accuracy of the classical light scattering technique it became possible to determine the width U = Mw/Mn − 1 of the molecular weight distribution of polymers. For this purpose a very stable laser and a lock‐in‐amplifier were used allowing an accuracy of 0,2–0,3% in the scattering intensity. The numerical evaluation of the polydispersity is done by a Gauß‐Newton procedure analysing the small curvature of the reciprocal scattering function. In an appropriate molecular weight range U is obtained with an error between 0,01 and 0,1 depending on the width of the molecular weight distribution of the sample tested.
Higher aliphatic aldehyde polymers, 8. Poly(undecanal)
Authors: Starr J. , Vogl O.
Published: April 2003

Crystalline poly(undecanal) (2) was prepared by anionic polymerization of undecanal (1) with lithium tert‐butanolate in methylcyclohexane. As the aliphatic side chain length of the monomeric aldehyde increases, the polymerization becomes increasingly difficult and 2 could only be obtained if the temperature profile during the polymerization was carefully controlled. 2 of reasonable molecular weight was obtained in nearly 50% yield and was identified by IR and NMR spectroscopy. X‐ray diffraction measurements showed the polymer to be highly crystalline. The paraffinic side chains of 2 were found to be primarily responsible for the polymer crystallization and the polymer side chain transitions were found between 40 and 60°C. Normally, more than one endothermic peak was found by DSC in this region. 2 could be extended through an orifice to a coherent filament whose x‐ray diffraction pattern showed negligible orientation. In contrast, other aldehyde polymers with shorter side chains gave good fiber patterns on extrusion.
Metal compounds in free radical processes, 4. polymerization of vinyl monomers initiated by the system nickel(II) chloride/N,N‐dimethylaniline
Authors: Barton̆ Jaroslav , Leboc Ivan , Capek Ignác
Published: April 2003

The system nickel(II) chloride (NiCl2)/N,N‐dimethylaniline (DMA) initiates the polymerization of methyl methacrylate and acrylonitrile. The thermal polymerization of styrene is not affected. From the polymerization and copolymerization studies as well as from spectral measurements in the UV and visible region it is concluded that this polymerization exhibits free radical character. Neither NiCl2 nor DMA used separately initiate the polymerization. The initiating species are assumed to be formed as a result of interaction between the vinyl monomer/NiCl2 complex {e.g. in the case of MMA, [Ni(CH3OH)6–x(MMA)x]2+2Cl−, (2)} and DMA. Possible causes for the different initiating efficiency of the system NiCl2/DMA for various vinyl monomers are also discussed.
Anthracene sensitized photooxidation of polystyrene, 2. Anthracene photochemistry in polystyrene films
Authors: Nowakowska Maria
Published: April 2003

The photooxidation of polystyrene films sensitized by anthracene was investigated. The quantum yield of singlet oxygen generation in the polystyrene‐anthracene system, irradiated with light at λ = 365 nm in the presence of oxygen was determined. A kinetic scheme of the photophysical and photochemical processes in the system was proposed and the rate constant of anthracene dimer formation in polystyrene was estimated.
Stereochemical structure and molecular weight distribution of polypropylenes prepared with vanadium‐based catalyst systems
Authors: Doi Yoshiharu , Takada Morio , Keii Tominaga
Published: April 2003

Vanadium tetrachloride combined with alkylaluminium could be shown to produce two types of polypropylenes, the syndiotactic and the isotactic ones, depending on both the kind of alkylaluminium component and polymerization temperature. It was found that the syndiotactic polypropylenes always have narrow molecular weight distributions (1,5≤M̄w/M̄n≤2,5), whereas the isotactic polypropylenes always have wide distributions (16≤M̄w/M̄n≤19), suggesting that the isotactic polymerizations are not induced by homogeneous but by heterogeneous catalysis. With the aid of ESR analysis for catalyst systems it was concluded that the syndiotactic polymerizations take place in a soluble complex of trivalent vanadium, whereas the isotactic polymerizations proceed on the insoluble vanadium dichlorides formed from the catalyst mixture.
Functional monomers and polymers, 54. Synthesis of poly‐β‐alanine from β‐alanine 4‐acyl‐2‐nitrophenyl esters
Authors: Hanabusa Kenji , Kondo Koichi , Takemoto Kiichi
Published: April 2003

A series of active β‐alanine 4‐acyl‐2‐nitrophenyl esters with different lengths of alkyl groups was prepared, and their polycondensation was studied in various solvents. The results of the polycondensation of these esters with triethylamine at room temperature show that the conversion and the degree of polycondensation of the resulting poly(β‐alanine)s depend on the chain length of the alkyl groups. No polymer was obtained in both protic and dipolar aprotic solvents such as methanol and DMSO, whereas nonpolar solvents such as diethyl ether, carbon tetrachloride, or benzene were found to be suitable for the polycondensation. The effect of a variety of amines on the polycondensation was examined for β‐alanine 4‐dodecanoyl‐2‐nitrophenyl ester (4e) in diethyl ether solution.
Thermische zersetzung von benzpinakol und benzpinakolbis(trimethylsilyl)ethern in UP‐harzen
Authors: Wolfers Heinrich , Rudolph Hans , Rosenkranz Hans‐Jürgen
Published: April 2003

During thermal cleavage of benzpinacol (1) in unsaturated polyester resins only 20–40% of the produced semibenzpinacol radicals (2) react via hydrogen transfer. The other radicals disproportionate into benzophenone and benzhydrol or add directly to the double bonds of the unsaturated polyester resin or to the growing polymer radicals. As during thermal cleavage of benzpinacol bis(trimethylsilyl) ether (5) in unsaturated polyester resins only up to 10% of the diphenyltrimethylsiloxymethyl radicals (6) undergo secondary fragmentation, we suppose that the curing of unsaturated polyester resins with 5 is initiated mainly by the relatively stable primary radicals 6. The different activity of the two compounds 1 and 5 in initiating radical polymerisation is explained by different mechanisms in the initiation process.
Heat capacities of water swollen hydrophilic polymers above and below 0°C
Authors: Pouchlý Julius , Biroš Ján , Beneš Svatopluk
Published: April 2003

The heat capacities of water swollen poly[2‐(2‐hydroxyethoxy)ethyl methacrylate] were determined in a DSC‐2 calorimeter within the temperature range 220–350K for concentrations from 0 to 1,2g of water per 1g of the polymer. At temperatures above 0°C the partial specific heat capacity of water in gel is concentration independent and equal to the specific heat capacity of pure liquid water. It seems, therefore, that water does not form stable icelike structures near polymer chains. To analyze phase transformations of water in gel below 0°C, general thermodynamic equations were derived and used as a basis for suggesting criteria which allow to decide whether in a given experiment the phase transformation proceeded in an equilibrium way. In measurements below the melting point of ice the conditions for an equilibrium process consist in the preceding heating of the frozen sample to a temperature close to the melting point, followed by cooling to 220K. The assessed composition dependence of the melting point depression is consistent with the dependence of activity on concentration obtained from measurements of water vapour sorption at 35°C. Analysis of data on the heat capacity below 0°C led to the conclusion that at a water content of 0,4g/g and lower, or at temperatures below 250K the crystallization of water from gel was inhibited by kinetic factors originating probably in the reduced diffusivity of water in gel, due to the reduced mobility of polymer chains. Hence, non‐freezing water need not be identical with “strongly bound” water; in the study of water structure in polymers based on heat capacities, preference should be given to data obtained at usual and elevated temperatures.
The model of specific volume of amorphous vinyl polymers
Authors: Roszkowski Zbigniew
Published: April 2003

A model of the specific volume of amorphous vinyl polymers, valid in the range of continuous expansion coefficients above and below the glass transition temperature is proposed. For the case of these polymers the volumetric criterion of the transition of an undercooled liquid in the glassy state, the parameters characterizing the chain and a rigorous definition of the free volume are formulated. The new terms inaccessible volume and nonequilibrium free volume are introduced. Moreover, the van der Waals volume of a substance from its properties is determined and a method is proposed to calculate the specific volume of a polymer in the rubbery state at 0 K, based on a consideration of molecular motions.
High pressure copolymerisation of maleic anhydride with cyclic olefins and substituted ethylenes
Authors: Kellou Mohamed , Jenner Gérard
Published: April 2003

The pressure effect on the rate of maleic anhydride copolymerisations with various substituted ethylenes was found to be considerable, leading to high negative values of the activation volume, especially when the comonomer is crowded with bulky substituents. No significant variation of the polymer composition was observed and the reactivity ratios were found to be less affected by pressure than rates and generally decrease slightly with increasing pressure. Pressure influences also the e‐value of the monomers.
Synthèse et étude de copolymères sequencés photochromiques
Authors: Goett Christian , Lambla Morand , Wippler Constant
Published: April 2003

New photochromic polymers were prepared by deactivating living homo or block copolymers with various 2H‐chromene‐2‐spiro‐2′‐indolines (3a–3d). Classical anionic polymerization was used throughout this work. By varying the chemical nature of the blocks as well as that of the photochromic units, a series of novel materials was obtained and their structure and behaviour were characterized.
N‐trifluoracetyl‐nylon 66 als polymeres reagenz
Authors: Günster Engelbert J. , Schulz Rolf C.
Published: April 2003

N‐Trifluoroacetyl‐Nylon 66 (2) obtained by the reaction of Nylon 66 (1) with trifluoroacetic anhydride is very suitable as a polymeric reagent for the trifluoroacetylation of amines and alcohols. The advantages of 2 compared with low molecular trifluoroacetylating reagents are discussed. The selectivity against different substituted anilines and against structurally isomeric secondary amines was studied intensively by kinetic measurements.