bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of poly‐O‐acyl‐amideoximes containing group IV A metals from poly(acrylonitrile)
Authors: Carraher Charles E. , Wang Long‐Shyong
Published: April 2003

Poly(acrylonitrile) was modified to give products of the form below via reaction with hydroxylamine and subsequently with group IV organometallic reactants:
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The products obtained with Cl2MR2 are crosslinked. Properties of the new polymers are briefly characterized.
Production of organometallic polymers by the interfacial technique. XXII. Synthesis of poly[alkylene(arylene)oxystannanes] using a new modified system
Authors: Carraher Charles E. , Scherubel Gary A.
Published: April 2003

Poly[alkylene(arylene)oxystannanes] of the form below have been synthesized from dichlorostannanes and diols using a modified nonaqueous interfacial system consisting of acetonitrile and hydrocarbons.
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The products are preferentially capped with alcohol end‐groups.
Stereokontrolle. VI. Zum mechanismus der radikalischen polymerisation von methylmethacrylat
Authors: Göldi Paul , Elias Hans‐Georg
Published: April 2003

Methylmethacrylat wurde in Substanz und in 14 verschiedenen Lösungsmitteln bei Temperaturen zwischen −5 und +120°C radikalisch polymerisiert. Die Taxie der Polymethylmethacrylate hängt außer von der Temperatur und vom Lösungsmittel noch von der anfänglichen Monomerkonzentration ab. Die Stereokontrolle erfolgt mindestens nach einer MARKOFF‐Statistik 1. Ordnung. Zwischen je einer Differenz der Aktivierungsenthalpien (ΔH − ΔH) und der entsprechenden Differenz der Aktivierungsentropien (ΔS − ΔS) besteht unabhängig von Monomerkonzentration und Lösungsmittel ein allgemeiner Kompensationseffekt (a, b = i/i, i/s, s/i, s/s). Die Kompensationstemperatur T0 ist unabhängig von der Art der Anlagerung. Die Kompensationsenthalpie ΔΔH hat den größten Wert für den Unterschied zwischen der Bildung einer isotaktischen und einer syndiotaktischen Diade an einer bereits bestehenden syndiotaktischen (s/i vs. s/s). Die Kompensationsenthalpie für die Differenz i/i vs. i/s ist dagegen praktisch gleich Null. Isotaktische Diaden bilden sich bei der Kompensationstemperatur bevorzugt an isotaktischen, syndiotaktische dagegen an syndiotaktischen. Die Tendenz zur Bildung heterotaktischer Triaden nimmt nicht in allen Lösungsmitteln mit steigender Temperatur zu.
Polymerization of epoxides by zirconocene dichloride
Authors: Kaeriyama Kyoji
Published: April 2003

Epoxides are polymerized homogeneously by some metallocene halides. Cp2TiCl2 is ineffective, Cp2ZrCl2 and Cp2ZrI2 are active as catalysts (Cp denotes the cyclopentadienyl group). Epichlorohydrin is polymerized to high conversions. The resultant polymers are amorphous and of low mol. wt. because of transfer reactions. The bridged compound (Cp2ZrCl)2O is also active and gives higher mol. wt. Phenyl glycidyl ether polymerizes well. The formation of oligomers from propylene oxide is also catalyzed by Cp2ZrCl2. A cationic mechanism is suggested for the polymerizations.
Polymerisation höhergliedriger cyclischer imine
Authors: Rentsch Christoph , Lüssi Heinz
Published: April 2003

Dodecamethylenimin und N‐Methyldodecamethylenimin lassen sich bei Temperaturen oberhalb 200°C polymerisieren. Als Katalysatoren dienen die Salze der Monomeren, LEWIS‐Säuren und Alkylierungsmittel. Zuerst bilden sich Oligomere, welche erst später in höhere Polymere und schließlich in vernetzte Produkte übergehen. Gleichzeitig werden kleine Mengen Ammoniak bzw. Trimethylamin gebildet. Der Vorgang beruht im wesentlichen auf einer Umalkylierung, an der sämtliche Aminogruppen teilnehem. Demzufolge lassen sich die gleichen Polymeren unter ähnlichen Bedingungen auch durch Polykondensation aus Diaminen unter Ammoniakabspaltung herstellen. Andere cyclische Imine mit mehr als 7 Ringgliedern verhalten sich ähnlich. Hexamethylenimin führt infolge der thermodynamischen Stabilität der sich bildenden N‐substituierten 7‐gliedrigen Iminringe nur zur Bildung niedermolekularer Produkte. Das gleiche gilt auch für das N‐Methylhexamethylenimin.
Frictional behavior of the correlated chain
Authors: Horta Arturo
Published: April 2003

The friction coefficient of linear macromolecules is calculated for the correlated chain model using KIRKWOOD's approximation. This model (proposed by SANCHEZ and FRANKENBERG) incorporates a certain long‐range correlation between the segments of a random chain, and contains two parameters: CF, which depends on this correlation (CF = 1 for a random coil and CF = 0 for a fully extended chain), and the radius of gyration RG. In the limit of long chains, the friction coefficient B is a function of these two parameters and the ratio B/6πη0RG (η0 = solvent viscosity) decreases with CF. This means that the correlation between segments has a greater influence on RG than on the equivalent STOKES radius of the macromolecule. These results are used to interpret the influence of excluded volume on B. The validity of the model is ascertained by comparing the theory with the light scattering envelopes and friction coefficients recently reported by MIJNLIEFF et al. for poly(α‐methylstyrene) in good and poor solvents.
Polymerisation of vinyl monomers by transition metal benzyl compounds. Part I. Initial observations
Authors: Ballard D. G. H. , van Lienden P. W.
Published: April 2003

A range of stable transition metal alkyl compounds of given formula M(CH2X)4(M = Zr, Ti, Hf) exhibit polymerisation activity in the absence of light towards certain vinyl monomers, e.g., styrene, p‐bromostyrene, methyl methacrylate and ethylene. Rates of polymerisation increase markedly on exposure to light at wavelengths between 450 and 600 nm. It has been established that these polymerisations are probably of the coordinated anionic type. At wavelengths below 450 nm the polymerisation is dominated by a radical process, the radicals being produced by the photolysis of the catalyst (zirconium tetrabenzyl).
Stereocontrol. VII. The relation between instantaneous and final diad and triad fractions in one‐way polymerization mechanism
Authors: Johnson Brian L. , Elias Hans‐Georg
Published: April 2003

The relationships between isotactic and syndiotactic diads and triads resp., on one hand, and the rate constants of the different propagation steps in MARKOV 1st and 2nd order processes have been calculated under the assumption of a steady state condition for the concentration of free radicals. Instantaneous and final diad fractions are equal only if

i and s stand for the formation of an isotactic or a syndiotactic diad at an existing diad A or B. A and B stand for i and s in a MARKOV 1st order process and for ii, is, si, and ss in a MARKOV 2nd order process.
Light scattering of polymethylmethacrylate solutions in binary solvent mixtures. Part 1. In acetone/chloroform mixtures
Authors: Fujishige Shoei , Elias Hans‐Georg
Published: April 2003

An atactic and an isotactic polymethylmethacrylate have been investigated by light scattering measurements at 25°C in acetone/chloroform mixtures. The reciprocal apparent weight average molecular weight (at c → 0) passes through a minimum, the coefficient of preferential adsorption through a maximum with increasing chloroform content of the mixtures. The second virial coefficient is no monotoneous function of the chloroform content.
Free volume theories for penetrant diffusion in polymers
Authors: Machin D. , Rogers C. E.
Published: April 2003

Free volume theories for the concentration dependence of organic penetrant diffusion coefficients in rubbery amorphous polymers have been correlated and extended with emphasis given to similarities and mathematical equivalence for small volume fractions of penetrant. The nature of the empirical parameter used in VASENIN's theory has been further clarified by considering the kinetic and thermodynamic aspects of the plasticization effect. Using similar assumptions to those originally used for rubbery polymers, VASENIN's theory is extended to treat solvent diffusion in glassy and semi‐crystalline polymers. A procedure has been developed to extend the applicability of FUJITA's theory over a wider range of polymer‐solvent composition. The general effects of plasticization leading to increase in penetrant diffusion coefficients and decrease in polymeric glass transition temperatures are considered as resulting from the same functional increase in fractional free volume of a mixture with increasing solvent content. It is suggested that the two phenomena should be quantitatively compared for mutual consistency rather than attempting to develop a fully rigorous treatment for either. In this way diffusion data can be predicted from measurements of glass temperature depression or vice versa.
Etude du mécanisme des polymérisations amorcées par les métaux alcalino‐terreux. III. Copolymérisation du butadiène, de l'isoprène et du styrène en millieu non polaire
Authors: Maleki P. , François B.
Published: April 2003

Nous avons étudié la copolymérisation de trois couples de monomères: butadiène/isoprène, butadiène/styrène et isoprène/styrène; cette copolymérisation est amorcée par des suspensions de calcium, strontium et baryum en milieu toluène. Les paramètres de copolymérisation ont été déterminés dans chaque cas. Les valeurs ainsi obtenues permettent de classer les trois monomères par ordre de réactivité vis‐à‐vis des différentes espèces anioniques en présence. Lorsque le promoteur est constitué par du calcium ou du strontium l'isoprène est moins réactif que le butadiène mais plus que le styrène. En présence du baryum au contraire le styrène est plus réactif que l'isoprène mais moins que le butadiène.
Preparation and polymerization of racemic and optically active tert‐butyl thiirane
Authors: Dumas Philippe , Spassky Nicolas , Sigwalt Pierre
Published: April 2003

Preparation and polymerization of tert‐butyl thiirane are described. The racemic monomer was obtained by reaction in aqueous solution of tert‐butyl oxirane and potassium thiocyanate. The levorotatory enantiomer was synthesized from R(−) 3.3‐dimethyl 1.2‐butane diol passing through the intermediate of the cyclic carbonate. Polymerization of the racemic monomer with coordinate type initiators give crystalline, soluble products of high molecular weights and high melting points (close to 205°C). Crystalline, soluble, high molecular weight polymers but of lower melting points (close to 160°C) could also be obtained with the levorotatory enantiomer, either by coordiante or purely anionic initiation. These polymers have high optical activities of positive sign in all the solvents used. NMR measurements show that racemic and optically active crystalline polymers have the same isotactic structure. The differences in melting point and X‐ray diagrams show the existence of several crystalline modifications. These results indicate a strong difference in the behaviour of tert‐butyl thiirane as compared to methyl thiirane.
Carbon‐13 nuclear magnetic resonance spectroscopy of polystyrene and poly‐α‐methylstyrene
Authors: Inoue Yoshio , Nishioka Atsuo , Chûjô Riichirô
Published: April 2003

The carbon‐13 high resolution nuclear magnetic resonance spectra with proton spin decoupling of polystyrene and poly‐α‐methylstyrene were measured. The spectra clearly split corresponding to triad, tetrad, and partially pentad placements, and these peaks were tentatively assigned. By comparison of the triad tacticity of poly‐α‐methylstyrene determined from carbon‐13 spectra with that from proton spectra, it was confirmed that the nuclear OVERHAUSER effect due to proton decoupling has little effect on the relative intensities of the peaks assigned to chemically equivalent carbons except for stereochemical configuration.

The stereospecific polymerization mechanisms are discussed on the basis of the microtacticity determined from carbon‐13 spectra. As a result, it is concluded that poly‐α‐methylstyrene polymerized with cationic and anionic catalysts can be described by BERNOULLIAN statistics, while the atactic polystyrene does not obey BERNOULLIAN but first or second order MARKOVIAN statistics.
Die spontane Desaktivierung beim oligomeren α‐Methylstyryl‐Natrium in Tetrahydrofuran
Authors: Schmitt B. J.
Published: April 2003

Bei der Alterung von oligomerem α‐Methylstyryl‐Na in Tetrahydrofuran (THF) erfolgt eine Hydridabspaltung an der aktiven Endgruppe und ein Protonentransfer vom Lösungsmittel. Der Selbstabbruch kann durch ein einfaches Schema von Simultanreaktionen beschrieben werden.
Experimental verification of effects of conditions of solutional fractionation on molecular weight distribution of the first fraction by atactic polystyrene/methylcyclohexane system
Authors: Kamide Kenji , Sugamiya Ken , Terakawa Toshikazu , Hara Tasuku
Published: April 2003

The solutional fractionations were carried out experimentally on lowering the temperature of solutions of atactic polystyrene in methylcyclohexane. The concentration of the initial solution and the relative amount of the polymer dissolving in the polymer‐lean phase (i.e., the amount of the fraction) were systematically changed. Gel permeation chromatography was applied to determine the molecular weight distribution (MWD) of the first fractions and the original polymer. In addition, polydispersity parameters including the ratio of the weight average molecular weight to the number average molecular weight, Mw/Mn, and the standard deviation, σ′, were calculated from MWD curves. Effects of the fractional conditions on the MWD for the first fractions were compared with those obtained by the computer simulation as well as the experimental results obtained in the case of the precipitational fractionation. The validity of the theoretical conclusions on the solutional fractionation, reached from the computer simulations, was definitely confirmed from the experiments.
Multimerisation: Assoziation und Aggregation. IX. Konzentrationsabhängigkeiten reduzierter Viskositäten bei offenen Assoziationen
Authors: Watterson John Grant , Elias Hans‐Georg
Published: April 2003

Die Konzentrationsabhängigkeiten reduzierter Viskositäten werden für Systeme mit offener Assoziation unter folgenden Annahmen theoretisch berechnet: von der Assoziationszahl unabhängige Gleichgewichtskonstanten der Assoziation, gleiche Teilchenform für alle Assoziate, Abwesenheit von thermodynamischen und hydrodynamischen Kreuzwechselwirkungen. Die Kurven πsp/c = f(c) können nach diesen Modellrechungen konvex oder konkav zur c‐Achse gekrümmt sein, Extremwerte aufweisen oder sogar praktisch linear erscheinen. Im letztea Fall liefert die konventionelle Auswertung meist zu hohe scheinbare HUGGINS‐Konstanten. Aus Viskositätsmessungen allein können bei Abwesenheit zusätzlicher Informationen, außer in sehr extremen l'ällen, weder Schlüsse auf die An‐oder Abwesenheit von Assoziationen noch auf einen bestimmten Typ von Assoziation geschlossen werden.
Aggregation and helix—coil transition of poly‐L‐glutamic acid in pyridine—water solution
Authors: Giancotti V. , Quadrifoglio F. , Crescenzi V.
Published: April 2003

The conformational state of poly‐L‐glutamic acid (PLGA) in the mixed solvent pyridine/water has been studied by means of different techniques (ORD, IR, PMR, and viscosity). It has been found that at low water contents PLGA forms aggregates the stability of which depends in a sensitive manner on temperature and solvent composition.

At higher water content PLGA undergoes a helix–coil transition.
The syntheses of protected 9‐vinyladenine monomers
Authors: Kaye Howard , Chou Hardy J.
Published: April 2003

In order to develope synthetic approaches to poly‐(9‐vinyladenines) of varying degrees of stereoregularity a series of protected 9‐vinyladenine monomers have been synthesized which are soluble in organic solvents.
Ein iteratives numerisches verfahren zur auswertung von elutionsanalysen an eng verteilten polymeren
Authors: Rauch B.
Published: April 2003

Ein iteratives Rechenverfahren zur Bestimmung der Molekulargewichtsverteilungsfunktionen aus experimentellen, mit der isothermen Elution ermittelten Daten – speziell für Polymere kleiner Uneinheitlichkeit – wird beschrieben. Hierbei wird die klassisch gewonnene Verteilung als Näherung betrachtet, rechnerisch auf der Basis des Phasengleichgewichts erneut fraktioniert und aus den ermittelten Fraktionen die Zusatzinformation zur Konstruktion einer besseren Näherung gewonnen. Um die Stabilität der Konvergenz des Verfahrens zu zeigen, wurde eine Simulationsrechnung durchgeführt. Schließlich wird das Verfahren an experimentell gewonnenen Daten eines aus zwei gut bekannten, eng verteilten Polystyrolen erzeugten Gemisches demonstriert und diskutiert.
Réactions d'amorçage de la polymérisation anionique de la vinyl‐2 pyridine et leur application à la synthèse de copolymères séquencés de la vinyl‐2 pyridine et du sulfure de propylène I. Copolymères comportant deux séquences
Authors: Gourdenne Albert
Published: April 2003

La réaction d'amorçage de la polymérisation anionique de la vinyl‐2 pyridine par le diphénylméthyl sodium a été étudiée par spectrophotométrie. Le diphénylméthyl sodium ne réagit pas avec les cycles pyridiniques mais, par contre sa conversion est incomplète, la vitesse de propagation étant bien supérieure à la vitesse d'amorçage. La synthèse de copolymères biséquencés linéaires de la vinyl‐2 pyridine et du sulfure de propylène confirme ces résultats.
Untersuchung der basischen Endgruppen bei der mit Aminsalzen initiierten kationischen Lactampolymerisation
Authors: Csürös Zoltán , Rusznák István , Bertalan György , Anna Péter , Kőrösi Jenő
Published: April 2003

Entsprechend dem von den Verfassern vorgeschlagenen Kettenwachstumsmechanismus sind bei der mit Aminsalzen initiierten kationischen Lactampolymerisation nicht nur Ammonium‐, sondern auch Amidin‐Endgruppen vorhanden. Es wurde eine Methode zur Bestimmung der beiden basischen Endgruppen nebeneinander ausgearbeitet. Zunächst wird die Gesamtkonzentration aller basischen Endgruppen durch potentiometrische Titration mit Perchlorsäure in nichtwäßrigem Medium bestimmt. In einer anderen Probe werden die Amino‐Endgruppen mit Essigsäureanhydrid acetyliert und die unverändert gebliebenen Amidin‐Endgruppen auf die gleiche Weise titriert.

Die Konzentration beider Endgruppen ändert sich im Laufe der Polymerisation in Abhängigkeit von der Temperatur und der Initiatorkonzentration charakteristisch. Die Gesamtbasizität nimmt in jedem Fall auf Grund hydrolytischer Prozesse zu, die durch die Einwirkung des während der Amidinbildung entstandenen Wassers ablaufen. Die Konzentration der Ammonium‐Endgruppen nimmt in jedem Fall in Abhängigkeit von der Temperatur und der Konzentrationen des Initiators ab, die Konzentration der Amidingruppen ändert sich in entgegengesetzter Richtung. Die Änderung der Endgruppenkonzentration ist mit den kinetischen Kurven der Polymerisation und dem vorgeschlagenen Wachstumsmechanismus in gutem Einklang. Beim Auftreten eines Wendepunkts entspricht dieser den Extremwerten der Endgruppenkonzentrationen.
Reactions at low temperature of AlEt3 or ethyl‐aluminum‐chlorides with Me3CCl and addition of ethylene to cationic species
Authors: Priola A. , Cesca S. , Ferraris G.
Published: April 2003

Reactions between Et3–xAlClx (where x = 0, 1, 2, 3) and Me3CCl, carried out in CH2Cl2, CH3Cl or n‐pentane at −78°C, have been investigated by VPC‐MS analysis of the resulting products. The use of CD2Cl2 and (CD3)3CCl made it possible to confirm the suggested reactions.

Under mild conditions and in the presence of ethylene the system EtAlCl2 + Me3CCl yields branched, saturated C6, C8, and C10 hydrocarbons.

Conductimetric and NMR observations during the reactions have confirmed the VPC–MS results, which could be interpreted according to an overall cationic mechanism involving the following reactions:

Abstraction of a β‐hydrogen atom from an ethyl group linked to Al and simultaneous formation of ethylene;

repeated addition of ethylene to cationic species;

termination by hydride transfer;

termination by chloride ion abstraction by carbonium ions

.
The chemical shifts and the conformations of linear hydrocarbons
Authors: Ando Isao , Nishioka Atsuo
Published: April 2003

The proton chemical shifts of some hydrocarbons (n‐C9H20, n‐C10H22, n‐C11H24, and n‐C22H46) were calculated assuming the extended chain with one gauche form and predominant contribution of the magnetic anisotropy effect of the C‐C bonds along the chain. It is suggested that the high field peak of the two splitted methylene signals of n‐C22H46 in α‐chloronaphthalene (α‐CINap) solution is assigned to the methylene protons next to the gauche bond in a planar zigzag chain, of which molecular motion is restrained strongly by α‐CINap molecules and the second methylene group next to the terminal methyl group, whereas the low field peak is assigned to other methylene protons, the molecular motion of which is restrained weakly. A small peak at lower field than the two large peaks is assigned to the gauche methylene protons in a planar zigzag chain the molecular motion of which is restrained by α‐CINap molecules.
The configuration of block copolymers of polyisoprene and polystyrene in dilute solution. I. Unperturbed dimensions
Authors: Urwin J. R. , Girolamo M.
Published: April 2003

The unperturbed dimensions of block copolymers of polystyrene and polyisoprene in dilute solution have been determined from measurements made under theta conditions, by application of the FLORY‐FOX theory to viscosity data. In solvents, where theta temperatures preclude direct evaluation, the STOCKMAYER‐FIXMAN method has been applied. The results show that unperturbed dimension determined under theta conditions, whether measured directly or by appropriate extrapolation procedures, vary linearly with composition. Thus the characteristic ratio for the block copolymer may be calculated from homopolymer data according to the relation

where x is the mole fraction and superscripts PS and PI refer to polystyrene and polyisoprene respectively. The steric factor σ = rr obeys a similar relation.

Short range interaction parameters have also been determined by application of equations relating osmotic second virial coefficients with the excluded volume and which have been shown to be reasonably successful when applied to homopolymers. Data from viscosity and osmometry methods are compared and discussed.
Hydrogenation of unsaturated polymers with diimide
Authors: Mango L. A. , Lenz R. W.
Published: April 2003

We have studied the homogeneous hydrogenation of a series of unsaturated polymeric substrates with diimide formed from the thermal decomposition of p‐toluenesulfonylhydrazide (TSH) at elevated temperatures (110 to 160°C) and in aromatic solvents. At a TSH/olefin ratio of 2.0, homopolymers of butadiene, polycyclohexadiene, and polyisoprene were quantitatively hydrogenated as were two styrene/butadiene copolymers. Alkyl branching at or near the residual polymer double bond, as in methyl rubber and poly‐2.5‐dimethyl‐2.4‐hexadiene, gave less than 50% hydrogenation. Polychloroprene was not hydrogenated by diimide (conversions less than 10%) which is in agreement with the behavior previously observed for low molecular weight olefins.

The unsaturated polymers which were successfully hydrogenated were soluble and, hence, showed no excessive crosslinking. Polycyclohexadiene and polyisoprene, the only samples evaluated for molecular weight changes, exhibited no chain degradation.

Some qualitative kinetic data were obtained using per cent conversion vs. time data. Under the conditions of toluene reflux and TSH/olefin ratios of 1.5, the relative rates of hydrogenation for cis, trans and vinyl butadiene units was kcis ≃ ktrans < kvinyl.

Byproducts from the diimide generation resulted in the introduction of 0.2 to 1.0% of p‐CH3C6H4SO2‐groups into the polymer based upon 100% of the double bonds originally present.
Polymerization of N‐vinylcarbazole by (3d)‐transition metal oxides
Authors: Biswas Mukul , Mishra Prashant K.
Published: April 2003

The bulk polymerization of N‐Vinylcarbazole (NVC) is carried out using some 3 d‐metal oxides as catalysts and the following order of reactivity is suggested for the various metal oxides studied:

the oxides of copper and cobalt being ineffective. Some kinetic studies are carried out with the NVC/MnO2 system. Endorsed by the observed retardation of the rate in the presence of water and thiophene a cationic mechanism is suggested for the polymerization. The incapability of the oxides of Cu and Co to act as good catalysts is tentatively explained by supposing that they act as oxidizing rather than π‐complexing polymerization catalysts. Stirring does not show any influence on the rate of polymerization.
Über die Wechselwirkung des Katalysators und Cokatalysators mit dem Monomeren und dem Polymeren bei der kationischen Polymerisation des Isobutylens. II. Modellstudium des Polymerisations‐Depolymerisations‐Gleichgewichts im System Triisobutylen/AlBr3/DBr/Heptan
Authors: Kříž Jaroslav , Marek Miroslav
Published: April 2003

Triisobutylen unterliegt bei der Reaktion mit AlBr3/DBr neben der Deuterierung einer Skelettisomerisierung und bildet höhere Oligomere. Beide Reaktionen werden durch die Spaltung der Skelettbindungen der intermediären Carboniumionen erklärt. Die Fragmente, die durch diese Spaltung entstehen, können mit weiteren Komponenten des Reaktions‐systems reagieren. Die mögliche Bedeutung dieser Reaktionen für den Mechanismus des Kettenabbruchs und der Kettenübertragung bei der kationischen Polymerisation des Isobutylens wird kurz diskutiert.
Cationic polymerization of 2‐methyl‐1.3‐dioxepane
Authors: Okada Masahiko , Yagi Kazuo , Sumitomo Hiroshi
Published: April 2003

2‐Methyl‐1.3‐dioxepane was polymerized in 1.2‐dichloroethane with triethyl oxonium tetrafluoroborate and boron trifluoride as initiators. This polymerization involves a monomer‐polymer equilibrium and the polymer consists of regularly alternating tetrahydrofuran and acetaldehyde units. The thermodynamic parameters for the polymerization were determined from the temperature dependence of the equilibrium monomer concentration as follows: ΔHSS = −2.1 ± 0.3 kcal/mole and ΔS0SS = −8.9 ± 1.3 cal/mole deg. The ceiling temperature for the 1 mole/1. solution is −37°C. The attempted polymerization of 2.2‐dimethyl‐1.3‐dioxepane gave only a crystalline cyclic dimer.
Condensation polymers from 7‐(2′.3′‐dihydroxypropyl)‐theophylline
Authors: Seita Toru , Yamauchi Kiyoshi , Kinoshita Masayoshi , Imoto Minoru
Published: April 2003

7‐(2′.3′‐Dihydroxypropyl)‐theophylline‐3′‐phosphate was synthesized using phosphorus oxychloride in trimethyl phosphate. This compound was condensed using N.N′‐dicyclohexylcarbodiimide as a dehydrating agent in refluxing dimethylformamide to oligomeric products which were separated into four peaks by chromatography using Sephadex G‐25. The major portion of the oligomeric product was found to have a molecular weight of more than 1000 according to gel‐filtration measurement. An oligomeric product was also obtained from the polycondensation of 7‐(2′.3′‐dihydroxypropyl)‐theophylline with phenoxyphosphoryl dichloride.
Polyvinyl alcohol containing N‐derivatives of cytosine, uracil, or adenosine‐5′‐phosphate as pendant groups
Authors: Seita Toru , Yamauchi Kiyoshi , Kinoshita Masayoshi , Imoto Minoru
Published: April 2003

Polyvinyl alcohols (P̄n ca. 500) having a nucleotide or one of its analogs, such as adenosine‐5′‐phosphate, N‐[(2′‐dihydrogenphosphato)ethyl]‐uracil and ‐cytosine, as pendant group were synthesized by condensation using DCC as dehydrating agent in refluxing DMF. The resulting polyvinyl alcohols showed a hypochromic effect up to 4% when mixed with denaturated RNA or DNA in aqueous solution. Low molecular weight PVA (P̄n = 8) containing nucleotide analogs showed no hypochromic effect with DNA or RNA.
Infrared spectra and sequence length distribution in free radical styrene/methacrolein copolymers
Authors: Kálal Jaroslav , Houska Milan , Seyček Otakar , Adámek Petr
Published: April 2003

The method of azoisobutyronitrile (AIBN)‐initiated bulk copolymerization of styrene (S) and methacrolein (M) was employed to determine the monomer reactivity ratios rS = 0.15 and rM = 0.55 (QM = 1.50, eM = 0.78). Quantitative IR spectroscopy in the region of 4000–450 cm−1 was used to elucidate the structure of copolymers. In addition to methacrolein units containing aldehyde groups, the copolymers may also contain cyclic hemiacetal structures formed by the reaction of the carbonyls of the neighboring methacrolein units. The carbonyl absorption at 1722 cm−1 showed that, up to 30 mole‐% methacrolein in the copolymer, almost all methacrolein units have free aldehyde groups. The number of cyclic structures increases with the concentration of methacrolein in the copolymer. The experimental data are in agreement with the statistical theory on the sequence length distribution. The shift of the styrene band at 540 cm−1 to higher wavenumber was investigated and related to the shortening of sequence length of the styrene units. The intensity of the styrene band at 760 cm−1 was related with the distribution of the MSM triads and the copolymer structure.
Methine and α‐methyl proton resonance in methyl acrylate/methacrylonitrile copolymers
Authors: Udipi K. , Harwood H. J. , Friebolin H. , Cantow H.‐J.
Published: April 2003

Methyl acrylate (A)/methacrylonitrile (M) copolymers, prepared by emulsion and solution polymerization at 50°C, were characterized by 220 MHz NMR spectroscopy. The methine and α‐methyl proton resonances of such copolymers consisted of three peak patterns, individual resonance areas being assignable to protons centered in various A or M centered triads. Triad fractions determined from methine and α‐methyl resonance patterns were in excellent agreement with calculated values based on reactivity ratios of rA = 0.39 ± 0.06 and rM = 3.56 ± 0.50 for copolymers prepared in emulsion and on reactivity ratios of rA = 0.24 ± 0.02 and rM = 3.21 ± 0.11 for copolymers prepared in solution.
Eine apparatur zur gaschromatographischen verfolgung der metathesereaktion kurzkettiger olefine
Authors: Zowade T. , Höcker H.
Published: April 2003

Es wird eine Apparatur beschrieben, die einen Reaktor, kombiniert mit einem Gaschromatographen, umfaßt und die es gestattet, Umsetzungen kurzkettiger Olefine bei der Metathesereaktion schnell und einfach zu erfassen. Die Leistungsfähigkeit der Apparatur wird u. a. am Beispiel der Metathesereaktion von Penten‐2 in Gegenwart des Katalysator‐systems WCl6/C2H5OH/(C2H5)3Al2Cl3 demonstriert.
Oxidative polymerization of 2,6‐xylenol by amine complexes
Authors: Komoto Hiroshi , Ohmura Kaoru
Published: April 2003

The manganese chloride‐tris(2‐hydroxyethyl)amine complex and copper(II)‐pyridine complexes in aqueous solution, which are inactive in organic solvents, have been found to possess a high activity for the oxidative polymerization of 2,6‐xylenol in aqueous solution. The catalytic activity increased remarkably after the addition of alkali to the manganese chloride‐tris(2‐hydroxyethyl)amine complex. Diphenoquinone, the CC coupling product, could not be found, and CO coupling occurred selectively. After adding alkali to the copper(II)‐pyridine complex hydrolysis took place. CO coupling occurs, however, selectively when the copper(II)‐tris(2‐hydroxyethyl)amine complex (1 : 1) is used which is stable against alkali.
Solution properties of poly(methyl methacrylate) in mixtures of two nonsolvents (carbon tetrachloride and n‐alcohols)
Authors: Deb Pramil Chandra , Palit Santi Ranjan
Published: April 2003

Binary mixtures of CCl4 and several n‐alcohols comprise cosolvents for poly(methyl methacrylate). The cosolvency has been explained in terms of the thermodynamic approach of SCOTT and also taking into account some specific effects. In the presence of light a reaction between CCl4 and alcohol was observed. Unperturbed molecular dimensions determined in the cosolvents agree well with those reported in the literature.
Zur synthese von oligomeren des nylons‐6.6 nach der anhydridmethode bei höheren temperaturen
Authors: Kusch Peter , Blessing Erika
Published: April 2003

In Modellversuchen wird gezeigt, daß die Synthese von Oligomeren des Nylons‐6.6 nach der Anhydridmethode auch bei Temperaturen weit oberhalb 0°C möglich ist. Hierbei wird festgestellt, daß die gebildeten gemischten Anhydride selbst bei 60°C über einen Zeitraum von einer Stunde stabil sind. Am Beispiel der Synthese eines langkettigen Nylons‐6.6‐Oligomeren werden die Vorteile der Oligomerensynthese nach dem Anhydridverfahren bei 50°C aufgezeigt.
Pyridine catalyzed polymerization of maleimide in water solution
Authors: Decker Danielle
Published: April 2003

By action of pyridine, maleimide undergoes polymerization in water at room temperature. The polymers formed have low molecular weights (Mn between 500 and 1000) and their structure seems to involve predominantly succinimide type units.
13C Nuclear magnetic resonance spectroscopy of polypropylene, 2. 13C spin‐lattice relaxation study in solution
Authors: Inoue Yoshio , Nishioka Atsuo , Chûjô Riichirô
Published: April 2003

Proton‐decoupled partially relaxed FOURIER transform (PRFT) NMR of 13C in natural abundance was used to determine spin‐lattice relaxation times (T1) of individual carbons of polypropylene and polyethylene in o‐dichlorobenzene solution and molten polyethylene. It is shown that the relaxation times of polypropylene carbons are independent of the difference in stereochemical configuration. From the values of the nuclear OVERHAUSER enhancement factor it is shown that the excess energy from equilibrium of all 13C in polypropylene and polyethylene are absorbed into lattice mainly through 13C–1H dipolar interactions. It is shown that the effective rotational motion of the skeletal carbons in polypropylene is isotropic. The activation energies of skeletal and internal methyl motions in polypropylene, separately, and skeletal motion in polyethylen in solutions were estimated from the temperature dependence of the correlation time. The assignment of the two peaks appearing in methine carbon region of polypropylene was briefly discussed.
Copolymerization of carbon dioxide and epoxide using dialkylzinc/dihydric phenol system as catalyst
Authors: Kobayashi Makoto , Tang Yang‐Lik , Tsuruta Teiji , Inoue Shohei
Published: April 2003

Copolymerization of carbon dioxide with epoxypropane (propylene oxide) in the presence of a diethylzinc/dihydric phenol system was examined. A spectroscopic study of the copolymer revealed that one aromatic group was introduced in the copolymer chain.

The osmometric number average molecular weight of the copolymer agrees with the molecular weight deduced from spectroscopic studies. The introduction of the aromatic group into the copolymer chain takes place at the initiation step of the copolymerization, and the catalytic activities of the diethylzinc/phenol systems depend on the presence or the absence of the ZnOXOZn group, where X may be phenylene, naphthylene or other aromatic divalent residues.
Donor acceptor interactions in polymeric systems, 1. Synthesis and properties of polyamides having the carbazole group in the main chain
Authors: Hayashi Yoshio , Tazuke Shigeo
Published: April 2003

Low temperature polymerizations of 3,6‐diamino‐9‐ethylcarbazole (1b) with the diacyl dichlorides 2a—e were investigated. In all cases polyamides of high relative molecular mass ([η] ≈ 1·102 cm3 g−1). could be obtained. These polyamides are polymeric electron donors in which the donor units are arranged with regular intervals. Donor acceptor interactions between polyamides and 1,3,5‐trinitrobenzene were studied. In comparison with the monomeric model compound 9‐ethyl‐3,6‐bis(propionylamino) carbazole (1c) the polymer donor showed a higher stability constant. However, there is no regularity in the sequence of stability constants in respect to the number of methylene units separating two carbazole groups. There is a possibility that donor units in the polymer molecules might be located in such a way that each donor unit could cooperate to form a donor‐acceptor complex. No specific interactions between the carbazole groups could, however, be detected by fluorescence spectroscopy. The importance of solvent effects was expressed by the results of absorption and emission spectroscopy.
Vinyl polymerization by metal complexes, 12. Initiation by poly(vinyl alcohol)‐copper(II) chelates
Authors: Kimura Keiichi , Inaki Yoshiaki , Takemoto Kiichi
Published: April 2003

The polymerizations of acrylonitrile, methyl methacrylate and styrene initiated by copper(II) chelates were studied in the presence of carbon tetrachloride. Polymeric and dimeric compounds of vinyl alcohol, that is poly(vinyl alcohol) and 1,3‐propanediol were chosen as ligands. It was found that these systems could initiate the polymerization of methyl methacrylate and styrene effectively. The activity of the polymer chelate was estimated by varying the metal/ligand mole ratio of the initiator system, the pH values and the polymerization temperature. From the results, the mechanism of the free‐radical formation was discussed.
Studies on functional micelles, 1. Preparation of cyclic dipeptides from phenylalanine S‐dodecyl ester
Authors: Kawabata Yasuziro , Kinoshita Masayoshi
Published: April 2003

The hydrochloride of phenylalanine S‐dodecyl ester (2b) reacts in pyridine/water at room temperature to afford 3,6‐dibenzyl‐2,5‐piperazinedione (3) in good yields. Phenylalanine S‐ethyl ester hydrochloride (2a), however, gives only small yields of 3 under the same conditions. This effect is explained with the assumption of a matrix reaction on the micelle surface. In contrast to the S‐ethyl ester the reaction of the S‐dodecyl ester leads to a mixture of two isomeric dioxopiperazines.
Statistical treatment of the grafting reaction
Authors: Ikada Yoshito , Horii Fumitaka
Published: April 2003

Statistical calculations were performed for the fundamental quantities in the grafting reaction starting from a substrate polymer with a uniform and a most probable molar mass distribution: e.g., the number of branches in one graft copolymer, the number average degree of polymerization (P̄n) of the backbone of the graft copolymer, the fraction of the mother polymer grafted. It is shown that P̄n of the graft copolymer prepared from a mother polymer with a most probable molar mass distribution decreases at first with increasing number of grafted branches, reaches a minimum and then increases, if the P̄n of the grafted branch is lower than that of the mother polymer. This peculiar behavior is attributed to the fact that the mother polymer molecule with a higher molar mass has a higher probability to participate in the grafting. In addition, the calculation denotes that the synthesized, unfractionated graft copolymer is a polymolecular mixture of the copolymer having branches whose number distribution is remarkably broad.
13C‐NMR spectrum of equibinary (cis‐1,4—1,2) polybutadiene
Authors: Furukawa Junji , Kobayashi Eiichi , Katsuki Nobuyuki , Kawagoe Takahiro
Published: April 2003

The proton decoupled natural abundant 13C‐NMR spectra of equibinary (cis‐1,4—1,2)‐polybutadiene were measured. Assignments of spectra were made for all peaks of the aliphatic range using chemical shift corrective terms estimated for the present system together with GRANT's parameters. Each peak was interpreted in terms of the diad or triad of cis‐1,4 and 1,2 units. The relative intensities of the peaks were in good agreement with the calculated ones from the random assumption with respect to the distribution of cis‐1,4 and 1,2 units. The gas‐chromatographic analysis of the ozonolysis product of the polymers also showed that the sequence distribution of cis‐1,4 and 1,2 units was random.
Feldionen‐ und Elektronenstoß‐Massenspektrometrie von Polymeren und Copolymeren, 3. Copolymere des α‐Methylstyrols mit Methylmethacrylat und Acrylnitril
Authors: Hummel Dieter O. , Düssel Heinz‐Jürgen
Published: April 2003

Die Pyro‐Feldionenmassenspektrometrie wurde zur Untersuchung der Primärfragmente und des Abbauverhaltens von α‐Methylstyrol(α‐MS)‐Copolymeren eingesetzt. α‐MS‐Methylmethacrylat(MMA)‐Copolymere depolymerisieren pyrolytisch unter weitgehender Rückbildung der beiden Monomeren. Die Retropolymerisation („Reißverschlußmechanismus„) geht meist über die Verknüpfungsstellen verschiedener Monomerer hinweg. Heterofragmente (α‐MS‐MMA) werden nur mit einer geringen Wahrscheinlichkeit gebildet; noch geringer ist die Konzentration von Homodimeren im Pyrolysat.

Primärfragmente des Polyacrylnitrils (PAN) sind Acrylnitril (AN), (AN)2, (AN)3, HCN, C3H5CN, C4H7CN, C5H9CN und höhere Nitrile. Bei der Pyrolyse von α‐MS‐AN‐Copolymeren retropolymerisieren α‐MS‐Sequenzen unter Rückbildung des Monomeren. Die Retropolymerisation macht an Heteroverknüpfungsstellen halt; hierbei bilden sich Heterofragmente des Typs α‐MS‐AN oder α‐MS‐(AN)2. Längere AN‐Sequenzen im Copolymeren führen bei der Pyrolyse wie bei PAN zu AN‐Oligomeren sowie zu höheren Alkencyaniden. Isolierte AN‐Einheiten führen zur Bildung von monomerem AN.
Inelastische Lichtstreuung von Cellulosenitratlösungen
Authors: Meyerhoff Günther , Büldt Georg
Published: April 2003

Es wird ein Homodyngerät zur Messung der inelastischen Lichtstreuung beschrieben, das mit einem Argon‐Ionenlaser ausgerüstet ist und mit einem Autokorrelator arbeitet.

Das Gerät wird benutzt, um das Verhalten der Fadenmoleküle von Cellulosenitrat in verdünnter Lösung zu untersuchen. Mit dieser Technik wird es möglich, sogar für unabgebaute native Cellulose die Diffusionskoeffizienten der Translation D zu bestimmen, die ein sehr niedriges D (<10−7 cm2 s−1) aufweisen und bisher nur näherungsweise bekannt waren, da die konventionellen Meßtechniken der optischen Beobachtung eines Konzentrationsausgleiches dann recht ungenau werden.
Polymere mit dem Zentralatom eines Makrocyclus in der Hauptkette, 1. Polykondensationsreaktionen mit Phthalocyaninsilicium‐ und Hemiporphyrazingermanium‐Verbindungen
Authors: Meyer Gunter , Wöhrle Dieter
Published: April 2003

Dihydroxyphthalocyaninsilicium (1b) und Dihydroxyhemiporphyrazingermanium (2b) werden mit verschiedenen einwertigen Alkoholen zu den niedermolekularen Bisalkoxy‐Derivaten (4 bzw. 5) und mit Thiophenol zu den Phenylthio‐Derivaten (11a und 11b) umgesetzt. Mit zweiwertigen Alkoholen und Phenolen köml;nnen Polymere der Struktur 6 und 7 bzw. 8a, b, 9a, b und 10a, b erhalten werden. Dichlorphthalocyaninsilicium (1a) und Dichlorhemiporphyrazingermanium (2a) reagieren mit Phenol bzw. mit Hydrochinon ebenfalls zu niedermolekularen und polymeren Phenoxy‐Derivaten. Die Umsetzung von 1b und 2b mit einund zweibasischen Carbonsäuren führt zu den entsprechenden Estern.

Die IR‐Spektren der dargestellten Verbindungen werden diskutiert. Thermogravimetrische und Halbleitermessungen (σ298K ≈ 10−7 bis 10−16Ω−1cm−1) werden beschrieben.
Polymerization by stable carbocations
Authors: Ledwith A.
Published: April 2003

Salts of stable carbocations such as triphenylmethyl and tropylium ions were used conveniently to estimate free ion propagation rate coefficients (k) for cationic homopolymerization of a series of alkyl vinyl ethers and N‐vinylcarbazole. Methyl vinyl ether and 2‐chloroethyl vinyl ether gave values of k approximately one order of magnitude less than those of branched alkyl derivatives, and an explanation in terms of conformational effects is presented. Results are compared with those from radiation induced polymerizations, and with data for related hydride ion abstraction processes, in an attempt to evaluate solvent effects on free ion reactivity.

The scope and applicability of stable carbocations to cationic polymerizations are surveyed and complicating side reactions exemplified by the systems: xanthylium ion—1,1‐diphenylethylene, tropylium ion—indene, xanthylium ion—THF, C6H5CO+SbCl—THF, and by the effect of perchlorate anions on chain transfer in polymerization of N‐vinylcarbazole.
Solvent effects on radical copolymerization of methyl methacrylate and acrylonitrile
Authors: Zafar M. M. , Mahmud Ruquia , Syed Azhar M.
Published: April 2003

Radical copolymerization of methyl methacrylate and acrylonitrile has been studied in six solvents at 60°C, and two monomer feed ratios. The nitrogen contents of the copolymers increases in the order: chloroform < dioxane < benzene < anisole < methyl pentyl ketone < bromobenzene, suggesting an influence of the solvent on the growing radicals.
Relation entre la structure et les propriétés mécaniques dynamiques de polyéthylènes haute pression chlorés
Authors: Humbert Gerard , Quenum Bienvenu M. , Berticat Philippe , Vallet Georges
Published: April 2003

Les propriétés mécaniques dynamiques de polyéthylènes chlorés de microstructures bien déterminées sont étudiées en basse fréquence dans un domaine de température compris entre −140°C et + 240°C. Une interprétation du comportement mécanique de ces produits en fonction de la constitution chimique de leurs chaǐnes est proposée.
Evaluation of the degree of branching from intrinsic viscosity measurements. Some properties of poly(vinyl chloride) solutions
Authors: Krozer S. , Carstensen P. , Bodelsen M. , Thirsing A.
Published: April 2003

The degree of branching of commercial samples of poly(vinyl chloride) (PVC) has been investigated. The analysis is based on measurements of the intrinsic viscosity in a Θ‐solvent. The composition of the Θ‐solvent mixture (61,5 Vol.‐% cyclohexanone, 38,5% 1‐butanol) was found from the first cloud point and checked by light scattering. The cluster formation of PVC in cyclohexanone is relatively slow. The analysis of the degree of branching is based on a theory developed earlier. The theory is checked with literature data. The number of branches for some commercial PVC samples are reported.
Low molecular weight polyethylene single crystals: Nucleation
Authors: Alfonso Gian C. , Valenti Barbara , Pedemonte Enrico
Published: April 2003

Several results are reported concerning the nucleation mechanism connected with the crystallization from a dilute solution containing a sharp fraction of low molecular weight polyethylene. The correlation between the number of nuclei and some parameters of the process, such as the concentration of the solution and the crystallization temperature, suggests a polymolecular mechanism involving the formation of nuclei with various stabilities. Other aspects of the phenomenon are discussed, which probably occur also in the crystallization of the unfractionated polymer.
Strukturuntersuchungen an adsorptionsschichten makromolekularer stoffe, 1. Haftstellenzahlen von linearen polyestern und polystyrol an aerosiloberflächen
Authors: Joppien Günter R.
Published: April 2003

Durch direkte IR‐spektroskopische Bestimmungen des Bruchteils gebundener Segmente (Haftstellenzahl) und der adsorbierten Menge von linearen, aliphatischen, gesättigten Polyestern, von Polystyrol und von Butylpropionat, adsorbiert aus verdünnter Lösung an Aerosil, wird die Struktur der Adsorptionsschichten beschrieben. Die Polyester werden mit nahezu allen Kettencarbonylgruppen über Wasserstoffbrücken an maximal 80% der freien Hydroxylgruppen der Aerosiloberfläche gebunden, soweit freie Adsorptionsplätze vorhanden sind. Sie bilden, unabhängig vom Molekulargewicht und von der chemischen Natur der Endgruppen, eine aus kleinen Schlaufen bestehende Schichtstruktur. Im Gegensatz dazu tritt nur jeder dritte aromatische Kern des Polystyrols mit der Aerosiloberfläche in Adsorptionswechselwirkung. Polystyrol und der Modellmonoester vermögen nur 50% der Oberflächenhydroxylgruppen zu besetzen. Die Adsorptionsdaten erfüllen die Langmuirsche Gleichung. Eine gute Übereinstimmung der Ergebnisse besteht zu den Voraussagen einer statistischen Theorie von Silberberg für Polymerenadsorption mit starker Adsorptionswechselwirkung. Die ermittelten Haftstellenzahlen werden den erheblich niedrigeren Werten der Literatur gegenübergestellt und auf der Basis der mittleren Abstände der Oberflächenhydroxylgruppen bei statistischer Verteilung sowie der errechneten maximalen Abstände adsorbierbarer Gruppen in den Polymerketten diskutiert.