bluuebunny/crossref_metadata_2025 huggingface dataset:
Radiolysis of polymethylmethacrylate in the presence of ethylmercaptan. II. An ESR investigation
Authors: Geuskens G. , Fuld D. , David C.
Published: April 2003

The ESR spectra of polymethylmethacrylate (PMM) samples irradiated at 77°K in the presence of ethylmercaptan (EM) consist of a signal assigned to radical anions of the additive superimposed on the spectrum obtained with pure PMM. Although the contribution of the radical anions increases with EM concentration, the total radical yield is independent of the presence of the additive (G = 0.70 ± 0.02). On heating the samples C2H5S• radicals are detected. A mechanism is proposed which is consistent with the ESR results and takes into account the protective effect of EM on the radiolysis of PMM.

Free radicals decay by steps at successive constant temperatures. The decay curves have been studied at 150°K as a function of the EM concentration and the results have been discussed.
Détermination des propriétés thermodynamiques de quelques systèmes binaires (mélanges de solvants – solution de polymères de bas poids moleculaire) à partir des données de la diffusion de la lumière
Authors: Fechner Barbara Maria , Strazielle Claude
Published: April 2003

Dans cet article nous avons examiné le problème de la détermination par diffusion de la lumière des fonctions thermodynamiques comme l'énergie libre d'excés, l'entropie d'excés et la chaleur de mélange de quelques systèmes binaires. Les résultats obtenus pour les systèmes benzène‐méthanol, chloroforme‐éthanol et benzène‐hexane sont comparés avec les données calorimétriques.

La détermination des fonctions thermodynamiques et du paramètre d'interaction χ a été également réalisée avec des solutions de polyoxyéthylène dans le méthanol: ce système se caractérise par un paramètre χ constant dans un grand domaine de concentration.
Zur Molekulargewichtsabhängigkeit der Parameter des ausgeschlossenen Volumens bei Poly‐α‐methylstyrol
Authors: Biskup U. , Cantow H.‐J.
Published: April 2003

Es wurden Lichtstreumessungen an relativ monodispersen Poly‐α‐methylstyrolen in Cyclohexan durchgeführt. Die Molekulargewichte der acht anionisch hergestellten Präparate liegen zwischen 4 · 104 und 4 · 106. Die Taktizität der Proben war mit NMR‐Spektroskopie charakterisiert worden. Es wurden Θ‐Punkte von 30–32°C gefunden. Diese niedrigen Θ‐Temperaturen sind mit einer relativ starken Temperaturabhängigkeit des zweiten Virialkoeffizienten A2 und ungewöhnlich großen Expansionskoeffizienten α des Trägheitsradius verbunden. Wir vermuten, daß dies auf taktische Heterogenitäten innerhalb der Polymerketten zurückzuführen ist.

Für ein von BERRY vorgeschlagenes Iterationsverfahren wurde ein Rechenprogramm erstellt, das auf der Gültigkeit der folgenden Gleichung für A2 basiert,

Das Programm errechnet aus der gemessenen Temperaturabhängigkeit von A2 gemäß der zugrunde liegenden Theorie B0 und die entsprechenden theoretischen Werte von A2 und Θ. Die Anwendung dieses Programms zeigt, daß ein solches Verfahren graphischen Methoden überlegen ist. So kann z. B. B0 und Θ auch aus Meßwerten deutlich oberhalb der Θ‐Temperatur bestimmt werden.

Die durch einen Vergleich mit Theorien von YAMAKAWA und KURATA ermittelten B0‐Werte unserer Proben nehmen eindeutig mit zunehmendem Molekulargewicht ab. Diese Diskrepanz zur Theorie kann mit Hilfe des Rechenprogramms auch an Meßwerten anderer Autoren nachgewiesen werden.
Vinyl polymerization. 286. Inhibiting effect of 2.2.6.6‐tetramethyl‐4‐oxo‐piperidine‐1‐oxyl in radical polymerization
Authors: Miura Yozo , Masuda Shunji , Kinoshita Masayoshi
Published: April 2003

An extremely stable free radical, 2.2.6.6‐tetramethyl‐4‐oxo‐piperidine‐1‐oxyl (I) effectively inhibits the radical polymerization of styrene and methyl methacrylate initiated by 2.2′‐azobis(2‐methyl‐propionitrile) (azodiisobutyronitrile). The inhibition period, measured by dilatometry, is proportional to the concentration of I. The rate of the initiation reaction, the ratio of the rate constants k/2kt, and the initiator efficiency, which were calculated from the consumption rate of the inhibitor, agree well with the values in the literature. 2.2.6.6‐Tetramethyl‐l‐(l‐methyl‐l‐cyanoethoxy)‐4‐oxo‐piperidine (II) and 2.2.6.6‐tetramethyl‐1‐benzyloxy‐4‐oxo‐piperidine (III), which are analogs of those expected to be formed in the polymerization systems by reactions of initiating or propagating radicals with I, did not effect the inhibition period and the polymerization rate. 2.2.6.6‐Tetramethyl‐l‐hydroxy‐4‐oxo‐piperidine (IV), a potential disproportionation product between I and initiating or propagating free radicals, showed a weak retarding effect.
Micellization of styrene/butadiene/styrene block copolymers in mixed solvents
Authors: Tuzar Zdeněk , Kratochvíal Pavel
Published: April 2003

Dilute solutions of styrene/butadiene/styrene (SBS) block copolymers of various compositions in selective solvent mixtures are studied by viscometry, equilibrium dialysis, differential refractometry and light scattering. The addition of ethanol as a selective precipitant to a dioxan solution of SBS leads to selective precipitation of butadiene blocks which are kept in solution by solvated styrene blocks. Under the given conditions (temperature, copolymer composition, mixed solvent composition) the forming micelles attain, at a certain copolymer concentration, a stable weight. The results of measurements show that the micelles are very small particles (radius of gyration up to 20nm) of a high weight (up to 15·106); consequently, the average volume fraction of the polymer in the space occupied by a micelle attains unusually large values (up to 0.35).
Viscosities of dilute solutions of poly(isobutyl methacrylate)
Authors: Zafar M. M. , Mahmood R. , Wadood S. A.
Published: April 2003

The intrinsic viscosities of six fractions (M̄n = 11.59·105 to 5.01·105) of poly(isobutyl methacrylate) in seven solvents at temperatures between 25°C and 60°C show the following order: chloroform > benzene > bromobenzene > dioxane > acrylonitrile > acetone > 2‐hydroxymethyltetrahydrofuran. Values of a and k in the expression [η] = k Ma show little variations with temperature in the case of good solvents, whereas these variations are more pronounced in the case of poor solvents. For chloroform, the best solvent, the value of a was found to be 0.78, and for 2‐hydroxymethyltetrahydrofuran at 25°C the value of a is 0.56. The theta temperature for 2‐hydroxymethyltetrahydrofuran is 19.5 ± 0.3°C.
Preparation of polymers containing fragments of N.N′‐tetramethylthiuram disulfide
Authors: Beniska Jozef , Štaudner Emil , Špirk Eugen
Published: April 2003

The preparation of polymethylmethacrylates at 80 and 95°C and of polystyrenes at 95°C using various concentrations of N.N′‐tetramethylthiuram disulfide (I) is described. The sulphur contents, the molecular weights and the UV spectra of the prepared polymers indicate the presence of fragments of I in the polymer chains and the decrease of the molecular weight with increasing concentrations of I. A sample of polystyrene was also examined by mass spectroscopy.
Alternating copolymerization and cyclocodimerization of acrylonitrile and butadiene in the presence of zinc chloride
Authors: Kuran Witold , Pasynkiewicz Stanislaw , Floriańczyk Zbigniew
Published: April 2003

The copolymerization of acrylonitrile (AN) and butadiene (BD) in the presence of zinc chloride was studied in further detail. The reaction yields as 1:1 copolymer of AN and BD together with varying amounts of the AN/BD cyclodimer 4‐cyanocyclohexane. The effects of varying monomer feed composition and molar proportion of ZnCl2/AN on the yield of the copolymer were determined. Further, it was observed, that the addition of free radical initiators and inhibitors markedly influence the course of the reaction. Initiators significantly reduce the polymerization induction period, characteristic of this copolymerization and enhance the yield of copolymer. Inhibitors conversely reduce the formation of copolymer but enhance formation of the cyclocodimer AN/BD.

Addition of styrene (ST) to the system BD/AN/ZnCl2 significantly increases the polymerization rate and results in the formation of a terpolymer AN/BD/ST containing 50 mole‐% AN.

Based on these results, various aspects of the copolymerization mechanism of AN with BD catalyzed by ZnCl2 are discussed.
Der einfluß benachbarter grundbausteine auf die ammonolyse von essigsäureestern phenolischer mehrkernverbindungen
Authors: Böhmer Volker , Wörsdörfer Klaus
Published: April 2003

Die Ammonolyse der Essigsäureester verschiedener phenolischer Zwei‐ und Dreikernverbindungen, die neben Methylphenolbausteinen jeweils einen Nitrophenolbaustein enthalten, wurde untersucht. In allen Fällen wird wie bei einkernigen Nitrophenylestern die Esterbindung im Nitrophenolbaustein ammonolytisch gespalten. Wenn die Bausteine über Methylenbrücken in ortho‐Stellung zu den phenolischen Hydroxylgruppen verknüpft sind, werden jedoch auch die Esterbindungen in den Methylphenolbausteinen gespalten, obwohl die Ester von Methylphenolen und Mehrkernverbindungen, die nur Methylgruppen als Substituenten tragen, unter gleichen Bedingungen durch Ammoniak nicht angegriffen werden. In übereinstimmung mit kinetischen Messungen anderer Autoren wird hierfür ein Mechanismus vorgeschlagen, dessen geschwindigkeitsbestimmender Schritt die Abspaltung eines Protons aus der Zwischenverbindung ist, die durch nucleophilen Angriff des Ammoniaks auf die Estercarbonylgruppe im Methylphenolbaustein entsteht. Diese Abspaltung erfolgt intramolekular unter Einwirkung der Nitrophenolatgruppe des benachbarten Bausteins.
Spectres de résonance paramagnétique électronique des catalyseurs de polymérisation à base de TiCl3. II. Etude théorique
Authors: Kodratoff Y. , Girard Y. , Kibler M. R. , Guyot A.
Published: April 2003

Le spectre de résonance paramagnétique électronique d'un échantillon de TiCl3 (Stauffer H) est analysé comme la somme de cinq signaux élémentaires dont trois représentent 85% du total et présentent une symétrie axiale. A l'aide de la théorie du champ cristallin et des résultats d'une étude spectroscopique UV‐visible en réflexion diffuse, on arrive à conclure que ces signaux proviennent de défauts internes de la structure cristalline; cette conclusion est en accord avec plusieurs observations expérimentales.
Copolymere aus Vinylhalogeniden und olefinen I. Qualitative IR‐spektroskopische untersuchungen an Vinylchlorid/Isobuten‐Copolymeren
Authors: Brück Dieter , Hummel Dieter O.
Published: April 2003

Die IR‐Spektren einer Reihe strahlenchemisch bei 23°C hergestellter Vinylchlorid/Isobuten‐Copolymerer wurden im Bereich von 5000 bis 400 cm−1 untersucht. Der Vergleich mit den Spektren von Modellsubstanzen zeigte, daß die Monomerbausteine in den Copolymeren überwiegend in Kopf‐Schwanz‐Anordnung vorliegen. Die Zuordnung der Banden zu den verschiedenen Strukturen beruht auf ihrer Intensitätsänderung mit steigender Meßtemperatur und zunehmendem Isobutengehalt.
The catalytic effects of the poly(vinylpyridine)‐ligand in the oxidative polymerization of phenols
Authors: Tsuchida Eishun , Kaneko Masao , Nishide Hiroyuki
Published: April 2003

In order to study the catalytic effects of the polymer‐ligand, copper‐poly(vinylpyridine) (Cu‐PVP) complexes were used as catalyst for the oxidative polymerization of phenols. The catalysis was discussed.

The rate of the 2,6‐dimethylphenol (XOH) polymerization catalyzed by the Cu‐PVP complex was slower than that catalyzed by a Cu‐pyridine complex. By the measurement of the kinetic constants, it was suggested that a bulky PVP ligand obstructed the coordination‐step of the monomer and the electron‐transfer‐step from the coordinated monomer to the cupric ion. The polymerization of the mixture of XOH and o‐cresol with Cu‐PVP as catalyst was saturated at a higher conversion, and the yield and the molecular weight of the polymer obtained were larger than in the cases where the Cu‐pyridine or the Cu‐γ‐picoline complex systems were used as catalysts. XOH is preferentially activated by the Cu‐PVP catalyst because its oxidation potential is lower, thus the effect of the PVP ligand may be observed.

XOH was polymerized by the swelled Cu‐PVP complex as a heterogeneous catalyst in benzene or a benzene containing mixture of solvents. The catalyst was recovered by filtration in a high yield and re‐used repeatedly. Cu‐PVP complexes are relatively stable toward alkali because of their chelate structure. The polymerization was accelerated 3 to 5 times in alkaline solution, and the side‐reaction was suppressed.
Molecular size and configuration of poly(3‐vinylpyrene)
Authors: Sitaramaiah Gullapalli , Jacobs Darryl
Published: April 2003

Solution properties of poly(3‐vinylpyrene) (PVπ) have been studied to determine the degree of hindrance to the flexibility of the vinyl chain by the pyrene pendant group. Fractionation of this polymer prepared by anionic polymerization, yielded nine narrow distribution fractions in the Mw range of 35 000–490 000 and the fractions were characterized by osmometry, light‐scattering and viscometry.

Intrinsic viscosities of the fractions were obtained in chloroform and tetrahydrofuran at 25°C and in o‐dichlorobenzene at different temperatures from 25–80°C. From the KUHN‐MARK‐HOUWINK relationship, [η] = KMa, K and a values were determined and the exponent varied in the order, chloroform (a = 0.500) < tetrahydrofuran (a = 0.547) < o‐dichlorobenzene (a = 0.655) suggesting that chloroform at 25°C is a theta solvent for PVπ. Cloud point titration indicated that a mixture of THF/methanol in the ratio of 92:8 (V/V) is also a theta solvent for PVπ at 25°C. A KΘ value of 5.2·10−4 determined for PVπ at 25°C gave a value for the unperturbed dimension (R/M)1/2 of 5.77·10−9 cm. The conformational parameter, σ was computed as 2.84 for PVπ which suggests that the hindrance to rotation of the vinyl chain by the pyrene group is approximately the same as in the case of carbazole in poly(n‐vinylcarbazole). Values of [η] in o‐dichlorobenzene decreased with the increase of temperature yielding an average negative d log [η]/dT value of 1.1·10−3. The expansion factor decreased in all cases with the rise of temperature. A decrease of unperturbed dimension with the increase of temperature was reflected in the d log KΘ/dT value of −2.0·10−3 from which (R/M)1/2 at 80°C was computed as 5.35·10−9 cm.
Styrene/p‐methoxystyrene random copolymers. Part III. Some remarks on dilute solution properties
Authors: Pizzoli Maria , Ceccorulli Giuseppina , Stea Gianni
Published: April 2003

Styrene/p‐methoxystyrene random copolymers of three different compositions and poly(p‐methoxystyrene) have been examined by viscosity measurements in some solvents (including good and Θ solvents) at different temperatures.

Current theories have been applied to evaluate the FLORY constant KΘ; the values obtained for the copolymers are quite different from the “ideal” values and are independent on the temperature.

The measurements in Θ solvents suggest that the conformations of the copolymers differ sometimes from the GAUSSian coil conformation.
Polymères optiquement actifs. XI. Polycondensats formophénoliques de la N‐benzoyl L‐tyrosine (TyB) et de la N‐p‐hydroxyphénylsulfonyl L‐phénylalanine (phhps). synthèse et activité optique
Authors: Beaumais Jacques , Vert Michel , Selegny Eric
Published: April 2003

Les polymères du titre sont préparés par polycondensation en milieu acide (Pa) et en milieu alcalin (Pb) du formaldéhyde avec les monomères phénoliques optiquement actifs N‐benzoyl L‐tyrosine (TyB) et N‐(p‐hydroxyphénylsulfonyl)‐L‐phénylalanine (PhHPS). Leurs compositions chimiques sont vérifiées à partir des spectres IR, de la masse (Mr) du motif monomère et de la comparaison avec d'autres polycondensats du même type. PaTyB, PbTyB et PbPhHPS ont la structure chimique attendue, par contre, PaPhHPS fait l'objet d'une réaction secondaire qui est identifiée. Les pouvoirs rotatoires de PaTyB et PbTyB dépendent du milieu de polycondensation. L'ècart varie d'un solvant à l'autre. II ne s'annule que dans la potasse 0,l M en presence de fortes concentrations de sels (KCl, LiBr). L'influence de l'eau dans le dioxanne et des sels dans la potasse 0,l M est étudiée par dispersion rotatoire (DRO). Les contributions de DRO partielles negatives mises en évidence sont attribuées des espèces chimiques labiles entre les groupes amide portés par les motifs monomères et le co‐soluté (H2O, KCI, LiBr).
Vinyl polymerization by metal complexes. VI. On the initiation mechanism of vinyl polymerization by the α‐amino acid ester/copper(II) system
Authors: Azuma Koji , Inaki Yoshiaki , Takemoto Kiichi
Published: April 2003

Polymerization of acrylonitrile and methyl methacrylate was studied in the presence of an α‐amino acid ester and copper(II) ion in dimethyl sulfoxide solution. The initiation mechanism of the polymerization by the α‐amino acid ester/copper(II) system was refered to the complex forming properties of the system, confirmed by spectroscopic measurements. The polymerization of both monomers was influenced by the kind of the α‐alkyl group of the α‐amino acid esters, but it was not affected by the kind of the ester groups. The carboxylic group of the esters was found to affect only the polymerization of methyl methacrylate. Based on the results, the character of the free radicals was discussed.
Cationic polymerizability of 1‐substituted vinyl ethers and styrenes
Authors: Masuda Toshio , Higashimura Toshinobu
Published: April 2003

To gain knowledge of the cationic polymerizability of 1,1‐disubstituted ethylenes, homopolymerizations of 1‐substituted vinyl ethers and styrenes, and also copolymerizations with the corresponding unsubstituted monomers are carried out. Methyl, ethyl, ethoxy, and phenyl groups are introduced in 1‐position. Ethyl 1‐methylvinyl ether and 1‐methylstyrene produce homopolymers in contrast to ethyl 1‐ethylvinyl ether, 1‐ethylstyrene and 1‐eth‐, oxystyrene which do not furnish the homopolymers. In the copolymerization, all of these 1,1‐disubstituted monomers are found to have greater reactivities for the unsubstituted propagating end than the corresponding unsubstituted monomers. It is concluded that 1,1‐disubstituted ethylenes suffer from steric hindrance in the cationic polymerization more than the corresponding 1,2‐disubstituted compounds, contrary to the situation in radical polymerizations. The change in reactivity of vinyl compounds with 1‐methyl substitution in various reactions is discussed.
Computer simulation of successively solutional refractionation of macromolecules
Authors: Kamide Kenji , Yamaguchi Keiko
Published: April 2003

A successively solutional refractionation (SSRF) method, analogous to the successively precipitational refractionation (SPRF) method proposed by KAMIDE et al., has been simulated for a 1% solution of polymer having a SCHULZ‐ZIMM distribution (the ratio of the weight‐ to number‐average degree of polymerization, X̄w/X̄n = 2,0) with X̄w = 300. The combination of the number of the fractions, i, with the number of the sub‐fractions per each fraction, j, as expressed by (i˜j), were chosen so that ij was 15, such as (15˜1), (5˜3), and (3˜5). The fractionation efficiency decreases in the order: (15˜1), (5˜3), (3˜5), (0˜15), where (0˜15) denotes the simple successive solutional fractionation which yields 15 fractions as a total number of the fractions. The (3˜5) and (5˜3) type refractionations were found to be very effective, except for a few initial fractions, to obtain fractions with X̄w/X̄n≤1,1. The two methods, i.e., the SCHULZ method and KAMIDE et al. method, for evaluating the cumulative molecular size distribution of the original polymer were compared with each other by using the refractionation data (X̄w and the amount of the subfractions). The SCHULZ method is apparently advantageous over the KAMIDE et al. method. SSRF is concluded to be suitable not for analytical purposes, but for preparative purposes.
Pyrolysis gas chromatographic investigation of ionically chlorinated polystyrenes
Authors: Okumoto Tadaoki , Takeuchi Tsugio
Published: April 2003

The microstructure of ionically chlorinated polystyrene with or without a catalyst and the distribution of chlorine in the aromatic nucleus of the polymers were studied by means of pyrolysis gas chromatography. Chlorinated polystyrene was pyrolyzed to yield characteristic chlorostyrenes (ortho and para) and dichlorostyrenes (2,4‐, 2,5‐, and 3,4‐) which gave good informations about substitution of the aromatic nucleus in the original polystyrene. The differences between two series of ionically chlorinated polystyrenes were also discussed from the yields of styrenes and monochlorostyrenes.
Zur berechnung der ungestörten dimensionen von propylen/vinylcopolymeren
Authors: Biskup U. , Cantow H.‐J.
Published: April 2003

Für ataktische und isotaktische Copolymere aus Propylen und 1‐Penten, Styrol oder Vinylchlorid wurden mit dem Modell der rotationsisomeren Zustände von FLORY die ungestörten Dimensionen 〈r〉/nl2 berechnet. Dabei wurde jeweils die chemische Zusammensetzung über den gesamten Bereich variiert. 〈r〉/nl2 ist bei allen Copolymeren kleiner als ein mit den Molanteilen gewichteter Mittelwert von 〈r〉/nl2 der zugehörigen Homopolymeren. Die Abhängigkeit von der Sequenzlängenverteilung, die durch das Produkt rA · rB der Copolymerisationsparameter charakterisiert wurde, erweist sich als gering. Dies gilt insbesondere im Bereich rA · rB < 1.
Asymmetric‐selective polymerization of DL‐leucine N‐carboxy anhydride with optically active amines
Authors: Bührer Heinrich G. , Elias Hans‐Georg
Published: April 2003

DL‐Leucine N‐carboxy anhydride was polymerized in dioxane, benzene, tetrahydrofuran, butanone, and N,N‐dimethyl formamide at temperatures between 10 and 55°C using 15 optically active primary and secondary amines as initiators. The optical yield of polymer can be described satisfactorily by an ideal copolymerization equation

for monomer conversions between 3 and 94% (R = const). The highest R was found for the initiation with (—)‐L‐proline methyl ester in dioxane at 25°C (R = 1,30). Ten different models are shown to fit the ideal copolymerization equation depending on whether homopropagation, heteropropagation, homoadsorption, and/or heteroadsorption is taken into account. Most reasonable on the basis of other published evidence seems to be a pure or by far dominating homopropagation (kLL = kDD; kLL[P*L] > kDL[P*D]; kDD[P*D] > kLD[P*L]) with a constant concentration of active chain ends with D‐ and L‐configurations, ([PL*] = const; [PD*] = const′; [PL*]/[PD*] ≠ 1) resp. The present nomenclature in this field is discussed.
Copolymerization of γ‐benzyl‐D,L‐glutamate NCA
Authors: Williams Fred D. , Brown Ronald D.
Published: April 2003

The copolymerization of γ‐benzyl D‐ and L‐glutamates has been investigated in dioxane at 25,35,50, and 65°C using hexylamine as initiator. Temperature changes had remarkably little effect on the overall rate constants indicating an activation energy of less than 1 kcal/mol. The rate curves indicated two stages in the polymerization process: an initial reaction of random coil with monomer which was independent of monomer composition and a final reaction between α‐helical polymer and monomer which occurred stereoselectively. The conclusion was reached that the origin of the stereoselectivity was a specific adsorption of monomer at a site between the α‐helical polymer and the “random” three or so end units of each polymer molecule.
Polymerization of oxiranylalkylamines and thiiranylalkylamines derived from achiral and racemic secondary amines
Authors: Huguet Jovanka , Vert Michel , Spassky Nicolas , Selegny Eric
Published: April 2003

The polymerization of N,N‐diethyl‐N‐(oxirane‐2‐ylmethyl)amine (Ia), by initiator systems such as ZnEt2/H2O, ZnEt2/CH3OH, AlEt3/H2O, and others, gives only low molecular weight polymers with low yields. The corresponding thiirane derivative, N,N‐diethyl‐N‐(thiirane‐2‐yl‐methyl)amine (IIa), with the same type of initiators gives high molecular weight polymers which are non‐crystalline contrary to the case of propylene sulfide. Physicochemical properties (UV and IR absorptions, neutralization and gelation during neutralization) of these polymers are studied. Higher homologues of IIa derived from racemic secondary amines R1R2NH are synthesized and polymerized with ZnEt2/H2O. The influence of the substitu ents R1 and R2 on the physical and chemical properties of the polymers is discussed.
Reactive polymers, 5. Synthesis of a 2,3‐epoxypropyl ethyl maleate/fumarate mixture and its copolymerization with styrene and ethylene
Authors: Kurosaki Toshikazu , Shibata Taiji , Iwakura Yoshio
Published: April 2003

A mixture of 2,3‐epoxypropyl ethyl maleate and fumarate (4) was obtained from ethyl potassium maleate and 1‐chloro‐2,3‐epoxy propane.

Copolymerization of 4 with styrene was carried out and the monomer reactivity ratios were found to be r1 = 0,30 and r2 = 0,05 (M1: styrene, M2: ester 4). Q and e values were found to be 0,55 and 1,28, respectively. Copolymerizations of 4 with ethylene were performed to improve the chemical reactivity of polyethylene, and the reactivity was studied by means of a homogeneous reaction with dibutylamine. The observed kinetic data may be divided into two parts: ko (non‐catalytic rate constant) = 1,75 · 10−5 dm3 mol−1 s−1, kc (product‐induced catalytic rate constant) = 2,25 · 102 dm6 mol−2 s−1 in DMF at 70°C.
Vinyl polymerization, 298. Polymerization of methyl methacrylate initiated by 4‐cyano‐1‐phenyl‐4,5‐dihyro‐1H‐v‐triazole
Authors: Bando Yoshihumi , Nakaya Tadao , Imoto Minoru
Published: April 2003

Using 4‐cyano‐1‐phenyl‐4,5‐dihydro‐1H‐v‐triazole (1) as initiator, the polymerization of methyl methacrylate (MMA) in benzene solution was performed at 75°C. The initial rate of polymerization was proportional to [1]0,43 and [MMA]1,27. The polymerization proceeded by a radical mechanism. The overall activation energy for the polymerization was 71,8 kJ mol−1 (at 65–85°C). The chain‐transfer constant of 1 for MMA was estimated as 0,0 at 75°C. The rate of thermal decomposition of 1 was also measured and the following rate equation was obtained: kd = 6,79 · 1014 exp (−121/RT) s−1 (E in kJ) (at 60–80°C). Based upon the experimental evidence, a mechanism is discussed for the initiation of the polymerization.
Operating conditions for successive precipitational fractionation of macromolecules, 1. Preparative fractionation
Authors: Kamide Kenji , Miyazaki Yukio , Yamaguchi Keiko
Published: April 2003

Operating conditions, such as initial concentration, vpo, fraction size, p, in successive precipitational fractionation (SPE), based on solubility, are studied on various polymers having SCHULZ‐ZIMM and WESSLAU distributions, the ratio of weight‐ to number‐average degree of polymerizations, X̄w/X̄n, ranging from 1,1 to 5. The vpo dependence of X̄w/X̄n in the fraction is larger, for the fractions having smaller p and for the fractions which are separated from a broader whole polymer. As p increases, X̄w/X̄n of the polymer remaining in the polymer‐rich phase decreases, passing through a minimum at a specific value of p, pmin, then increases, irrespective of vpo, the type, and breadth of the molecular weight distribution (MWD) of the original polymer. For SCHULZ‐ZIMM type polymers, the standard deviation, σ', of MWD in the polymers in both phases behaves just like X̄w/X̄n with an increase in p. For the WESSLAU type polymers, on the other hand σ' decreases monotonically with increasing p.

By SPF it is theoretically impossible for WESSLAU type polymers that the fractions have a smaller σ' compared to that of the original polymer. The X̄w/X̄n of the polymer in a polymerlean phase, separated from a 1,0% solution of a polymer with the WESSLAU distribution (X̄w/X̄n = 5, X̄w = 300) under the conditions of p = 99/100, is extremely small. The fractionation of polymers with large X̄w in a solvent exhibiting a negative concentration dependence of χ is equivalent with that from a more concentrated solution.
Kinetik der umsetzung von butadien mit sec‐butyllithium unter modellbedingungen
Authors: Sgonnik Vladimir , Schadrina Elena , Kalninsch Karl , Erussalimsky Boris
Published: April 2003

Die Umsetzung zwischen Butadien (M) und sec‐Butyllithium (BuLi) in einem Isooctangemisch wurde bei hohem BuLi/M‐Verhältnis im Temperaturbereich von −20°C bis +25°C untersucht; die Reaktionskinetik wurde mit Hilfe von IR‐Spektren untersucht. Für die Aktivierungsenergie der Startreaktion ergab sich ein Wert von 50 ± 17 kJ/mol (12 ± 4 kcal/mol), die Geschwindigkeitskonstante der Initiierung wurde bei 10°C zu 1,5 · 10−3 dm3 mol−1 s−1 bestimmt.

Die Reaktionsordnung in bezug auf BuLi liegt zwischen 0,8 und 0,9. Dafür scheinen die Mischassoziate vom Typ (BuLi)n · (BuMLi)m verantwortlich zu sein. Ihre Bildung wurde durch die IR‐Spektren einer künstlichen Mischung von sec‐BuLi mit Oligobutadienyllithium bestätigt.
Polymers containing stable free radicals, 4. Preparation of 2,4‐diphenyl‐6‐(3‐maleoyliminophenyl)‐3,4‐dihydro‐s‐tetrazin‐1(2H)‐yl and its anionic polymerization
Authors: Miura Yozo , Kinoshita Masayoshi
Published: April 2003

2,4‐Diphenyl‐6‐(3‐maleoyliminophenyl)‐3,4‐dihydro‐s‐tetrazin‐1(2H)‐yl (6) was synthesized and anionically polymerized with a catalytic amount of sodium 1,4‐dihydro‐1,4‐naphthalenediide, with a conversion up to 96%. The polymer was a dark green powder with a content of radical groups of about 58% (based on unit mol), and its relative molecular mass was about 4 800, corresponding to 12 monomeric units.
The dissociation constants of N‐hydroxymethyl‐2,4,6‐triamino‐s‐triazines(methylol melamines) and methylated analogues
Authors: Tashiro Tatsuo , Shimura Yukio
Published: April 2003

The dissociation constants (pKb) of N‐(hydroxymethyl)‐2,4,6‐triamino‐s‐triazines (methylol melamines) (1) and N‐methoxymethyl‐2,4,6‐triamino‐s‐triazines (methylated methylol melamines) (2) were determined by electrometric titration. The pKb values of 1, having an average degree of formaldehyde substitution of n < 3, and of 2, having an average degree of methoxymethyl group substitution of m = 0,2—6,0, were constant in the region between the initial pH and the half neutralization point or its vicinity. On the other hand, the pKb values of 1 having n > 3 increased with decreasing pH. Thus, a different behavior of protonation between 1 and 2 was observed, and the causes were discussed. Linear correlations were found between pKb and n as well as m.
Separation of trans‐1,4, cis‐1,4 and 1,2‐vinyl polybutadienes by thin layer chromatography
Authors: Donkai Nobuo , Murayama Nobumichi , Miyamoto Takeaki , Inagaki Hiroshi
Published: April 2003

A study on thin layer chromatographic (TLC) separation of polybutadienes with three different microstructures, namely, trans‐1,4, cis‐1,4, and 1,2‐vinyl, was carried out. An experimental procedure to separate three possible binary mixtures of these polymers into each component species is established in an alternate use of carbon tetrachloride and amyl chloride as developer. Further it is shown that this procedure combined with a two‐dimensional TLC development technique allows to separate the ternary polymer mixture into components. In addition, the chromatographic behavior of so‐called “equibinary” polybutadienes has been investigated using the technique established so far.
Synthèse de polymères étoiles par réaction de polymères ω‐fonctionnels sur des polyisocyanates
Authors: Pinazzi Christian , Esnault Jacques , Lescuyer Gilles , Villette Jean‐Paul , Pleurdeau Alain
Published: April 2003

La présente étude a pour but la réalisation de réseaux macromoléculaires possédant des propriétés viscoélastiques. La synthèse de ces réseaux implique deux étapes: synthèse de polymères fonctionnels possédant des extrémités actives et réaction de condensation sur des agents polyfonctionnels. Afin de déterminer les conditions de ces réactions de condensation, une étude préalable a été réalisée sur des polymères ramifiés en étoile. Ces polymères sont obtenus par réaction d'un polymère ω‐fonctionnel avec un tri‐, tétra‐ ou pentaisocyanate. Les polymères utilisés dans cette étude sont des polyisoprène, polybutadiène, polystyrène, copolymères séquencés diène‐styrène possédant tous une extrémité hydroxyle. La réaction de polymère liquide ω‐monohydroxylé avec des isocyanates conduit, par formation d'uréthanes, à des polymères ramifiés en étoile. La structure de ces polymères étoiles est confirmée par spectrographie de NMR et par détermination des masses moléculaires.
Stabile Polyphenoxyle, 2. Polymerisationsverhalten von Monomeren mit sterisch behinderter, freier oder geschützter phenolischer Hydroxylgruppe
Authors: Braun Dietrich , Meier Bertold
Published: April 2003

2,6‐Di(tert‐butyl)‐4‐vinylphenol (1 a), 2,6‐Di(tert‐butyl)‐4‐isopropenyl‐phenol (1 b) und 2,6‐Di(tert‐butyl)‐4‐isopropenylanisol (1 c) sind nur kationisch polymerisierbar. Als Initiatoren können alle Protonen‐ und LEWIS‐Säuren verwendet werden. Eine radikalische oder anionische Polymerisation dieser Monomeren ist erwartungsgemäß nicht möglich.

Von den drei untersuchten Monomeren polymerisiert 1 a bei −78°C in Methylenchlorid in sehr kurzer Zeit nahezu vollständig. 1 c kann man unter gleichen Bedingungen nur bis zu Umsätzen von höchstens 28% polymerisieren. Am schlechtesten polymerisiert 1 b, aus dem nur 1 bis 3% hochmolekulare Produkte erhalten werden.

Bei der kationischen Copolymerisation von 1 a und von 1 b mit Styrol werden die Phenolmonomeren bevorzugt in die Polymerketten eingebaut. Dieses Verhalten drückt sich in den Copolymerisationsparametern aus: 1 a /Styrol: r1 = 3,4 und r2 = 0,046, 1b/Styrol: r1 = > 1 und r = 0,076.

1 a und 1 b zeigen sowohl bei der Homo‐ als auch bei der Copolymerisation immer dann eine Tendenz zur Bildung von vernetzten Polymerisaten, wenn aus den Monomeren bzw. Comonomeren während der Wachstumsreaktion sec‐Carboniumionen gebildet werden können. Dagegen führt die Homopolymerisation von 1 c und 1 b immer zu in Benzol löslichen Polymerisaten. Als Ursache der Vernetzung wird eine Kettenübertragungsreaktion von wachsenden sec‐Makrocarboniumionen mit den Hydroxylgruppen anderer Polymerketten angenommen.
Electrochemically initiated bulk polymerization of trioxane
Authors: Mengoli Giuliano , Vidotto Graziano
Published: April 2003

The electroinitiated bulk polymerization of trioxane containing tetrabutylammonium perchlorate as background electrolyte has been investigated at the temperature of 66,5°C.

The polymerization can be started by a very small charge initially supplied and does not present significant termination features.

The resulting polymers have high molecular weights, which are dependent on the current amounts, and show satisfactory thermal stability. The species initiating the polymerization is perchloric acid, which is produced by anodic oxidation of the perchlorate ion, followed by hydrogen atom abstraction from trioxane.

Bulk trioxane polymerizations catalyzed by added perchloric acid, show in fact similar features as to kinetic chain length, molecular weight of the polymers and polymerization rate, with respect to the electroinitiated trioxane polymerizations.
Cationic polymerization of cyclic sulfides
Authors: Goethals Eric J.
Published: April 2003

The mechanism of the cationic polymerization of cyclic sulfides, initiated with triethyloxonium salts is reported. Differences due to changing the counter‐ion from BF to SbCl are discussed. Initiation consists of the alkylation of monomer forming a cyclic sulfonium ion which is the active species in the propagating step. A generally occurring termination reaction is the formation of non‐strained (linear or cyclic) sulfonium ions. In the case of epithiopropane (propylene sulfide) these can slowly re‐initiate the polymerization by an intramolecular reaction forming the 3‐membered cyclic sulfonium salt. This re‐initiation is not possible with the thietanes because of the greater difficulty to form 4‐membered cyclic sulfonium salts. When SbCl is the counter‐ion, an additional, more drastic termination can occur most probably by reaction of the growing chain with the counter‐ion, thereby forming an alkyl chloride and SbCl5. After the polymerization of propylene sulfide with BF as the counter‐ion, the polymer degrades to low molecular weight oligomers, predominantly the cyclic tetramer. This degradation is a back‐biting reaction occuring via sulfonium salts. With SbCl as the anion, the sulfonium salts are destroyed by the termination reaction and degradation does not occur.

It was possible to follow the concentration of the growing species (4‐membered cyclic sulfonium salt) during the polymerization of 3,3‐dimethylthietane by means of 300 MHz NMR spectroscopy. By measuring the rate constants of propagation for different initiator concentrations or in the presence of different amounts of an indifferent electrolyte, it was possible to calculate separate rate constants for propagation via free ions (k) and via ion‐pairs (k). The ratio k/k was about 60 when BF was the anion and 35 when it was SbCl.
13C‐NMR spectra of polyalkenylenes and of some diolefin polymers and copolymers
Authors: Gatti Giuseppe , Carbonaro Antonio
Published: April 2003

The examination of 13C‐NMR spectra of some unsaturated homopolymers (polyalkenylenes and polypentadienes) has shown that it is possible to distinguish beween 1,2‐and 1,4‐structures and between cis‐ and trans‐configuration of the double bonds along the chain. By using this technique, it has been possible to obtain evidences on the structure and the relative orientation of monomeric units in alternating copolymers of isoprene with acrylonitrile or propene. Copolymers of butadiene with these two latter comonomers were also examined by this method.
Synthesis and properties of N‐hydroxymethylcarbamates and their derivatives
Authors: Takeuchi Shigeya
Published: April 2003

The dicarbamates 3a–d were synthesized by the method of Kraft. Their reaction with formaldehyde in the presence of alkali or acid afforded in one case the mono‐N‐hydroxymethyl derivative 4 and with 3a–c the N,N′‐bis(hydroxymethyl) derivatives 5a–c. These were transformed into the corresponding N,N′‐bis(alkoxymethyl) derivatives 6a–f by reaction with alcohols at pH 2,2. The reaction of the N‐hydroxymethylcarbamates with urea afforded urea derivatives of type 9 and 10.
Addition of chlorine and nitrogen dioxide to linear polybutadiene. Degree of isomerization
Authors: Hernández Luis González , Rueda Luis Ibarra
Published: April 2003

The reaction of chlorine or nitrogen dioxide with polybutadiene consists mainly in their addition to the double bonds of the polymer, but it is often followed by a number of secondary reactions, such as crosslinking and cis‐trans isomerization. The addition reaction of nitrogen dioxide is always accompanied by cyclisation.

The cis‐trans isomerization, the effect of the solvent nature and catalyst, and the CCl trans‐gauche configuration in the reaction with chlorine were studied by IR spectroscopy.

The cis‐trans isomerization, the degree of cyclisation, and the proportion of crosslinked double bonds, in the reaction of nitrogen dioxide were also studied by IR spectroscopy.
Reaction of excited oxygen species with polymer films
Authors: MacCallum James R. , Rankin Clive T.
Published: April 2003

The reaction of atomic oxygen and singlet oxygen molecules with films from various polymeric substrates was studied. The polymers used were poly(vinyl chloride), polyacrylonitrile, polystyrene, nylon 66, and poly(ethylene terephthalate). Atomic oxygen reacted readily with all of these polymers. The reaction was confined to the surface layers which results in the polymer films becoming more hydrophilic. No change was observed in the contact angle of water with films of poly(vinyl chloride) and polystyrene after they had been exposed to singlet oxygen molecules for several hours.
Thermal degradation of some model compounds of PVC
Authors: Varma I. K. , Grover S. S.
Published: April 2003

The liquid phase dehydrochlorination of 1‐chlorododecane (1‐DDCl), 2‐chlorododecane (2‐DDCl), 1,1,3‐trichlorononane (TCN), and dichlorononene (DCN) was investigated in the temperature range of 202—262°C in a nitrogen atmosphere. On the basis of the decomposition rate constant and activation energy the stability order for the dehydrochlorination in liquid phase was found to be 1‐DDCl>2‐DDCl>TCN>DCN. The influence of the solvents methyl salicylate and eugenol on the dehydrochlorination of these chloro compounds was different from their influence on the dehydrochlorination of PVC. Therefore, a molecular mechanism for dehydrochlorination believed to be operating in these chloro compounds may not be operating in PVC degradation.
Die rolle des zentralatoms bei der ringöffnenden polymerisation. Vergleich zwischen wolfram und molybdän
Authors: Lehnert Günther , Maertens Dieter , Pampus Gottfried , Zimmermann Manfred
Published: April 2003

Die beiden Katalysatorsysteme aus MoCl5, (ClC4H8)2O, Sn(C2H5)4 und WCl6, (C2H5)2O, Sn(C2H5)4 sind zur ringöffnenden Polymerisation von Cycloolefinen gut geeignet. Anhand der Versuchsergebnisse wird der Einfluß der Zentralatome auf die Bildung der aktiven Spezies erörtert. Zur Erklärung unterschiedlicher Reaktionsweisen wird unter anderem die Raumerfüllung der Metallhybridorbitale diskutiert.
Fonctionalisation des polyalcadiènes: Étude sur molécules modèles des structures accessibles à partir des polymères de l'isoprène par utilisation de l'isocyanate de chlorosulfonyle
Authors: Pinazzi Christian P. , Noireaux Patrick , Reyx Danièle
Published: April 2003

La réaction de l'isocyanate de chlorosulfonyle (1) avec les alcènes permet d'envisager la réalisation de lactames et d'amides N‐chlorosulfonées qui constituent des intermédiaires de synthèse.

Dans le but d'obtenir des composés macromoléculaires fonctionnels, nous avons envisagé l'utilisation de cette réaction pour la modification chimique de polyisoprènes de microstructures‐1,4 ou 3,4 prédominantes. Afin de définir les modifications de microstructures provoquées par action de ce réactif, sur ces polymères, nous avons étudié la réaction envisagée sur leurs molécules modèles.

Ainsi, il nous a été possible de déterminer les pourcentages de formation de microstructures lactames et amides N‐chlorosulfonées pour chaque type d'enchaînements polyisopréniques. D'autre part, nous avons étudié les transformations des lactames N‐chlorosulfonées en lactames libres, en hydrochlorures d'amino‐acide et en nitriles insaturés.

Ce travail permet de définir les références spectrales des microstructures susceptibles de se former lors de l'application aux polymères. Il nous autorise en outre à sélectionner le type d'enchaînement polyisoprénique qu'il conviendra de choisir pour conduire avec plus hauts rendements et la meilleure sélectivité aux composés macromoléculaires fonctionnels recherchés pour des applications spécifiques.
Study of photopolymer, 10. Cationic polymerization of vinyloxyethyl acrylate
Authors: Nishikubo Tadatomi , Kishida Masahiko , Ichijyo Taro , Takaoka Tsuneo
Published: April 2003

Cationic polymerizations of vinyloxyethyl acrylate (VEA) catalyzed by boron trifluorideether complex were carried out in toluene at 10, −10, and −30°C. In this system, a critical catalyst concentration (C0) exists; when the catalyst concentration is below this concentration, the polymerization of VEA cannot be initiated. The rate of polymerization is expressed as –d[M]/dt=kp(C*)·[M]a, where a was found to be 0,44 (at 10°C), 0.51 (at −10°C), and 0,63 (at −30°C), respectively.

From these results, it is concluded that the rate of polymerization of VEA is proportional to the first power of catalyst concentration and to 0,44–0,63 power of monomer concentration between 10 and −30°C, respectively.

Furthermore, it is recognized that an increasing monomer concentration tends to decrease the degree of polymerization.
Vinyl polymerization by metal complexes, 17. Effect of nitriles on the vinyl polymerization initiated by imidazole‐copper (II) complex
Authors: Inaki Yoshiaki , Shirai Hirofusa , Takemoto Kiichi
Published: April 2003

Polymerization of vinyl monomers initiated by the imidazole‐copper(II) complex was studied in dimethyl sulfoxide solution. Different from the case of acrylonitrile, the polymerization of styrene and methyl methacrylate did not proceed, even in the presence of various sort of nitriles. From these findings and the copolymerization behaviour of acrylonitrile with styrene and methyl methacrylate, together with the spectroscopic data, the presence of acrylonitrile monomer is essential for generating active species to initiate the polymerization.
Untersuchungen zum oxidativen Abbau nativer Cellulose, 3. Polymerisationsgrad und Polymerisationsgrad‐Verteilungen im Verlauf des Abbaus von Alkalicellulose durch Sauerstoff
Authors: Jovanović S. , Palma A. , Schulz G. V.
Published: April 2003

Der zeitliche Ablauf des oxidativen Abbaus von Cellulose wird unter standardisierten Bedingungen durch Messung des Zahlenmittels, Pn (osmotisch), des Gewichtsmittels Pw (Lichtstreuung, Viskosität) und der Verteilungen des Polymerisationsgrades gemessen. Die Bildung der Spaltstellen verläuft in 2 Stufen mit den unterschiedlichen Geschwindigkeitskonstanten k1 und k2. Diesem Prozeß überlagert sich am Anfang die Bildung intramolekularer Vernetzungsstellen. Unter Verwendung der Statistik vernetzter Moleküle von Stockmayer ergeben sich Beziehungen, welche es erlauben, aus dem Zeitablauf von Pn und Pw die Zahlenwerte von k1, k2 und die Zahl der Vernetzungsstellen zu bestimmen. Pro natives Cellulosemolekül mit Pn=Pw=1,35·104 bilden sich unter den angegebenen Bedingungen durchschnittlich 4 Vernetzungsstellen.

Sowohl die Zeitkurven als auch die Verteilungen des Polymerisationsgrades geben keinen Hinweis darauf, daß in der native Cellulose bereits „Lockerstellen”︁ vorhanden sind.
Statistical analysis of experimental data from polymers in dilute solutions, 1. Dependence of linear expansion factors of poly(methyl acrylate) on molecular weight
Authors: Guaita Marino , Chiantore Oscar
Published: April 2003

The theoretical relationships by Flory, Kurata‐Stockmayer, Stockmayer‐Fixman, and Ptitsyn, between the linear expansion factor of polymer coils and molecular weight are applied to poly(methyl acrylate) fractions. By employing statistical procedures, it is shown that the Flory relationship represents only a crude approximation, whereas those by Kurata‐Stockmayer, Stockmayer‐Fixman, and Ptitsyn have to be considered as satisfactory mathematical models.
Polymerization of cis‐ and trans‐7,9‐dioxabicyclo [4.3.0] nonane
Authors: Kops Jørgen , Spanggaard Hans
Published: April 2003

The polymerization of cis‐ and trans‐7,9‐dioxabicyclo[4.3.0]nonane (1a) and (1b) was investigated in bulk and in solution with phosphorus pentafluoride and triethyloxonium hexachloroantimonate as initiators. The cis‐isomer 1a forms in high yield the cyclic dimer 2a. The trans‐isomer 1b polymerizes readily under similar conditions to relatively low molecular weight polymers, whereas in 1,1,2,2‐tetrachloroethane solution predominantly the cyclic dimer 2b is formed. The polymerization of the trans‐isomer 1b in toluene‐d8 solution is of first order with respect to monomer, and the concentration of active species appears to remain constant throughout the reaction. The polymerization of 1b in toluene‐d8 with PF5 as initiator is completely reversible with temperature change, and the standard ceiling temperature T is 118°C (cone.: 1 mol/dm3 in toluene‐d8). The cyclic dimer 2b polymerizes at −25°C to the same equilibrium product composition as the corresponding monomer 1b.
Über poly(1,3,5‐triazin)e und poly(1,2,4‐triazin)e
Authors: Wahl Bernd , Wöhrle Dieter
Published: April 2003

Durch Polycyclokondensation von Terephthalamidrazon mit 1,2‐Diketonen wurden in hohen Ausbeuten niedermolekulare und polymere 1,2,4‐Triazine dargestellt. Die Umsetzung von Amidinen wie Terephthalamidin mit Aldehyden ergab in einer Polycyclokondensation niedermolekulare und polymere 1,3,5‐Triazine. Thermische Analysen der Poly(1,2,4‐triazin)e und der Poly(1,3,5‐triazin)e wurden durchgeführt und die Pyrolysemassenspektren dieser Verbindungen aufgenommen.