bluuebunny/crossref_metadata_2025 huggingface dataset:
Mathematical model of polyaddition of 1‐chloro‐2,3‐epoxypropane to α, ω‐diols
Authors: Novák Jiří , Šváb Vladimír
Published: April 2003

A mathematical model for the composition of products resulting from a polyaddition of 1‐chloro‐2,3‐epoxypropane to ethylene glycol was constructed on the presumption that the reactivites of the 3‐chloro‐2‐hydroxypropyloxy end groups are equal, that the remaining hydroxyl groups have also identical reactivities, and that the oxirane ring opens to give exclusively Cα‐ethers. By comparing the calculated and experimentally obtained percentage of unreacted ethylene glycol (for various chosen kinetic parameters) at variable initial mole ratios in the moment of complete conversion of 1‐chloro‐2,3‐epoxypropane, the relative reactivities of all three hydroxyl groups could be determined. The reactivity ratio of the hydroxyl group in the 3‐chloro‐2‐hydroxypropyloxy end group to the initial hydroxyl group in the diol was found to be 0,6 and that of the remaining diol group to the initial diol group to be 0,5.
Crystallization of polypeptides in the course of polymerization, 2. Chain folded crystals of polyglycine and poly‐β‐alanine
Authors: Komoto Tadashi , Kim Kea Yong , Minoshima Yoshiaki , Oya Masanao , Kawai Toru
Published: April 2003

The polymerization of N‐carboxy anhydrides of glycine and β‐alanine was studied in acetonitrile with butylamine as initiator. As was expected from the similarity of the backbone chain structure to nylons, the polymer precipitated in the form of a spherulite consisting of ribbon like crystalline units just as in the case of nylons previously reported. The molecules in the ribbon like crystals were arranged antiparallel forming a hydrogenbonded sheet. The result contrasts with that reported previously on some α‐amino acids which gave helical polymer molecules organized in the form of an extended chain crystal. The mechanism of the crystal growth has been discussed along the same line as in the case of nylons.
Funktionelle monomere und polymere. X. Wechselwirkung zwischen nucleinbasenhaltigen makromolekülen
Authors: Kawakubo Fumio , Kondo Koichi , Takemoto Kiichi
Published: April 2003

Einige monomere, dimere und polymere Derivate von N‐Methylaminopurin, N,N‐Dimethylaminopurin und Äthoxypyrimidon wurden dargestellt. Die NMR‐ und UV‐Spektren dieser neuen Substanzen wurden gemessen und miteinander verglichen. Außerdem wurden die Polymer‐Polymer‐Wechselwirkungen spektroskopisch untersucht. Es ergab sich, daß nur Poly(9‐vinyladenin) und Poly[6(N‐methylamino)‐9‐vinylpurin] mit Ribonucleinsäure in wäßriger Lösung hypochrome Effekte zeigen.
Ein neuer weg zur synthese von polystyrol und styrol‐copolymeren mit primären aromatischen aminogruppen
Authors: Seliger Hartmut
Published: April 2003

Es wird ein Verfahren zur Überführung aromatischer Nitrogruppen von Polymeren des Styrols in primäre aromatische Aminogruppen beschrieben, bei dem Phenylhydrazin als Reduktionsmittel angewandt wird. Polystyrole von verschiedenem Nitrierungsgrad sowie Copolymere von Styrol mit Divinylbenzol, Methylacrylat und 4‐Vinylpyridin wurden untersucht. Die Reaktion verläuft in Lösung von Phenylhydrazin allein oder in Mischungen geeigneter Lösungsmittel bei höherer Temperatur quantitativ und ohne Vernetzung löslicher Polymerer.
Polymerization of aromatic aldehydes, 8. Cationic copolymerization of 2,2′‐biphenyldicarbaldehyde with styrene
Authors: Kunitake Toyoki , Tsugawa Shunichi , Aso Chuji
Published: April 2003

Cationic copolymerizations of 2,2′‐biphenyldicarbaldehyde (II) (diphenaldehyde) with styrene were carried out with BF3O(C2H5)2 in dichloromethane. The copolymers were white powders (MW: 6000∼7000) and soluble in common organic solvents. The monomer reactivity ratios (BF3O(C2H5)2, CH2Cl2, −78°C) were: r1 (II) = 0,13 ± 0,07; r2 (styrene) = 0,70 ± 0,05. The IR data showed the presence of pendant aldehyde groups corresponding to 20–40% of II units. The content of pendant aldehyde groups increased with the content of II in the copolymer. Therefore, the intramolecular cyclization of II must occur in competition with the monomer addition during the propagation step. Recovery of the bis‐hydrazone of II on acid hydrolysis of the copolymer was consistent with the monomer sequence estimated from the reactivity ratio. Attempted homopolymerization of II was not successful.
Die copolymerisation von trans, trans, cis‐1,5,9‐cyclododecatrien mit methylacrylat
Authors: Tokarzewski Ludomir , Socha Jerzy
Published: April 2003

Die Copolymerisation des Systems Methylacrylat/Cyclododecatrien wurde untersucht. Die Copolymerisationsparameter wurden bestimmt und die Eigenschaften der Copolymeren untersucht.
Determination of the basicity of some cyclic ethers and cyclic formals
Authors: Mateva R. , Fratev F. , Pavlova M.
Published: April 2003

The tendency of some cyclic ethers and cyclic formals (“oxacyclic compounds”) to form protonated complexes was studied by means of UV spectroscopy. The degree of basicity (pKBH+) was evaluated on the basis of the HAMMET indicator functions.

The process of complex formation was followed at different values of the HAMMET function in dilute spectroscopically pure sulfuric acid. The pKBH+ values of four of the seven examined compounds correlated very well with the pKBH+ values obtained by a method different in principle. This was taken as an indication of the objectivity of the evaluation of the basicity of the “oxacyclic compounds” by spectral methods regardless of the fact that these compounds are very weak bases and form colourless protonated complexes.
Crystallization of polypeptides in the course of polymerization, III. Further studies on the growth mechanisms of poly(L‐alanine) crystals
Authors: Fujie Akira , Kōmoto Tadashi , Ōya Masanao , Kawai Tōru
Published: April 2003

In order to establish the mechanism proposed previously for the formation of the extended chain crystals during the heterogeneous polymerization of the LEUCHS anhydride 4‐methyl‐2,5‐oxazolidinedione (L‐alanine NCA) in acetonitrile, oligo‐L‐alanines were prepared by purely organic chemical methods. Their solubility, conformations in various solvents and those in the crystallized states were studied and compared with those in the crystals formed directly in the course of the heterogeneous polymerization. It was found that the growing chain molecules became insoluble in acetonitrile and crystallized into the β‐conformation when they attained a \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {\rm{DP}} $\end{document}
of 3.

As the growing chains in the course of the heterogeneous polymerization attained \documentclass{article}\pagestyle{empty}\begin{document}$\overline {\rm{DP}}$\end{document} of 10–13 (i.e. 7–10 from the basal plane of the original skeleton crystals) by further polymerization, they crystallized into the α‐helical conformation. Due to the topochemical nature of the chain growth, this critical length for the formation of the α‐helix is shorter than that found in solution for the corresponding oligomers already synthesized (i.e., \documentclass{article}\pagestyle{empty}\begin{document}$\overline {\rm{DP}}$\end{document} > 10).

It was also shown that the crystalline nuclei with the β‐conformation, formed in the very early stages of the polymerization, remain throughout the polymerization.

In order to examine the rôle of acetonitrile in this particular type of polymerization, the polymerization of L‐alanine NCA was studied also in dioxane and propionitrile. The chains grown from the basal plane of the skeleton crystals with the β‐conformation remain in some state like random coils until they attain the critical length for the formation of the α‐helix. This critical length seems to depend on the solvation power (including the steric factor) of the solvent used. In the case of acetonitrile, the dipole‐dipole interaction with polypeptides may play an important rǒle in this type of solvation.
Synthese und reaktionen difunktioneller N‐acyl‐β‐lactame
Authors: Kricheldorf Hans R.
Published: April 2003

Die Darstellung difunktioneller N‐Acyl‐β‐lactame gelingt am besten durch Acylierung von N‐Trimethylsilyl‐lactamen mit geeigneten Säurechloriden unter Abspaltung von Trimethylchlorsilan. N‐Acyl‐β‐lactame reagieren leicht mit Aminen und Alkoholen, wobei ausschließlich Ringöffnung erfolgt. Durch Additionspolymerisation difunktioneller N‐Acyl‐β‐lactame an Diamine, Diole oder Amidoalkohole ist eine Vielzahl von Polymeren verschiedener Struktur zugänglich, die neben Amidgruppen auch Harnstoff‐, Thioharnstoff‐, Urethan‐ oder Estergruppen in regelmäßigen oder unregelmäßigen Sequenzen enthalten.
Polymères liquides à extrémités alkoxysilanes
Authors: Brossas Jean , Pinazzi Christian P. , Clouet Gilbert , Clouet Françoise
Published: April 2003

Nous avons effectué la synthèse de polymères à bas masses moléculaires rélatives — polymères liquides — susceptibles d'une part d'être compatibles avec des résines polyester et d'autre part de pouvoir effectuer des liaisons chimiques avec les structures silanols libres du verre. Pour cela, nous avons préparé des polydiènes α,ω‐dicarbanioniques isomoléculaires et nous avons ensuite effectué la réaction de terminaison par addition d' alkoxychlorosilanes. Afin d'étudier les structures obtenues, nous avons préparé des substances modèles, notamment à partir de terpénoïdes naturels.
On the mechanism of anionic polymerization of maleic anhydride, 2
Authors: Zweifel Hans , Völker Theodor
Published: April 2003

The triphenyl and tributyl phosphine initiated polymerization of maleic anhydride was investigated. The structure of the macro zwitterions, formed under the given reaction conditions, depended on the initiator employed. If the polymerization was initiated by triphenyl phosphine, the macromolecules contained succinic anhydride units and cyclopentanone derivatives, formed from further rearrangement. If, however, tributyl phosphine was employed as initiator, the polymers were mostly made up of conjugated ketoolefinic units. IR, NMR and mass spectrometric measurements were carried out to determine the structure of the polymers. Existence of the macro zwitterions was proved by high voltage electrophoresis.

The semi‐conductor properties of the polymers containing conjugated ketoolefinic units are discussed.

Spectroscopic investigation of the kinetics of the triphenyl phosphine initiated polymerization of maleic anhydride showed that the initiation reaction of the ylide, formed with the monomer, proceeded about 90 times slower than the propagation reaction due to addition of the monomer to the growing chain‐end.
Influence du degré de ramification sur la température «theta» de quelques polymères dans différents solvants
Authors: Candau Françoise , Strazielle Claude , Benoit Henri
Published: April 2003

L'abaissement de la temperature Θ observé pour les polystyrènes ramifiés dans le cyclohexane est généralisé a d'autres systèmes: polystyrène dans 1e malonate d'éthyle, la décaline et un mélange de solvants (benzène 78%, méthanol 22%) — ainsi qu'à d'autres polymères tels que le polyisoprène dans la méthylpropylcétone et l'acétate de polyvinyle en solution dans la heptanone‐3 et l'éthanol.

La température Θ (mesurée par diffusion de la lumière) et la température de précipitation Tp (mesurée par méthode de séparation de phase) de ces polymères est inférieure dans tous les cas à celle des polymbres linéaires de même nature chimique. L'abaissement ΔΘ observé croit avec le degré de ramification.
Studies on organometallic compounds as polymerization catalysts, 6. Diethylcadmium/additive system for propylene oxide polymerization
Authors: Ishimori Michihiro , Nakasugi Osami , Yokobori Katsuichi , Tsuruta Teiji
Published: April 2003

Organocadmium compounds as catalysts for propylene oxide polymerization were studied. It was found that the Cd(C2H5)2CH3COSH system has an excellent catalytic activity for reactions forming polymers of high rel. mol. mass. In contrast, Cd(C2H5)2ROH, RSH and RCOOH systems showed little or no catalytic activity. The favoured activity of the Cd(C2H5)2CH3COSH system is discussed in terms of dπ  dπ bonding, on the basis of spectroscopic studies.
Kinetics of chain growth in binary copolymerization
Authors: Tosi Camillo , Chioccola Giampiero
Published: April 2003

The chain propagation step in binary copolymerizations was studied. The composition of copolymers with any arbitrary degree of polymerization was compared with the stationary limit, obtained from the differential form of the copolymerization equation and determined by the transition probabilities alone. It was shown that the n‐mer composition approaches the value characteristic of the copolymer in a manner which differs not only quantitatively but also qualitatively, depending on the product of the reactivity ratios. The three cases of physical significance, viz. block (r1r2 > 1), random (r1r2 = 1) and alternating (r1r2 < 1) copolymers, are thoroughly discussed.
Cellulose single crystals
Authors: Ramesh Ravi , Patel Chiman K. , Patel Raman D.
Published: April 2003

An attempt was made to crystallize cellulose II by hydrolyzing cellulose acetate (DP = 345) in dilute acetic acid medium. Though the cellulose chains are known to be less flexible, they exhibit a crystal structure similar to that obtained for flexible synthetic polymers. The effects of temperature and of acetic acid concentration on the crystal structure were studied. It was shown that cellulose could be crystallized in a variety of structural features if the strong intermolecular hydrogen bonding, which under ordinary circumstances dominates the flexibility of the backbone, is avoided by appropriate experimental conditions.
Contribution à l'étude des propriétés électriques et mécaniques dynamiques de quelques polyéthylènes chlorés à saturation
Authors: Nguyen Ung Long , Berticat Philippe , May Jean‐François , Vallet Georges
Published: April 2003

Les propriétés électriques de polyéthylènes chlorés en suspension (taux de chlore, 73% environ) ont été étudiées à la fréquence de 5 MHz dans une gamme de température de 20 à 80°C. Les relaxations observées varient avec la structure chimique du polymère.

Les propriétés mécaniques dynamiques ont été étudiées en basse fréquence dans une gamme de température de −100 à +190°C. On n'observe pas de parallélisme entre propriétés électriques et mécaniques pour ces polymères dont les chaînes sont très rigides.
Über die synthese und die eigenschaften einiger mono‐, bis‐ und poly‐azine aromatischer heterocyclen
Authors: Manecke Georg , Kautz Johannes
Published: April 2003

Polymere (Polyazine), die das reversible, bivalente Redoxsystem der 2,2′‐Azine aromatischer Heterocyclen enthalten, wurden aus bifunktionellen Salzen und Hydrazin dargestellt. Aus diesen Salzen und Hydrazonen wurden Bisazine als Modellverbindungen für die Polyazine erhalten. Durch Oxidation wurden Poly‐ und Bi‐Radikale dargestellt, die durch ihre ESR‐Spektren und die elektrische Leitfähigkeit charakterisiert wurden. Die Bisazine wurden polarographisch untersucht.
Influence de la masse moléculaire, de la polydispersité et de la température sur les phénomènes de solvatation préférentielle de polystyrènes linéaires dans différents mélanges de solvant
Authors: Hert Marius , Strazielle Claude , Benoit Henri
Published: April 2003

Dans cet article nous présentons les résultats d'une étude de l'adsorption préférentielle du polystyrène en mélange de solvants en fonction de différents paramètres. En premier lieu, nous avons examiné l'influence de la densité en segments intramoléculaire (effet de la masse moléculaire et de la polydispersité du polymère) sur ce phénomène. L'effet de la température sur le coefficient de solvatation a également été considéré. Pour certains de nos résultats expérimentaux, il existe un bon accord avec les théories thermodynamiques de l'adsorption préférentielle, cependant le manque de connaissances relatives à la variation avec la densité en segments intramoléculaires et la température, des paramètres d'interaction thermodynamiques, ne permet pas une étude quantitative rigoureuse.
Über synthese und polymerisation von ß‐aminosäure‐N‐carbonsäureanhydriden
Authors: Kricheldorf Hans R.
Published: April 2003

Durch Hydrolyse von ß‐Isocyanatocarbonsäure‐trimethylsilylestern, die aus cyclischen Carbonsäureanhydriden mittels Trimethylsilylazid (8) gewonnen wurden, konnten neue ß‐Aminosäure‐N‐carbonsäureanhydride dargestellt werden. Aus der Untersuchung der Polymerisation von 9 ß‐Aminosäure‐N‐carbonsäureanhydriden mit verschiedenen basischen Katalysatoren und unter verschiedenen Reaktionsbedingungen ging hervor, daß die Wirksamkeit der Katalysatoren mit zunehmender Basizität steigt und die höchsten rel. mol. Massen mit den am wenigsten basischen Katalysatoren oder auch bei niederen Reaktionstemperaturen erhalten werden. Die aufgrund von elementaranalytischen und NMR‐spektroskopischen Endgruppenbestimmungen errechneten rel. mol. Massen liegen in keinem Falle über 10000. Bei der thermischen Decarboxylierung der N‐Carbonsäureanhydride entstanden neben den Polyamiden auch niedermolekulare Nebenprodukte. ß‐Lactame konnten nicht nachgewiesen werden.
Effect of average molecular weight of the original polymer on phase separation characteristics of multicomponent polymer/single solvent system
Authors: Kamide Kenji , Miyazaki Yukio , Sugamiya Ken
Published: April 2003

When solutions of a polymer with a molecular weight distribution (MWD) having a great variety of the average molecular weights are precipitationally fractionated, the effect of the average molecular weight on the phase separation features can be discussed by means of a hypothetical calculation technique.

The FLORY‐HUGGINS‐FUJISHIRO theory was employed as a basic tenet for the simulation. The partition coefficient, σ, as well as the volume ratio of the polymer‐lean phase to the polymer‐rich phase, R, decrease with an increase in the average molecular weight of the original polymer under the same operating conditions, including initial concentration, vpo, the concentration dependence of the polymer/solvent interaction parameter, p, and the amount of fraction, p. The standard deviation of the fraction, σ', (Eq. (3)), for a given p reveals a maximum at a specific vpo. In the cases where the original polymers differ in the average molecular weight, but have the same X̄w/X̄n and where the original polymers have the same σ', the fractionation efficiency, defined by \documentclass{article}\pagestyle{empty}\begin{document}$ (\overline X _w /\overline X _n )/(\overline X _w^0 /\overline X _n^0 ) $\end{document}, is lowered with a decrease in the average molecular weight (suffix zero means the original polymer), i.e., the molecular weight distribution of the fractions, obtained under the same operating conditions, becomes broader. The average molecular weight of the original polymer affects insignificantly the characteristics, but the accuracy of estimating the MWD of the original polymer becomes inferior.
Effect of molecular weight distribution of the original polymer on separation characteristics in successive precipitational fractionation
Authors: Kamide Kenji , Yamaguchi Keiko , Miyazaki Yukio
Published: April 2003

An attempt has been made to confirm the validity of conclusions deduced in the previous papers in which a single sample with a specific molecular weight distribution, was mathematically fractionated. Polymers with a SCHULZ‐ZIMM distribution and WESSLAU distribution (ratio of the weight‐ to number‐average degree of polymerization, X̄w/X̄n = 1,05–5) were brought into a solution, which was cooled to cause precipitation according to the simulative procedure of KAMIDE and SUGAMIYA. The molecular weight distribution (MWD) of the fractions is approximately symmetrical and can be expressed by the normal distribution function, irrespective of the MWD of the original polymer. If the MWD of the original polymer is highly skew in the lower molecular weight region, the fraction, separated from a comparatively concentrated solution at very small p, yields a doubly‐peaked MWD (p is the amount of fraction expressed as weight ratio). As the width of the MWD of the original polymer increases, the MWD of the higher order fraction becomes narrower and X̄w of the fraction decreases rapidly in the fractionation process. The standard deviation, σ' for the polymer in the polymer‐rich phase is larger than that in the polymer‐lean phase, regardless of the type and breadth of the MWD of the original polymer, and the order of fractionation, provided that the fraction size is small. When the initial concentration is not exceedingly low, the KAMIDE method is by far preferable to the SCHULZ method for estimating accurately the MWD of the original polymer from the fractionation data. In a given fractionation run the log‐log plot of polymer concentration in a precipitate vs. X̄w can be approximated by a straight line.
The vibrational spectra of some normal polyolefins
Authors: Fraser Graham V. , Hendra Patrick J. , Chalmers John M. , Cudby Michael E. A. , Willis Harry A.
Published: April 2003

The IR and RAMAN spectra of several normal isotactic polyolefins are presented and the effect of cooling is studied. The structural implications of side‐chain and main‐chain crystallization are discussed.
Étude par relaxation du carbone‐13 des mouvements segmentaires de la poly(vinyl‐2 pyridine)
Authors: Chachaty Claude , Forchioni Alain , Ronfard‐Haret Jean‐Claude
Published: April 2003

Les mouvements segmentaires de la poly(vinyl‐2 pyridine) (PV2P) en solution dans CDCl3 et CD3OD ont été étudiés par mesure du temps de relaxation T1 des carbones‐13. Le temps de relaxation de ces carbones est pratiquement indépendant de la masse moléculaire et de la tacticité du polymère. Il est cependant un peu plus long pour les carbones des cycles que pour ceux de la chaîne, ce qui suggère un mouvement lent de libration de ces cycles autour de l'axe Cα—C5. Dans le cas de la forme polyélectrolyte de la PV2P (ion pyridinium) on note un accroissement sensible de la rigidité de la chaîne du fait de la répulsion qui s'exerce entre les cycles chargés positivement. Des expériences complémentaires de R.P.E. indiquent que les protons α de la chaîne se situent dans le plan des cycles pyridyles, ce qui permet de définir la position d'équilibre de ces derniers par rapport à la chaîne.
Optically active hydrocarbon polymers with aromatic side chains, 4. Stereospecific homo‐ and copolymerization of phenyl‐α‐olefins
Authors: Carlini Carlo , Ciardelli Francesco , Pini Dario
Published: April 2003

The polymerization of optically active phenyl‐α‐olefins, such as (R)‐4‐phenyl‐1‐hexene (1) and (S)‐5‐phenyl‐1‐heptene (2), has been performed by TiCl3/(“ARA”) or VCl4/Al[CH2CH(CH3)2]3 catalyst. 2 gives polymers which are amorphous at room temperature; no evidence of stereoregularity is obtained by IR investigation, whereas 1H‐NMR spectra seem to give some indication of steric order. By contrast, the polymers from 1, which are largely insoluble in boiling solvents, are crystalline at X‐ray examination according to an isotactic structure. The copolymerization of 1 with 4‐methyl‐1‐pentene (3) gives statistical copolymers which appear to be coisotactic. This is confirmed by crystallinity at X‐ray examination, IR and optical activity data.
Optically active hydrocarbon polymers with aromatic side chains, 5. Conformational and chiroptical properties of stereoregular polymers of phenyl‐α‐olefins
Authors: Carlini Carlo , Ciardelli Francesco , Lardicci Luciano , Menicagli Rita
Published: April 2003

The chiroptical properties of stereoregular polymers of optically active 4‐phenyl‐1‐hexene (1) and 5‐phenyl‐1‐heptene (2) as well as of the copolymers of 1 with 4‐methyl‐1‐pentene (3) were investigated. The comparison of the rotatory power and of the CD spectra in the spectral region of the π→π* electronic transitions of the aromatic chromophore of these polymers with the corresponding properties of optically active phenylalkanes allows the conclusion that the macromolecules of the homopolymer of 1 as well as of its copolymer with 3 contain chain blocks in helical conformation with a predominant direction of the screw. No evidence of this type was obtained for the polymers from 2. Conformational analysis based on molecular models shows that in the case of 1 having R absolute configuration, the favoured direction of the screw is the right handed one as found for poly[(R)‐4‐methyl‐1‐hexene]. The relationships between the conformation of the macromolecules and CD of the phenyl chromophore between 275 and 185 nm are consistent with previous results concerning copolymers of styrene with optically active α‐olefins.
Beitrag zur hydroxymethylierung von hydroxyphenylenmethylen‐verbindungen sowie IR‐ und UV‐spektroskopische untersuchungen dieser verbindungen
Authors: Kämmerer Hermann , Niemann Wilhelm
Published: April 2003

Es wurden höhermolekulare α‐Brom‐ bzw. α‐Methyl‐ω‐hydroxy[(2‐hydroxy‐5‐methyl‐1,3‐phenylen)methylene] nach LEDERER und MANASSE dargestellt; die höchste erreichte rel. mol. Masse betrug rund 700. Mit steigender rel. mol. Masse wuchsen Zahl und Anteil der Nebenprodukte, so daß die Reinigung bis zur dünnschichtchromatographischen Reinheit immer verlustreicher wurde und die Ausbeuten auf 10–15% abfielen. Einige der Nebenprodukte wurden isoliert; ihre Konstitution wurde aufgeklärt und durch IR‐ und UV‐Messungen bestätigt. Tetrasubstitutionsbanden, Methylengruppen‐ und Hydroxylgruppenbanden der IR‐Spektren wurden eingehend untersucht. Die HUNTERsche Beziehung wurde bestätigt und ihre allgemeinere Gültigkeit aufgezeigt.
Dimerization and polymerization of butadiene with zero‐valent nickel and protonic acids
Authors: Furukawa Junji , Kiji Jitsuo , Konishi Hisatoshi , Yamamoto Kazuyoshi , Mitani Shin‐Ichi , Yoshikawa Susumu
Published: April 2003

The behavior of hydridonickel coordination compounds as catalysts for the oligomerization and polymerization of butadiene in various solvents was studied. In the presence of alcohol bis(tricyclohexylphosphine)chlorohydridonickel (4, X = Cl) (HNiCl[P(C6H11)3]2) catalyzes the linear dimerization. With hydridotetrakis(phosphite)nickel(1+) (2) ([HNi{P(OR)3}4]+), which is prepared from tetrakis(phosphite)nickel (1) (Ni[P(OR)3]4) and trifluoroacetic acid, dimerization occurs in sec‐alcohol but there is no reaction in tert‐alcohol. The main product is 2‐methylenevinylcyclopentane (8). The other products are 4‐vinylcyclohexene (10), 1,5‐cyclooctadiene (5), 1,3,7‐octatriene (7) and 1,3,6‐octatriene (9). The hydridonickel coordination compound, prepared with inorganic acids, does not afford the dimers but the 1,4‐trans polymer.
Investigations on the initiation mechanism of the acrylonitrile/butadiene alternating copolymerization in the presence of organometallic catalysts
Authors: Kuran Witold , Pasynkiewicz Stanisław , Florjańczyk Zbigniew
Published: April 2003

The alternating copolymerization of acrylonitrile and butadiene in the presence of organo‐aluminum compounds of the type RAlCl2 could be shown to be initiated by free radicals formed by cleavage of the AlR bond. The R• and radicals were detected under polymerization conditions by ESR spectroscopy, and the presence of the R groups in the copolymer and co‐oligomers could be confirmed by NMR and IR spectroscopy, and by elemental analyses. The results were discussed in terms of an initiation mechanism previously postulated by the authors.
Column fractionation of poly(oxymethylene diacetate)
Authors: Olcese Tito , Ackermann J. , Radici P. , Bianchi Umberto
Published: April 2003

A column fractionation technique for poly(oxymethylene diacetate) is described. Fractionation is achieved by using a single solvent, N,N‐dimethylformamide, at a gradually increasing temperature.

The mode of introduction of the crystallizable polymer into the column is a decisive factor for the reproducibility and efficiency of fractionation. Best results are obtained by introducing the polymer as a gel phase.
Syntheses and properties of new aromatic‐aliphatic copolyimides
Authors: Iwakura Yoshia , Yang Chin‐Ping , Uno Keikichi
Published: April 2003

Aromatic aliphatic copolyimides (19a–m) containing pyromellitdiimide and glutar‐ or succinimide rings in the main chain were synthesized by a two‐step reaction of specified dianhydrides (5a, b) with primary diamines (11a–h). In the first step, poly(amic acid)s (17/18) having pyromellitdiimide rings were prepared by the reaction of 2,2′‐pyromellitdiimido‐diglutaric or disuccinic anhydride (5b, 5a) with 11a–h in polar solvents. In the second step, the conversion of 17/18 to the copolyimides 19a–m was carried out either thermally or by chemical means. 5b and 5a were synthesized by the reaction of pyromellitic anhydride with glutamic or aspartic acid, respectively. No gelation was observed during a long period of storage of the poly(imidoamic acid)s 17/18 in polar solvents at room temperature. For their conversion to copolyimides, a dehydrating agent such as acetic anhydride and a catalyst such as pyridine were applied successfully. The copolyimides gave clear, tough and flexible films from DMSO solution. They show excellent stabilities at high temperatures and against oxidative degradation. IR spectra, solubilities, TG analyses and the formation of the new copolyimides were studied and compared with those of corresponding model compounds.
Thermodynamic studies based on corresponding states theory for solutions of polystyrene in ethyl methyl ketone
Authors: Nakajima Akio , Hamada Fumiyuki , Yasue Kenji , Fujisawa Koichi , Shiomi Tomoo
Published: April 2003

The polymer solution theory on the corresponding state principle developed by FLORY was examined by comparing the thermodynamic parameters calculated theoretically with experimental results. The osmotic pressure of the polystyrene/ethyl methyl ketone system was determined for solutions of polymer concentrations 10 to 30% at 10 to 55°C. Using X12 and Q12 parameters best fitting to these data, the calculated parameters were compared with experimental results. Both the entropy parameter ψ1 and enthalpy parameter χH, 1 were negative and decreased with increasing temperature. FLORY'S theory elucidates appreciably well the thermodynamic quantities with the use of the adjustable parameters X12 and Q12, but there seems to remain still some disagreement with experimental results. SHULTZ‐FLORY'S method for determining the Θ‐temperature was discussed based on this theory.
Heats of dilution of atactic polystyrene in ethyl acetate
Authors: Baba Yoshihiro , Katayama Haruyoshi , Kagemoto Akihiro
Published: April 2003

The heats of dilution and the volume change for the system polystyrene/ethyl acetate were measured. It was shown that the values of the interaction heat parameter as well as those of the excess volume change their positive sign to a negative one at about the same molar mass of the polymer. This is explained in terms of drastic changes of the conformation of the polymer molecules as soon as a certain molar mass is attained.
Pentad tacticity of polymethacrylonitrile through 13C‐NMR spectroscopy
Authors: Inoue Yoshio , Koyama Kenji , Chûjô Riichirô , Nishioka Atsuo
Published: April 2003

The pentad stereochemical placements in polymethactylonitrile were analyzed by using proton‐decoupled natural abundance FOURIER transformed 13C‐NMR spectra. The data of pentad microtacticity were used to examine the stereospecific polymerization mechanisms. Two types of polymethacrylonitrile were used. The relative intensities of pentad peaks for the polymer prepared with free radical catalyst by bulk polymerization at 80°C were reasonably interpreted by the BERNOULLIan model. Those for the polymer, prepared with diethylmagnesium in toluene at 70°C, may be described by both the stereoblend model and the firstorder MARKOVian model, but not by BERNOULLIan model.
Crystallization of polypeptides in the course of polymerization, 6. Effect of the heteroatom attached to the β‐carbon on the crystal growth
Authors: Kōmoto Tadashi , Ōya Masanao , Kawai Tōru
Published: April 2003

In order to examine the growth mechanisms of polypeptides with a heteroatom, S, on the β‐ and γ‐carbons which give the α‐conformation and the α‐helical conformation, resp., in the course of a heterogeneous polymerization, we have studied kinetics of the heterogeneous polymerization of S‐methyl‐L‐cysteine N‐carboxy anhydride (NCA), S‐benzyloxycarbonyl‐L‐cysteine NCA and L‐methionine NCA initiated by butylamine in acetonitrile and the morphologies of the resultant polymers. As was anticipated, it has been verified that poly‐(S‐substituted‐L‐cysteines), which take only the β‐structure as the ordered form, gave the chain‐folded crystals. In all the cases studied, long lath‐like crystals formed in the early stages of polymerization thickened into round rod‐like fibers as the polymerization proceeded. A possible model was proposed for the growth mechanism of these polymer crystals, taking into account the cross‐β‐structure. It has been revealed that poly(L‐methionine) with the α‐helical structure gave the extended chain crystals.
Estimation of the rate constant of termination by the monomer in the anionic polymerization of methyl methacrylate
Authors: Löhr G. , Müller A. H. E. , Warzelhan V. , Schulz G. V.
Published: April 2003

Based on the assumption that the termination reaction in the anionic polymerization of methyl methacrylate in THF with cumyl cesium as initiator is exclusively caused by the monomer, the termination rate constant kt(±) for the ion‐pairs of polymethylmethacrylcesium is estimated by analyzing the molecular weight distribution (MWD) of polymer samples prepared at different temperatures under otherwise identical reaction conditions. The activation energy of the termination reaction of the ion‐pairs is found to be about 11 kcal/mol (46 kJ/mol). – The relatively broad MWD of the non‐deactivated chains (the so called internal nonuniformity) reveals the existence of ion‐pairs with different reactivity.
Polyreaktionen in orientierten Systemen, 3. Polymerisation ungesättigter Benzylidenaniline mit flüssig‐kristallinen Eigenschaften
Authors: Perplies Eberhard , Ringsdorf Helmut , Wendorff Joachim H.
Published: April 2003

Die Acrylsäure‐ und Methacrylsäureester 3a–m wurden synthetisiert und auf ihr nematogenes Verhalten untersucht. Zwei Monomertypen wurden zur Untersuchung des Polymerisationsverhaltens herangezogen. Dabei zeigte sich, daß die Polymerisationsgeschwindigkeit beim übergang vom nematischen in den isotropen Bereich sprungartig ansteigt. In Abhängigkeit von der Darstellungsweise des Polymeren ergaben sich Unterschiede in der Struktur. Polymere, die bei 20°C in Lösung dargestellt werden, sind amorph, während Lösungsmittel‐polymerisate, die bei −78°C hergestellt und anschließend getempert wurden, eine Struktur aufweisen, die mit der der Polymeren aus der nematischen Phase nahezu übereinstimmt. Diese Tatsache kann als Hinweis dafür angesehen werden, daß bei tiefen Temperaturen Monomer‐aggregate in Lösung vorliegen.
ESR investigations of γ‐irradiated sulfur‐containing vinylpolymers
Authors: Mönig Hans , Ringsdorf Helmut
Published: April 2003

The formation and behaviour of radiation‐induced free radicals in statistical copolymers of ethoxyvinylthiomethane (1a) with N‐vinylpyrrolidone (2) (1:2,5) and of ethylthiovinylthiomethane (1b) with 2 (1:3,5) has been studied using electron spin resonance spectroscopy. After a γ‐irradiation of the copolymers at 77K Cα‐radicals in the vinylpyrrolidone moieties could be detected. Investigations on the behaviour of these radicals with an annealing procedure revealed that only in the copolymer (3b) with the dithioacetal group a transfer reaction of hydrogen atoms to the Cα‐radicals in the vinylpyrrolidone moieties occurs. This process may be regarded as a repair mechanism.
Untersuchungen zur ringöffnenden Polymerisation der 2‐Imino‐1,3‐oxazolidine
Authors: Kieser Manfred , Hamann Karl
Published: April 2003

Es wurde die ringöffnende, zu Poly(ureylenäthylen)en (Polyäthylenharnstoffen) führende Polymerisation der 2‐Imino‐1,3‐oxazolidine untersucht.

Aus 3‐Phenyl‐2‐phenylimino‐1,3‐oxazolidin (1) und sauren Verbindungen ließen sich kristalline Addukte isolieren, die aber nur dann als Initiatoren für die Polymerisation von 1 wirksam waren, wenn die saure Komponente mit dem Iminostickstoff koordiniert war.

Die kinetische Untersuchung der Polymerisationsreaktion ergab, daß keine Induktionsperiode auftritt und die Reaktion nach einem Zeitgesetz pseudo 1. Ordnung verläft, was für eine bimolekulare Reaktion des geschwindigkeitsbestimmenden Schritts der Polymerisationsreaktion spricht.

Diese Ergebnisse ließen sich mit denen in Einklang bringen, die für die Ringöffnungsreaktion der Iminooxazolidine mit organischen Säuren im niedermolekularen Bereich gefunden wurden.
Study of the isothermal bulk polymerization of methyl methacrylate by differential scanning calorimetry
Authors: Malavašič Tatjana , Vizovišek Ivan , Lapanje Savo , Može Adolf
Published: April 2003

Course and kinetics of the isothermal bulk polymerization of methyl methacrylate were studied by differential scanning calorimetry. The initiator used was 2,2′‐azoisobutyronitrile. The polymerization was investigated at temperatures between 70 and 90°C at constant initiator concentration, 5,2.10−2 mol dm−3. The heat of polymerization at 70°C is −52,3 kJ/mol (−12,5 kcal/mol) and decreases, i.e. becomes more negative, with increasing temperature. Initial rate constants for the polymerization were also determined and from them the overall activation energy, 77 kJ/mol (18,4 kcal/mol), which is in good agreement with the literature value. Another series of polymerization experiments were performed at 80°C with variable amounts of the initiator. The heat of polymerization found is −52,8 kJ/mol (−12,6 kcal/mol) and depends only slightly on the initiator concentration. The overall rate of polymerization at low degrees of conversion depends on the square root of the initiator concentration. These findings thus corroborate the conclusion reached by other authors that differential scanning calorimetry is a useful method for studying the kinetics of polymerization.
Viscosities of dilute solutions of poly(tetrahydrofurfuryl methacrylate)
Authors: Zafar Mukhtar Mohammed , Mahmood Ruqia
Published: April 2003

The intrinsic viscosities of seven fractions (from M̄n = 1,69.105 to M̄n = 6,13.105) of poly(tetrahydrofurfuryl methacrylate) in eleven solvents at temperatures between 30° and 50° show the following order: tetrachloroethane > dichloroethane > tetrahydrofuran > chloroform > benzene > bromobenzene > ethyl acetate > carbon tetrachloride > methyl pentyl ketone > acetone > 2‐hydroxymethyltetrahydrofuran. Values of HUGGINS slope constants range between 0,34 to 0,48 for the unfractionated polymer and the magnitudes of a and k in the expression [η] = kMa show little variations with temperature in case of good solvents whereas the opposite is observed in case of poor solvents. The theta temperature for 2‐hydroxymethyltetrahydrofuran containing 20% methanol is 31,2 ± 0,3° and 3,49, 5,72, and 4,97 are the values for K0.104, (r/M)1/2.109 and (r/Z)1/2.108, respectively.
Stereoselective copolymerization of racemic α‐olefins with ethylene by isospecific Ziegler‐Natta catalyst
Authors: Ciardelli Francesco , Locatelli Paolo , Marchetti Massimo , Zambelli Adolfo
Published: April 2003

Copolymers of ethylene with racemic and optically active 3,7‐dimethyl‐1‐octene (3,7‐DM‐1‐O) have been prepared in the presence of ZIEGLER‐NATTA isospecific catalysts. The copolymers of racemic 3,7‐DM‐1‐O have been separated in fractions having optical activity of opposite sign by chromatography on optically active poly[(S)‐3‐methyl‐1‐pentene]. The degree of separation obtained is very close to that found for the isotactic homopolymer of 3,7‐DM‐1‐O. The fractional precipitation of both types of copolymers has been also carried out in order to obtain information on the distribution of the comonomers. The results exclude a mere steric control by the growing chain end. The stereoselectivity can be better explained on the basis of the presence of asymmetric catalytic complexes, which are stereospecific in the isotactic sense.
New light on an old polymerisation. The polymerisation of styrene by HClO4 in methylene chloride
Authors: Pepper David Charles
Published: April 2003

Problems of interpretation of the mechanisms in the polymerisation of styrene by HClO4 in CH2Cl2, especially of chain propagation are discussed and experimental results from recent studies of the bimodal molecular weight distributions found in polymers prepared at 0 C and below, and of the kinetics of the rapid, non‐stationary, precursor polymerisation at −80 C and other low temperatures are presented. The former indicate simultaneous, but independent, propagation at 0 C by pseudo‐ionic and ionic species. The latter reveal the transient existence at low temperatures of an ionic species (absorbing at 340 nm) identified as the (poly)styryl carbenium ion. The measurements permit estimates of the free‐ion propagation rate constant at −80 C to −45 C, and suggest the unexpected conclusion that propagation by ion pairs is several fold faster than by free ions. Both species however appear to be not simple, but strongly complexed by monomer. It is speculated also that monomer complexation of the perchloric acid initiator plays an important rôle in determining whether pseudo‐ or true ionic mechanisms predominate.
Cationic polymerization of aliphatic olefins: Highlights of latest developments at the university of akron
Authors: Kennedy J. P.
Published: April 2003

The cationic copolymerization of isobutylene and β‐pinene (2(10)‐pinene) yields random copolymers which exhibit interesting physical properties. E.g., high molecular weight copolymers containing isobutylene/β‐pinene in the ratio of 90/10 and 97/3 are sulfur‐vulcanizable ozone‐resistant elastomers. Copolymer synthesis was accomplished with Friedel‐Crafts halides e.g., C2H5AlCl2, BF3, etc. using ethyl chloride diluent at low temperatures. The structure of the copolymers was determined by NMR spectroscopy. The reactivity ratios of isobutylene and β‐pinene are stongly affected by temperature, however, are much less sensitive to the particular Lewis acid used. Interestingly, with C2H5AlCl2, the individual reactivity ratios become equal to unity below ca. −100°C, i.e., the copolymerization becomes azeotropic.

The mechanism of cationic olefin polymerizations induced by various alkylaluminum compounds has been investigated by model reactions. The rate of the reactions. The rate of the reaction

equation image

is strongly affected by the nature of the (CH3)3CX and the CH3X solvent (X=Cl, Br. I). Unexpectedly, the sequence of rates of this reaction was found to be (CH3)3CCl>(CH3)3CBr>(CH3)3Cl. Further, an intensive study of the 2,4,4‐trimethyl‐1‐pentene/(CH3)3Al/(CH3)3CCl model system gave a series of important mechanistic insights. E.g., if an alkylaluminum compound having a β‐hydrogen in respect to aluminum is used as the coinitiator e.g., (C2H5)3Al, [(CH3)2CHCH2]3Al, etc., rapid hydridation terminates the reaction:
Hydride ion transfer processes and cationic polymerization of cyclic acetals
Authors: Penczek Stanisław
Published: April 2003

Four topics related to the cationic polymerization of cyclic acetals and mainly based on the author's results are reviewed.

The kinetics of the H− transfer from linear and cyclic acetals and ethers to the triphenylmethyl cation were examined. A linear correlation between the 1H‐NMR shift of the H‐atom to be transferred as H− anion and the enthalpy of activation (ΔH) was observed for H− donors which are linear and cyclic‐planar or deviate slightly from planarity. Puckered rings, like 1,3,5‐trioxane were found to be very poor H− donors. A linear relationship between ΔH and ΔS was observed for all studied compounds.

The equilibria carbenium ion ↔ oxonium ion involving the unpaired triphenylmethyl cation and different linear and cyclic acetals and ethers were studied. A linear relationship between the basicity of the involved nucleophile (expressed as pKa or pKb) and the enthalpy of equilibrium (ΔH) was found.

The chemistry of the elementary reactions leading eventually to the formation of the active species in the polymerization of 1,3‐dioxolane was investigated. The latter was used as a model monomer and initiated with triphenylmethyl salts with various stable anions like AsF and SbF or with the unstable SbCl. The importance of the ambident reactivity of 1,3‐dioxolan‐2‐ylium cations was pointed out and the kinetics of cationation via ring opening of these salts was described.

1,3‐Dioxolan‐2‐ylium salts were shown to be sufficiently stable to be slowly transformed into the linear cations (k̄cat ≈ 10−3 to 10−4 mol−1 dm3 s−1 at 25°C). This slow reaction was partially responsible for the induction periods observed in the polymerization of 1,3‐dioxolane.

The kinetics and mechanism of the chain propagation of 1,3‐dioxolane were described and a structure (20) was proposed for the growing centres. It was indicated that the growing species, being the tertiary oxonium ions use the polymer segments as ligands and in contrast to the oxycarbenium ions do not abstract hydride anions (H−).
Zur ermittlung der struktur und unverträglichkeit von pfropfcopolymeren durch messungen der lichtstreuung und phasentrennung in lösung
Authors: Kuhn Rainer , Alberts Heinrich , Bartl Herbert
Published: April 2003

Theoretische Betrachtungen zeigen, daß man bei Pfropfcopolymeren durch Lichtstreuungsmessungen in Lösung außer den Molekulargewichten und Trägheitsradien der Pfropfäste auch die Unverträglichkeit der Pfropfäste mit der Pfropfunterlage ermitteln kann, wenn das verwendete Lösungsmittel isorefraktiv mit der Pfropfunterlage ist, und man den Gewichtsanteil an Pfropfästen kennt.

Die neue Methode der Unverträglichkeitsbestimmung aus anomalen Zimm‐Diagrammen wird an Mischungen aus Polystyrol und einem chemisch einheitlichen statistischen Äthylen/Vinylacetat‐Copolymeren geschildert und auf Fraktionen von entsprechenden Pfropfcopolymeren angewandt.

Die Ergebnisse der Lichtstreuung werden mit den Ergebnissen der Phasentrennung aus Trübungspunktmessungen verglichen.
Study of the isothermal bulk polymerization of vinyl acetate by differential scanning calorimetry
Authors: Može Adolf , Vizovišek Ivan , Malavašič Tatjana , Černec Franc , Lapanje Savo
Published: April 2003

The course and kinetics of the isothermal bulk polymerization of vinyl acetate were studied by differential scanning calorimetry. The initiator used was 2,2′‐azoisobutyronitrile. The polymerization was investigated at temperatures between 55 and 70°C at constant initiator concentration, 5,0.10−2 mol/l. The heat of polymerization at 60°C is – 19,5 kcal/mol and decreases with increasing temperature. Initial rate constants for the polymerization were also determined and from them the overall activation energy, 21,6 kcal/mol. Another series of polymerization experiments were performed at 60°C with variable amounts of the initiator. The overall rate of polymerization at low degrees of conversion depends on the square root of the initiator concentration which is in agreement with the assumed kinetic scheme.
Kernresonanzspektroskopische mikrostrukturanalyse von vinylchlorid‐propen‐copolymeren, 1. NMR‐spektroskopische bestimmung der bruttozusammensetzung und der kompositiven triaden für vinylchlorid‐propen‐copolymere
Authors: Sielaff Günter , Hummel Dieter O.
Published: April 2003

Copolymere aus Vinylchlorid (VC) und Propen (P) wurden durch hochauflösende magnetische Protonenresonanz bei 100 MHz untersucht. Aus dem Vergleich mit den Homopolymerspektren konnten die Resonanzkomplexe der Copolymerspektren zugeordnet, die Bruttozusammensetzung der Copolymeren ermittelt und die Copolymerisationsparameter berechnet werden.

Der Methinresonanzkomplex der VC‐Einheiten ließ sich durch Spinentkopplung in fünf Peaks aufspalten. Ihre Zuordnung zu kompositiven und konfigurativen Triaden erfolgte anhand eines graphischen Trennverfahrens. Das zur Ermittlung der Copolymerisationsparameter verwendete Wachstumsmodell wurde mit den gemessenen Triadenhäufigkeiten auf seine Gültigkeit hin geprüft.