bluuebunny/crossref_metadata_2025 huggingface dataset:
Metathetischer abbau von cis,cis‐1,6‐cyclodecadien zu cyclopenten,
Authors: Küpper Friedrich W. , Streck Roland
Published: April 2003

Nach dem Metathesemechanismus ist die Bildung von Polypentenylenen (3) nicht nur aus Cyclopenten (1), sondern auch aus dem bei der Polymerisation von Cyclopenten im 1. Reaktionsschritt gebildeten 1,6‐Cyclodecadien (2) zu erwarten. Entsprechende Bemühungen, cis,cis‐1,6‐Cyclodecadien (2) in Polypentenylene zu überführen, blieben vor längerer Zeit ohne Erfolg. Die Ursache dafür dürfte in der bei Raumtemperatur vorliegenden Konformation dieses Cycloolefins zu suchen sein. Es gelang nun – in übereinstimmung mit den an Dreidingmodellen gewonnenen Voraussagen – cis,cis‐1,6‐Cyclodecadien‐(2) bei Temperaturen über 50°C in Cyclopenten (1) zu spalten. Dies eröffnet die technisch interessante Möglichkeit, unabhängig von C5‐Crackolefinschnitten reines 1 aus äthylen und Butadien zu synthetisieren.

Die massenspektrometrische Analyse der bei den Umsetzungen auftretenden Nebenprodukte gab Hinweise für die Richtigkeit unserer Hypothese über den Verlauf der Polypentenylen‐Bildung und führte zu Erkenntnissen über die Ursachen von häufig unerwünschten Nebenreaktionen bei der Umsetzung von Olefinen mit wolframhaltigen Metathesekatalysatoren.
Synthesis of aromatic polyamides from isocyanatocarboxylic acid chlorides and dimethylsulfoxide or water
Authors: Iwakura Yoshio , Uno Keikichi , Chau Nguyen
Published: April 2003

Aromatic isocyanatocarboxylic acid chlorides (1a–i) reacted with stoichiometrical quantities of dimethyl sulfoxide in ether to yield poly(N‐carboxyanhydride)s (5) which were converted into polyamides (6) by heating them at elevated temperatures. Isocyanatocarboxylic acid chlorides also reacted with water to produce polyamides 6. The reaction paths were followed by quantitative analysis of carbon dioxide evolved, by measurement of IR spectra, and by thermal analysis of the polymers.
Pharmacologically active polymers, 7. Cyclophosphamide‐ and steroidhormone containing polymers as potential anticancer compounds
Authors: Batz Hans G. , Ringsdorf Helmut , Ritter Helmut
Published: April 2003

A number of acrylic and methacrylic esters and N‐vinyl monomers of cyclophosphamide‐ and testosterone derivatives were prepared. The monomers were homopolymerized and copolymerized with hydrophilic monomers to yield watersoluble products.
Gelation in the reactions of dicarboxylic acid dichlorides with triols
Authors: Smith Robert S. , Stepto Robert F. T.
Published: April 2003

Gelation in reactions of triols with dicarboxylic acid dichlorides was studied at various dilutions. Adipoyl dichloride and sebacoyl dichloride were reacted with three triols of different molecular weights. The pairs of reactants were chosen so that the reaction systems were characterised by a range of values of v, the number of bonds in the smallest ring structure which could form. In all cases gelation occurred at extents of reaction in excess of those predicted by the Flory‐Stockmayer theory. The excess reaction increased with dilution, and decreased with increase in v.

The results are interpreted in terms of a combination of Frisch's and Kilb's theories of gelation, in which λ, the intramolecular branching parameter of Frisch, is given by the equation λ = const. v−3/2{(OH)0+(COCl)0}−1.
13C‐kernresonanzspektren von ligninen, 5. Oligomere ligninmodellsubstanzen
Authors: Nimz Horst , Lüdemann Hans‐Dietrich
Published: April 2003

Die 13C‐NMR‐Spektren von Ligninmodellsubstanzen mit einer “α‐O‐4”‐Bindung werden mitgeteilt. Die Änderung der chemischen Verschiebungen durch Acetylierung und Umsetzung mit Fluor‐2,4‐dinitrobenzol wird an Ligninmodellsubstanzen untersucht.
Über den einfluß von fängern auf die hochfeldpolymerisation von α‐methylstyrol
Authors: Wablat Wolfgang , Schmidt Werner Fritz , Schnabel Wolfram
Published: April 2003

Die durch Feldemission (FE) in flüssigem α‐Methylstyrol ausgelöste Polymerisation wird durch Kationenfänger (N(C2H5)3, H2O, Cyclopropan) inhibiert. Die Elektronenfänger SF6, N2O, CO2 und O2 inhibieren ebenfalls, wobei die Inhibitorwirksamkeit in der genannten Reihenfolge abnimmt. Dieses Verhalten wird darauf zurückgeführt, daß von der Hochfeldelektrode emittierte Elektronen Monomermolekeln ionisieren; dabei gebildete Radikalkationen starten die kationische Polymerisation. Durch Kationenfänger wird daher die Wachstumsreaktion inhibiert, während Elektronenfänger die Startreaktion inhibieren.

Bei der durch Feldionisation (FI) gestarteten Polymerisation sind Elektronenfänger wirkungslos; Kationenfänger inhibieren dagegen.

Aufgrund der Abhängigkeit der spezifischen Polymerausbeute von der N(C2H5)3‐Konzentration wurde abgeschätzt, daß im Falle der FE nur 1 bis 10% der emittierten Elektronen polymerisationsauslösend wirken. Im Falle der FI starten bis zu 100% der an der Hochfeldelektrode erzeugten Ladungsträger kinetische Ketten.

Bei allen Versuchen wurde Oligomeres (Polymerisationsgrad 3 bis 4) durch eine Kettenreaktion gebildet. Die spezifische Oligomerausbeute nahm bei der FE‐initiierten Polymerisation mit steigender SF6‐Konzentration bemerkenswert zu.
HR‐NMR study of formation and structure of the stereocomplex of poly(methyl methacrylate) in solution
Authors: Spěváček Jiří , Schneider Bohdan
Published: April 2003

From high‐resolution NMR spectra of mixtures of solutions of isotactic and syndiotactic poly(methyl methacrylate), the content p of the associated stereocomplex was determined. From the values of p, the minimum length of associated syndiotactic sequences was found to be ca. 10 monomeric units in aromatic solvents and ca. 3 such units in CCl4 and CD3CN. In the associated stereocomplex the ratio of monomeric units in isotactic and syndiotactic sequences is (iso/syndio) = 1:1,5; the process of dissociation of the stereocomplex with increasing temperature is reminiscent of the melting of microcrystallites. The melting point of associated segments in a given solvent increases with the length of the associated sequences.
Sedimentation and light scattering study of block copolymer association
Authors: Tuzar Zdeněk , Petrus Vladimír , Kratochvíl Pavel
Published: April 2003

Dilute solutions of a three‐block styrene‐butadiene‐styrene copolymer in the mixed selective solvent tetrahydrofuran/allyl alcohol exhibit a more or less pronounced turbidity. Sedimentation analysis and light scattering reveal that these solutions contain two components, namely, a molecularly dissolved copolymer (unimer) and rather compact supermolecular aggregates (micelles) with a relatively narrow molecular weight distribution. The unimer/micelles weight ratio and the weight of micelles were determined as a function of the composition of the mixed solvent, temperature, and copolymer concentration.
Azo‐Initiatoren, 3.. Lösungsmitteleinfluß auf den thermischen zerfall von p‐methoxyphenylazo‐2‐methylpropandinitril
Authors: Kerber Robert , Nuyken Oskar , Steinhausen Rainer
Published: April 2003

p‐Methoxyphenylazo‐2‐methylpropandinitril (1) zerfällt thermisch in allen angewendeten Lösungsmitteln nach 1. Ordnung, abhängig von der Viskosität und Polarität des Lösungsmittels, jedoch verschieden schnell. Unter der Annahme einer nichtsynchronen Spaltung der C—N‐Bindungen der Azogruppen lassen sich diese experimentellen Beobachtungen sowohl im Hinblick auf die Geschwindigkeitskonstanten als auch hinsichtlich des dabei nur unvollständig freigesetzten Stickstoffs widerspruchsfrei erklären.

Die berechneten thermodynamischen Funktionen des Übergangszustandes zeigen, daß ΔG≠ nahezu unabhängig vom Lösungsmittel 115±4kJ/mol beträgt und deshalb für die Charakterisierung des thermischen Zerfalls der Azoverbindungen besonders geeignet erscheint.

Zur Stützung des radikalischen Zerfallsmechanismus wurde die Azoverbindung 1 zur Initiierung der Polymerisation von Acrylnitril in Methanol und von Styrol in Toluol eingesetzt.
Cationic polymerization of cyclic amines, 3. Polymerization of azetidine
Authors: Schacht Etienne H. , Goethals Eric J.
Published: April 2003

Azetidine (1) polymerizes under the influence of various cationic initiators. In methanol and with perchloric acid as initiator, the monomer 1 is first converted into a dimer (N‐(3‐aminopropyl)azetidine (3)) which then polymerizes further to polymer. When all monomer has disappeared, the reaction mixture consists for 70% of the dimer 3. The rate constant of dimer formation at 70°C is 1,50·10−3 dm3mol−1s−1. The formation of 3 is attributed to the higher basicity of 1 compared to 3, which causes a transfer of a proton from the protonated 3 to 1. The structure of the polymer was determined by 300 MHz 1H‐NMR spectroscopy. It contains 20% of tertiary, 60% of secondary and 20% of primary amino functions.
Polymers containing stable free radicals, 6. Reactions of 2,4,6‐triphenyl‐3,4‐dihydro‐s‐tetrazin‐1 (2H)‐yl (1,3,5‐triphenylverdazyl) with organometallic compounds
Authors: Miura Yozo , Morimoto Yuzo , Kinoshita Masayoshi
Published: April 2003

2,4,6‐Triphenyl‐3,4‐dihydro‐s‐tetrazin‐1(2H)‐yl (1) (1,3,5‐triphenylverdazyl) was allowed to react with ethyl‐ and butyllithium, ethyl‐, isopropyl‐, and butylmagnesium bromide, as well as benzylmagnesium chloride to give the coupling products 2a–d. These results indicate that structures corresponding to 2 are present in the polymers resulting from vinyl monomers containing the verdazyl structure, if they are initiated with alkyllithium or a Grignard reagent. A reaction mechanism is discussed.
Modellsubstanzen für polymere Redoxsysteme, 8. Tetra‐ und hexavalente Redoxsysteme vom 1,4‐Benzochinon‐Typus
Authors: Storck Winfried , Manecke Georg
Published: April 2003

Es werden die Synthese und die Eigenschaften von 2‐(1,4‐Benzochinon‐2‐ylmethyl)‐5‐methyl‐1,4‐Benzochinon (2b), der drei isomeren Bis(1,4‐Benzochinon‐2‐ylmethyl)benzole 8a, 9a und 10a und der drei hierzu homologen Bis[2‐(1,4‐Benzochinon‐2‐yl)äthyl]benzole 8b, 9b und 10b beschrieben. Sie stellen oligomere Redoxsysteme dar. Durch 1H‐NMR‐spektroskopischen Strukturbeweis von 2‐(2,5‐Dihydroxybenzyl)‐1,4‐Benzochinon (4) wird belegt, daß in saurer Lösung teiloxidierte tetravalente Redoxsysteme vom BenzochinonTypus ein miteinander verknüpftes Hydrochinon‐ und Chinonsystem darstellen. Die teilreduzierte, o‐verknüpfte Bis(chinonyl)‐Verbindung 8a bildet in Lösung leicht einen intramolekularen CT‐Komplex, was bei den anderen Verbindungen nicht beobachtet wird.

Als spezielle Modelle für Oxidations‐Reduktions‐Polymere wurden ferner drei völlig symmetrische, hexavalente Redoxsysteme synthetisiert und charakterisiert: Tris(1,4‐Benzochinon‐2‐yl)‐methan (17), Tris(1,4‐Benzochinon‐2‐ylmethyl)benzol (19a) und Tris[2‐(1,4‐Benzochinon‐2‐yl)äthyl]benzol (19b).
Ion‐radical mechanism of the polymerization of 2,6‐dimethylphenol by oxidative coupling catalysed by CuCl2‐amine complex
Authors: Kresta Jiři , Tkáč Alexander , Přikryl Rudolf , Malik Ludovít
Published: April 2003

The preparation of poly[oxy‐(2,6‐dimethyl)‐1,4‐phenylene] (2) via polymerization of 2,6‐dimethylphenol (1) by oxidative coupling with CuCl2‐amine complexes is described. The reaction mechanism was studied by means of ESR, NMR spectroscopy, and conductivity measurements. It was established that the CC coupling products (dipheno‐quinones) are formed by recombination of phenoxyl radicals and that the very high selectivity of the CuCl2‐amine complex catalysts in the formation of 2 (CO coupling) is due to the cationic mechanism based on the consecutive reaction of the phenoxyl radicals with Cu(II) complexes. This consecutive reaction of the phenoxyl radicals with Cu(II) complexes is responsible for the non‐measurable level of polymeric radicals 5 by ESR, previously reported.
A new method for the synthesis of polymers containing amide and imide groups in the main chain
Authors: Iwakura Yoshio , Uno Keikichi , Chau Nguyen
Published: April 2003

Poly(pyromellitdiimidoarylenecarbonyliminoaryleneiminocarbonylarylene)s [poly(amide‐imide)s] (7 and 12) were prepared from pyromellitic dianhydride (6) and dicarbamates (5) (diurethanes) containing amide linkages. The same polymers could also be prepared directly from aromatic isocyanatocarboxylic acid chlorides (10), diamines (11) and 6. In the latter method, the addition of an equimolar amount of water was required for the formation of the imide ring in the main chain of the polymer. Model reactions were carried out to determine the reaction conditions for the two methods. Reaction mechanisms are proposed.
Growth mechanism of crystals of glycine‐L‐alanine copolymer in the course of polymerization
Authors: Kim Kea Yong , Kōmoto Tadashi , Katakai Ryoichi , Ōya Masanao , Kawai Tōru
Published: April 2003

In order to examine the growth mechanism of copolymer crystals formed during polymerization, the heterogeneous copolymerization of glycine N‐carboxy anhydride (NCA) and L‐alanine NCA has been studied in acetonitrile. In the polymerization systems with higher contents of glycine, the crystal growth occurs through formation of the cross‐β type structure as proposed previously for poly(S‐methyl‐L‐cysteine), giving rise to chain‐folded crystals and rather high conversions. The high conversion is accounted for by the widening of the cross‐section of the β‐chains in the backbone crystal, due to the introduction of L‐alanine residues into the polyglycine chain. Copolymerization at higher contents of L‐alanine leads to conversions over 90% and extended chain crystals, due to the formation of α‐helices on the ribbon‐like crystals composed of the β‐structure just as in the case of L‐alanine NCA homopolymerization, indicating the occlusion of the glycine residues into the helices.
The curing reaction of an epoxide resin with 2‐ethyl‐4‐methylimidazole, a calorimetric study of the kinetics of formation of epoxide‐imidazole adducts
Authors: Barton John M. , Shepherd Peter M.
Published: April 2003

The kinetics of formation of the 1:1 and 2:1 adducts of (in terms of equivalents of epoxide) 2,3‐epoxypropyloxybenzene (2) and 2,2‐bis[p‐(2,3‐epoxypropyloxy)phenyl]‐propane (1) with 2‐ethyl‐4‐methylimidazole (3) have been investigated by differential scanning calorimetry (DSC). A comparison of isothermal and dynamic data for the 1:1 system 2/3 showed that the dynamic rate cannot simply be equated to the isothermal rate, but the true dynamic rate equation, dα/dt = (∂α/∂tT)+(∂α/∂Tt) (dT/dt), gave good agreement with the isothermal data. The dynamic DSC measurements indicate that all of the reactions approximate to first order kinetics and have similar values for activation energy (E = 81–93 kJ/mol) and pre‐exponential factor (log A ≈ 9–10). The results support the suggestion that adduct formation is likely to be the first stage of the resin curing reaction catalyzed by 3.
Mathematisches Modell der polyaddition von 1‐chlor‐2,3‐epoxypropan an ein diol
Authors: Novák Jiřiacute; , Šváb Vladimír
Published: April 2003

In dem mathematischen Modell, mit dem die Produktzusammensetzung bei der Polyaddition von 1‐Chlor‐2,3‐epoxypropan (1) (Epichlorhydrin) an ein Diol berechnet wurde, wurde die Voraussetzung gemacht, daß die Reaktivitäten der 3‐Chlor‐2‐hydroxypropyloxy‐Endgruppen gleich (d. h. von der Molekülgröße unabhängig) sind und daß sich der Epoxidring von 1 nur unter Bildung der Cα‐Äther öffnet. Ein Vergleich des für verschiedene kinetische Parameter berechneten und des experimentell im Augenblick des völligen Durchreagierens von 1 bestimmten Anteiles von nicht abreagiertem 1,2‐Propandiol (bei verschiedenen Ausgangsmolverhältnissen 1/Diol) erlaubte die Bestimmung der Verhältnisse der Geschwindigkeitskonstanten von fünf möglichen Reaktionen des untersuchten Systems. Für die Polyaddition von 1 an 1,2‐Propandiol wurde die beste Annäherung bei den relativen Geschwindigkeitswerten K1 = 0,8; K2 = 0,6 und K3 = K4 = 0,5 erzielt.
Molecular dimensions of polymers dissolved in binary mixtures of polar and non‐polar solvents, 2. Poly(methyl methacrylate)
Authors: Dondos Anastasios , Havredaki Vassiliki , Mitsou Artemis
Published: April 2003

Viscometric measurements are performed for poly(methyl methacrylate) fractions dissolved in the following solvent mixtures: benzene/chloroform, benzene/tetrahydrofuran, benzene/ethyl acetate, and dioxane/chloroform. The polymer exhibits a conformational transition which occurs in a narrow region of solvent composition. This transition is expressed by a discontinuity of the intrinsic viscosity, Huggins' constant, and the unperturbed dimensions.

At the transition point all solvent mixtures present approximatively the same dielectric constant.
Polymerisationen und polymerisationsinitiatoren, 16. Einfluß von Thioxo‐Gruppen in barbitursäurederivaten auf die polymerisationsauslösung von methacrylsäure‐methylester
Authors: Bredereck Von Hellmut , Menzel Peter , Argosino Rosalinda , Bihlmaier Werner
Published: April 2003

5‐Alkyl‐1,3‐dimethylbarbitursäuren lösen in Gegenwart von Cu2+, Cl− und Luftsauerstoff die radikalische Polymerisation von Methacrylsäuremethylester aus. Die Initiatorwirkung wi+d durch Thioxo‐Gruppen in 2‐Stellung etwas verstärkt, in 4‐ bzw. 4,6‐Stellung dagegen stark vermindert. Die Wirkung dieser 4‐ bzw. 4,6‐Thioxobarbitursäuren als Inhibitoren beruht auf der Stabilisierung der primär gebildeten Radikale durch die benachbarten Thioxo‐Gruppen, wodurch Weiterreaktion am S‐Atom unter Dimerisierung zu Disulfiden erfolgt. Bei der Cu(II)‐katalysierten Polymerisationsauslösung wird die Inhibierung durch die Bildung schwerlöslicher Kupfer(I)thioxobarbiturate noch verstärkt.
Thermal properties of isotactic polypropylene quenched from the melt and annealed
Authors: Fichera Annamaria , Zannetti Roberto
Published: April 2003

DSC investigations on isotactic polypropylene (it‐PP) quenched from the melt and annealed over a range of temperatures are reported. The results confirm the existence of saturation levels of the ordered phase for different annealing temperatures, previously revealed by X‐ray diffraction methods.

Thermal, X‐ray diffraction, and density data are correlated in terms of the extent of the ordered phase present in the it‐PP.
Relative reactivity of cis‐ and trans‐1,3‐pentadiene in the cationic copolymerization with isobutene
Authors: Priola Aldo , Cesca Sebastiano , Ferraris Giuseppe , Bruzzone Mario
Published: April 2003

cis‐1,3‐Pentadiene (2) and trans‐1,3‐pentadiene (3) were copolymerized with isobutene (1) in the presence of (C2H5)2AlCl+(CH3)3CCl or (C2H5)2AlCl+Cl2 in the range of temperatures between —35 and —70°C. The reactivity ratios, determined at —55°C, are:r1.2=5,0 and r1.3=2,3, while the chain transfer coefficients are Kt.2=50 and Kt.3=113. The activation energies are: EMv.2= —13,8kJ/mol (—3,3 kcal/mol) and EMv.3= —16,7kJ/mol(—4,0 kcal/mol). Spectroscopic analyses (IR, 1H‐NMR) showed that in both copolymers the 1,4‐trans structure is prevalent over the 1,2‐trans‐enchainment. The fact that 3 is more reactive than 2 can be correlated with a greater electron‐density (13C‐NMR data) on C‐1 in compound 3.
Polymorphosis of poly(oxymethylene) crystals grown in a cationic polymerization system of 1,3,5‐trioxane in solution
Authors: Iguchi Masatoshi , Murase Ichiki
Published: April 2003

The morphology of poly(oxymethylene) appearing in the polymerization system of 1,3,5‐trioxane in cyclohexane using BF3 [or BF3O(C2H5)2] and water catalysis was studied in parallel with the kinetic behaviour of the reaction. Feather‐shaped crystals, whose poor reproducibility was a problem, were found to be formed in a limited range of catalytic conditions. As a function of the mole ratio H2O/BF3, the change of morphology was ordered as follows: needle‐like crystals (H2O/BF3<0,05), heterogeneous products (H2O/BF3=0,05 to 3), feather‐shaped crystals (H2O/BF3=3 to 10). and amorphous products (H2O/BF3>10). A new type of single‐crystal, tapered hexagonal rod, was found in the same catalytic region where feathershaped crystals were formed. The results of older preliminary work in a polar solvent, where a hexagonal, plate‐like crystal had been obtained, are also briefly reconsidered in the discussion.
Dilute solution properties of critically branched systems
Authors: Gordon M. , Kajiwara K. , Peniche‐Covas C. A. L. , Ross‐Murphy S. B.
Published: April 2003

Light‐scattering measurements were carried out on critically branched polycondensates of 1,3,5‐benzenetriacetic acid and 1,10‐decanediol, and the results were analysed according to the theory of cascade processes, developed especially for this system, viz. the pathweighting generating function method. It is postulated that the amount of chain expansion found in these branched copolycondensate samples was due to short‐range rather than long‐range interactions. The long‐range interactions seem to vanish in the critically branched state. The rotational isomeric state model was used to calculate the comparative unperturbed dimensions for the linear homologue of the above polycondensate, i.e. poly(1,3‐benzenediacetic acid/1,10‐decanediol).
On the source of X‐ray small angle scattering in rubbers vulcanized with methacrylic acid salts
Authors: Anfimov Boris , Dontsov Anatoli , Ferracini Elena , Ferrero Adele , Hosemann Rolf , Riva Fernando
Published: April 2003

Styrene‐butadiene rubber (SBR) is mixed with zinc methacrylate (ZnM) powder SBR: ZnM = 5:1 by weight. Wide angle X‐ray diffraction proves that the ZnM crystallites are larger than 240Å. The pure SBR and the SBR‐ZnM mixture exhibit the same small angle X‐ray pattern, indicating particle sizes for SBR and ZnM beyond the resolving power. After annealing the SBR‐ZnM mixture for 30min at 155°C a weak small angle X‐ray scattering (SAXS) pattern appears which indicates particles of 160Å diameter with a polydispersity of gy = 0,2. The same particle size is found from wide angle X‐ray scattering (WAXS) which proves that these particles are ZnM microcrystals and split from the larger crystals. Heating the mixture SBR‐ZnM (100 parts by weight) with 0,8 parts by weight dicumylperoxide, (bis(1‐methyl‐1‐phenylethyl)peroxide) for 30min at 155°C gives rise to a seven times stronger WAXS pattern with the same particle dimension 160Å and polydispersity gy = 0,2. The particle scattering is superimposed by a paracrystalline interference which indicates that the ZnM particles have a mean distance of 250Å and hence are homogeneously spread over the SBR matrix. The ZnM particles have lost their innercrystalline structure, since the WAXS reflection has become very diffuse. Striking similarities to the graft copolymerization of styrene on polyethylene are discussed.
Synthèse par voie radicalaire de polymères à extrémités hydroxylées, 2 Synthèse de polybutadiènes
Authors: Pinazzi Christian , Legeay Gilbert , Brosse Jean‐Claude
Published: April 2003

La polymérisation du butadiène amorcée par l'eau oxygénée en milieu alcoolique, conduit à la formation d'oligomères de faibles masses moléculaires (voisines de 500) et de polymères hydroxytéléchéliques dont la masse moléculaire est comprise entre 1500 et 11000. Les produits formés présentent essentiellement une structure 1,4 (trans). Les polymères possèdent entre deux et trois hydroxyles par macromolécule, ce chiffre pouvant atteindre six dans certains cas. Les études systématiques ont été rélisées en faisant varier les proportions d'alcool, d'eau oxygénée et du monomère constituant le mélange réactionnel.
Effect of structure on glass transition temperatures of poly(methacrylic ester)s with bulky side groups
Authors: Gargallo Ligia , Russo Mauricio
Published: April 2003

The values of the vitreous transition temperature, Tg, of three poly(methacrylic ester)s having bulky side groups are correlated with structural effects. Tg has been obtained experimentally by means of differential calorimetry and by the tensiometric method suggested by Ferroni. The experimental values of Tg agree well with the calculated ones obtained by the method of Van Krevelen. The values of Tg determined by differential calorimetry are markedly affected by the heating rate and by the molecular weight of the fractions.

The solubility parameters of the polymers studied have been estimated. Poly(p‐tert‐butylphenyl methacrylate), (BPh), exhibits higher values for the solubility parameter, the steric hindrance parameter σ and the glass transition temperature Tg than poly(p‐tert‐butylcyclohexyl methacrylate), (BCy), and poly(neopentyl methacrylate), (NPe).

These results have been interpreted in terms of intermolecular forces and steric hindrance effects, which would be greater in BPh than in BCy and NPe.
Kinetik der Bromierung von Phenolen und phenolischen Mehrkernverbindungen, 1. Mechanismus und meßmethode
Authors: Böhmer Volker , Niemann Wilhelm
Published: April 2003

Die Bromierung von 2‐(2‐Hydroxy‐5‐methylbenzyl)‐4,6‐dimethylphenol (1) und 2‐[2‐Hydroxy‐3‐(2‐hydroxy‐5‐methylbenzyl)‐5‐methylbenzyl]‐4,6‐dimethylphenol (2a) wurde in Eisessig bei 22°C untersucht. Die Reaktion läßt sich für [Br2]0 = 1,4·10−3 bis 6,0·10−3 mol dm + und Konzentrationen der phenolischen Verbindungen [P]0 zwischen 1,1·10−3 und 5,5·10−3mol dm−3 durch das folgende Geschwindigkeitsgesetz beschreiben:

Während die gebildete Bromverbindung keinen Einfluß auf die Reaktionsgeschwindigkeit hat, verlangsamt der entstehende Bromwasserstoff die Reaktion. Die Bromierung ist trotzdem zur Bestimmung der Reaktionsfähigkeit von Phenolen und phenolischen Mehrkernverbindungen gut geeignet, da die Reaktion leicht durch Messung der Absorption des Broms bei 450 nm verfolgt werden kann. Zur Auswertung wurde dabei für kleine Umsätze (15%) ein Geschwindigkeitsgesetz 2. Ordnung zugrunde gelegt und die formale Geschwindigkeitskonstante k′2 als Funktion der Bromkonzentration bestimmt.
Kinetik der radikalischen Copolymerisation des 3,3,3‐Trichlorpropens mit Styrol in Substanz
Authors: Szafko J. , Turska E. , Lopatina G. P.
Published: April 2003

In dieser Arbeit werden Untersuchungsergebnisse über die Kinetik der mit Dicyclohexyl‐peroxidicarbonat initiierten Substanz‐Copolymerisation von 3,3,3‐Trichlorpropen (TClP) mit Styrol bei 60°C mitgeteilt. Es wurde die Abhängigkeit der Copolymerisationsgeschwindigkeit von der Zusammensetzung des Monomergemisches bestimmt. Unter Annahme einer linearen Abhängigkeit der Initiierungsgeschwindigkeit vi von der Zusammensetzung des Monomergemisches wurde der Parameter Φ (relative Konstante des alternierenden Abbruchs) berechnet, wobei mit Änderung des Molenbruchs von Styrol in der Mischung von 0,136 bis 0,851 die Konstante Φ nicht monoton von 81 bis 243 ansteigt. Experimentell wurde jedoch gezeigt, daß vi keine lineare Funktion der Zusammensetzung der Monomermischung ist. Mit den experimentellen Werten für vi folgt unabhängig von der Zusammensetzung des Monomergemisches für Φ ein Wert von 72±10. Die Copolymerisationsparameter für das System TClP/Styrol betragen r1 (TClP)=0,017 und r2 (Styrol)=7,8.
Anionic polymerization of siloxanes. Mechanism of initiation with triorganosilanolates
Authors: Chojnowski Julian , Mazurek Mieczysław
Published: April 2003

The kinetics of initiation of the polymerization of 2,2,5,5‐tetramethyl‐1‐oxa‐2,5‐disilacyclopentane (2) with sodium phenyldimethylsilanolate 1a and two of its phenyl substituted derivatives was investigated as model reaction for studying the initiation and crosspropagation steps in anionic polymerization of cyclic siloxanes in non‐polar media.

A redistribution of siloxane units between living ends of the polymer and also between living end and initiator was demonstrated to occur commonly in the siloxane anionic polymerization system affecting the initiation and crosspropagation.

However, the living silethylenesiloxane polymer system 3 showed no redistribution and the initiation, followed by the dissapearance of phenyldimethylsilanolate, showed a first internal order and a fractional external order with respect to the initiator. The same fractional order was found in the propagation step with respect to the living ends. The results can be rationalized on the basis of a mechanism in which silanolate groups aggregation (cyclic or cage structures) convert active species into dormant centres. The analysis of the kinetic scheme including the formation of simple and mixed aggregate series of optional multiplicity leads to the conclusion that the scheme under some assumptions suits the kinetics observed. Solvation processes as well as the increase of the negative charge density on the silanolate oxygen by electron releasing substituents increase the reactivity of the silanolate.
Propriétés physiques et mécaniques d'un copolymère séquencé polystyrène‐polyisoprène‐polystyrène hydrogéné
Authors: Laramée André , Goursot Paul , Prud'homme Jacques
Published: April 2003

La séquence polyisoprénique d'un copolymère séquencé polystyrène‐polyisoprène‐polystyrène (SIS) préparé par voie anionique par le butyl‐lithium dans le benzène a été hydrogéné. Les propriétés de ce copolymère ont été étudiées par analyse enthalpique différentielle (DSC) et par tensiométrie et comparées à celles du copolymère non hydrogéné. Les deux polymères sont des élastomères amorphes présentant deux transitions vitreuses caractéristiques d'un système à deux phases. La température de transition vitreuse de la phase polyisoprène hydrogéné n'est que de 4°C supérieure à celle du polyisoprène non hydrogéné. Les courbes de traction mesurées sur des films préparés par évaporation de solvant avant et après hydrogénation montrent un comportement identique aux faibles allongements bien que la tension et l'allongement de rupture soient plus faibles dans le cas du copolymère hydrogéné. L'étude des cycles de traction montre que le copolymère hydrogéné ne présente pas les réarrangements importants observés en première traction dans le cas des copolymères SIS. A cet égard son comportement est beaucoup plus près de celui d'un caoutchouc vulcanisé. Ceci indiquerait une meilleure séparation et une plus grande rigidité des domaines de polystyrène dans le matériau hydrogéné.
Inhibition effect of 1,1,4,4‐tetraphenyl‐2‐tetrazene in the radical polymerization of styrene
Authors: Sugiyama Kazuo , Nakaya Tadao , Imoto Minoru
Published: April 2003

1,1,4,4‐Tetraphenyl‐2‐tetrazene (1) inhibits the radical polymerization of styrene initiated by 2,2′‐azoisobutyronitrile. The inhibition period is proportional to the concentration of 1. The rate of the initiation of polymerization and the ratio of the rate constants of propagation and termination reactions k/2kt, were calculated from the consumption rate of the inhibitor. Some aromatic amines did not effect the inhibition period and the polymerization rate. Tetraphenylhydrazine showed a retarding effect.
The formation of a coloured complex of partially saponified poly(vinyl acetate) with iodine in the presence of potassium iodide
Authors: Hayashi Sadao , Takama Michihiro , Kaneko Ichiro , Hojo Nobumasa
Published: April 2003

The red‐violet complex which was formed from partially saponified poly(vinyl acetate) and iodine in the presence of potassium iodide was investigated by the Benesi‐Hildebrand method. The molar absorption coefficient of the complex at the absorption maximum (488 nm) was found to be 4,74.1041/(mol cm) at 10°C and to decrease with rising temperature. The concentration of units resulting from vinyl acetate (acetoxyethylene units), which can take part in the complex formation with iodine, was below 1% of the total content of acetoxyethylene units in the polymer. The changes of enthalpy (ΔH) and entropy (ΔS) were found to be −45,01 kJ mol−1 (−10,75 Kcal/mol) and −48,40 J mol−1 K−1 (−11.56 cal mol−1 K−1) at 15°C, respectively.
Studies on functional micelles, 6. Micellar effect in the preparation of poly(β‐alanine) from thio‐β‐alanine S‐alkyl esters
Authors: Kawabata Yasuziro , Kinoshita Masayoshi
Published: April 2003

The S‐dodecyl (1e), S‐decyl (1d), and S‐octyl esters of thio‐β‐alanine (1c) were condensed in the presence of a base in aqueous media to give poly(β‐alanine) in yields of 44, 24, und 2%, respectively. The degrees of polycondensation of the obtained poly(β‐alanine) were 13, 12, and 20, respectively. S‐hexyl ester (1b) and S‐ethyl ester (1a) gave no polymer. The process of this polycondensation reaction was explained by a proposed matrix reaction on the micelle surface.
Vinyl polymerization, 334. Polymerization of methyl methacrylate initiated with poly(styrene‐co‐acrolein) or poly(styrene‐co‐methyl vinyl ketone)
Authors: Imoto Minoru , Oishi Maku , Ouchi Tatsuro
Published: April 2003

The polymerization of methyl methacrylate (MMA) initiated with styrene/acrolein, [poly(St/AL)], or styrene/methyl vinyl ketone, [poly(St/MVK)] statistical copolymers was kinetically studied. The rates of polymerization, Rp, were found to obey the following equations:

The overall activation energies were 58,6 kJ/mol (14 kcal/mol) [poly(St/AL)] and 62,8 kJ/mol (15 kcal/mol) [poly(St/MVK)], respectively.

Effects of several metallic ions on the polymerization rate were also studied, and thereby it was found that Fe(II), Fe(III), and Cu(II) ions at adequate concentrations are able to promote the polymerization.
Die Copolymerisation von Natriumäthylensulfonat mit Acrylnitril
Authors: Kapko Jerzy , Wegorkiewicz Ewa
Published: April 2003

Zur Klärung widersprüchlicher Angaben über Copolymerisationsparameter des Comonomerenpaares Natriumäthylensulfonat (NaAS)/Acrylnitril (AN) wurde eine Reihe von Radikalpolymerisationen in konz. Zinkchlorid‐Lösung durchgeführt. Die Berechnung der Copolymerisationsparameter zu rNaAS=0,13 und rAN=8,10 zeigte, daß beide Comonomere ein ideales System bilden (rAN. rNaAS ≈ 1).
Hydrophobic polyelectrolytes: Preparation and conformational properties of poly(styrene‐co‐methacrylic acid)
Authors: Conio Giuseppina , Patrone Eligio , Russo Saverio , Trefiletti Vincenzo
Published: April 2003

Random copolymers of styrene and methacrylic acid were prepared in a wide composition range, and their conformational properties were investigated by potentiometric methods in different solvent media. A conformational transition occurs as a function of the degree of ionization (α). The Gibbs free energy change of the transition between uncharged conformers (ΔG0) was determined. The dependence of ΔG0 on styrene content as well as on the composition of the solvent mixture and the temperature, shows that the uncharged polyelectrolyte chains assume a compact conformation (globule) stabilized by hydrophobic interactions of maximum strength.

Rough considerations on the electrostatic free energy of the macroion indicate that the dimensions of the compact form increase between α=0 and the transition point, so that the “globule” does not participate in the conformational change. It is suggested that this latter occurs in a one‐dimensional system, depending on the interaction of neighboring groups.
A kinetic study of the acid catalysed degradation of cellulose triacetate in chloroform/acetic anhydride solution
Authors: Bhatti Muhammad A. , Howard Peter
Published: April 2003

The kinetics of the degradation of cellulose triacetate in chloroform/acetic anhydride mixtures containing a perchloric or sulphuric acid catalyst was studied. The change in molecular weight with time was followed viscometrically, employing Maron's singlepoint method to evaluate limiting viscosity number values and using appropriate Mark‐Houwink constants for the chloroform/acetic anhydride mixtures. The dependence of the first‐order rate constant on concentration of catalyst, acetic anhydride, and cellulose triacetate, as well as polymer molecular weight and temperature was investigated. An explanation of the results, based on both H+ and Ac+ (acetylium ion) acting as the catalytic degradation species, is given; this is also shown to account for the degradation behaviour in similar cellulose acetate systems observed by previous workers.
Pressure dependence of the thermal conductivity of some polyamides
Authors: Andersson Per
Published: April 2003

The pressure dependences of the thermal conductivities of five polyamides (nylons) have been determined in a cylindrical geometry at 300K and in the pressure range 0–25 kbar. The conductivities increase strongly with pressure, the values at 25 kbar being higher by the factors 1,83, 1,90, 1,89, 2,07, and 2,03 for, respectively, nylon 66, nylon 610, nylon 6, nylon 11, and nylon 12, than those at atmospheric pressure. The results are compared with other experimental results and with theoretical calculations. The difference in conductivity response to pressure between the different varieties is discussed.
Metal complexes of poly(2‐vinylpyridine 1‐oxide), poly(4‐vinylpyridine 1‐oxide) and 2,2′‐trimethylenedipyridine 1‐oxide
Authors: Alshaikh‐Kadir Khalid , Holt Paul
Published: April 2003

Poly(2‐vinylpyridine 1‐oxide) (3), poly(4‐vinylpyridine 1‐oxide) (4), and the dimeric analogue 2,2′‐trimethylenedipyridine 1‐oxide (2) form metal complexes with chlorides of copper(II), zinc, mercury(II), iron(III), cobalt(II), and nickel(II) salts. Due to steric reasons 4 forms two series (type 6 and 7) of complexes by intramolecular or intermolecular crosslinking in which the ratio NO/metal is 2:1 (type 6) or 1:1 (type 7), whereas 3 and its model compound 2 can form only intramolecular 2:1 complexes of type 5.
13C‐NMR‐sequenzanalyse, 5. Synthese von nylon‐5 und alternierenden copolyamiden der 5‐aminovaleriansäure aus 5‐isothiocyanatovaleriansäure
Authors: Kricheldorf Hans R. , Schilling Gerhard
Published: April 2003

Aus 5‐Aminovaleriansäure (2) wurde im Eintopfverfahren der 5‐Isothiocyanatovaleriansäure‐trimethylsilylester (1) hergestellt und aus diesem die 5‐Isothiocyanatovaleriansäure (3), welche thermisch unter verschiedenen Bedingungen zu Nylon‐5 kondensiert wurde. Über das ebenfalls aus dem Silylester 1 zugängliche 5‐Isothiocyanatovaleriansäurechlorid (4) wurde das N‐(5‐Isothiocyanatovaleryl)‐β‐alanin (5) und die N‐(5‐Isothiocyanatovaleryl)‐4‐aminobuttersäure (6) erhalten, Monomere, die sich zu alternierenden Copolyamiden der 5‐Aminovaleriansäure kondensieren lassen. Der thermische Abbau von Nylon‐3, ‐4, ‐5 und ‐6 sowie einiger alternierender Copolyamide wurde anhand der thermogravimetrischen Analyse untersucht und die Abbaumechanismen diskutiert. Die 13C‐NMR‐Spektren von alternierenden Copolyamiden des β‐Alanins, der 4‐Aminobuttersäure und der 5‐Aminovaleriansäure werden verglichen und Beziehungen zwischen den Sequenzen und der chemischen Verschiebung der CO‐Signale ermittelt.
Cationic polymerization of p‐substituted α‐methylstyrenes, 2. Crystalline polymers from p‐methyl‐ and p‐isopropyl‐α‐methylstyrene
Authors: Lenz Robert W. , Sutherland Judith E. , Westfelt Lars C.
Published: April 2003

Under identical conditions of cationic polymerization at low temperature 2‐(p‐tolyl)‐1‐propene (α,p‐dimethylstyrene) gave polymers with much higher syndiotactic contents than unsubstituted α‐methylstyrene. All samples of poly(α,p‐dimethylstyrene) were crystalline, but poly(α‐methylstyrene) did not crystallize even at high degrees of stereoregularity. Similarly polymers of p‐isopropyl‐α‐methylstyrene were crystalline, and the crystalline properties of copolymers of the three monomers were investigated and compared to those of the homopolymers. The rôles of stereoregularity and crystallizability in forming crystalline products were considered.
Experimenteller nachweis des molekulardispersen charakters der mischung von zwei polymeren und bestimmung des chemischen potentials in diesen mischungen
Authors: Kruse Wolfgang A. , Kirste Rudolf G. , Haas Jean , Schmitt Burghard J. , Stein Dieter J.
Published: April 2003

Mit Hilfe der Neutronenkleinwinkelstreuung wird der molekulardisperse Charakter einer glasklaren Mischung von zwei Polymeren bei Abwesenheit eines niedermolekularen Lösungsmittels in einem Fall nachgewiesen, im anderen widerlegt. Falls eine molekulardisperse Mischung vorliegt, können das chemische Potential und die Knäueldimensionen bestimmt werden. Polymethylmethacrylat und Styrol‐Acrylnitril‐Copolymere bilden für gewisse Zusammensetzungen des Copolymeren molekulardisperse Mischungen. Sie sind exotherm, besitzen eine negative Exzeßentropie und die Molekülknäuel sind gegenüber den ungestörten Knäueldimensionen expandiert. Die Theorie der Löslichkeitsparameter von Hildebrand und Scott ermöglichte zwar die Auffindung des mischbaren Systems, aber die gemessenen zweiten osmotischen Virialkoeffizienten sind in der Größenordnung verschieden von denen, die nach dieser Theorie vorausberechnet werden können.
Polymere brenzcatechin‐derivate, 2. Über die alternierende copolymerisation von 4‐propenylbrenzcatechin‐derivaten mit maleinsäureanhydrid durch tributylboran
Authors: Iwabuchi Susumu , Kojima Kuniharu , Nakahira Takayuki , Hosoya Hiromichi
Published: April 2003

Die Copolymerisation von Maleinsäureanhydrid (MAn) und 4‐Propenylbrenzcatechin‐Derivaten, wie Eugenol (1), Isoeugenol (2), Safrol (3) und Isosafrol (4), initiiert durch Tributylboran, wurde in Cyclohexanon bei 30°C in Anwesenheit von Sauerstoff untersucht. Es wurde gefunden, daß unabhängig von den Monomeransätzen in allen Fällen 1:1‐Copolymerisate entstehen, während unter Stickstoff weder 1 noch 3, wie bereits berichtet, mit MAn copolymerisiert. Ferner wurde gefunden, daß Maleinsäureanhydrid mit den Isopropenylverbindungen bzw. Styrol‐Derivaten 2 und 4 ca. 102 mal schneller reagiert als mit den entsprechenden Allylverbindungen 1 und 3. Demnach scheint nicht nur der Sauerstoff, sondern auch die Struktur der Seitenketten eine entscheidende Rolle in diesen Copolymerisationssystemen zu spielen. Der Reaktionsmechanismus wird diskutiert. Es ist bemerkenswert, daß die 1:1‐Copolymerisate aus MAn und 2, bzw. aus MAn und 4, thermisch sehr stabil sind; sie werden erst bei Temp. > 300°C endothermisch abgebaut.
Ring‐chain equilibria in the metathesis reaction of cycloolefines
Authors: Höcker Hartwig , Reimann Walter , Riebel Klaus , Szentivanyi Zsolt
Published: April 2003

Polyoctenylenes and polydodecenylenes prepared by the methathesis reaction exhibit a bimodal molecular weight distribution. The low molecular weight fraction consists of cyclic oligomers, the high molecular weight fraction is assumed to contain linear polymers. The distribution of cyclic oligomers together with the polymer material indicates a ring‐chain equilibrium. The slope of the plot log Kx (molar cyclization equilibrium constant) vs. log x (degree of polymerization) is close to −2,5 as predicted by the Jacobson and Stockmayer theory for unstrained macrocycles.
On the reversible crosslinking of elastomers by boranes
Authors: Schnecko Hans , Steffen Ulrich
Published: April 2003

Attempts are reported to test the reactivity of boron‐alkyl and of boric ester bonds in polymers with regard to thermal, oxidative, or hydrolytic stability. Polymer substrates were natural rubber and low molecular weight liquid polybutadiene as well as some telechelics (OH‐functional polybutadiene, poly(ethylene glycol) and allyl‐tipped poly(ethylene glycol) or polystyrene, respectively, the latter as model compounds); as reagents, borane‐amine complexes and free borane were employed. It turned out that only with a large number of in‐chain double bonds sufficient network stability was obtained which was then irreversible. All saturated telechelics investigated revealed insufficient stability against hydrolysis and oxidation at room temperature.
Strukturbestimmung eines 1,4‐poly(1,3‐pentadien)s durch 13C‐NMR‐spektroskopie
Authors: Elgert Karl‐Friedrich , Ritter Wolfgang
Published: April 2003

Die Polymerisation des trans‐1,3‐Pentadiens wurde mit Butyllithium als Initiator bei 80°C in Heptan durchgeführt. Die Struktur der Polymerkette wurde durch 13C‐NMR‐Spektroskopie bei 90,51 MHz bestimmt.

85% 1,4‐ und 15% 1,2‐Verknüpfung wurden bestimmt. Die 1,4‐Verknüpfung setzt sich aus 70% trans‐ und 30% cis‐Verknüpfung zusammen. 50% Abweichung von der „Kopf‐Schwanz‐Verknüpfung”︁ wurden gefunden. Die Wahrscheinlichkeit einer meso‐Diade beträgt in der „Kopf‐Schwanz‐Verknüpfung”︁ m=0,5, während sie für die „Kopf‐Kopf‐Verknüpfung”︁ m=0,66 beträgt.
Microtacticity and hydrodynamic behaviour of poly(trityl methacrylate) prepared in hexamethylphosphoric triamide
Authors: Niezette Joseph , Hadjichristidis Nikos , Desreux Victor
Published: April 2003

Trityl methacrylate was polymerized with 2,2′‐azodiisobutyronitrile at 60°C in a homogeneous hexamethylphosphoric triamide (HMPT) solution. The isotactic microstrucutre found by NMR spectroscopy was less important for this polymer than for poly(trityl methacrylate) prepared in benzene, a precipitating medium.

Some aspects of the hydrodynamic behaviour of poly(trityl methacrylate) were examined in HMPT at 25°C. Relations between the intrinsic viscosity, the root‐mean‐square end‐to‐end dimension, and the weight average molecular weight were established. The unperturbed dimension 〈r〉1/2 was determined from viscosity and light scattering measurements using the well known extrapolation methods of Kurata‐Stockmayer, Stockmayer‐Fixman, Cowie, Inagaki‐Kurata, and Baumann.

Poly(trityl methacrylate) adopts a moderately expanded conformation in HMPT at 25°C. The correlation of the chain rigidity with the molar volume of the side group of polymethacrylic esters shows that poly(trityl methacrylate) has a higher chain rigidity than other polymethacrylates on account of the steric hindrance of the trityl group and of the strong interactions between the aromatic rings.
Synthese und Charakterisierung sulfongruppenhaltiger Polyester
Authors: Kerber Robert , Nuyken Oskar , Pöschl Ernst
Published: April 2003

Aus Dimethyl‐3,3′‐sulfonyldipropionat (1) und Äthylenglykol (2) wurden Polyester mit einem mittleren Molekulargewicht von ca. 104 hergestellt. Der Sulfongruppengehalt der Polymeren ließ sich durch systematischen Austausch der Esterkomponente 1 gegen Dimethylterephthalat (4) in der Ausgangsmischung gezielt verändern. Spektroskopische Methoden (1H‐NMR, IR), Schwefelanalyse, die mittels Dampfdruckosmometer und Ultrazentrifuge bestimmten Molekulargewichte sowie die Viskositätszahlen dienten zur Charakterisierung der erhaltenen Produkte. Kurzzeitige Behandlung der sulfongruppenhaltigen Polymeren mit wäßriger Natriumhydroxid‐Lösung oder alkoholischer Natriummethanolat‐Lösung spaltet diese in niedermolekulare Bestandteile.
Dilute solution properties of alternating copolymers from methacrylonitrile and styrene and methacrylonitrile and α‐methylstyrene
Authors: Cincu Cornel , Uglea Constantin V.
Published: April 2003

Kuhn‐Mark‐Houwink‐Sakurada relations were obtained in various solvents for alternating copolymers from methacrylonitrile and styrene, (MAN‐ST), and from methacrylonitrile and α‐methylstyrene, (MAN‐αMST).

The values of the unperturbed dimensions, Kθ or A=(r/M)1/2 and conformational parameter σ were determined using usual extrapolation techniques.

The values of the unperturbed dimensions are dependent on the solvent nature and are quite different from the “ideal” values calculated on the basis of additivity rules from the unperturbed dimensions of the parent homopolymers.
On the thermal degradation of poly‐ε‐caprolactone
Authors: Iwabuchi Susumu , Jaacks Volker , Kern Werner
Published: April 2003

The thermal degradation of poly(oxycarbonylpentamethylene), (poly‐ε‐caprolactone), (3), was investigated at 220°C and 80 mm Hg under nitrogen. 3 was found to be thermally much more stable than poly(oxycarbonylethylene), (poly‐β‐propiolactone), (1), although it decomposed faster than poly(oxycarbonyl‐1,1‐dimethylethylene), (polypivalolactone), (2). The reaction was of the first order with a rate constant of k=6,2.10−4 min−1 and proceeded via a “zipper mechanism” to yield monomeric ε‐caprolactone.
Polymerization of β‐aminopropionitrile
Authors: Ree Keiu , Minoura Yuji
Published: April 2003

The polymerization of β‐aminopropionitrile (β‐APN) was carried out by using basic catalysts such as sodium sec‐butoxide in organic solvents and gave polyamidine which was converted to poly‐β‐alanine by hydrolysis. Poly‐β‐alanine was identified by IR and 1H ‐NMR spectra and elemental analysis. The degree of polymerization was determined to 9,1 by vapor pressure osmometry. Free β‐alanine was obtained by hydrolysis of the poly‐β‐alanine. From a kinetic study of this polymerization, it was found that the rate of polymerization was

The polymerization mechanism of β‐APN is discussed.