bluuebunny/crossref_metadata_2025 huggingface dataset:
Cationic polymerization of styrenes by protonic acids and their derivatives, 2. Two propagating species in the polymerization by CF3SO3H
Authors: Sawamoto Mitsuo , Masuda Toshio , Higashimura Toshinobu
Published: April 2003

The bimodal molecular weight distribution (MWD) of the polymers and the polymerization rate in the cationic polymerization of styrene by CF3SO3H were studied under a variety of conditions. Both the decrease of the dielectric constant of the reaction mixture and the addition of a common‐ion salt (Bu4N+SO3CF) reduced the polymerization rate and the formation of the higher molecular weight portion of the polymers (the high polymer). It appears that of the two propagating species the one which forms the high polymer is more ionically dissociated and more reactive in propagation. Salt effects indicate that in nitrobenzene the propagating species is a solvent‐separated ion pair and/or a free ion. The effects of monomer concentration on the bimodal MWD have shown that there are different chain‐breaking reactions for the two propagating species. The possibility that the monomer is complexed with one of the growing species is also discussed.
Bestimmung der ungestörten Dimensionen von Makromolekülen aus Lichtstreuungsmessungen unter Berücksichtigung der Molekulargewichtsverteilung
Authors: Bareiss Rolf E. , Bellido José
Published: April 2003

Es werden die Formeln für die Polymolekularitätskorrekturfaktoren zweier Varianten des Baumann‐Verfahrens zur Bestimmung der ungestörten Dimensionen von Makromolekülen, welche eine Schulz‐Flory‐ bzw. eine logarithmische Normalverteilung der Molekulargewichte aufweisen, angegeben. Die experimentelle Prüfung mit Poly(α‐methylstyrol)‐,[Poly(1‐methyl‐1‐phenyläthylen)]‐Mischungen, welche in guter Näherung Schulz‐Flory‐ bzw. logarithmische Normalverteilungen der Molekulargewichte aufweisen, zeigt, daß sowohl für das Baumann‐Stockmayer‐Fixman‐ als auch für das Baumann‐Kurata‐Stockmayer‐Verfahren die lineare Extrapolation für Polymerhomologe mit beliebiger Breite der Molekulargewichtsverteilung möglich ist und zu den gleichen Werten für die ungestörten Dimensionen wie für Polymerhomologe mit enger Molekulargewichtsverteilung führt, wenn die Werte für das Gewichtsmittel des Molekulargewichts Mw und das z‐Mittel des Trägheitsradiusquadrats 〈S̄2〉z mit den entsprechenden Polymolekularitätskorrekturfaktoren qMw bzw. qsz multipliziert werden.
Functional monomers and polymers, 31. On the stereoregularity of vinyl polymers containing nucleic acid bases
Authors: Akashi Mitsuru , Inaki Yoshiaki , Takemoto Kiichi
Published: April 2003

N‐β‐Methacryloyloxyethyl derivatives of adenine, thymine, uracil, and theophylline were polymerized at 60°C in various solvents, using azodiisobutyronitrile as an initiator, and the polymers obtained were further converted to poly(methyl methacrylate). From the high resolution NMR spectra of poly(methyl methacrylate) thus derived, the stereoregularity of the polymers originally prepared was determined. The NMR spectra measured at 150°C in dimethyl sulfoxide‐d6 showed three peaks based on α‐methyl protons, which were assigned to the components of the syndiotactic triad (S), heterotactic triad (H), and isotactic triad (I). In the free‐radical polymerization of these monomers containing nucleic acid bases at 60°C, the polymerization rate was found to be influenced by the sort of the bases and solvents used, while the stereoregularity of the polymers seems not to be affected by them.
Funktionelle monomere und polymere, 33. Synthese von stereoregulären vinylpolymeren mit nucleinbasen in den seitenketten
Authors: Inaki Yoshiaki , Takada Hiroshi , Kondo Koichi , Takemoto Kiichi
Published: April 2003

Stereoregular polymethacrylates containing adenine, uracil, or theophylline residues in the side chains (4a–c), were prepared starting from isotactic and syndiotactic poly[1‐(2‐bromoethoxycarbonyl)‐1‐methylethylene] (2) by reaction with the sodium salts of the corresponding nucleic bases. NMR‐ and UV‐spectroscopic studies of the polymers were carried out.
The oxidative coupling of 2,6‐xylenol catalyzed by polymeric complexes of copper, 1. Kinetic study of the catalysis by copper(II)‐complexes of partially aminated polystyrene
Authors: Schouten Arend Jan , Prak Nanno , Challa Ger
Published: April 2003

The oxidative coupling reaction of 2,6‐xylenol (3) catalyzed by copper(II) complexes of chemically modified polystyrene was investigated. Under the applied reaction conditions the main reaction product was 2,6,2′,6′‐tetramethyl‐1,1′‐dioxo‐4,4′‐bicyclohexa‐2,5‐dienylidene (4). It was found that the polymeric complexes behave quite different from the low molecular analogue and that these differences can mainly be ascribed to a better complexation of copper within polymer coils. It appeared that a Michaelis‐Menten description of the kinetics fits rather well when the concentration of the phenol was not too high.
NMR studies on the growing species of cyclic acetals in their cationic polymerization. 1H‐NMR spectra of oxycarbenium ions formed in some model reactions
Authors: Yokoyama Yasuaki , Okada Masahiko , Sumitomo Hiroshi
Published: April 2003

The ionic species formed in the reaction of 1,3‐dioxane with triethyloxonium salts were examined by 1H‐NMR spectroscopy under various conditions. The signal assignable to the protons of the positively charged end‐methylene group appeared at δ = 9,9–16,6 ppm, depending on temperature, solvents, and counter ions. The quenching of the ionic species with sodium ethoxide provided 1,3‐dioxane, 1,3‐diethoxypropane, and 3,5,9‐trioxaundecane. The removal of diethyl ether from the reaction mixture containing the ionic species shifted the end‐methylene proton signal to a higher magnetic field and favored the formation of 1,3‐dioxane in the quenching reaction. Similar phenomena were observed for the ionic species produced in the reaction of 1‐chloromethoxy‐3‐ethoxypropane with antimony pentachloride. These results indicate the oxycarbenium ionic nature of the ionic species formed in the above reactions. On the basis of these model reactions, the growing species of cyclic acetals in the cationic polymerization is discussed.
Thermischer Abbau von linearen polymeren unter nicht isothermen bedingungen
Authors: Schneider Ioan‐Adam , Hurduc Natalia
Published: April 2003

Bei der Untersuchung des thermogravimetrischen Verhaltens von linearen Polymeren unter nichtisothermen Bedingungen in Luft ergab sich, daß, ein einfacher Vergleich der Kurven aus der dynamischen Thermogravimetrie (TG und DTG) keine genaueren Aussagen bezüglich des thermischen Abbaues zuläßt. Erst ein Versuch, diese Kurven vor allem unter Berücksichtigung des Umsatz‐ und Aufheizgeschwindigkeitseinflusses kinetisch auszuwerten, führte zu deutlichen Unterschieden. Diesen entsprechend, baut unter den verwendeten Bedingungen anionisches PMMA nach einem Kettenmechanismus ab, wogegen beim anionischen PS zwei parallele Reaktionen ablaufen. Bei linearem PE ist der Abbau so kompliziert, daß keine näheren Angaben gemacht werden können.
Synthese und halbleitereigenschaften von phthalocyaninartigen polymeren mit Tetrathiafulvalen‐Einheiten
Authors: Koßmehl Gerhard , Rohde Michael
Published: April 2003

4,5,4′,5′‐Tetracyano‐2,2′‐bi‐1,3‐dithiolylidene (tetracyanotetrathiafulvalene) (1) was found to react with metal acetylacetonates (2a–m) to give dark, insoluble, and infusible polymers 3a–m with phthalocyaninelike structure. The electrical conductivity of the polymers was investigated (σ298K < 6·10−5 Ω−1 cm−1), and a linear relationship between the logarithm of the electrical conductivity and the activation energy of the different polymers was found (compensation effect). Measurements of the thermoelectric power proved p‐conduction.
Free radical polymerization of unconjugated dienes, 17. Copolymerization of dimethyl 2,6‐dimethyleneheptanedioate with methyl methacrylate in benzene solutions
Authors: Casorati Ernesto , Martina Alfredo , Guaita Marino
Published: April 2003

Since dimethyl 2,6‐dimethyleneheptanedioate (1) yields, by free radical polymerization in benzene solutions, soluble polymers without any residual unsaturated groups, the hypothesis is made that either the molecule of this monomer or the radical into which the molecule is converted by the attack of a growing chain has a pseudocyclic conformation. To test the validity of this hypothesis, 1 was copolymerized in benzene with methyl methacrylate. The values found for the reactivity ratios can be interpreted on the basis of conformations of the molecules of 1, in which the two unsaturated groups partially shield each other, in agreement with the hypothesis that the molecule itself has a preferred conformation prefigurating a cyclic structure.
Effet de la concentration sur la transition conformationnelle des copolymères séquencés et greffés
Authors: Dondos Anastasios , Benoît Henri
Published: April 2003

In this paper we have been studying the effect of concentration c on reduced viscosity ηsp/c for a triblock copolymer poly(methyl methacrylate)/polystyrene/poly(methyl methacrylate) and for a graft copolymer of the same nature.

The temperature of the experiments has been chosen in the range where the conformation changes from a segregated form to a pseudogaussian one. For this temperature range ηsp/c is not a linear function of concentration but the points ηsp/c vs. c are situated on two straight line segments with a well defined intercept.

We discuss the phenomenon in comparison to results obtained on mixtures of homopolymers. These results suggest a strong and anomalous dependance of molecular conformation on concentration.
Microstructure and melting point of stereoregular polymers. A tentative experimental correlation for isotactic polypropylene
Authors: Pavan Andrea , Provasoli Augusto , Moraglio Giovanni , Zambelli Adolfo
Published: April 2003

Fractions of predominantly isotactic polypropylene with varying stereoregularity were examined by NMR analysis and by hot‐stage optical microscopy, and the stereochemical composition and the melting point of each fraction were determined. From the stereochemical composition the average length of the isotactic stereoblocks is evaluated, and the experimental results are compared to the lengths calculated according to two statistical models of stereospecific propagation. The experimental melting points are then related to the experimental average lengths of isotactic stereoblocks, and the correlation is discussed.
Deuteron NMR relaxation and molecular motion of polystyrene in solution
Authors: Grandjean Jean , Sillescu Hans , Willenberg Bernd
Published: April 2003

Deuteron relaxation times T1 of polystyrenes deuterated at the backbone (PS‐d3) and the phenyl ring (PS‐d5), respectively, have been measured in solutions of benzene and diethyl malonate as a function of concentration and temperature. We conclude that the motion of the phenyl ring is faster than that of the backbone, the difference being smallest at high temperatures around 180°C. The temperatures dependence is discussed in relation to the activation energies in polystyrene.
Cationic polymerization of styrenes by protonic acids and their derivatives, 4. Homo‐ and Co‐polymerizations of para‐substituted styrenes by CF3SO3H
Authors: Sawamoto Mitsuo , Masuda Toshio , Higashimura Toshinobu
Published: April 2003

p‐Methyl‐ and p‐chlorostyrenes (pMeSt and pClSt) were polymerized by CF3SO3H in methylene chloride at 0°C and gave polymers with a bimodal molecular weight distribution (MWD). This indicates that the polymerizations involve two independent propagating species: a dissociated and a non‐dissociated species. Their selectivities toward monomers were compared in the copolymerizations of pMeSt and pClSt with styrene (St) by CF3SO3H in benzene, methylene chloride, and nitrobenzene solvents. Decreasing solvent polarity and the presence of a common‐ion salt ((n‐C4H9)4N+SO3CF−3) greatly increased the reactivity difference between the monomers. Thus the non‐dissociated species is more selective than the dissociated species. In contrast, the composition of pMeSt‐St copolymers produced by BF3O(C2H5)2 did not change with the solvent polarity. The difference in nature between the propagating species generated by CF3SO3H and by BF3O(C2H5)2 is discussed.
Über polyarylenalkenylene und polyheteroarylenalkenylene, 8. Synthesen und charakterisierung von poly(imidazo[4.5‐f]benzimidazol‐2,6‐diylvinylenarylenvinylen)en und einigen ihrer oligomeren
Authors: Manecke Georg , Brandt Lothar , Koßmehl Gerhard
Published: April 2003

Some poly(imidazo[4.5‐f]benzimidazol‐2,6‐diylvinylenarylenevinylene)s (13aa–cc) were prepared via the Knoevenagel condensation starting from 2,6‐dimethylimidazo[4.5‐f]benzimidazole (4a) or its N1, N7 ‐dimethyl‐ and ‐diphenylderivatives (4b, c) and aromatic dialdehydes. Analogous reactions of 4a and 4c with monoaldehydes and of 2‐methylbenzimidazole with dialdehydes led to oligomer model compounds (6a–d, 8a–e, 9, 10a–d, 12) which were also prepared via another reaction type (Wittig reaction). The chemical structures were confirmed by elemental analysis, IR, and electronic spectra. The oligomers, in addition, were characterized by mass spectra and some were identified by independent synthesis. Electrical conductivities and thermical degradations of the polymers and of some of the oligomers were also investigated.
Herstellung, charakterisierung und lösungseigenschaften von einheitlichen styrol‐α‐methylstyrol block‐copolymeren
Authors: Rahlwes Dieter , Kirste Rudolf G.
Published: April 2003

An improved anionic polymerization technique for the preparation of highly uniform styrene/α‐methylstyrene linear two‐block copolymers is described. Three sets of samples with molecular weights M were prepared under equal experimental conditions, namely polystyrenes (2 · 105 < M < 3 · 106), poly(α‐methylstyrene)s (7 · 104 < M < 4 · 106), and block copolymers (2 · 105 < M < 2,5 · 106). Ultracentrifugation in a density‐gradient does not show any chemical heterogeneities in the block copolymers. The molecular polydispersity U = Mw/Mn–1 is U = 0,03 or less as estimated from GPC‐measurements. The high molecular and chemical homogeneity of the block copolymers and the optical similarity of the two segment types yield light scattering measurements which give molecular weights Mw, radii of gyration 〈r2〉1/2 and second virial coefficients A2 with almost the same accuracy as in the case of homopolymers. The radii of gyration and the intrinsic viscosities of the block copolymers give no evidence for any “intramolecular phase separation” in the good solvent toluene. The coil conformation corresponds closely to that of the homopolymers.
Functional metal‐porphyrazine derivatives and their polymers, 1. Synthesis of metal‐[2,9or10(or 2,16or17)bis(3,4‐dicarboxybenzoyl)]phthalocyanine derivatives
Authors: Shirai Hirofusa , Yagi Sadafumi , Suzuki Akira , Hojo Nobumasa
Published: April 2003

The diimide of metal‐[2,9or10(or 2,16or17)bis(3,4‐dicarboxybenzoyl)]phthalocyanine(diPc) (where i = imide) 2 or 3 were prepared from 3,4,3′,4′‐benzophenonetetracarboxylic dianhydride (BTDA) (1), phthalic anhydride (PA), urea, and metal salts such as CuCl2, CoCl2, and FeCl3 etc. at 170°C. In the case of copper, the diPc monomer 2 or 3 and the dimer 4 or 5 could be synthesized. Those copper complexes are stable to all of the chemical procedures. However, the core metals of Fe(III), Co(II), Ni(II) and Zn(II)‐diPc were partially removed in the acid treatment. Metal phthalocyanine derivatives which have four carboxyl groups in the peripheral site, metal‐[2,9or10(2,16or17)bis(3,4‐dicarboxybenzoyl)] phthalocyanine(daPc) (a = acid) 6 or 7, were synthesized by hydrolysis of the metal‐diPc. The metal‐daPc are soluble in water, in aprotic solvents such as N,N′‐dimethylformamide, and also in sulfuric acid. The physicochemical properties of some metal‐daPc derivatives were investigated.
Über die druckabhängigkeit der viskoelastischen und physikalisch‐chemischen eigenschaften von polymeren, 2. Spezifisches volumen und thermische ausdehnung einiger polymeren beim schmelzen und kristallisieren
Authors: Karl Veit‐Holger , Asmussen Frithjof , Ueberreiter Kurt
Published: April 2003

Measurements of specific volumes are described as function of temperature and pressure of melting or crystallizing linear polyethylene, isotactic polypropylene, and polyoxymethylene. A pressure range of 50 to 1600 bar permits determination of relative volume changes as function of temperature and pressure. Pressure influence on melting points, temperature hysteresis between melting and crystallization and their volume changes as well as the thermodynamic driving force of phase change have been investigated. Clausius‐Clapeyron's equation permits calculation of heats of crystallization.
Studies on polymerizations initiated by syncatalytic systems based on aluminium organic compounds, 6. Comparison with isobutene polymerizations initiated by ethylaluminium dichloride or aluminium trichloride
Authors: Maina Marcello Di , Cesca Sebastiano , Giusti Paolo , Ferraris Giuseppe , Magagnini Pier Luigi
Published: April 2003

The results of previous studies carried out on the polymerization of isobutene initiated by diethylaluminium halides plus halogens are compared with results obtained with other syncatalytic systems such as diethylaluminium chloride (or triethylaluminium) plus hydrochloric acid (or tert‐butyl chloride), as well as with results obtained with aluminium compounds such as ethylaluminium dichloride or aluminium trichloride which do not require co‐initiators to initiate the polymerization of isobutene. The kinetic data indicate clearly that the polymerization of isobutene initiated by syncatalytic systems is characterized by a relatively slow initiation and by the absence of important termination reactions and of transfer with monomer. In contrast to this, the polymerizations initiated by strong Lewis acids such as ethylaluminium dichloride or aluminium trichloride show a much faster initiation and stop at incomplete conversion which indicates that at least one efficient termination reaction is operative. It is also demonstrated that this termination reaction produces at least one substance which acts as a co‐initiator for the isobutene polymerization initiated by diethylaluminium halides or triethylaluminium.
A study on mechanism of excimer formation through fluorescence quenching for isotactic and atactic polystyrenes and poly(p‐methylstyrenes) in solution
Authors: Ishii Tadahiro , Handa Takashi , Matsunaga Satoru
Published: April 2003

The mechanism of excimer formation and deactivation for isotactic and atactic polystyrenes, and isotactic and atactic poly(p‐methylstyrenes) was studied by comparison of the rate parameters which were calculated from the fluorescence quenching and the decay time measurements of excimer emission band. The activation energy of excimer formation was obtained from the effect of temperature change on fluorescence intensity. The rate parameters of excimer formation for isotactic polymers are in the order of 109 s−1 and larger than those for atactic polymers. The activation energy for isotactic polymers is smaller than that for atactic polymers. These results show that isotactic polymers can form the excimer more easily than atactic polymers. The facility of excimer formation for isotactic polymers is interpreted as lower energy barrier required to achieve the excited excimer state.
Determination of the tacticity of polyacrylonitrile and its oligomers by 13C NMR spectroscopy
Authors: Balard Henri , Fritz Hans , Meybeck Jean
Published: April 2003

13C NMR spectroscopy allows the determination of the microtacticity of polyacrylonitrile (PAN) and its models, the dimer, trimer, and tetramer of acrylonitrile (1a–c). In the case of the oligomers, the carbons of the chain are the most stereosensitive ones, but in the case of PAN it is the carbon of the cyano group. The 13C NMR spectrum of PAN composed of ten peaks which can be assigned to the ten possible pentad configurations.
Studies on chitin, 3. Preparation of pure chitin, poly(N‐acetyl‐D‐glucosamine), from the water‐soluble chitin
Authors: Kurita Keisuke , Sannan Takanori , Iwakura Yoshio
Published: April 2003

Pure chitin, poly(N‐acetyl‐D‐glucosamine), was successfully prepared by acetylating the partially deacetylated water‐soluble chitin with acetic anhydride‐pyridine or with acetic acid‐dicyclohexylcarbodiimide. Although enough selectivity between amino and hydroxyl groups was not shown, acetylation with acetic anhydride‐pyridine gave rise to the complete acetylation of amino groups and thereby O‐, N‐acetylated chitin was formed. The ester groups were then selectively transformed to hydroxyl groups by means of either hydrolysis or transesterification to give the pure chitin. Acetic acid‐dicyclohexylcarbodiimide system was found to enable one step complete and selective acetylation of amino groups under very mild conditions and it appeared to be superior to the others for the purpose.
Polymer induced aggregation of dye molecules. Influence of the attachment of dye molecules as side groups
Authors: Smets Georges J. , Simionescu Bogdan
Published: April 2003

By radical polymerization, 7‐(N‐acryloyl‐N‐methyl)‐3‐dimethyliminio‐3H‐phenothiazine chloride (1) has been transformed in the N‐substituted polyacrylamide carrying Azure B side groups, poly{1‐[N‐(3‐dimethyliminio‐3H‐phenothiazin‐7‐yl)‐N‐methylaminocarbonyl]ethylene chloride}. On addition of poly(acrylic acid) dye‐polymer interactions and metachromasy phenomena have been examined using absorption spectrometry.

Similarly, 1 has been copolymerized with acrylic acid. Intramolecular functional interaction causes a bathochromic absorption band (652 nm) which persists partially on addition of poly(acrylic acid), and affects dye‐aggregation and metachromasy.
Diastereomere Alkene als Modelle für die 13C‐NMR‐Spektroskopie von Polymeren
Authors: Ritter Wolfgang , Elgert Karl‐Friedrich
Published: April 2003

Trans‐3,4,7,8‐tetramethyl‐5‐decene is a low molecular weight model of poly‐2,5‐(2,4‐hexadiene). Eight resonance signals can be observed in the 13C NMR spectrum of the carbon double bond which are assigned to the relative configurations of the asymmetric carbon atoms. The configurational splitting can be described partially by additive constitutional and configurational shift parameters, which have been determined from a number of alkenes with up to four asymmetric carbon atoms. However, full additivity is not reached as the conformation of the substituents of the carbon double bond influences the shift differences due to the relative configurations of the asymmetric carbon atoms.
Diastereomere Alkane als Modelle für die 13C‐NMR‐Spektroskopie von Polymeren
Authors: Elgert Karl‐Friedrich , Ritter Wolfgang
Published: April 2003

Low molecular weight alkanes, e.g. 3,7‐dimethylnonane, with two asymmetric carbon atoms are suitable models for the assignment of the configurational splitting in the 13C NMR spectrum of the alternating copolymer from ethylene and propylene, poly(1‐methyltetramethylene).
Synthesis and properties of aliphatic unsaturated polymers with 1,3,4‐oxadiazole‐2,5‐diyl units
Authors: Schopov Ivan , Vodenicharova Margarita
Published: April 2003

Two polymers built up of 1,3,4‐oxadiazole‐2,5‐diyl and vinylene resp. ethynylene groups (polymers 2 and 3) were prepared by polycondensation of fumaramide resp. acetylenedicarboxamide with hydrazine sulfate in polyphosphoric acid. 2 and 3 exhibit the properties of conjugated polymers—dark colour, semiconductivity, and paramagnetism. The electric conductivity measurments were performed on pellets and on thin films in sandwich and surface cells. The comparison of the semiconducting properties of the polymers mutually and with poly‐p‐xylylidene leads to the conclusion that the trans‐double bond is a better building unit for conjugated semiconductive polymers than the triple bond and the 1,3,4‐oxadiazole‐2,5‐diyl residue is better than the 1,4‐phenylene unit.
Kinetische und morphologische Untersuchungen zur polymerisation von oxacyclischen Monomeren im festen Zustand, 1. Zur Morphologie der bei der Polymerisation von 1,3,5,7‐Tetroxocan mittels chemischer Katalysatoren entstehenden Polyoxymethylene
Authors: Muñoz‐Escalona Antonio
Published: April 2003

In order to elucidate the reaction mechanism of the chemically induced solid‐state polymerization of 1,3,5,7‐tetroxocane, the nascent morphology of poly(oxymethylene), (POM) crystals was investigated. The results show that POM has a lamellar morphology consisting of folded polymer chains. This morphology is different from that of the fibrous morphology obtained by radiation induced solid‐state polymerization of 1,3,5,7‐tetroxocane. Based on this the reaction takes place according to a crystallization succeeding polymerization mechanism, where the monomer passes through the gasphase to reach the reaction center.
Energy transfer and singlet energy migration in a polymer
Authors: Fouassier Jean‐Pierre , Lougnot Daniel‐Joseph , Faure Jean
Published: April 2003

Kinetic parameters of singlet and triplet states of a polymer having pendant anthracene groups were investigated in solution using a mode locked laser spectroscopy. The lifetimes of the two transient states and the rate constants of the bimolecular quenching by oxygen were measured. The experimental data allow the problems of energy transfer between oxygen and triplet or singlet states to be discussed. In some cases, direct evidence is given for a migrational process of singlet energy.
Configurational dependences of carbon‐13 and proton NMR spin‐lattice relaxation times of various polymethacrylates
Authors: Hatada Koichi , Kitayama Tatsuki , Okamoto Yoshio , Ohta Koji , Umemura Yoshihiro , Yuki Heimei
Published: April 2003

Isotactic and syndiotactic poly(alkyl methacrylate)s (R = CH3, C2H5, isoC3H7, n‐C4H9 and t‐C4H9) were prepared by anionic mechanism and the spin‐lattice relaxation times T1 of individual carbons and protons were measured mainly in toluene‐d8 by the inversion‐recovery Fourier transform (IRFT) method. The T1's of the carbons in the isotactic polymers were consistently longer than those of the comparable carbons in the syndiotactic polymers. The ratios of 13C‐T1's for syndiotactic and isotactic polymers were always in the range of ca. 0,4–0,6 for all types of carbons. The 13C‐T1's decreased with an increase in the bulkiness of the ester group in both polymers. From the measurements of the nuclear Overhauser enhancement (NOE) it was found that the spin‐lattice relaxations of carbons in polymethacrylates are dominated by 13C‐1H dipolar interactions and that the extreme narrowing condition is satisfied at least above 70°C. The effect of solvent on 13C‐T1 was also studied. The results of the measurements of 1H‐T1's were parallel to those in the carbons' case. It was concluded that the dependence of T1 upon the configuration of the polymer is mainly caused by the configurational dependence of the segmental mobility of the polymer.
Designing of oligoesteramides based on cohesive energy density calculations
Authors: Huczkowski Paweł , Kapko Jerzy
Published: April 2003

On the basis of cohesive energy calculations it was predicted that oligoesteramides with a molar ratio of ester/amide units in the molecule of 4:1 will be soluble in styrene, thus enabling to prepare from it unsaturated polyesteramides useful for cold setting, similarly to unsaturated polyesters. The oligoesteramides were prepared by N‐nitrosation of polyamide‐6, degradation of the N‐nitrosoderivative, and esterification of the end‐groups with ethylene glycol and subsequently with maleic anhydride. Reaction conditions are reported as well as the setting of the resin with styrene.
Polypentenylene durch metathese. Ringstruktur, molekulargewichte und oligomerenbildung
Authors: Witte J. , Hoffmann M.
Published: April 2003

The ring opening polymerisation of cyclopentene was induced by a series of homogeneous metathesis catalysts of systematically varied composition. The resulting polymers formed by these catalysts show bimodal distributions, which consist of linear macromolecules and small amounts of cyclic oligomers. The molecular weight of the high polymer fraction is quantitatively explained by the concentration of the acyclic olefin present in the system. The molecular weight distribution corresponds to a statistical scission of the macromolecules by the acyclic olefin. The oligomers have a cyclic structure. They are formed more slowly than the linear high polymers. The oligomer formation ist not affected by the presence of acyclic olefins. The rate of formation decreases with increasing monomer concentration. The molecular weight distribution of the oligomer fraction shows a maximum at a DP of 6 and broadens to higher molecular weights with the reaction time.
Bestimmung der chemischen Heterogenität statistischer Copolymerer anhand von Untersuchungen an Poly(styrol‐co‐butylacrylat) und Poly(styrol‐co‐butylmethacrylat), 1. Untersuchungen zur Gültigkeit der integrierten Copolymerisationsgleichung bei mittleren und hohen Umsätzen
Authors: Gruber Erich , Knell Walter L.
Published: April 2003

Styrene was copolymerised with butyl acrylate and butyl methacrylate, resp., in a solution of benzene, conducting the reaction to various conversions (5–95%). The over‐all composition of the copolymers was analysed by IR‐spectroscopy and elemental analysis. At sufficiently low yields the copolymerisation parameters were determined according to Fineman‐Ross and Mayo. After a slight adjustment of these parameters the integrated copolymerisation equation by Meyer and Lowry could be applied very well to describe the results, even at high yields. By using this equation, distribution curves of the chemical composition of the copolymers were calculated. Benoit's parameters P and Q of chemical heterogeneity were evaluated as a function of composition of the reaction mixture and conversion.
Synthesis of graft copolymers with polyamide grafts
Authors: Nitadori Yoshiaki , Rempp Paul , Franta Emile
Published: April 2003

Graft copolymers with polybutyramide (nylon‐4) grafts onto a polystyrene backbone were synthesized by reacting 2‐pyrrolidone, in the presence of some of its potassium salt, with a backbone chain fitted with randomly distributed acyllactam sites, which act as “promoters”. To achieve the same goal with a polyisoprene backbone the latter was first treated with some iodo isocyanate, and reacted thereafter with 2‐pyrrolidone. In the first case the samples obtained are the expected graft copolymers, whereas in the second case side reactions lead to crosslinks. It is noteworthy that the rate of 2‐pyrrolidone polymerization is increased when some salt (like KI) is present.
Syntheses and properties of polysaccharide‐type polymers, 1. Poly(trans‐3,4‐dihydroxytetrahydropyran‐6,2‐diyloxymethylene)
Authors: Okada Masahiko , Sumitomo Hiroshi , Komada Hajime
Published: April 2003

Poly(trans‐3,4‐dihydroxytetrahydropyran‐6,2‐diyloxymethylene) (4), a new polysaccharide‐type polymer containing two hydroxyl groups in its repeating unit, was prepared from poly(5,6‐dihydro‐2H‐pyran‐6,2‐diyloxymethylene) (2) which was obtained by the ring‐opening polymerization of 6,8‐dioxabicyclo[3.2.1]oct‐3‐ene (1): The unsaturated polymer 2 was epoxidized with m‐chloroperbenzoic acid in methylene chloride or with hydrogen peroxide‐benzonitrile in a mixed solvent of methanol and chloroform, and the resultant polymer was then hydrolyzed with potassium hydroxide in aqueous, 1,4‐dioxane under moderate conditions. The hydrolyzed polymer 4 was characterized by elemental analysis, periodate oxidation, 1H NMR and IR spectroscopy. Water sorption of 4 was measured at various humidities at 20°C and compared with those of related polymers. The water sorption isotherm of 4 showed a marked resemblance to that of natural dextran which has an identical backbone structure but three hydroxyl groups per repeating unit.
Carbon‐13 nuclear magnetic resonance studies of poly(N‐vinylcarbazole)
Authors: Kawamura Tokiji , Matsuzaki Kei
Published: April 2003

The 13C NMR spectra of poly(N‐vinylcarbazole), [poly(1‐(N‐carbazolyl)ethylene)], prepared under various polymerization conditions were measured at 25,03 MHz in 1,4‐dioxane solution. The spectra were assigned by the chemical shifts and T1 measurements of the polymers and N‐ethylcarbazole as a model compound. The absorption of methylene and methine carbons varied by the polymerization methods. It was tentatively presumed that the polymers obtained by radical polymerization had syndiotactic‐rich structures and the polymers prepared with BF3O(C2H5)2 isotactic‐rich structures. The hindered internal rotation of the bulky carbazolyl group at the main chain of poly(N‐vinylcarbazole) was also observed. The 13C NMR spectra indicated that the polymerization of N‐vinylcarbazole with nitroethane proceeded by a radical mechanism while that with chloranil, (2,3,5,6‐tetrachloro‐1,4‐benzoquinone), proceeded by a cationic mechanism.
Bestimmung des partiellen spezifischen volumens von Gelöt‐Stoffen in Lösungen unbekannter Konzentration
Authors: Floßdorf Josef , Süßenbach Ute
Published: April 2003

Partial specific volumes are usually evaluated from the dependency of the solution density on the concentration of the solute. For this purpose, the mass concentrations must be known. Here we propose a method that does not require the knowledge of the absolute concentration, but rather that of any quantity proportional to it, e. g. optical density or refractive index. Two runs of measurements in solvents of different densities will not only yield accurate values of the partial specific volume, but additionally the coefficient that relates the absolute density to the quantity used, that is the absorption coefficient of the refractive index increment, respectively, in the just mentioned examples. When small amounts of biogenic material need to be recovered in their native state from the pycnometric measurements for further purposes, this method is of particular advantage.
Synthesis of oligopeptides by polymerization of aminoacetonitrile and α‐aminopropionitrile with sodium sec‐butoxide and subsequent hydrolysis
Authors: Ree Keiu , Minoura Yuji
Published: April 2003

The polymerization of aminoacetonitrile (AAN) and α‐aminopropionitrile (α‐APN) with sodium sec‐butoxide was carried out in an organic solvent. The resulting oligoamidines were converted to oligoglycine and oligo(α‐alanine), respectively, by subsequent hydrolysis. In the polymerization of AAN, a black by‐product containing conjugated CN bonds was formed. Oligoglycine and oligo(α‐alanine) were identified by IR and 1H NMR spectra, elemental analysis, thin layer chromatography, and hydrolysis. Their number average degrees of polymerization were determined to be 2,9 for oligoglycine, and to be 3,2 for oligo (α‐alanine) by determination of the N‐terminal group. It was found that the polymerization represents a consecutive addition.
Reaktion an ziegler‐natta‐katalysatoren, 16. Metathese‐abbau von polybutadien‐derivaten mit sauerstoff bzw. schwefel enthaltenden Substituenten
Authors: Hummel Klaus , Wedam Othmar A. , Kathan Wolfgang , Demel Hans
Published: April 2003

Methylene groups of 1,4‐polybutadiene were partially brominated with N‐bromosuccinimide. A subsequent Grignard‐Wurtz‐reaction with 4‐methoxyphenyl‐, 3,4‐dimethoxyphenyl‐, and 2‐thienylmagnesium bromide resulted in an exchange of the bromine atoms for 4‐methoxyphenyl, 3,4‐dimethoxyphenyl and 2‐thienyl groups. Another type of modification was the reaction of 1,4‐polybutadiene with 4‐methoxytoluene and o‐resp: p‐toluic acid methylester in the presence of dicumyl peroxide. Thereby 4‐methoxyphenylmethyl and 2‐ resp. 4‐methoxycarbonylphenylmethyl groups were introduced into the polymer. The modified polymers were investigated by IR‐spectroscopy and degraded by olefin metathesis with 4‐octene using a WCl6/Sn(CH3)4 catalyst. The degradation products were separated by gas chromatography and identified by mass spectrometry.
NMR studies of conformation and molecular motion of poly(methyl methacrylate) in solution
Authors: Inoue Yoshio , Konno Tetsuo
Published: April 2003

NMR shift reagent, tris(dipivalomethanato)europium(III), was applied to the 1H NMR measurement of isotactic and syndiotactic poly(methyl methacrylate) in solution in the temperature range 25–80°C. The solvents used were benzene (C6D6), chloroform (CDCl3), and carbon tetrachloride (CCl4). By comparing the observed values of paramagnetically induced shift with the values of geometric factor calculated for several kinds of conformational models hitherto proposed for these polymers, the possible conformations of the respective polymers in solution were eludicated. Furthermore the variation, as a function of temperature, of the carbon‐13 spin‐lattice relaxation times of individual carbons of isotactic and syndiotactic poly(methyl methacrylate) in benzene and chloroform solutions were measured and the correlation between the molecular motion and the conformation is discussed. It is pointed out that the conformation depends both on the stereochemical configuration and the nature of solvent, and the molecular motion depends both on the conformation and the configuration.
Polymer modification and synthesis using sulfenyl derivatives, 7. Mechanism of blocky sequence formation in adducts of benzene‐ and toluenesulfenyl chlorides with 1,4‐polybutadiene
Authors: Buchan Gavin M. , Cameron G. Gordon , Chishti S. Asif A.
Published: April 2003

The 50 per cent adduct of benzenesulfenyl chloride (1b) to cis‐1,4‐polybutadiene shows a two‐phase morphology as has been observed in the corresponding adduct of p‐toluenesulfenyl chloride (1a). These adducts appear to contain blocky structures which may form if the sulfur atom on a reacted monomeric unit can activate the olefinic bond of an adjacent, unreacted monomeric unit. Kinetic and model compound studies on the additions of 1a and 1b to polybutadiene support this explanation. The activating mechanism does not operate during addition of 2‐nitrobenzenesulfenyl chloride (1c) and 2,4‐dinitrobenzenesulfenyl chloride (1d), which, therefore, yield adducts with a single‐phase morphology.
Pendant‐type poly(4‐vinylpyridine)‐Cr(III) and ‐Co(III) complexes
Authors: Nishide Hiroyuki , Hata Seiji , Tsuchida Eishun
Published: April 2003

Pendant‐type poly(4‐vinylpyridine) (PVP)‐Cr(III) complexes (1) and ‐Co(III) complexes (2) with various degrees of coordination (x) were prepared, and the structures and properties of the polymer complexes are discussed. The magnetic susceptibility of 1 showed that 1 is paramagnetic and that the Cr(III) ions do not interact with each other, although they were coordinated along the PVP chain at high concentration. The far‐infrared absorption bands, assigned to the stretching of the coordinative bond between Co and the pyridine‐unit of PVP shifted to lower wave numbers in 2, as compared with the corresponding pyridine complex 4. It is thus considered that the coordinative bond in 2 is weaker than in the monomeric pyridine complex 4, owing to the steric hindrance of PVP; the Co(III) chelates coordinated at high concentration. This consideration is supported by the ESR parameters of 1. The dissociation temperature of the coordinative bond between Co and PVP increased with x. It is presumed that the PVP complex 2 has a rigid structure such that more energy is required to break the coordinative bond.
Non‐ideality in vinyl polymerisation, 1. Free‐radical polymerisation of styrene with benzoyl peroxide
Authors: Deb Pramil C. , Gaba Ishwar D.
Published: April 2003

Styrene was polymerised in benzene with benzoyl peroxide at 60°C covering a wide range of concentrations of both monomer and initiator. It is known that benzoyloxyl radicals obtained from spontaneous decomposition of benzoyl peroxide are susceptible to secondary dissociation because of high average life‐time of the former radicals (≈10−9 s). Mathematical formulation is presented regarding the effect of secondary dissociation and monomer concentration on the characteristic constant of primary radical termination. The graphical procedure presented here without recourse to induced decomposition of the initiator is found to be a simple but reasonably accurate method for determining the ratio of rate constants of secondary dissociation to initiation. Polymerisation data obtained also at 40, 50, 70, and 80°C for 6 mol/l of monomer in benzene has been utilised to estimate the approximate value of the energy of activation for initiation. The value so obtained (≈74kJ/mol) is substantially higher than that for propagation. This is apparently due to the structural difference of the radicals reacting with the monomer.
Radical polymerization and copolymerization of some vinyl phosphates
Authors: Hayashi Kazuko
Published: April 2003

Diethyl vinyl phosphate (1), diphenyl vinyl phosphate (2), and phenyl divinyl phosphate (3) were prepared, and their polymerization and copolymerization behaviors as well as the hydrolysis of the polymers obtained were investigated. The monomers 1 and 2 were homopolymerized to give low molecular weight polymers, probably as a result of high chain transfer reactivity to monomer. Although the monomer 3 gave a cross‐linked polymer, this polymerization was found to proceed mainly by a cyclopolymerization mechanism to give a polymer with a five‐membered ring unit which was readily hydrolyzed. The alkaline hydrolysis of poly(1) occurred only partly and thus pure polyvinyl alcohol was not obtained. From the copolymerizations of 1 and 2 with vinyl monomers such as vinyl chloride, the reactivities of these monomers were found to be somewhat lower than that of vinyl acetate.
Polymerization of anhydro sugar derivatives. Cationic polymerization of 5,6‐anhydro‐1,2‐O‐isopropylidene‐α‐D‐glucofuranose and structure of the polymer
Authors: Uryu Toshiyuki , Kitano Kissho , Tachikawa Hiromichi , Ito Katsuhiro , Matsuzaki Kei
Published: April 2003

The cationic polymerization of 5,6‐anhydro‐1,2‐O‐isopropylidene‐α‐D‐glucofuranose (1), containing an oxirane ring, gave a polymer whose structure was found to be poly(5,6‐anhydro‐1,2‐O‐isopropylidene‐α‐D‐glucofuranose) (2). Polymerizations with phosphorus pentafluoride, boron trifluoride etherate, stannic chloride, or antimony pentachloride below 10°C for 0,04 to 240h gave yields of 51,7 to 97,5% of polymers with M̄n in the range of 1290 to 9500. Polymerization above 20°C produced insoluble gels. The specific rotations of the polymers changed with the polymerization conditions, being in the range of −31,6° to −15,0°. The mechanism of the epoxide polymerization of the 5,6‐anhydro sugar derivatives is discussed.
The influence of intermolecular interactions on the polymerization, 1·1H NMR investigation of solutions of naphthalene and methyl methacrylate, of 2‐naphthyl methacrylate, and of 1‐naphthyl methacrylate
Authors: Boudevska Hrissanta , Brutchkov Christo , Koleva Vera
Published: April 2003

The solutions of methyl methacrylate (MMA) and naphthalene (N), of 2‐naphthyl methacrylate (2‐NM) and of 1‐naphthyl methacrylate (1‐NM) in chloroform, acetone, acetonitrile and N,N‐dimethylformamide are studied by 1H NMR spectroscopy. In chloroform and in pure MMA, N causes a shift of the signal of the high field vinyl proton Ha of MMA to higher field, whereas in acetone and acetonitrile the signal of Ha has the τ‐value for MMA in the absence of N. The Ha signals of 2‐NM and 1‐NM in acetone, acetonitrile and N,N‐dimethylformamide shift downfield as compared with those in chloroform. The τ‐value of the downfield vinyl proton Hb does not vary with a change of the solvent. The separation of the vinyl signals Δ=τ(Ha)—τ(Hb) becomes equal to that of pure MMA.

The formation of 1:1 complexes between the electron donating naphthalene ring and the electron accepting methacrylic double bond is assumed. The stability constant of the MMA‐N complex is 0,22 1.mol−1. Some structures for the complexes are proposed on the basis of molecular models of the monomer molecules. The results confirm the known theories for the influence of the solvents in radical polymerization of MMA. They can explain the kinetic changes of polymerization of 2‐NM and 1‐NM.
Subkatalytische effekte im system isopren/oligoisoprenyllithium/N,N,N′N′‐tetramethylethylendiamin, 2. Umsatzabhängigkeiten der molekulargewichtsverteilung und mikrostruktur der polymere
Authors: Davidjan Asya , Nikolaew Nikolai , Sgonnik Vladimir , Belenkii Boris , Nesterow Vladimir , Krasikow Valerii , Erussalimsky B.
Published: April 2003

Molecular weights and structural characteristics of the polymers formed in the system isoprene/oligoisoprenyllithium (OILi)/N,N,N′,N′‐tetramethylethylenediamine (TMD)/hexane (mole ratio TMD/OILi‐0,01) at various conversions at −30°C were determined. The applied conditions made it possible to judge the relative activity of various types of growing chains. The results obtained suggest an opposite influence of the complex formation with respect to the associated and non‐associated organolithium compounds. It was found that the former are activated (in comparison to the non‐complexed associates), whereas the latter (in comparison to the non‐complexed monomeric forms MnLi) become less active by complex formation. The possible causes of this different behaviour are considered.
15N NMR spectroscopy, 813C and 15N NMR investigation on cis and trans amide groups in polyamides and lactams
Authors: Kricheldorf Hans R. , Schilling Gerhard
Published: April 2003

Natural abundance 15N NMR spectra of various aliphatic lactams and of the corresponding polyamides were measured in trifluoroacetic acid. Cis and trans amide bonds were found to have nearly identical shifts and identical 1JNH coupling constants. Increasing chain length of the monomeric units and increasing ring size result in a downfield shift of the 15N signals. The 13C NMR spectra display, on the other hand, remarkable shift differences for lactams and Nylons. The polyamides show a monotonic downfield shift of the carbonyl signal with increasing chain length of the monomeric unit in contrast to the lactams. The 13C NMR spectra of the lactams were measured in various solvents; they show a downfield shift of the carbonyl signals with increasing acidity of the solvent. Protic solvents also favor strongly the cis‐form of 1‐aza‐2‐cyclononanone over the trans‐form.
15N NMR spectroscopy, 9. Solvent effects on polypeptides and polyamides
Authors: Kricheldorf Hans R.
Published: April 2003

Natural abundance 15N NMR spectra of Nylon‐2 to Nylon‐8 were measured in 2,2,2‐trifluoroethanol, formic acid, trifluoroacetic acid, and fluorosulfonic acid. The 15N NMR spectra of several sequence polypeptides containing Gly‐Gly units were measured in the same solvents depending on their solubility and chemical stability. The shifts of these polymers were compared with each other and strong downfield shifts (up to 20 ppm) were found with increasing acidity of the solvents. The downfield shift was more pronounced in the case of ω‐aminoacyl units when compared with α‐amino acid residues. ϵ‐Caprolactam shows shift effects that parallel those of Nylon‐6. Polysarcosine, poly(L‐lysine) (5), iso‐poly(L‐lysine) (6) and the sequence polymer (Tau‐ϵ‐Aca)n (7) were measured in dimethyl sulfoxide, water, formic acid, and trifluoroacetic acid. Polysarcosine, like polyglycine, shows comparatively small shift effects on changing the solvent, and polylysine as well as isopolylysine behave also similarly to other polypeptides, despite their charged side chains. With respect to solvent effects the sulfonamide group of 7 behaves differently from all other amide groups. The solvent effects are mostly explained by hydrogen bonds and protonation of the amide group.
Enzymes immobilisées, 10. Immobilisation de la trypsine sur des perles de copolymères d'acroléine et de N‐vinylpyrrolidone
Authors: Brown Eric , Racois André , Grimaud Edouard , Lecoq Jean‐Claude , Tixier René , Corgier Monique
Published: April 2003

The copolymerization in inverted emulsion of acrolein with N‐vinylpyrrolidone is described. The resulting copolymer, called VINAC, was obtained as spherical hydrophilic beads. VINAC was successfully used to immobilize trypsin, presumably via imine bond formation. The water‐insoluble enzyme derivatives thus obtained have a total enzymatic activity which can reach the value of 29% in certain cases.