bluuebunny/crossref_metadata_2025_split huggingface dataset:
Energy transfer and singlet energy migration in a polymer
Authors: Fouassier Jean‐Pierre , Lougnot Daniel‐Joseph , Faure Jean 
Published: April 2003

AbstractKinetic 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

AbstractIsotactic 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

AbstractOn 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

AbstractThe 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

AbstractStyrene 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

AbstractGraft 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

AbstractPoly(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

AbstractThe 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

AbstractPartial 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

AbstractThe 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

AbstractMethylene 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

AbstractNMR 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

AbstractThe 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

AbstractPendant‐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

AbstractStyrene 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

AbstractDiethyl 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

AbstractThe 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

AbstractThe 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

AbstractMolecular 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

AbstractNatural 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

AbstractNatural 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

AbstractThe 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.