bluuebunny/crossref_metadata_2025_split huggingface dataset:
Donor acceptor interactions in polymeric systems, 7. Structure matching effect in interpolymer EDA complex formation
Authors: Tazuke Shigeo , Nagahara Hajime 
Published: April 2003

AbstractInterpolymer EDA complex formation between polyesters bearing pendant carbazolyl groups and polyurethanes bearing pendant trinitrofluorenonyl groups was investigated in dioxane at 25°C. Complex formation depends on the degree of polycondensation (DP) as well as on structure matching of polymeric D and polymeric A. With increasing DP, the solubility of the D polymer‐A polymer mixture trends to decrease. Even when the polymer complexes do not precipitate, the Ketelaar's plots do not always fall on a straight line. These phenomena were interpreted as due to higher order complex formation and/or dependence of the formation constant on the fraction of saturation. It was found that polymeric donor acceptor pairs in which the number of atoms in a repeating main chain unit are identical for D and A polymers form a stronger complex than other combinations. It was concluded that structure matching of an interacting pair is a favourable condition to form tight complexes as in the case of antigenantibody interactions.
Syntheses and properties of poly(iminoethylene) derivatives containing nucleoside moieties
Authors: Murakami Akira , Konishi Yoshiyuki , Shimidzu Takeo 
Published: April 2003

AbstractCationic polynucleotide model compounds such as poly[N‐(adenosin‐5′‐yl)iminoethylene hydrochloride‐co‐N‐(5‐ribosyl)iminoethylene hydrochloride‐co‐iminoethylene] (1a) and poly‐[N‐(uridin‐5′‐yl)iminoethylene hydrobromide‐co‐N‐(5‐ribosyl)iminoethylene hydrobromide‐co‐iminoethylene] (1b) were synthesized by alkylation of linear poly(iminoethylene) with 5′‐chloro‐5′‐deoxyadenosine and 5′‐bromo‐5′‐deoxyuridine, respectively. In aqueous solution the adenine moieties of 1a are stacked one above the other, whereas the uracil moieties of 1b are scarcely stacked. These model compounds interact with mononucleotides at relatively low concentration (0,5 mmol.dm−3). The magnitudes of UV hypochromicities are decreasing for the various systems in the order of purine/purine > purine/pyrimidine > pyrimidine/pyrimidine. Stacking is the dominant mode of base‐base interaction.
Syntheses and properties of polysaccharide‐type polymers, 4. Synthetic polysaccharides containing amino groups
Authors: Komada Hajime , Okada Masahiko , Sumitomo Hiroshi 
Published: April 2003

AbstractNew Polysaccharide‐type polymers containing amino groups in their main chains were synthesized by chemical modification of poly(5,6‐dihydro‐2H‐pyran‐6,2‐diyloxymethylene) (2). Thus, the unsaturated polyacetal 2, having a dihydropyran ring in the repeating unit, was obtained by ring‐opening polymerization of 6,8‐dioxabicyclo[3.2.1]oct‐3‐ene (1), and it was epoxidized with m‐chloroperoxybenzoic acid followed by the reaction of the epoxide with ammonia or dimethylamine in aqueous solutions to yield polysaccharides containing the corresponding β‐aminoalcohol groups (4a and 4b). Visible spectroscopy revealed that 4a and 4b interacted with copper(II) ion in aqueous solutions. A qualitative biological test showed that both 4a and 4b inhibited the growth of microorganisms. Sulfated derivatives of 4a and 4b were prepared by reaction of 4a and 4b with chlorosulfuric acid in formamide. Their anticoagulant activities were evaluated by the “Activated Partial Thromboplastin Time (APTT) method” and compared with that of dextran sulfate.
Structure and properties of segmented poly(ether esters), 4. Compatibility of oligo(tetramethylene terephthalate)s with oligoethers and block copoly(ether ester)s
Authors: Hässlin Hans‐Walter , Dröscher Michael 
Published: April 2003

AbstractThe mutual compatibility of oligo(tetramethylene terephthalate)s 1a—d and their compatibility with oligoethers 2, 3, and 4 and block copoly(ether ester)s 5a—c based on poly(tetramethylene terephthalate) and poly(oxytetramethylene) is reported. From the binary phase diagrams of the oligoesters it is concluded that the oligoesters do not cocrystallize and the melt of the lower melting compound is not a good solvent for the higher melting homologue. For the trimer/pentamer (1b/1c)‐blend the eutectic composition contains 3 mole‐% of the pentamer 1c. Oligo(oxytetramethylene) (3) is a better solvent for the oligoesters than oligo(oxyethylene) (2). The addition of an oligoester to the block copoly(ether ester) induces a change in the phase behaviour of the polymer, resulting in a melting point of the blend higher than for the pure polymer or oligomer.
Helix‐coil transition of poly(γ‐benzyl‐L‐glutamate) in a mixture of dichloroacetic acid/1,2‐dichloroethane
Authors: Roots Jaan , Edsman Katarina , Nyström Bo 
Published: April 2003

AbstractThe thermally induced inverted helix‐coil transition of poly(γ‐benzyl‐L‐glutamate) (M̄w ≈ 320 000) in a mixture of dichloroacetic acid/1,2‐dichloroethane (80/20 w/w) has been observed by the temperature dependence of both the refractive index increment and the partial specific volume; the transition is centered around 31°C. A correlation of the refractive index increment and the partial specific volume data, utilizing an equation based on the Onsager‐Böttcher theory, had no significant success.
Influence of sensitisers on the photostabilising action of a hindered piperidine compound in polypropylene
Authors: Allen Norman S. 
Published: April 2003

AbstractThe influence of prior thermally generated hydroperoxides and added anthraquinone have been examined on the photostabilising action of a hindered piperidine compound, bis(2,2,6,6‐tetramethyl‐4‐piperidinyl) sebacate, in polypropylene film using ESR spectroscopy and flash photolysis techniques. The hindered piperidine compound was found to effectively inhibit both the hydroperoxide and carbonyl group sensitised photooxidation of the polymer. Using ESR spectroscopy evidence is presented to show that the hindered piperidine compound reacts stoichiometrically with the hydroperoxide groups generated by thermal oxidation to give a stable nitroxyl radical. On flash photolysis of anthraquinone in hexane transient formation due to the semi‐quinone radical and subsequent formation of the hydroquinone were found to be effectively inhibited by a stable N‐oxyl radical compound but not the amine. It is concluded that the nitroxyl radical is the effective stabilising species and operates by a radical scavenging mechanism to form the hydroxylamine.
Biosoluble polymers for drug delivery
Authors: Singh Maninder , Vasudevan Padma , Ray Alok R. , Guha Sujoy K. 
Published: April 2003

AbstractThe immobilization of α‐chymotrypsin on periodate oxidized cellulose as a biocompatible carrier was investigated. The properties and release of the enzyme from the polymer were studied. It was found that after an initial spurt, the amount of the released enzyme attains a practically constant value and the released enzyme retains its activity and shows increased heat stability. Such systems may be useful for a slow delivery of drugs and enzymes in the body.
Micellisation de copolymères séquencés polystyrène‐polyvinylpyridinium, 1. Méthodes d'études. Influence de la nature du solvant
Authors: Selb Joseph , Gallot Yves 
Published: April 2003

AbstractThe dilute solution properties of polystyrene‐poly(4‐vinyl‐N‐ethylpyridinium bromide) block copolymers (PS‐PVPQ) are studied in solvents selectively solvating polyelectrolytic moieties (mixtures: water‐methanol‐0,1 M LiBr). For these multicomponent systems, the validity of the data given by light scattering, viscosity and sedimentation velocity measurements, is discussed. Diblock copolymers exhibit four different types of behaviours, depending on solvent composition. The macromolecules are dissolved singly in methanol, but they are associated when water is present. When the water content increases, the association degree passes through a maximum. Since the solutions may contain two species of particles, i.e. the single molecules and the multimers with a narrow weight distribution, the term of micellization for this association phenomenon is correct. Despite their high “molecular weight”, the micelles are small and hence they are very compact. Unlike results from other micellar polymeric systems, the micelle occurrence is accompanied by an increase of the intrinsic viscosity. The hydrodynamic volume of a micelle does not depend on the micellar weights; this can be explained by a star‐like micellar model. Thus, the parameter determining the size of a micelle is not the number of molecules per micelle, but the length of the “branches”, i.e., the “soluble” blocks.
The structures of poly(vinyl fluoride) at elevated temperatures and after heavy rolling
Authors: Preedy John E. , Wheeler Ernest J. 
Published: April 2003

AbstractThe structures of poly(vinyl fluoride), (P(VF)), were investigated at elevated temperatures and after heavy rolling at various temperatures. In the former case the marked increases in both crystallite size and the unit cell a‐dimension above 140°C were accompanied by a reduction in crystallinity, indicating a melting and recrystallization process. When compared to the polyethylenes, thermal behavioural differences may be attributed to the polarity of the P(VF) molecules. Notable changes in deformation structure were obtained upon varying the rolling temperature. Above 60°C heavy rolling produced a hexagonal {1010} 〈0001〉 texture, the paracrystallites having a clearly oriented lamellar structure. At 60°C and below more complex textures were produced, the microparacrystallites of the predominant component having a platy morphology. At −80°C, the deformation structure also showed extensive voiding.
Synthesis of polydiphenylgermylene single crystals from diphenyldichlorogermane
Authors: Kong Eric Siu Wai , Wunderlich Bernhard 
Published: April 2003

AbstractPolymer single crystals with a germanium backbone have been synthesized. The synthesis involves a thermally induced generation of divalent radicals, transport of these radicals and subsequent addition polymerization on a cold surface. The polymerization was carried out under vaccum. Crystallization during polymerization was found to occur resulting in extended chain macromolecular crystals. These crystals were prismatic with a number‐average molecular weight of 11300. The melting range of the \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} ({\rm GePh}_2 \rlap{--})_{\rm n} $\end{document} crystals is 285 to 295°C. The glass transition temperature of the same polymer in its amorphous state was found to be 96°C (20°C/min heating rate using differential thermal analysis). The crystal structure of the intermediate octaphenylcyclotetragermane is compared to that of octaphenylcyclotetrasilane and polydiphenylgermylene.
Solid state polymerization and physical properties of crystalline complexes of phenazine and diacetylene‐monocarbonic acids
Authors: Tieke Bernd , Bloor David 
Published: April 2003

AbstractThe polymerization behaviour and physical properties of 2:1 complexes of 2,4‐diynoic acids and phenazine have been studied by optical and Raman spectroscopy and X‐ray diffraction. Models are proposed for the molecular arrangements in the pure acids and the complexes, which explain the unique ability of the phenazine to form complexes. The polymerization of the complexes proceeds via a homogeneous solid‐solution up to a limiting value of 65% polymer. During the reaction a rearrangement of the aliphatic side‐chains occurs, which affects the optical absorption of the polymer backbone.
Kinetics of polymerization of tetrahydrofuran initiated by acetyl perchlorate
Authors: Alamo Rufina , Guzmán Julio , Fatou José G. 
Published: April 2003

AbstractThe kinetics of the polymerization of tetrahydrofuran by acetyl perchlorate in methylene chloride solution was studied, and the results were compared with those previously reported by using perchloric acid/acetic anhydride as catalyst. The initiation and propagation mechanisms are discussed by taking into account the influence of the counterion. The initiation reaction takes place instantaneously, but the propagation proceeds by macroesters and macroions and the contribution of macroester to propagation is much lower than the contribution of macroions.
Préparation d'adsorbants chromatographiques plurifonctionnels et asymétriques. Application à la purification de la céphalosporine C
Authors: Sacco Daniel , Dellacherie Edith 
Published: April 2003

AbstractSome asymmetric and polyfunctional stationary phases were prepared by attachment of the ε‐amino group of L‐lysine copper complex to crosslinked polystyrene or agarose, substituted or not by hydrophilic spacer arms. After copper elimination, the sorbents exhibit three functions, one of a carboxylic acid and one of an α‐primary amine, and moreover one of a secondary amine located at a variable distance far from the asymmetric carbon, but near the backbone of polymer. These sorbents were tested in the chromatographic extraction of cephalosporin C (1) from an aqueous mixture containing several α‐amino acids. They exhibit an affinity higher for the antibiotic than for the amino acids and even for the dicarboxylic amino acids.
Recherche de télomères à activité pharmacologique potentielle, 2. Télomères de l'acide acrylique et greffage de composés hydroxylés
Authors: Bauduin Gérard , Bondon Daniel , Martel Jacques , Piétrasanta Yves , Pucci Bernard 
Published: April 2003

AbstractSeveral telomers of acrylic acid with carbone tetrachloride were prepared. Their average degree of polymerization, which was between 10 and 50, was determined by several analytical methods (elemental analysis, viscosimetry, and GPC). From the kinetic equations of telomerization a relation between DPn of these telomers and the experimental conditions is established. Fixation of hydroxylic compounds through direct esterification was studied and it was found that the prepared telomers can be used as hydrosoluble carriers for drugs containing primary alcohol or phenol functions.
Polystyrene‐immobilised imidazole ligands; synthesis and complex formation with transition metal salts
Authors: Welleman J. A. , Hulsbergen F. B. , Reedijk J. 
Published: April 2003

AbstractThe modification of polystyrenes (1 – 8% cross‐linked) by imidazole ligands, via chloromethylation, is described. The resulting resins, having 10–40% of the phenyl groups substituted by a CH2(N)‐imidazolyl group, have been treated with first‐row transition metal salts under varying conditions. Upon reaction of the modified polymer with the transition metal salts in CHCl3, a shrinking of the polymer is observed which is explained by additional cross‐linking by the metal ions. The final products have the general formula Mt(PS‐Iz)m(NnBuIz)nX2, in which PS‐Iz stands for a polystyrene‐bound imidazole ligand, NnBuIz forN‐butylimidazole (a ligand used to solubilize the metal salts in CHCl3) and X for the anion (perchlorate, nitrate, tetrafluoroborate, chloride, bromide). Metal ions used are Co(II), Ni(II), Cu(II), and Zn(II); values of 2–6 have been found formin most cases. The value ofnusually is very small (0,2–1,0) in most cases. Spectroscopically the polymeric coordination compounds behave like the corresponding monomeric coordination compounds, Mt(N‐benzylimidazole)mX2, indicating that the imidazole ligands in the polymer are quite flexible in their coordination behaviour, except in case of very low degrees of substitution or high degrees of cross‐linking.
Subkatalytische Effekte in Systemen Isopren/Organolithium/Elektronendonator, 3. System Isopren/Oligoisoprenyllithium/1,2‐Dimethoxyethan
Authors: Davidjan Asya , Nikolaew Nikolai , Sgonnik Vladimir , Krasikow Valerii , Belenkii Boris , Erussalimsky B. 
Published: April 2003

AbstractMolecular weights and structural characteristics of the polymers formed in the system isoprene/oligoisoprenyllithium (OILi)/1,2‐dimethoxyethane (DME)/hexane (mole ratio DME/OILi = 0,01) for various conversions at −30°C were determined. The results obtained corroborate the former conclusion that the complexation of an electron donor with the monomeric form of the growing chain reduces the reactivity of the latter.
Polymethacrylic acid Derivatives, 1. Preparation, Characterization, and Potentiometric study of poly(N‐methacryloyl‐L‐alanine‐co‐N‐phenylmethacrylamide)
Authors: Morcellet‐Sauvage Joëlle , Morcellet Michel , Loucheux Claude 
Published: April 2003

AbstractPoly(N‐methacryloyl‐L‐alanine) and poly(N‐methacryloyl‐L‐alanine‐co‐N‐phenylmethacrylamide) containing up to 38 mole‐% of N‐phenylmethacrylamide were synthesized by radical copolymerization. These polymers were characterized by UV and IR spectroscopy and by conductimetric titrations. The samples were then studied by potentiometric titrations in pure water and in aqueous organic solvents, in the temperature range of 5 ‐ 65°C. The experimental results show that, opposite to poly(methacrylic acid), poly(N‐methacryloyl‐L‐alanine) takes no compact structure in water. The insertion of N‐phenylmethacrylamide induces the appearance of this compact structure over 15 mole‐% of this residue. Thereafter, the stability of the compact structure increases when increasing the amount of N‐phenylmethacrylamide. Experimental results suggest that it is due to increasing Van der Waals interactions between the hydrophobic side chains.
Polymerisationsauslösung mit substituierten ethanen, 3. Struktur und Taktizität der Oligomeren aus Methylmethacrylat und 1,1,2,2‐Tetraphenyl‐1,2‐diphenoxyethan
Authors: Balard Henri , Błedzki Andrzej , Braun Dietrich 
Published: April 2003

AbstractThe 1H NMR‐spectra of MMA oligomers with two phenoxydiphenylmethyl end groups, 1, are discussed. The syndiotactic and isotactic dimers and two heterotactic and one syndiotactic trimer could be identified, whereas no isotactic trimer was found.
Effect of solvent on 13C NMR chemical shifts of tetrad methylene carbons of poly(vinyl chloride)
Authors: Ando Isao , Asakura Tetsuo 
Published: April 2003

AbstractThe 13C NMR chemical shifts of tetrad CH2 carbons of poly(vinyl chloride) are observed in solvents covering a wide range of relative dielectric constants and show extreme sensitivity to the solvent. The chemical shifts are interpreted theoretically by means of the solvaton‐CNDO/2 MO theory.
Comportement viscosimétrique des télomères acrylate d'éthyle/tétrachlorure de carbone
Authors: Piétrasanta Yves , Rigal Gérard , Schaeffner Pierre 
Published: April 2003

AbstractThe intrinsic viscosities of some acrylic telomers prepared by redox catalysis were measured with an Ubbelohde capillary viscosimeter. The variation of density during dilution appears to be a very important parameter. Thus, the viscosimetric results become coherent according to Huggins' theory on polymers, and a calibration curve available for the whole range of molecular weights can be established.
Functionalization of poly(ethylene glycol) and monomethoxy‐poly(ethylene glycol)
Authors: Bückmann Andreas F. , Morr Michael , Johansson Göte 
Published: April 2003

AbstractSimple methods are described for the substitution of poly(ethylene glycol) and monomethoxy‐poly(ethylene glycol) substitution. Affinity ligands, coenzymes, or enzymes can be covalently attached to the substitution product or they can be used as liquid ionexchangers.
Hydrogenation of alkenes, alkynes, and other substrates catalyzed by polymeric Pd(II) complexes of 2,3,6,7‐octanetetraone tetraoxime
Authors: Yukimasa Hidefumi , Sawai Hiroaki , Takizawa Takeo 
Published: April 2003

AbstractCoordination polymers prepared from 2,3,6,7‐octanetetraone tetraoxime and bis(benzonitrile)palladium dichloride catalyzed the hydrogenation of alkenes, alkynes, carbonyl compounds, azobenzene and other substrates with some selectivity. The catalytic activity and selectivity were dependent on the palladium content in the complex.
Molybdenum complexes with polymer‐bound cysteine and their catalysis in acetylene reduction
Authors: Koide Mikio , Suganuma Noriyuki , Tsuchida Eishun , Kurimura Yoshimi 
Published: April 2003

AbstractWater soluble polymers with cysteine residues (Pcys) were synthesized by the copolymerization of S‐benzyl‐N‐benzyloxycarbonyl‐4'‐vinyl‐L‐cysteineanilide and acrylic acid or methacrylic acid. These copolymers were reacted with Mo(V)2O to Mo(V)‐Pcys complexes with di‐μ‐oxo bridged binuclear structure. The absorption maximum of these complexes appears at 330 nm in aqueous solution. ESR study suggests that mononuclear Mo(III)‐Pcys complexes (g = 1,997) are formed by reduction of Mo(V)‐Pcys complexes with NaBH4. These Mo(III)‐Pcys complexes are effective catalysts for the reduction of acetylene in the presence of NaBH4 and their catalytic activities are 2—3 times greater than that of the corresponding low molecular weight Mocysteine complex. The higher activity of the polymer complexes is explained by the enhancement of the proportion of monomuclear species due to the stretching of the polymer chain caused by the electrostatic repulsions between the carboxyl anions on the side chains.
Die emulsionscopolymerisation von tetrafluorethylen mit propylen bei niedrigen temperaturen
Authors: Kojima Gen , Hisasue Michio 
Published: April 2003

AbstractTetrafluoroethylene and propylene were copolymerized in emulsion at low temperatures (≈25°C) by use of a redox catalyst containing ammonium peroxodisulfate, ferrous sulfate, ethylenediaminetetraacetic acid (EDTA) and hydroxymethane sulfinate. The kinetical study suggested that the working mechanism of the catalyst conforms the following scheme:
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where the reduction of the ferric ion seems to be rate determining (i.e. k1 ≫ k2) and the hydroxyl ion plays an important role. The overall polymerization reaction is supposed to proceed according to the Case I of the Smith‐Ewart theory under the experimental conditions examined.
1H and 13C NMR spectra of poly(propyl α‐bromoacrylate) and poly(methyl α‐bromoacrylate)
Authors: Hatada Koichi , Kitayama Tatsuki , Saunders Keith , Lenz Robert W. 
Published: April 2003

AbstractThe 13C NMR spectra measured at 25 MHz of the methyl and propyl esters of isotactic and syndiotactic poly(α‐bromoacrylate) were sufficiently resolved to be analysed for pentad tacticity sequences. The pentad tacticity of the syndiotactic polymers prepared with free radical initiators at −40°C agreed with those calculated for Bernoullian sequence distributions based on Pr values of 0,83–0,87. The tacticities of the isotactic polymers prepared with heterogeneous catalysts were determined on the basis of these assignments. Good internal consistency was obtained between the calculated and observed pentad proportions from the quaternary and carbonyl carbon peaks in the spectra of these polymers. The order of chemical shifts for the meso and racemic dyads and tetrads in these polymers were opposite to those found in the equivalent methacrylate polymers, but as with the latter, the 13C‐T1 values were longer in the isotactic than in the syndiotactic polymers.
Micellisation de copolymères séquencés polystyrène‐polyvinylpyridinium, 2. Influence des caractéristiques moléculaires des copolymères
Authors: Selb Joseph , Gallot Yves 
Published: April 2003

AbstractThe influence of the molecular characteristics of polystyrene‐poly(4‐vinyl‐N‐ethylpyridinium bromide) block copolymers (PS‐PVPQ) on their dilute solution properties is investigated in a solvent selective for polyelectrolytic moieties (water‐methanol‐0,1 mol/1 LiBr mixtures). It is shown that the association degree depends much more upon the length of the insoluble hydrophobic part of the macromolecule than on the length of the soluble hydrophilic part. Micelle dimensions could not be determined from light scattering measurements because of the compactness of the particles. Attempts for the calculation of micelle size were made using a star‐like micellar model.