bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the structure of radically obtained maleic anhydride/C4‐alkene copolymers
Authors: Bortel Edgar , Stysło Maria 
Published: April 2003

AbstractThe radical heterophase copolymerization of maleic anhydride (1) with isobutene (2), 1‐butene (3) or with a petrochemical C4‐fraction free from butadiene (C4) yielded copolymers with a molecular weight of 424 · 103, 291 · 103 and 190 · 103 g/mol, respectively. The structures of poly(1‐co‐2), poly(1‐co‐3) and poly(1‐co‐C4) obtained were elucidated by 13C NMR, 1H NMR and IR spectroscopy. Irrespective of whether 2, 3 or C4 was used as comonomer, the appropriate 13C NMR, 1H NMR and IR spectra proved to be essentially identical. These spectra confirm the presence of the 1,1‐dimethylethylene structural units in the repeating units of each of the copolymers investigated. Thus, the radical copolymerization of 1‐butene with maleic anhydride is accompanied by a rearrangement within the 1‐butene molecule due to hydrogen and methyl shift.
X‐ray diffraction studies of monomeric and polymeric 5,7‐dodecadiynylene bis(N‐ethylcarbamate) (ETCD)
Authors: Downey Milton J. , Hamill Gregory P. , Rubner Michael , Sandman Daniel J. , Velazquez Christopher S. 
Published: April 2003

AbstractCrystals of the monomer and polymer of the bis‐ethylurethane of 5,7‐dodecadiyne‐l, 12‐diol (1 a, ETCD), systematic name: 5,7‐dodecadiynylene bis(N‐ethylcarbamate) have been studied by X‐ray powder and single‐crystal photographic techniques. Lattice constants at 20°C were obtained from both single‐crystal and powder data and are in satisfactory agreement with a previous report. Lattice constants at 130–135°C were obtained from powder data and reveal that the lattice expands in volume by 4% on heating from 20°C, in contrast to a previous report which indicated a volume contraction on heating. Rotation photographs of poly(ETCD) crystals before and after extraction of unpolymerized monomer with boiling methanol reveal that solvent extraction renders many reflections more diffuse. Weissenberg h0l‐photographs of the polymer reveal sufficient disorder so as to preclude a high‐precision structural determination. Rotation and Weissenberg photographs of monomeric ETCD at 20°C manifest the major reflections of the polymer.
Polymeric phthalocyanines and their precursors, 15. Syntheses of alkylenedioxy bridged polymeric phthalocyanines and their absorption capacities for organic solvents in comparison to other phthalocyanines
Authors: Wöhrle Dieter , Schulte Bernd 
Published: April 2003

AbstractAlkylenedioxy bridged polymeric phthalocyanines 3a – d were synthesized by the reaction of the tetracarbonitriles 2a–d with copper(II) chloride or copper in bulk. As compared with other tetracarbonitriles the reactions applying 2a – d, which contain a flexible alkylene chain, run at relatively low reaction temperatures leading to good yields of polymers with a high degree of anelation of phthalocyanine rings (Pc > 100). In contrast to their low swelling factors and their low surface areas, polymeric phthalocyanines, with different bridging units between the chelate rings in the solid state exhibit good absorption capacities for organic solvents, mainly from the liquid state.
Drawing of ultra‐high‐molecular‐weight polyethylene in the melt. Influence of crystallization history
Authors: van Aerle Nick A. J. M. , Lemstra Piet J. 
Published: April 2003

AbstractUltra‐high‐molecular‐weight polyethylene (UHMW‐PE) can be drawn in the melt in a limited temperature range between the melting point of lamellar crystals, appr. 135°C, and the orthorhombic → hexagonal phase transition temperature, at appr. 155°C. In this particular temperature range, referred to as region 2, drawing results in the formation of a composite structure composed of fibrous crystals as a result of strain‐induced crystallization of the high molecular weight fraction, embedded in a melt of lower molecular weight material. After cooling to room temperature, this latter fraction crystallizes using the fibrous crystals as crystallization nuclei. The resulting structure exhibits a shish‐kebab morphology. Solution‐crystallized as well as melt‐crystallized UHMW‐PE samples were studied with respect to draw efficiency and structure formation during deformation in the melt.
Polymeric chiral crown ethers, 2. Syntheses and chiral recognition of polymers consisting of (S)‐ or (R)‐2,2′‐binaphthyl‐21‐crown‐6 units through cyclopolymerization of divinyl ethers
Authors: Kakuchi Toyoji , Sasaki Hiroshi , Yokota Kazuaki 
Published: April 2003

AbstractOptically active divinyl ethers, (−)‐(S)‐ and (+)‐(R)‐2,2′‐bis[2‐(2‐ vinyloxyethoxy)ethoxy]‐1,1′‐binaphthyl [(S)‐1 and (R)‐1], were synthesized and polymerized with cationic catalysts. The resulting polymers are composed of only cyclic constitutional units, (S)‐ and (R)‐dinaphtho‐[2,1‐r:1,2‐t]‐1,4,7,11,14,17‐hexaoxaperhydrocyclohenicosen‐8,10‐ylene. Both (S)‐ and (R)‐polymers show nearly equal values of optical rotation, but in opposite directions. The ability of chiral recognition of the (R)‐polymer towards racemic primary alkylammonium salts was investigated with salts of 1‐phenylethylamine, valine, phenylalanine and phenylglycine, and found to be very similar to that of the corresponding model crown ether.
Influence of inter‐turn hydrogen bonding on the stabilization of the helical inclusion complex of amylose
Authors: Hui Yongzheng , Gai Yonghua 
Published: April 2003

AbstractTwo different modes of interaction between 2‐chloro‐N‐dodecylpyridinium iodide (CDPI) and randomly substituted methylamylose (MA), which is mainly composed of 2,3‐O‐methylamylose or 6‐O‐methylamylose (6‐MA), are reported. The fluorescence intensity of CDPI is enhanced and its reactivity toward alkaline hydrolysis is retarded upon the addition of MA. Both cases show a saturation‐type relationship with increasing concentration in the case of MA, indicating the formation of an inclusion complex. In addition to the contribution of hydrophobic‐lipophilic interaction, the intramolecular hydrogen bonding of the host may also play an important role in stabilizing its helical conformation, as proved by the fact that the dissociation equilibrium constant, Kd, evaluated from kinetic data, increases with increasing degree of substitution of MA. This deduction is confirmed by experiments using 6‐MA as the host instead of MA. With increasing concentration of added 6‐MA, a linear relationship for the fluorescence and a bell‐type profile for the hydrolysis of CDPI are found. These results can be interpreted by the solubilization of CDPI in 6‐MA micelles. As in the case of cyclodextrin, in each turn of the amylose helix, the primary hydroxyl groups are located on one side and the secondary groups on the other side. Therefore, in the case of 6‐MA, where the primary hydroxyl groups are completely blocked, the macromolecules lose the ability to adopt a helical conformation. In conclusion, inter‐turn hydrogen bonding is an important factor contributing to the formation and stabilization of the helical inclusion complex of amylose.
(5,10,15,20‐Tetraphenylporphyrinato)manganese acetate as a novel initiator for the ring‐opening polymerization of 1,2‐epoxypropane
Authors: Kuroki Masakatsu , Aida Takuzo , Inoue Shohei 
Published: April 2003

Abstract(5,10,15,20‐Tetraphenylporphyrinat o)manganese acetate (2) was found to bring about the ring‐opening polymerization of 1,2‐epoxypropane (3) (R2 = CH3) under mild conditions to give the polymer with a bimodal molecular weight distribution consisting of a sharp main peak and a small shoulder on the higher molecular weight side. The polymerization was found to proceed even in the presence of a protic compound such as an alcohol or a carboxylic acid to give the polymer with a unimodal very narrow molecular weight distribution. The number of the polymer molecules is in good agreement with the sum of those of 2 and the protic compound, demonstrating the “immortal” nature of polymerization.
Synthesis of amorphous films from phenylsilanes by plasma chemical vapor deposition
Authors: Nakamura Takashi , Sinigersky Vesselin A. , Hirano Tsuneo , Fueki Kazuo , Koinuma Hideomi 
Published: April 2003

AbstractPhenylsilane and methylphenylsilane were decomposed by an rf (radio frequency) glow discharge to investigate the effect of aromatic substitution on the reactivity of the silanes as well as on the structures and properties of the deposited films. The spectral analyses and the optical band gaps of the films indicate that the films deposited at low rf‐powers have polysilane‐like chains with pendant phenyl groups, and that the films deposited at high rf‐powers are substantially silicon carbon alloys containing unsaturated carbon clusters. Although all the as‐deposited films are nearly insulators, the conductivities were improved by as such as six orders of magnitude by either a substitutional doping with diborane or a chemical doping with iodine.
Azo polymers — syntheses and reactions, 1. Terpolymers from styrene, butadiene and azo monomers
Authors: Nuyken Oskar , Weidner Richard 
Published: April 2003

AbstractTerpolymerization of styrene, butadiene and azo monomers yield polymeric azo initiators. The incorporation of the azo monomers into the terpolymers is almost ideal under “cold rubber” conditions, meaning that the composition of the products does not change with conversion. The retarding effect of some of the azo monomers is explained by the formation of hydrazyl radicals. This view is supported by experiments in which the azo monomers were replaced by model azo compounds.
Ordered and disordered glasses: A comparison of thermodynamical and dynamical properties
Authors: Jungbauer Dietmar A. , Wendorff Joachim H. , Kreuder Willi , Reck Bernd , Urban Claus , Ringsdorf Helmut 
Published: April 2003

AbstractCharacteristic dynamical properties of the glassy state were studied for side‐chain polymers in which either an isotropic glassy state or a nematic glassy state could be induced at will. The dynamical properties of such ordered and disordered glasses were found to be identical. This may indicate that the decrease of the volume taking place at the isotropic‐nematic transition leaves the free volume unchanged. It was furthermore observed that the glassy state is able to stabilize a given structure both with respect to a first‐ and second‐order phase transition for kinetic reasons.
Copolymerization reactivities, electron structure and nuclear magnetic resonance spectra of vinylazoles
Authors: Ivashkevich Oleg A. , Gaponik Pavel N. , Bubel Oleg N. , Kovalyova Tamara B. 
Published: April 2003

AbstractData obtained on the electronic structure of a series of C‐ and N‐vinylazoles using the SCF MO method in MNDO approximation and analysis of the 13C and 1H NMR data as well as their copolymerization reactivity ratios in the copolymerization with styrene have shown individual correlations between the relative activity 1/r (r is the copolymerization reactivity ratio of styrene) and the chemical shifts of the terminal vinyl carbon atoms in 13 C NMR spectra, between 1/r and chemical shifts of the protons in trans‐position towards the substituent in 1H NMR spectra, and between 1/r and the net effective charges on the terminal vinyl carbon atoms for each type of monomers considered. The correlations obtained and the analyses obtained from the monomers studied within the modified Alfrey‐Price scheme indicate that the reactivity of vinylazoles in copolymerization is mainly influenced by two factors: the acceptor inductive effect of a substituent in the vinyl bond and the conjugation effect. These factors operate in a different manner for C‐ and N‐vinylazoles and determine their different reactivity in radical copolymerization with styrene.
Stereoassociation of poly(methyl methacrylate): Study on the complexation stoichiometry and structural characteristics of the aggregates
Authors: Katime Issa A. , Quintana José R. 
Published: April 2003

AbstractA study of the composition of a poly(methyl methacrylate) (PMMA) stereocomplex and the structure of the stereocomplex particles is described. The study was conducted in dilute solutions of tetrahydrofuran (THF), using polymer pairs of an isotactic (ISO) and two syndiotactic (SYN) poly(methyl methacrylate)s of different tacticity. Gel permeation chromatography measurements of the stereocomplex obtained from mixing ISO and SYN‐1 give an optimum ratio of 1:1,5, while for the other polymer pair (ISO/SYN‐2) this relation ranges between 1:2,5 and 1:4. As the tacticity of the syndio‐PMMA samples decreases the optimum ratio increases. The study of the structure of the particles was performed by light scattering measurements of the stereocomplex fractions obtained at the outflow of the chromatographic system. The stereocomplex particles show an exponential relationship between the radius of gyration RG and the molecular weight M, viz. RG = K · Ma which is not very far from that of the linear unperturbed dimensions of PMMA. The numerical value of the exponent a being lower than 0,5 suggests a slight tendency towards the spherical shape of pseudobranched structures expected for these aggregates.
New polymer syntheses, 30. Thermotropic polyesters of 2‐(2‐naphthylthio)terephthalic acid
Authors: Kricheldorf Hans R. , Döring Volker , Beuermann Ilka , Eckhardt Volker 
Published: April 2003

Abstract2‐(2‐Naphthylthio)terephthalic acid (3 b) was synthesized from 2‐naphthalenethiol and dimethyl 2‐nitroterephthalate. Homopolyesters of this diacid were prepared by thermal condensation with the diacetates of hydroquinone or 4,4′‐biphenyldiol. Copolyesters were obtained by concondensation with 4‐acetoxybenzoic acid. For comparison a homopolyester was prepared from 2‐(2‐naphthyloxy)terephthalic acid and hydroquinone. DSC measurements and microscopic observation under polarized light revealed that the homopolyesters are semicrystalline and form a nematic mesophase above their melting points. The polyester from 3 b and hydroquinone crystallizes significantly more rapidly than the polyester of 2‐(2‐naphthyloxy)terephthalic acid. All copolyesters are amorphous and form a nematic phase between the glass‐transition temperature (130 –140°C) and the temperature at which rapid thermal decomposition takes place (470 ± 10°C). The polyesters were also characterized by elemental analyses, viscosity measurements, thermomechanical analyses and thermogravimetry.
Copolymerisation von acetylen mit acetylenderivaten, 2. Copolymerisation von acetylen mit 3,3‐dimethyl‐1‐butin
Authors: Kanischka Gerd , Höcker Hartwig 
Published: April 2003

AbstractThe coordinative copolymerization of acetylene with 3,3‐dimethylbutyne in toluene with MoCl5 was investigated. The copolymers were characterized spectroscopically as well as by means of gel permeation chromatography and differential scanning calorimetry. The copolymer composition was determined by means of the absorption coefficient of characteristic IR bands of 3,3‐dimethyl‐1‐butin. Planar polyen sequences can be determined by means of UV spectroscopy. The transformation temperatures for the copolymers are below the temperature obtained for the cis‐trans isomerization of pure polyacetylene. The molecular weight of the copolymers is lower than that of the copolymers of acetylene with phenylacetylene. The dependence of solubility and stability of the copolymers on the content of vinylene units shows the same tendency as observed for copolymers from acetylene and phenylacetylene; with increasing acetylene content the solubility decreases, while the instability increases. Increasing temperatures and light irradiation favour oxidation and degradation reactions. The oligomer fractions contain tert‐butylbenzene, 1,3‐ and 1,4‐di‐tert‐butylbenzene as well as 1,2,4,‐ and 1,3,5‐tri‐tert‐butylbenzene.
Synthesis and rheological study of some maleic acid and fumaric acid stereoregular polyesters, 3. Synthesis of a series of configurationally pure aliphatic polymaleates
Authors: Djonlagić Jasna , Sepulchre Marie‐Odile , Sepulchre Maurice , Spassky Nicolas , Jaćović Mihailo S. 
Published: April 2003

AbstractA series of aliphatic polymaleates was prepared by polycondensation of potassium maleate with α,ω‐dibromoalkanes Br(CH2)n Br (n = 1, 2, 3, 4, 5, 6, 8 and 10) in 1‐methyl‐2‐pyrrolidone. In practically all cases the formation of high‐molecular‐weight polyesters is accompanied by the production of substantial amounts of cyclic oligomers. This polycondensation reaction, carried out at moderate temperature, allows to obtain configurationally pure polymaleates. The resulting unsaturated polyesters are highly viscous liquids with glass transition temperatures below room temperature.
Synthesis and structural study of an ABA block copolymer consisting of poly(γ‐benzyl l‐glutamate) as the A component and poly(propylene glycol) as the B component
Authors: Cho Chong‐Su , Kim Seon‐Woong , Sung Yong‐Kiel , Kim Kae‐Yong 
Published: April 2003

AbstractABA type block copolymers composed of poly(γ‐benzyl L‐glutamate) (PBLG) as the A component and poly(propylene glycol) as the B component were obtained by polymerization of γ‐benzyl L‐glutamate N‐carboxyanhydride, initiated by amine groups at both ends of poly(propylene glycol). From circular dichroism measurements in ethylene dichloride solution as well as from infrared spectra measurements in the solid state, it was found that the polypeptide block exists in the α‐helical conformation, as in PBLG homopolymer. Wide‐angle X‐ray diffraction patterns for the block copolymers depend on the casting solvent and show basically similar reflections as the PBLG homopolymer.
Light scattering as tool for the determination of adiabatically performed temperature changes
Authors: Kiepen Friedheinz , Borchard Werner 
Published: April 2003

AbstractThe temperature changes caused by adiabatic pressure changes were studied in a polymersolvent system at high pressures. It is shown that the temperature determination by means of light scattering measurements is in good agreement with thermodynamic calculations of the temperature change for adiabatic pressure changes. The directly measured temperature changes by use of a thermocouple are found to be far too small.
Macrocyclization equilibria in polycycloolefins
Authors: Suter Ulrich W. , Höcker Hartwig 
Published: April 2003

AbstractMacrocyclization equilibrium data from metathesis reactions of cycloolefins (cyclobutene, cyclooctene, and cyclododecene) are compared with predictions of a novel, simple rotational isomeric state (RIS) scheme for polyalkenes with at least three single bonds between adjacent double bonds. The predictions agree with experiment within the combined experimental errors, supporting the conformational models and confirming that macrocyclization equilibrium has indeed been established in the metathesis reactions.
Urea‐induced “denaturation” of a polymer membrane with poly(L‐glutamic acid) domains for permeation
Authors: Chung Dae‐won , Maeda Mizuo , Inoue Shohei 
Published: April 2003

AbstractThe effect of urea on the permeability was investigated for potassium ion, phenyl‐1,2‐ethanediol, and sugars for a membrane from the graft copolymer 3a containing poly(butyl methacrylate) and poly(L‐glutamic acid) moieties and having polypeptide domains for permeation. The membrane treated with urea shows an increase in permeability and diminishes its ability to recognize the molecular size of permeating sugars, owing to a conformational change of the poly(L‐glutamic acid) chains induced by urea.
Unperturbed dimensions of polymers in binary and ternary systems
Authors: Tejero Roberto , Gómez Clara , Celda Bernardo , Gavara Rafael , Campos Agustin 
Published: April 2003

AbstractThe unperturbed dimensions parameter KΘ is one of the most important characteristics of a polymer chain. For binary systems (polymer/solvent) and mostly for ternary systems (polymer/solvent(1)/solvent(2)) the KΘ values show large discrepancies with respect to those under thetaconditions in a single solvent. These discrepancies can be explained by considering that the interaction parameter χ (and consequently the coil dimensions or the number of intramolecular contacts between polymer segments) changes with molecular weight M. Assuming this dependency, a modified Stockmayer‐Fixman equation is proposed from which a unique value of KΘ for a given polymer, independent of M, is obtained. The use for ternary polymer systems of an interaction parameter between polymer and the solvent mixture (χ3M) which depends on M, allows to calculate a single KΘ value for a polymer in different mixtures of solvents and justifies the proportionality found between KΘ deviations and the excess Gibbs free energy between both solvents of the solvent mixture.
Prediction of second virial coefficients from intrinsic viscosities in ternary polymer systems
Authors: Celda Bernardo , Gavara Rafael , Gómez Clara , Tejero Roberto , Campos Agustin 
Published: April 2003

AbstractDeviations in the determination of the unperturbed dimensions of polymers arising in ternary polymer systems (solvent (1)/solvent (2)/polymer) can be explained by the inaccurate use of an interaction parameter independent of polymer molecular weight. On this basis, a new formalism for the calculation of the second virial coefficient from intrinsic viscosity is proposed. This formalism was tested (and compared with well established formalisms) for all ternary polymer systems with simultaneous intrinsic viscosity and second virial coefficient data in the literature.
EPR spectrum of radicals produced in the thermal decomposition of tetrakis(p‐methoxyphenyl)succinonitrile
Authors: Szőcs Ferenc , Plaček Jan , Eichholz Hermann , Braun Dietrich 
Published: April 2003

AbstractThe thermal decomposition of tetrakis(p‐methoxyphenyl)succinonitrile (1) results in two identical cyanobis(p‐methoxyphenyl)methyl radicals (2). The hyperfine structure constants of the EPR spectrum of 2 were determined and a computer simulated spectrum was found to be in good agreement with the experimental one. The spin density at the central carbon atom is some‐what lower than that of the cyanodiphenylmethyl radical.
Polyuréthannes à propriétés émulsifiantes et électrolytiques, 1. Cinétique de condensation des alkylimino‐2,2′ diéthanols et de leurs dérivés sulfobétaïniques avec divers monoisocyanates
Authors: Gerard Jean‐François , Perchec Pierre Le , Pham Quang Tho 
Published: April 2003

AbstractThis work deals with model reactions allowing the synthesis of low‐molecular‐weight polyurethanes with electrolytic and emulsifier properties. The kinetics of addition reactions of 2,2′‐alkyliminodiethanols (3a – c) and their ammonium sulfonate derivatives 5 and 6 with propyl (8a) and cyclohexyl isocyanate (8b) were studied in DMSO and in the bulk. The tertiary amino groups of 3 exhibit catalytic effects, whereas the ammonium sulfonate internal salts inhibit the reaction. 8a is 2 – 3 times more reactive than 8b and the addition rates decrease with increasing R. Autoassociations (OH ··· OH) should mainly be intramolecular because of the proximity of the alcohol groups. In bulk the 8a + 3 additions apparently follow second order kinetics. On the other hand, the third order law must be taken into account with 8b. In contrast, in DMSO, due to the strong (solvent, OH and/or NCO) complexations, the kinetics do neither follow the simple second order, nor the third order law. By the use of two successive second order kinetics, diols were found more reactive than their monoalcohol‐monocarbamate derivatives. However, the difference in reactivity decreases with increasing reaction temperatures. Sulfobetaine units may be inserted into the polyurethane chains if diols with ammonium sulfonate groups are used as comonomer, but their weak reactivity must be taken into account.