bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biomedical behavior of synthetic polyion complexes toward blood platelets
Authors: Kataoka Kazunori , Tsuruta Teiji , Akaike Toshihiro , Sakurai Yasuhisa 
Published: April 2003

AbstractA group of polyion complexes (PICs) was checked as candidate for non‐thrombogenic biomaterials. To evaluate blood‐compatibility of different types of PIC, the interaction of the PICs with blood platelets was examined by passing fresh blood through a column packed with glass beads which were precoated with PIC. The course of morphological change of the platelets adhered on the surface was observed by scanning electron microscopy. The behavior (adhesion, aggregation, and deformation) of the platelets on the beads' surface was found to be significantly influenced by the mole ratio of polyanion to polycation in the PIC. The blood‐compatibility could be shown to depend also on the chemical structure of the polycation component of the PIC. Among the PICs examined, the newly synthesized PIC 5 showed the best results in terms of the number of adherent platelets and the degree of their deformation. The good blood‐compatibility of 5 is presumabley attributable to the easiness in getting to stoichiometric neutralization.
Polymere charge‐transfer‐komplexe auf der basis von polyvinylalkoholacetalen, 2
Authors: Geißler Ulrich , Schulz Rolf C. 
Published: April 2003

AbstractPoly[2‐(1‐naphthyl)‐1,3‐dioxan‐4,6‐diylmethylene] (3), poly[2‐(2‐naphthyl)‐1,3‐dioxan‐4,6‐diylmethylene] (5), 1‐naphthalenecarbaldehydetrimethyleneacetal (7) and 2‐naphthalenecarbaldehydetrimethyleneacetal (8) were synthesized and characterized by UV‐ and fluorescencespectroscopy. In addition triplet‐triplet absorption maxima and triplet‐lifetimes were determined by flash technique. The naphthalene derivates were found to act as donors in the charge‐transfer complex formation with such electron acceptors as tetracyanoethylene, 2,5‐cyclohexadien‐1,4‐diylidenedimalonodinitrile and 2,4,5,7‐tetranitro‐9‐fluorenone. The equilibrium constants of the charge‐transfer complexes were determined spectrophotometrically by the methods of Benesi‐Hildebrand, Benesi‐Hildebrand‐Scott and Foster‐Hammick‐Wardley.
Catalyst activation in the metathesis polymerization of cyclooctene
Authors: Finter Jürgen , Wegner Gerhard , Nagel Eric J. , Lenz Robert W. 
Published: April 2003

AbstractThe addition of unsaturated organic halides during the metathesis polymerization reaction of cyclooctene, using a WCl6/diisobutylaluminium chloride/2,6‐di‐tert‐butyl‐4‐methylphenol catalyst, was found to cause instantaneous conversion of the unreacted monomer to polymer. Both 1,2‐dichloroethene and 1,6‐dibromo‐3‐hexene were found to be very effective for this purpose. When 1,4‐dichloro‐2‐butene was added during the reaction, unusual and unexplained products were obtained, but when it was added to the catalyst before the start of the reaction a very fast polymerization occurred yielding high molecular weight polymers. Changes in polymer melting points with reaction time suggested that isomerization occurred after polymerization and that the initial polymers formed had slightly blocky, trans unit sequences.
Photo‐oxidative degradation and stabilization of isotactic poly(1‐butene) in solid state, 1
Authors: Chandra Ramesh , Singh Raj Pal 
Published: April 2003

AbstractThe kinetics of photo‐oxidative degradation and stabilization of poly(1‐butene), [poly(1‐ethylethylene), PB‐1] at 253, 7 nm and a constant intensity of 2,38·10−9 Einstein.s−1·cm−2 (1,12·10−3 J·mol−1·s−1·cm−2) was studied in the absence and presence of 0,1 wt.‐% 6‐(2‐hydroxyphenyl)‐2,4‐diphenyl‐1,3,5‐triazine (1) dispersed evenly in the matrix of polymer films in the temperature range of 267 to 313 K. The progress of the reaction was followed by measuring the rate of chain scission of the polymer. It has been confirmed by light scattering and potassium ferrioxalate actinometric measurements that random scission of the polymer chain occurs and 1 acts as a stabilizer to the photo‐oxidative degradation processes. Irrespective of the variations in the values of ΔH≠ and ΔS≠ the values of ΔF≠ remain almost constant around 159 kJ·mol−1 indicating that the rate determining step is the same for both systems.
Solution properties of poly(N‐1,1‐dimethyl‐3‐oxobutylacrylamide), 2. Excluded volume in 2‐butanone at 25°C
Authors: Chiantore Oscar , Guaita Marino 
Published: April 2003

AbstractThe excluded volume parameter B for poly(N‐1,1‐dimethyl‐3‐oxobutylacrylamide) in 2‐butanone at 25°C is evaluated either from limiting viscosity numbers or from second virial coefficients as obtained in light scattering measurements, and also through a procedure in which both kinds of experimental data are simultaneously employed. The values so obtained are in reasonable agreement, except for the one evaluated by applying the original Stockmayer‐Fixman equation, which is largely underestimated as already found for other polymer‐solvent systems.
Théorie des chaînes de markov et distribution moléculaire dans les copolycondensats linéaires, 3. Systèmes à n états
Authors: Durand Dominique , Bruneau Claude Marcel 
Published: April 2003

AbstractBy the application of Markov chains theory to stochastic graphs representing monodimensional macromolecular systems it is possible to study the molecular distribution of macromolecular systems. The use of matrix calculus leads to simple mathematical expressions for the different molecular distribution functions. These functions due to their generality can be applied to many different systems. They give in particular, the molecular distribution resulting from the coupling of linear primary polymers having themselves a given molecular distribution. Finally, in the mathematical model developed, it is possible to take into account the differences of reactivity between functional groups; thus, systems having intrinsically non‐equireactive functional groups and systems where the non‐equireactivity of the sites may be assigned to substitution effects can been studied with this model, the only consequence being an increase in the number of the possible states of the system.
Über lichtstreuergebnisse in polystyrol‐lösungen, 2. Einfluß von zeitlich variablen Struktureffekten
Authors: Woliński Leszek , Witkowski Konrad , Turzyński Zbigniew 
Published: April 2003

AbstractEvidence is given for changes of structure caused by the interaction of light of wavelengths i ≥ 270 nm with the molecules of polystyrene solutions in presence of atmospheric oxygen. The kinetics of the changes is followed by measuring the light scattering intensity, in order to investigate the influences of solvent and concentration. Beside photodissociation absorption effects are discussed.
Polymer oxidation and secondary cage combination of peroxyl radicals
Authors: Garton A. , Carlsson D. J. , Wiles D. M. 
Published: April 2003

AbstractThe photo‐oxidation of solid polymers at ambient temperatures is shown to be greatly affected by the low mobility of radicals in the solid state. When a radical pair, produced by photo‐initiation, escapes the initial polymer cage, the probability of its recombination remains high even after several propagation steps. This phenomenon, known as secondary cage recombination, has a pronounced effect on the kinetics of oxidation and on the mechanism of photostabilisation by radical scavengers. The occurrence of secondary cage recombination is demonstrated for polypropylene photo‐oxidation and a kinetic analysis is developed to predict the consequences of this effect.
Electrochemical oligomerization of sulfonanilides onto copper sheet anodes
Authors: Mengoli Giuliano , Musiani Marco M. , Daolio Sergio , Folonari Carlo 
Published: April 2003

AbstractMethanesulfonanilide and benzenesulfonanilide, salified by a suitable amine were electrolyzed with Cu sheets as anodes in water/organic solvent medium. Coherent insulating coatings on the Cu sheets were thus obtained, which on the basis of various analytical tests resulted to have an oligomeric structure. One electron oxidation of the anilide anions and carbonium‐nitrogen coupling of the intermediate free radicals are suggested as the main steps of anilides oligomerization.
Polymerization of vinyl monomers in the presence of the ethylaluminium dichloride‐p‐chloranil catalytic system
Authors: Florjańczyk Zbigniew , Kuran Witold , Lusztyk Ewa 
Published: April 2003

AbstractPolymerizations of acrylonitrile, methacrylonitrile, methyl acrylate, and methyl methacrylate initiated by the system ethylaluminium dichloride (EtAlCl2)‐p‐chloranil (PClA) were studied. The effect of the catalyst system components on the initiation, propagation and termination steps is discussed in terms of a free radical reaction mechanism. The catalytic system EtAlCl2‐PClA behaved similarly in the copolymerization of MMA with styrene as in the free radical homopolymerization of MMA. Polymerizations of vinyl monomers, not forming relatively stable complexes with EtAlCl2 (in contrast to acrylic and methacrylic monomers), such as vinyl chloride, styrene and isobutylene, were also studied in the presence of the EtAlCl2‐PClA system.
Studies with microgels as matrices for molecular receptor and catalytic sites: The exceptional reactivity of hydroxyaminocarbonyl groups in polymers with a high level of cross‐linking monomer feed
Authors: Weatherhead Richard H. , Stacey Kenneth A. , Williams Andrew 
Published: April 2003

AbstractA copolymer was prepared under emulsion conditions from a feed composed of methyl methacrylate, ethylene dimethacrylate, and 4‐nitrophenyl acrylate in the mole ratio 0,57:0,14:0,29, respectively. Treatment with hydroxylamine gave a modified polymer with carboxylic and hydroxyaminocarbonyl residues in the mole ratio 22:3,7. The polymer molecule had a diameter of 400 Å and an approximate molecular weight of 18 000 000. The polymer‐catalysed cleavage of 4‐nitrophenyl esters depends on the fraction of ionised hydroxyaminocarbonyl groups (FB), and at low values of FB the reactivity (kn = dk2/dFB) is some 30‐fold less efficient than that of monomeric hydroxamic acid of similar pKa. The value of kn increases with FB; at values of FB close to unity, kn exceeds that at low values by an amount in excess of 30 000. The value of kn at full ionisation is some 1 000‐fold larger than that of the monomeric species. The macromolecules are permeable to substrates despite the high percentage of cross‐linking, and it is proposed that the exceptional enhancement is due to the hydrophobic microscopic medium for the reaction of the last groups to ionise together with the high negative charge. It is proposed that the hydroxyaminocarbonyl groups with high reactivity are acting at the core of the macromolecule, whereas those at low values of FB are surface moieties. A cage effect also operates, holding the substrate in the vicinity of the nucleophile. The macromolecules exhibit an exclusion effect particularly marked for negatively charged substrates, which do not show significant curvature in plots of rate constant versus FB. 4‐Nitrophenyl caproate also does not exhibit a large activation with increase in FB, and this substrate may only be partially excluded from the macromolecular core.
Effect of chain composition of poly(ethylene terephthalate) structure and properties
Authors: Fakirov Stoyko , Seganov Ilija , Kurdowa Ewgenija 
Published: April 2003

AbstractThe effect of 2,2′‐oxydiethanol (diethylene glycol, DEG) content (ranging from 2 to 15 mol‐%) on unit cell dimensions, density, melting point, and small angle X‐ray scattering (SAXS) of undrawn and drawn annealed (in the range from 80 to 260°C) poly(ethylene terephthalate), (PET), is studied. It is established that the unit cell parameters are almost unaffected by the DEG content. A significant decrease of the melting point and the degree of crystallinity of PET is observed, however. A decrease of the density of fully amorphous copolyester is established too, which is important for calculating the crystallinity from density measurements. At the same time a remarkable increase of both SAXS intensity and long spacing is registered. It is assumed that the effect of bonded DEG on PET structure and properties can be explained by the predominating comonomer (DEG) units distribution in the amorphous regions–only a small portion of them is involved in the crystallites as lattice defects.
Effect of adjacent functional groups on the electron‐donor‐acceptor complex formation of diethyl 2,2‐bis(dinitrobenzyl)malonates and 2,2‐bis(4‐dimethylaminobenzyl)malonate
Authors: Ohno Naonori , Kumanotani Ju 
Published: April 2003

AbstractIn order to study the effect of adjacent functional groups on electron‐donor acceptor (EDA) complex formation, the following donor or acceptor compounds were synthesized: diethyl 2‐(2,4‐dinitrobenzyl)malonate (13), diethyl 2,2‐bis(2,4‐dinitrobenzyl)malonate (14), diethyl 2‐(3,5‐dinitrobenzyl)malonate (5), diethyl 2,2‐bis(3,5‐dinitrobenzyl)malonate (6), diethyl 2‐(4‐dimethylaminobenzyl)malonate (10), diethyl 2,2‐bis(4‐dimethylaminobenzyl)malonate (11). The acceptor compounds 5, 6, 13, and 14 were complexed with N,N‐dimethyl‐4‐dimethylaminoaniline (1) as donor, and the donor compounds 10 and 11, with 1,3,5‐trinitrobenzene (2) as acceptor. The wave length of the absorption maximum (λmax), the association constant (KCT), the enthalpy (δH), and entropy (δS) of these EDA complexes were determined. It was found that λmax of complexes 6–1 and 11–2 show a bathochromic shift compared with complexes 5–1 and 10–2, and the values of KCT, −δH, and −δS are higher. The value of λmax for complex 14–1 is not different from that of complex 13–1, and the values of KCT, −δH, and −δS are lower. It was concluded that the stability of the EDA complexes of the 2,2‐dibenzylmalonate derivatives 6, 11, and 14, is influenced by π‐electron interaction between the adjacent two benzene rings.
Synthesis and electrical properties of monomeric and polymeric iron‐phthalocyanines
Authors: Nalwa Hari S. , Sinha Jai M. , Vasudevan Padma 
Published: April 2003

AbstractA set of experimental conditions are described for the synthesis of monomeric and polymeric iron‐phthalocyanines and compared with those reported in the literature. The dielectric constant and resistivity of characterised samples are studied as a function of temperature. The data indicate possible transitions at 90 and 180°C for monomeric iron‐phthalocyanine whereas polymeric iron‐phthalocyanine shows no breaks.
Katalysatoren beim thermischen Abbau von Polymeren, 1. Über den katalytischen Abbau von Polypivalolacton
Authors: Lüderwald Ingo , Sauer Werner 
Published: April 2003

AbstractThe ability of different metal oxides and acetates to catalyze the thermal degradation of poly(pivalolactone) into cyclic oligomers has been investigated. Magnesium oxide was found to be the most active catalyst which converts poly(pivalolactone) completely into oligomers within less than two hours at 547 K. The influence of temperature and catalyst concentration and the distribution of cyclic oligomers is discussed.
Overall and individual effects in systems including organolithium compounds
Authors: Erussalimsky Boris L. 
Published: April 2003

AbstractExperimental and quantum chemical data are used for the problem of the relative rǒle of individual factors considering the overall effects which are characteristic of certain Licontaining systems. Recourse is made to the following processes: polymerization of isoprene in the presence of subcatalytic amounts of electron donors; polymerization of acrylonitrile by RLi and ROLi initiators; polymerization of dienes by butyllithium (n‐BuLi) and tert‐butyllithium (tert‐BuLi).
Characterization of blends of high density polyethylene with isotactic polypropylene
Authors: Blackadder David A. , Richardson Michael J. , Savill Norman G. 
Published: April 2003

AbstractIsotactic polypropylene and high density polyethylene are thermodynamically incompatible with one another yet it is possible to prepare physical blends of the two polymers and fabricate solid test specimens with a high degree of cohesion. This paper describes the preparation of such specimens and the investigation of their structure. Direct and indirect evidence builds up a model for the blends involving the degree of dispersion. The techniques include optical microscopy, density measurements and differential scanning calorimetry (DSC). Each blend, formed by deposition from solution, is a fine dispersion of the minor component in the major component. The degree of crystallinity of a blend is identical to that calculated from the crystallinities of the pure components in the appropriate ratio. During melting of the blends there is little interaction between the components but there are mutual effects during recrystallization. The α and β forms of polypropylene arise under appropriate conditions.
Cation‐binding ability of tactic poly(crown ether)s
Authors: Kimura Keiichi , Maeda Takumi , Shono Toshiyuki 
Published: April 2003

AbstractCation‐binding ability of tactic poly(crown ether)s was evaluated by solvent extraction of alkali metal picrates. It was found that isotactic poly(crown ether)s bind particular cations, which can be easily sandwiched by two neighboring crown ether units, a little more effectively than syndiotactic ones. No difference of cation‐binding ability was, however, observed between the corresponding d,l‐ and meso‐bis(crown ether)s. This suggests that the rigidity of the poly(crown ether)s, in combination with the tactic configurations, causes the difference in the cation‐binding ability.
Immobilized enzymes, 13. Immobilization of trypsin previously protected by a synthetic water‐soluble macromolecular inhibitor
Authors: Brown Eric , Racois André 
Published: April 2003

AbstractA new water‐soluble acrylic polymer 5, with spacer‐arms bearing benzamidine groups, was synthesized as a polymeric inhibitor to protect trypsin during immobilization of this enzyme on two different water‐insoluble carriers, i.e., VINAC‐S and ACAPROSUC. The latter is an acrylic polymer and bears sidechains ending with succinimido ester groups, whereas VINAC‐S is a polyvinylic matrix having aldehyde groups. The trypsin‐VINAC‐S conjugates prepared in the presence of the polymeric inhibitor 5 were twice as active towards N2‐benzoyl‐L‐arginine ethyl ester, and four times as active towards haemoglobin, as the corresponding conjugates prepared in the absence of 5. More than 80% of the overall initial esterolytic activity of trypsin was retained by the corresponding ACAPROSUC conjugate, when the immobilization reaction was carried out in the presence of 5. The overall residual activity of the conjugate was 46% when operating in the absence of 5. The above method of enzyme protection should prove very useful in immobilized enzyme methodology and technology.
Schrittweise synthesen und eigenschaften einiger cyclopentamerer aus methylenverbrückten (5‐alkyl‐2‐hydroxy‐1,3‐phenylen)‐bausteinen
Authors: Kämmerer Hermann , Happel Günter , Mathiasch Bernd 
Published: April 2003

AbstractThree cyclopentamers (2a–c) and a chainlike pentanuclear oligomer (3a) were prepared by stepwise syntheses. The molecules of the cyclic compounds with 20 links contain o,o′‐methylene bridged 2‐hydroxy‐5‐methyl‐1,3‐phenylene or 2‐hydroxy‐5‐tert‐butyl‐1,3‐phenylene units in a strictly defined manner. The properties of the cyclic pentamer 2a and the chainlike pentanuclear oligomer 3a were compared. They differ by their solubilities, melting points, IR and 1H NMR spectra (pseudorotation) and fragmentation behaviour shown by their mass spectra. The pseudorotation of the cyclic compounds were quantitatively studied.
Polymere kryptanden, 1
Authors: Manecke Georg , Reuter Peter 
Published: April 2003

AbstractThe synthesis of a vinyl group containing cryptand, 18‐vinyl‐5,6‐benzo‐4,7,13,16,21,24‐hexaoxa‐1,10‐diazabicyclo[8.8.8]hexacos‐2‐ene (8), was developed. Gel type copolymers with different polarities of the matrix were obtained from 8 and styrene or 8 and 1‐vinyl‐2‐pyrrolidone, crosslinked with 1,4‐divinylbenzene. A copolymer with 4,4'‐divinylbiphenyl as crosslinking agent was prepared in a macroporous form. The ability of the different copolymers to form complexes with the alkali metal cations as well as the selectivity of the copolymers towards these cations were investigated.
Polymerization of lactams, 39. Condensation as side reaction in the anionic polymerization of 2‐pyrrolidone
Authors: Roda Jan , Votrubcová Zdeňka , Králíček Jaroslav , Stehlíček Jaroslav , Pokorný Svatopluk 
Published: April 2003

AbstractPolymerization mixtures before extraction and extracted polymers prepared by the anionic polymerization of 2‐pyrrolidone with various initiating systems were characterized by their content of β‐ketoamide structures (5) as a measure of side reactions of the propagation sites by condensation. With N‐acyllactams, used as activators, the content of these structures 5 in poly(2‐pyrrolidone) was found to increase proportionally to the polymerization time, which may have a negative effect on the thermal stability of the polymer.
Carbon‐13 relaxation study of crosslinked gels of poly(methyl methacrylate)
Authors: Asakura Tetsuo , Suzuki Kazuomi , Horie Kozo , Mita Shigeru 
Published: April 2003

AbstractThe motion of covalently crosslinked gels of poly(methyl methacrylate) (PMMA) swollen by benzene‐d6 was studied by means of 13C NMR spectroscopy. The dependence of the segmental motion of PMMA on stereosequence was not affected by the presence of the covalently crosslinked part in the chain; isotactic sequence was more mobile than syndiotactic sequence. The spin‐lattice relaxation times, T1's, for all the 13C nuclei of PMMA swollen with benzene (benzene content, 90 wt.‐%, 0,01 mole‐% of crosslinking) were considerably longer than those observed for the linear PMMA (benzene content, 75 wt.‐%). Moreover, all the T1 values decreased with increasing of the degree of crosslinking, regardless of the crosslinking agent and reached to the values of T1 observed for uncrosslinked PMMA or to slightly larger values when the content of crosslinking agent was 1 mole‐%. However, the nuclear Overhauser enhancement data were essentially independent of the degree of crosslinking within experimental error.
Oxidative polymerization of 2,6‐bis(3‐methyl‐2‐butenyl)phenol
Authors: Nishide Hiroyuki , Suzuki Yuji , Tsuchida Eishun , Yamada Shigetoshi 
Published: April 2003

AbstractOxidative polymerization of 2,6‐bis(3‐methyl‐2‐butenyl)phenol (1) was carried out by copperpyridine catalyst. 1 was oxidatively polymerized to yield poly[oxy‐2,6‐bis(3‐methyl‐2‐butenyl)‐1,4‐phenylene] (2) in a similar manner as it has been observed for 2,6‐dimethylphenol (3a). 2 is an oily material with a degree of polymerization of 6,2. 1 and 3a copolymerized with similar reactivity to form the copolymer 4 (degree of polymerization 16 to 29). The 3‐methyl‐2‐butenyl groups in the polymer show enough chemical reactivity for an addition of bromine or graft‐polymerization.
Aliphatic polyamides containing tricyclic fused rings
Authors: Niume Kazuma , Toda Fujio , Uno Keikichi , Hasegawa M. , Iwakura Y. 
Published: April 2003

AbstractA series of polyamides containing thianthrene, phenoxathiin, and dibenzo‐p‐dioxin units were synthesized from the corresponding tricyclic fused ring diamines and aliphatic diacid chlorides by solution polycondensation at low temperature. These polyamides showed improved thermal stability, while maintaining the good solubility of aliphatic polyamides. The thermal stability of the series of polyamides increased in the order of the thianthrene containing polymers < phenoxathiin containing polymers < dibenzo‐p‐dioxin containing polymers. Glass transition temperatures of these polymers were estimated by thermomechanical analysis as well as by temperature‐resistivity curves. Polyamides derived from 2,8‐oriented tricyclic diamines showed somewhat lower glass transition temperatures than those from 2,7‐oriented diamines.