bluuebunny/crossref_metadata_2025 huggingface dataset:
Polymere charge‐transfer‐komplexe auf der basis von polyvinylalkoholacetalen, 2
Authors: Geißler Ulrich , Schulz Rolf C.
Published: April 2003

Poly[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

The 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

The 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

The 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

By 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

Evidence 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

The 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

Methanesulfonanilide 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

Polymerizations 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

A 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

The 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

In 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

A 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

The 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

Experimental 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

Isotactic 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

Cation‐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

A 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

Three 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

The 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

Polymerization 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

The 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

Oxidative 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

A 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.
Formation and properties of triol‐based polyester networks
Authors: Fasina Ayoola B. , Stepto Robert F. T.
Published: April 2003

Networks have been prepared by reacting polyoxypropylene triols with sebacoyl chloride at equal concentrations of hydroxyl and acid chloride groups. The reactions were allowed to go to completion to form the networks studied. The gel points of the reaction mixtures were also determined and used as a basis for the correlation of the properties of the networks formed at complete reaction. Reactions were carried out at 27°C, in bulk and in diglyme as solvent, and the shear moduli of networks formed, in the dry state and at equilibrium swelling in diglyme, were measured at the same temperature using uniaxial compression. Deviations from Gaussian behaviour wer found to decrease as the dilution of the reaction mixture forming the network increased. For apparent values of the molecular mass between junction points (Mc) greater than about 104, essentially Gaussian stress‐strain behaviour was observed. For the triols used, such values of Mc may be obtained from dilute reaction systems. Values of Mc increased with pre‐gel intramolecular reaction and indicate that in the limit of a perfect gelling system, a perfect network is formed. The values of Mc found are generally larger than those expected for the perfect network (M), irrespective of whether phantom or affine behaviour is assumed, and are consistent with network imperfections being elastically ineffective loops, caused by pre‐gel intramolecular reaction, rather than entanglements.
The heats of dilution of poly(1‐vinyl‐2‐pyrrolidone)/alcohol systems
Authors: Ogawa Hideo , Baba Yoshihiro , Kagemoto Akihiro
Published: April 2003

In order to obtain information about the heat interaction parameter between poly(1‐vinyl‐2‐pyrrolidone) (PVP) and alcohols, a flow microcalorimeter equipped with a new type of pump was constructed, and heats of dilution of PVP in alcohol solutions were measured using this microcalorimeter at 298,15 ± 0,001 K. The heat interaction parameter depends considerably on the concentration of the polymer and the chain length of the alcohols.
Conformational transition in poly[4‐(1,1,3,3‐tetramethylbutyl)phenyl methacrylate] and poly(4‐tert‐butylphenyl methacrylate) in dilute solutions
Authors: Sarabia Carmen , Radic Deodato , Gargallo Ligia
Published: April 2003

Temperature dependence of viscosity data and refractive index increment was investigated on two polymers: poly[4‐(1,1,3,3‐tetramethylbutyl)phenyl methacrylate] (1a) and poly(4‐tert‐butylphenyl methacrylate) (1b) in dilute solution. A discontinuity in intrinsic viscosity was observed over a narrow temperature range. From this behaviour it was possible to visualize sharp changes of unperturbed dimensions (Kθ) and thermodynamic parameters (B). This phenomenon can be accounted for by assuming conformational changes of the chain in the chosen solvent in a specific temperature range. These changes can be also observed by discontinuities in refractive index increments dn/dc. In the case of 1b the conformational change disappears on addition of a polar solvent (CHCl3).
Syntheses of thermotropic liquid crystalline polymers, 1. Azoxy and azo type polyesters
Authors: Iimura Kazuyoshi , Koide Naoyuki , Ohta Ryo , Takeda Masatami
Published: April 2003

Azoxy and azo type polyesters were obtained by combination of an azoxybenzene or an azobenzene group as a mesogenic core with different flexible chain lengths of ethylene glycol groups. The thermal properties of these mesomorphic polymers are discussed related to their chemical structures. The mesomorphic temperature region becomes narrower with increasing flexible chain length. Further, the transition temperature from the mesomorphic phase to the isotropic liquid is higher for the azoxy type polyester than for the azo type polyester.
Polymere Phthalocyanine und ihre Vorstufen, 3. In situ Gasphasensynthese und einführende elektrochemische Charakterisierung polymerer Phthalocyanine auf metallischen Trägern
Authors: Bannehr Rüdiger , Jaeger Nils , Meyer Gunter , Wöhrle Dieter
Published: April 2003

The gas phase reaction of 1,2,4,5‐tetracyanobenzene (3) with metal sheets like Cu, Ni, Co, Fe, and Ti exhibits the in situ formation of polymeric phthalocyanine coatings 1. The electrochemical behaviour of layers of 1 is investigated by means of cyclic voltametric measurements. Determination of layer‐thickness and electrical resistance is also performed.
Oxydation photothermique d'élastomères de polyuréthannes thermoplastiques, 1. Propriétés des hydroperoxydes formés
Authors: Gardette Jean‐Luc , Lemaire Jacques
Published: April 2003

The photothermal oxidation of thermoplastic polyurethane elastomers was studied, observing the behaviour of four types of model polymers based upon various hard segments (aromatic or aliphatic) and various elastomeric phases (polyether or polyester). Four types of hydroperoxy groups were observed. By chemical titrations of these hydroperoxides and spectrophotochemical measurements, the thermal and photochemical stability of these compounds was studied. An interpretation of the appearance of hydroxylated compounds during photothermal oxidation is given for the four model polymers.
Substituted and branched polychalcones, 2. Polymeric and solubility properties of the polychalcones
Authors: Malm Bo , Lindberg J. Johan
Published: April 2003

The polymeric and solubility properties of polychalcones 2a, b prepared by Friedel‐Crafts acetylation of vanillin (3a) and p‐hydroxybenzaldehyde (3b) were investigated. The polymers had limited solubility, and only polychalcones obtained from vanillin were completely soluble in dimethyl sulfoxide (DMSO); the others swelled in this solvent. Approximate values for the average molecular weights between cross‐links, Mc, were calculated from the swelling in DMSO using the Flory‐Rehner equation. Average molecular weights (Mw and Mn) and molecular weight distributions of the soluble fraction were determined by gel permeation chromatography on Sephadex G gels in DMSO. Mn corresponded to the molecular weights of the polymers in ethanol and of the acetylated materials in chloroform obtained with a vapour pressure osmometer.
On the photoinitiation of free radical polymerization‐laser flash photolysis investigations on thioxanthone derivatives
Authors: Amirzadeh Gholamreza , Schnabel Wolfram
Published: April 2003

Laser flash photolysis studies and stationary polymerizations were carried out with the aim to elucidate kinetics and mechanisms of photoinitiation processes based on thioxanthone (TX)/amine interactions. During these studies prominence was given to reactions which significantly influence the initiator efficiencies. Thus, rate constants of the reactions 3TX* + monomer (kq), 3TX* + amine (kXH), and ketyl radical + monomer (k) were determined; kq decreases according to the series: styrene (St) > N‐vinyl‐2‐pyrrolidone (VP) > methyl methacrylate (MMA) > acrylonitrile (AN) > butyl vinyl ether (BVE) > vinyl acetate (VA) from 6·109 l·mol−1·s−;1 to 2·104 l·mol−1·s−1. Substitution in the 2‐position of TX by methyl (MTX), isopropyl (ITX) and Cl (CTX) generally causes a decrease of kq, except for the systems CTX/VP and CTX/BVE. The kXH values range from 6 to 8·109 l·mol−1·s−1 for typical amines, e.g. ethyl 4‐((dimethylamino)benzoate). Ketyl radicals react rather slowly with monomers; for CTX k in l·mol−1·s−1: 7·103 (St), 4·102 (VP), 4·101 (MMA), ⩽ 10 (BVE). O2 reacts rapidly with ketyl radicals: k = 2·109 l·mol−1·s−1 (TX). Rates of polymerization ν (monomer consumption) determined at [M] = 5 mol/l and [amine] = 10−1 mol/l are equal for TX, ITX, MTX, and CTX, but increase according to the series AN < MMA < VP; ν depends on the thioxanthone and the monomer concentration according to ν ∝ [TX]1/2[M].
Interaction of polystyryl radical with copper(II) complexes
Authors: Baruah Shashi Dhar , Dass Narendra Nath
Published: April 2003

The polymerization of styrene initiated by 2,2′‐azoisobutyronitrile (AIBN) was studied in N,N‐dimethylformamide (DMF) solution at 60°C in the presence of tetrakis(N,N‐dimethylformamide)copper(II) perchlorate, and also in the presence of its monoazido copper(II) complex [Cu(DMF)3N3]+. The monoazido complex in DMF was prepared in situ by mixing solid sodium azide with tetrakis(N,N‐dimethylformamide)copper(II) perchlorate in a mole ratio of 1:1. The nature of the complex was established by Job's method. The equilibrium constant K for the reaction [Cu(DMF)4]2+ + N ⇌ [Cu(DMF)3N3]+ + DMF determined by the limiting logarithmic method was found to be 1,25 · 104l · mol−1. The presence of [Cu(DMF)4]2+ ions in the polymerization systems caused retardation, but [Cu(DMF)3N3]+ ions produced well defined induction periods. The rate constants at 60°C for the interaction of polystyryl radical towards [Cu(DMF)4]2+ and [Cu(DMF)3N3]+ ions were calculated to be 6,6 · 102 and 5,74 · 104 l · mol−1 · s−1, respectively.
On the kinetics of hydrolytic degradation of native cellulose
Authors: Marx‐Figini Marianne , Coun‐Matus Mari
Published: April 2003

The kinetics of the hydrolytic degradation of celluloses the molecular properties of which still correspond largely to those of the native state are studied. The hydrolytic agent has been 0,5 mol/l aqueous solution of KHSO4. The degrees of polymerization were determined viscosimetrically in copper ethylene diamine (CuEn) as solvent under standard conditions. In order to convert viscosity‐average and weight‐average degrees of polymerization DPη and DPw in the corresponding number‐average DPn, a DPw/DPn calibration curve had been elaborated using polymer analogeous nitrates of a series of samples degraded under the same conditions. The results reveal that hydrolytic degradation of native cellulose takes place by two simultaneously occurring kinetic mechanisms, for which the following rate constants were derived: k1 = 0,12 h−1, k2 = 3,88·10−6 h−1, and k1 = 0,79 h−1; k2 = 38,35 · 10−6 h−1, corresponding to a degradation temperature of 40°C and 60°C, respectively, and related to an initial degree of polymerization DP0 = 13 000. The number of faster cleaving bonds per molecule (β1) and the number average of normally splitting bonds being between two “weak links” (β2) resulted in β1 ≈ 3,5 and β2 ≈ 3 600. The activation energies of the rapid and the slower reaction were found to be 20 kcal/mol (83,7 kJ/mol) and 24 kcal/mol (100,4 kJ/mol), respectively. Additional degradation experiments on the same, but pre‐swollen or pre‐reduced samples did not provoke any variations in the results. It can be excluded, therefore, that the simultaneous occurrence of two kinteic mechanisms is a consequence either of facts which involve diffusion control, or the existence of “stressed” bonds. The found relatively high activation energies rather permit to assume native modifications in the chemical structure of the cellulose molecule as the most probable reason for the faster bond splitting reaction.
NMR study of molecular motion in solid and molten polystyrene: Application of the deuteron dilution technique
Authors: Lindner P. , Rössler E. , Sillescu H.
Published: April 2003

The proton spin‐lattice relaxation time T1 was determined at 13,8, 55,2, and 90 MHz in polystyrene (PS‐d0) and polystyrene deuterated at the chain (PS‐d3) and the phenyl groups (PS‐d5), respectively, at temperatures between −130 and +230°C. Furthermore, T1 was measured in isotopic mixtures of PS‐d3 and fully deuterated PS‐d8 where a separation into intramolecular and intermolecular contributions was possible through the deuteron dilution technique. Above 130°C, various distributions of correlation times provide a semiquantitative understanding of the different motins seen by the protons of the partially deuterated systems. Rotating frame relaxation times in PS‐d3 and PS‐d5 reveal librational motions in the solid glass (below 100°) where the amplitudes of the phenyl group librations are much larger than those of the chain oscillations, but the correlation times are of the same order of magnitude.
Styrene polymerization induced by anilino radicals
Authors: Sugiyama Kazuo , Oda Tetsuo , Maeshima Toshihisa
Published: April 2003

The polymerization of styrene (St) initiated by 1,4‐dimethyl‐1,4‐diphenyl‐2‐tetrazene (1c) is studied kinetically in benzene. The polymerization proceeds through a radical mechanism. The rate equation is as follows: Rp = k [1c]0,5[St]1,0. The overall activation energy for the polymerization of St is found to be 105,9 kJ · mol−1. The efficiency of the initiator is also calculated to be 0,67. On the basis of the results, the initiating ability of N‐methylanilino radicals is discussed.
Preparation of amide and amine groups containing copolymers of methyl methacrylate and their performance in solid polymer composites
Authors: Orbay Murat , Laible Richard , Dulog Lothar
Published: April 2003

Methyl methacrylate (MMA) was copolymerized with acrylamide, N‐methylacrylamide, N,N‐dimethylacrylamide, 1‐vinyl‐2‐pyrrolidone, 4‐vinylpyridine, and 2‐dimethylaminomethyl methacrylate in 1,4‐dioxane solution at 65°C, using AIBN as initiator, to yield copolymers with comonomer contents between about 5 and 50 mole‐%. The monomer reactivity ratios were evaluated. The copolymerizations are in general non‐azeotropic and non‐ideal. The amine group containing comonomers are preferentially incorporated in relation to MMA, but MMA is preferentially incorporated in relation to the amide group containing comonomers. The average molecular weights of the copolymers, with the exception of the N,N‐dimethylacrylamide copolymer, decrease with increasing comonomer concentration, especially in the case of the amine group containing comonomers. The increasing content of amide and amine group containing monomeric units in the copolymers influences the adsorption of the polymers on an iron oxide red pigment, the dispersion stability, as well as the adhesion of the polymer coatings on steel plates and their corrosion protection.
Branching in terminally functional polymers of low molecular weight caused by chain transfer with initiator radicals
Authors: Ivantchev Sergey S. , Barantsevich Eugene N. , Kartavykh Valentin P. , Dratch Valery A.
Published: April 2003

Equations to calculate the density of branching arising from chain transfer to polymer with initiator radicals in terminally functional polymers of low molecular weight were derived for various polymerization conditions. The branching density was shown to be affected by the feed procedure. The relative amount of branching was found to be lower with a single addition of monomer and initiator than with continuous feed of initiator during the reaction. These conclusions were confirmed experimentally.
Enzyme‐analogue built polymers, 13. On the introduction of amino‐ and boronic acid groups into chiral polymer cavities
Authors: Sarhan Ali , Wulff Günter
Published: April 2003

With the aid of D‐glyceric acid as a template, an amino‐ and a boronic acid group, respectively, were introduced in a defined steric arrangement into polymers. For this, the monomer D‐N‐(4‐vinylphenyl)carbamoylethylenedioxy(4‐vinylphenyl)borane (1) was copolymerized into macroporous polymers under various conditions. The template D‐glyceric acid was split off from the polymer with 20% HCl in methanol. The specificity of the polymers obtained with one amino‐ and one boronic acid group, respectively, per cavity was derived from their ability to resolve racemic glyceric acid. Racemic resolution was also observed on equilibration of the polymers with D,L‐methyl glycerate and D,L‐glyceraldehyde.
Conformational analysis of poly(methyl acrylate) by 1H nuclear magnetic resonance spectroscopy
Authors: Matsuzaki Kei , Kawazu Fumio , Kanai Taiichi
Published: April 2003

The 1H NMR spectra of poly(methyl acrylate‐d1) +CHDCH(COOCH3)+n were measured in o‐dichlorobenzene and CDCl3 in the temperature range between − 20 and 145°C. Trans and gauche coupling constant were determined from the temperature dependence of the geminal coupling constants, neglecting g' conformers. It was estimated that the proportion of trans conformer is 1,5 to 1,9 times that of the gauche conformer in this temperature range.
Polymer conformation and NMR chemical shifts, 4. Contrast of 13C NMR spectra between poly(methyl acrylate‐alt‐styrene) and poly(methyl methacrylate‐alt‐styrene)
Authors: Koinuma Hideomi , Tanabe Tsuneaki , Hirai Hidefumi , Hirano Tsuneo
Published: April 2003

The presence of the α‐methyl group in the alternating methyl methacrylate‐styrene copolymer produces a remarkable difference in its 13C NMR spectra as compared with the spectra of the alternating methyl acrylate‐styrene copolymer; cotacticity‐dependent splittings occur only in the former spectrum. A theoretical interpretation was attempted for this characteristic spectral variation in terms of the calculated time‐averaged chemical shifts for carbons in the dyads constituting the alternating copolymers. Each (meso or racemic) dyad sequence is considered to exist in several conformational states which are mutually exchanging rapidly and the probabilities of which are determined by a statistical mechanical procedure. The calculation of cotacticity‐dependent chemical shifts is conducted for the side chain carbonyl, aromatic C1 and methoxyl carbons as well as for some main chain carbons to give good agreement with the observed peak splittings, especially with respect to the side chain carbons. In accordance with the reported assignment, the calculated differences in shielding factors between meso and racemic dyads for the side chain carbons of poly(methyl methacrylate‐alt‐styrene) are positive, i.e. the meso or isotactic peak appears at higher field than the racemic or syndiotactic peak. Furthermore, the resulting values are relatively large (≈0,63 ppm) in conformity with the experiment. The calculation for the carbons in poly(methyl acrylate‐alt‐styrene) gives a very small shielding difference (−0,04 to 0,06 ppm) by the dyad cotacticity, being consistent with the observation, i. e. absence of peak splittings.
X‐ray diffraction study of oriented diamides
Authors: Ania Fernando , Rueda Daniel R. , Calleja Francisco J. Baltá
Published: April 2003

The crystal unit cell of a series of normal diamides, RNHCO(CH2)2nCONHR (1) with RCH3(CH2)5 and n varying from 0 up to 4, has been determined from X‐ray diffraction patterns of oriented films. This work forms part of the study to investigate the relation between microstructure and physical properties, in particular diamagnetism. The unit cell is tricline for all members of the series having one chain molecule per unit cell. The structure of normal diamides consists of extended chains tilted 75° from the sheet edge allowing hydrogen‐bond formation within the sheet. The long spacings obtained have been associated to oblique structures of hydrogen‐bonded sheets, except for the diamide with n = 1. A. shear between adjacent hydrogen‐bonded sheets of 3 repeating chain units offers the most probable explanation for the structure of 1 with n = 0,2,3 and 4.
Aromatic poly[(amino)amide]s and poly(imidazo[4,5‐f]benzimidazole)s derived from poly[(tosylamino)amide]s, 1
Authors: Kehayoglou Aristides , Karayannidis Georgious , Sideridou‐Karayannidou Irini
Published: April 2003

New poly[(amino)amide]s (4) deriving from 1,2,4,5‐benzenetetraamine and terephthalic, isophathalic, or 2,5‐furandicarboxylic acid (2a–c) were indirectly prepared by detosylation of the corresponding new poly[(tosylamino)amide]s 3, which were obtained by low‐temperature solution polymerization of 4,6‐ditosylamino‐1, 3‐phenylenediamine (1) with the dicarboxylic acid dichlorides 2a–c. In a subsequent step the poly[(amino)amide]s were converted by polydehydrocyclocondensation into the heat‐resistant aromatic poly(imidazo[4,5‐f]benzimidazole)s (5) by heating in a high vacuum. The results of elemental analysis, IR and UV spectroscopy, inherent viscosity measurements, molecular weight determination (osmometry), and thermal analysis (DSC, TG) of the prepared polymers are compared and discussed.
Terpolymérisation acrylonitrile‐styène‐acrylate de méthyle, 2. Synthèse de terpolymères homogènes en composition par polymérisation en émulsion
Authors: Rios Lèonardo , Guillot Jean
Published: April 2003

Previous Kinetic studies of the emulsion polymerisation of the three component system acrylonitrile (A) — styrene (S) — methyl acrylate (M) have shown that S is much more reactive than A and M, which have practically the same reactivities. As a consequence, in batch process a large copolymer composition drift is observed versus conversion. To avoid this damageable drift, two techniques were investigated, to get homogeneous macromolecules. (1) Application of the well known “semi‐continuous technique” which appeared not to be totally satisfactory, since the initial batch polymer fraction generally has a composition different from the further polymer when the monomer feed is added under starving conditions; a mixture of various macromolecules is the result. (2) The use of the composition controlled reactor, developed in this laboratory, which consists in a continuous monitored readjustment of monomer feed composition. However, due to the heterogeneous medium of an emulsion copolymerization, the copolymer exerts a small chemical heterogeneity which may be practically negligible at high monomer/water ratio. It is finally proposed that a thermodynamic approach might overcome such a behaviour and insure an actual control of the copolymer composition.
Asymmetric cyanohydrin synthesis catalyzed by synthetic dipeptides, 2
Authors: Oku Jun‐ichi , Ito Naofumi , Inoue Shohei
Published: April 2003

In the asymmetric addition of hydrogen cyanide to benzaldehyde to give mandelonitrile, a cyanohydrin, the highest enantiomeric excess (e.e.) ever reported (90%) was obtained with (2d) whereas the corresponding linear dipeptide gave a very low e. e. This high e. e. decreased with the reaction time, because of the racemization of the product. All cyclic dipeptides used containing an (S)‐histidine residue preferred the (R)‐product. A scheme for the interaction between the catalyst and the reactants to give the (R)‐product is proposed.
The anionic polymerization of styrene oxide. Polymer structure and direction of ring opening
Authors: Jedliński Zbigniew , Kasperczyk Janusz , Dworak Andrzej , Matuszewska Barbara
Published: April 2003

The direction of the oxirane ring opening in the polymerization of styrene oxide by sodium methoxide was determined on the basis of the structure of the products obtained. The oxirane ring opening was found to occur almost exclusively in β‐position. This result was compared with a model reaction, i.e. the methanol addition to styrene oxide in the presence of sodium methoxide. In the model reaction the oxirane ring opening occurred to ca. 35% in α‐position and to ca. 65% in β‐position.
Polymethacrylic acid derivatives, 4. Solubilization of azobenzene, a water insoluble nonpolar compound
Authors: Morcellet‐Sauvage Joëlle , Morcellet Michel , Loucheux Claude
Published: April 2003

Measurements of the solubilization of a water insoluble compound, azobenzene, inside the hydrophobic domains of compact conformations, were carried out using different polymers and copolymers. The influence of the tacticity of the polymer and the hydrophobic character of the copolymers was investigated, as well as specific intramolecular interactions between the hydrophobic residues. The influence of the solubilization on the spectral properties (λmax and εmax) of azobenzene and the copolymers was also studied. Experimental results show that no close correlation exists between the solubilizing power and the stability of the compact conformation, especially since some copolymers which take a compact conformation have no solubilizing power.
Statistics of random macromolecular networks, 2. Stepwise polymerization of polyfunctional monomers bearing A and B coreactive groups
Authors: Durand Dominique , Bruneau Claude‐Marcel
Published: April 2003

The development in the preceding paper is extended to the stepwise polymerization of polyfunctional monomers bearing A and B coreactive groups, a monomer being able to carry together A and B functional groups. The molecular parameters characterizing the post‐gel properties of such macromolecular networks are derived quite as directly as in the order I systems and have expressions which are morphologically analogous.
Liquid crystalline side chain polymers and their behaviour in the electric field
Authors: Ringsdorf Helmut , Zentel Rudolf
Published: April 2003

The electro‐optical properties of liquid crystalline polymers with polar mesogenic units in the side chain were investigated. It could be shown, that in an electric field, they show all effects known from low molecular weight liquid crystals, e.g. the Freedericksz‐transition, the DAP‐effect, the formation of William's domain, and the dynamic scattering. The optical response times are slightly longer than for low molecular weight liquid crystals, but in some cases at higher temperatures as short as 200 ms. By comparison of different polymers and some corresponding liquid crystalline monomers, it is found that: (1) the difference between the measuring temperature and the glass transition temperature mainly determines the optical response times, (2) the fixation of mesogenic groups to a polymer main chain via spacers influences the threshold voltage. Low values are found for long spacers. These results allow a discussion of the influence of polymer fixation of the mesogenic groups on their liquid crystalline properties, pointing to a partial decoupling of the motions of main chains and side chains.