bluuebunny/crossref_metadata_2025 huggingface dataset:
Overtone absorption in macromolecules for polymer optical fibers
Authors: Groh Werner
Published: April 2003

The development of polymer optical fibers (POF) leads to the fundamental question about the lowest loss attainable with organic polymers. In the present paper, we address this question with experimental and theoretical work on vibrational overtone absorption of different molecular bonds, which is the dominant loss contribution in POF's. The investigations, the first of their kind for several bonds, show good agreement between experiment and theory for the experimentally accessible CH‐, CD‐, and OH‐vibrations. Applied to CF‐, CCl‐, and (CO)‐ vibrations, the calculations lead to the conclusion that in the most important wavelength region 600 – 900 nm fully halogenated polymers show a negligible loss contribution due to overtone absorption. In these cases, the theoretical lower loss limit should be a few dB/km.
On the additive nature of the first‐order interactions at the trifunctional branch points in copolymers of ethylene and a larger 1‐alkene
Authors: Mathur Saubhagya C. , Mattice Wayne L.
Published: April 2003

The characteristic ratio and its temperature coefficient were examined for alternating copolymers of ethylene and propylene. The stereochemical composition covers the entire range from racemic through meso. Two different assignments, τ = 0 and σ, were used for the statistical weight employed when a methylene group participates in simultaneous first‐order interactions with another methylene group and a methyl group. The best description of the conformational properties of the alternating copolymers is achieved with the larger value for τ. This assignment is the one that would be expected if the first‐order interactions were pair‐wise additive.
Synthesis and properties of thermotropic liquid‐crystalline polymers containing transition metals
Authors: Hanabusa Kenji , Higashi Jun‐ichi , Koyama Toshiki , Shirai Hirofusa , Hojo Nobumasa , Kurose Akio
Published: April 2003

New thermotropic, liquid‐crystalline polyesters (5a, b, 6a, b) with mesogenic bipyridinediyl units were synthesized. They form complexes with Fe(II) and Cu(II) salts. Homopolyesters 5a, b, containing no metal or less than a certain amount of metal, are smectic. A nematic mesophase was observed in the case of copolyester 6a, b. The structural properties of a polyester complex 5a with Cu, as crystal, liquid‐crystal and isotropic liquid, were examined by ESR.
Saturated polyesters as emulsifiers for emulsion copolymerization of unsaturated polyester resins with styrene
Authors: Baumann Harald , Joos Betina , Funke Werner
Published: April 2003

Intramolecularly crosslinked macromolecules (ICM) from unsaturated polyesters (UP) and styrene, respectively from technical divinylbenzene (t‐DVB), were prepared by emulsion copolymerization (ECP). Saturated polyesters of different compositions and molar masses between 1200 and 2400 were used as emulsifiers (ESP). The influence of molar mass and structure at various concentrations of the ESP on yield, number and diameter of the ICM and their composition was studied. For comparison, also sodium dodecyl sulfate (SDS) was used as emulsifier.
13C NMR analysis of ethyl chain‐end groups: A method for active site investigation in Ziegler‐Natta catalysis
Authors: Sacchi Maria Carmela , Locatelli Paolo , Tritto Incoronata
Published: April 2003

The stereoregularity of the insertion of the first propene unit into the active titanium‐ 13CH2CH3 bond is evaluated, by 13C NMR analysis, in highly regular polypropene samples prepared in the presence of different traditional and high yield Ziegler‐Natta catalytic systems. Selectively enriched aluminiumalkyls are used as cocatalysts. The comparison of the data obtained shows that the ratio between the erythro and threo placement of the first propene unit varies from one catalyst to the other and represents a reproducible character of each system. Some suggestions about steric features of the active sites of the different catalytic systems are inferred.
Polymers with pendant carbazolyl groups, 4. Photoconductive properties of some polysiloxanes with pendant carbazolyl groups
Authors: Domes Helmut , Fischer Reiner , Haarer Dietrich , Strohriegl Peter
Published: April 2003

The photoconductive properties of a series of polysiloxanes with pendant carbazolyl groups (1a—c) are described. In these polymers the carbazole moieties are separated from the siloxane backbone by alkylene spacers of different length. The properties of the novel compounds are compared with the well known photoconductor poly(N‐vinylcarbazole) and the model compound N‐isopropylcarbazole. Effective charge carrier mobilities were measured by means of the time‐of‐flight technique. Polymer 1a exhibits the largest carrier mobility of the three polysiloxanes. The mobilities for polymers 1b and 1c are somewhat smaller and comparable to poly(N‐vinylcarbazole). The transport of charge carriers in an amorphous material can be described as a hopping process. The activation energy for that process was calculated from the temperature dependence of the carrier mobility. The polysiloxanes 1a—c show the same activation energy of about 0,6 eV. The activation energies in poly(N‐vinylcarbazole) and N‐isopropylcarbazole are of the same magnitude as in the polysiloxanes. Two different models were used for evaluating the mobility data. The field dependence of the carrier mobility is best described by a modified version of Gill's model whereas no distinction between the two models could be made from the temperature dependence of the mobility.
Polymere Protonenschwämme, 1. Synthese von Monomeren auf der Basis von Naphthalin und Fluoren
Authors: Hallensleben Manfred L. , Kansy Hartmut
Published: April 2003

1,8‐Bis(dimethylamino)‐4‐(4‐vinylphenyl)naphthalene (33), 1,8‐bis(dimethylamino)‐4‐(4‐vinylbenzyl)napthalene (35), 4,5‐bis(dimethylamino)‐9‐(4‐vinylbenzyl)fluorene (37) and 4,5‐bis(dimethylamino)‐9,9‐bis(4‐vinylbenzyl)‐fluorene (38) were synthesized as potential vinyl monomers.
Can lewis acids initiate the polymerization of cyclic siloxanes via direct addition?
Authors: Jordan Elisabeth , Lestel Laurence , Boileau Sylvie , Cheradame Hervé , Gandini Alessandro
Published: April 2003

Following a preliminary report stating that ethylboron sesquitriflate initiates the polymerization of hexamethylcyclotrisiloxane (D3), a more rigorous investigation was carried out to ascertain that cyclic siloxanes can indeed be polymerized by Lewis acids without the intervention (cocatalysis) of proton‐donor impurities. The evidence gathered with this strong boron Lewis acid suggested that direct initiation does occur, although its efficiency is much lower than that of an equivalent amount of a strong Brønsted acid. The use of a sterically hindered pyridine was a key factor in discriminating between monomer protonation and direct initiation.
Syntheses of thermotropic poly(azine‐ether)s derived from 2,4‐hydroxybenzaldehyde and 2,4‐dihydroxyacetophenone
Authors: Marcos Mercedes , Navarro Fernando , Oriol Luis , Serrano Jose Luis
Published: April 2003

Poly(azine‐ether)s (1a and 1b) derived from 2,4‐dihydroxybenzaldehyde and 2,4‐dihydroxyacetophenone, respectively, were synthesized by condensation of the corresponding dicarbonyl monomer (2a or 2b) containing 10 methylene units with hydrazine hydrate. For the preparation of 1a ethanol or acetonitrile were found to be the best solvents, DMF or 1,4‐dioxane for the preparation of 1b. The liquid‐crystalline behaviour of the polymers was studied by DSC and on the hot stage of a polarizing microscope. All of them formed nematic mesophases in melts.
Synthèse et copolymérisation d'acrylamides comportant le groupement dihydroxyphosphoryloxyalkyle
Authors: Touet Joël , Pierre Chantal , Brown Eric , Boschetti Egisto
Published: April 2003

ω‐Aminoalkyl dihydrogen phosphates 5a–c, 7 and 9 were obtained in a simple and reproducible fashion by O‐phosphorylation of the corresponding aminoalcohols with ClPO3H2 generated in situ by controlled hydrolysis of POCl3. Reaction of these phosphates with acrylic or methacrylic anhydride in water/THF mixture afforded a series of new acrylic monomers (11a–h) bearing a phosphoryl group. Inverted emulsion copolymerization of the latter with the hydrophilic comonomers N‐[1,1‐bis(hydroxymethyl)‐2‐hydroxyethyl]acryl‐ or methacrylamide (12a or 12b) and with the cross‐linker N,N′‐methylenediacrylamide (13) afforded various gels in the form of spherical beads. Preliminary experiments showed that some of these copolymers could be efficiently used as stationary phases for the separation of proteins by ion‐exchange chromatography.
Acrylamide polymerization photoinitiated by HCrO4−
Authors: Fageol Patrick , Bolte Michèle
Published: April 2003

The photoredox process occurring between HCrO4− and acrylamide (AAm) leads to the formation of chromium(III) and polyacrylamide. The influence of pH, monomer concentration, absorbed light intensity Ia and chromium(VI) concentration on the polymerization rate Rp are reported. Two different domains are detected as a function of chromium(VI) concentration: At low concentration, where Rp increases with chromium concentration, a process of termination by mutual annihilation of the macroradicals accounts for the experimental dependence Rp ∝ [AAm]3/2 · Ia. At higher concentration, Rp decreases when the chromium concentration increases; a process of oxidative termination of the radicals by chromium(VI) is involved corresponding to a dependence Rp ∝ [AAm]2. Ia. The evolution of the polymer molecular weight as a function of the different parameters controlling the polymerization is described.
Studies on syntheses and permeabilities of special polymer membranes, 70. Permeation and separation characteristics for aqueous alcoholic solutions by evapomeation and pervaporation through polystyrene membranes
Authors: Uragami Tadashi , Morikawa Takeshi
Published: April 2003

Permeation and separation characteristics of methanol/water and ethanol/water mixtures by evapomeation and pervaporation through unelongated and biaxially elongated polystyrene membranes were investigated under various conditions. All polystyrene membranes predominantly permeated water molecules in both methods. Permeation rates in the case of evapomeation were smaller than those of pervaporation, but the separation factors in the former case were greater than those in the latter. The separation factors through the biaxially elongated polystyrene membrane were larger than those of the unelongated polystyrene membrane, this value being ca. 1500 for an azeotropic mixture of ethanol/water. Permeation and separation mechanisms through these polystyrene membranes involved in both membrane separation techniques are discussed from the viewpoints of solution‐diffusion of permeating molecules and of the membrane structure.
Investigations of poly(vinyl alcohol)/poly(N‐vinyl‐2‐pyrrolidone) blends, 1. Compatibility
Authors: Ping Zheng‐Hua , Nguyen Quang Trong , Néel Jean
Published: April 2003

Blends of crystallizable poly(vinyl alcohol) (PVA) with poly(N‐vinyl‐2‐pyrrolidone) (PVP) made from aqueous solutions appear to be miscible in the whole composition range according to DSC results. A large negative value of the interaction parameter between the two polymers was found from melting point depressions. IR spectroscopy evidenced compatibility of the two polymers on a molecular level. DSC, density and IR results all show a proportion of pure PVA crystallites in blends, which decreases with increasing PVP content and becomes nil at about 50 wt.‐% of PVP. However, close examination of the hydroxyl stretching region of the blends indicates the presence of organized regions of PVA beyond this limit. According to IR results, the sequence of decreasing hydrogen‐bonding power should be the following: multiple hydroxyl‐hydroxyl bonding in organized PVA regions, hydroxyl‐carbonyl bonding between the two polymers, and simple hydrogen‐hydrogen bonding in amorphous PVA regions. It appears that the PVA component can be held in the amorphous state by hydrogen bonding with the PVP component when there is a sufficient amount of the latter in the blend. The amorphous part of PVA is compatible with PVP, but the crystallizable part is not in its most stable form.
Influence of the structure on the photodegradation of poly(vinyl chloride), 3. Dependance of the quantum yield of dehydrochlorination on the isotactic content
Authors: Castillo Francisca , Martinez Gerardo , Sastre Roberto , Millán José Luis
Published: April 2003

The photodehydrochlorination of four poly(vinyl chloride) (PVC) samples of different tacticities, as studied previously, was compared with that of a PVC sample after being modified to various degrees by nucleophilic substitution with sodium benzenethiolate (NaBT). In order to separate the influence of substituted structures from that of the chromophoric group grafted onto the polymer, a series of PVC mixtures with sec‐butyl phenyl sulfide (BPT), of compositions similar to those of modified polymers was also studied. The evolution of HCl was found to be a linear function of the absorbed dose in all cases. The quantum yield of dehydrochlorination, ΦHCl, as obtained from the slopes, appeared to decrease with the isotactic content. The results suggest specific isotactic triads to be markedly reponsible for the photodehydrochlorination, which would account for a mechanism based on the occurrence of chlorines of low dissociation energy at such triads.
Anionic synthesis of chain‐end functionalized polymers using 1,1‐diphenylethylene derivatives. Preparation of 4‐hydroxyphenyl‐terminated polystyrenes
Authors: Quirk Roderic P. , Zhu Lin‐fang
Published: April 2003

A new, general functionalization reaction for polymeric organolithium compounds was developed based on their quantitative reaction with 1,1‐diphenylethylene derivatives. The utility of this method was demonstrated by preparation of 4‐hydroxyphenyl‐terminated polystyrene (2b) by reaction of polystyryllithium in benzene at room temperature with 1‐[4‐(tert‐butyldimethylsiloxy)phenyl]‐1‐phenylethylene (1a) followed by hydrolysis with dilute hydrochloric acid. The course of the functionalization reaction was monitored by ultraviolet‐visible spectroscopy at 406 nm. Polystyrene 2b was characterized by size exclusion chromatography, thinlayer chromatography, membrane osmometry, end‐group titration and both 1H and 13C NMR spectroscopy. All experimental evidence is consistent with quantitative functionalization via the 1,1‐diphenylethylene derivative.
Kinetics of group transfer polymerization of tert‐butyl methacrylate in tetrahydrofuran
Authors: Doherty Martin A. , Müller Axel H. E.
Published: April 2003

The reaction kinetics for the group transfer polymerization (GTP) of tert‐butyl methacrylate (TBMA) using a silyl ketene acetal initiator and a nucleophilic catalyst are investigated. The reaction is shown to be of first order in both monomer and catalyst concentrations. The “livingness” of this system appears to be influenced by the reaction temperature. At temperatures above −20°C, deactivation is observed, with its severity increasing with increasing temperature. This deactivation is attributed to a depletion of catalyst by side reactions. It was demonstrated that reactivation is made possible by the addition of more catalyst. This result is in contrast to the anionic polymerization of TBMA, where no deactivation was observed even at ambient temperature. At temperatures below −20°C no deactivation is observed; however, at these temperatures, the reactions manifest induction periods with lengths increasing with decreasing temperature. The rate constants are lower than those for the GTP of methyl methacrylate (MMA) by a factor of 1,5 to 2. The following Arrhenius parameters were obtained for the propagation rate constants: activation energy, Ea = (19,1 ± 3) kJ/mol, preexponential factor, log10 A = (7,05 ± 0,3). These values are comparable with those obtained for MMA. The molecular weight distributions are similar to those obtained in the GTP of MMA, i.e. the ratio of weight‐to number‐average molecular weights is rather high for low monomer conversions and narrows to M̄w/M̄n ≥ 1,3 for full conversion. This is attributed to the rates of the catalyst exchange equilibrium.
Synthesis and structure of a “living” copolymer of propylene and 1,5‐hexadiene
Authors: Doi Yoshiharu , Tokuhiro Naoko , Soga Kazuo
Published: April 2003

A soluble V(acac)3/Al(C2H5)2Cl system was found to polymerize 1,5‐hexadiene to give a living polymer in toluene at −78°C. Hydrogenation of poly(1,5‐hexadiene) was conducted to determine the chain microstructure. The 13C NMR analysis of hydrogenated poly(1,5‐hexadiene) indicated that the poly(1,5‐hexadiene) is composed of alternating units of 1,3‐cyclopentylenemethylene and 1‐vinyltetramethylene. In addition, living copolymers of propylene and 1,5‐hexadiene were prepared and characterized by analysis of the 1H and 13C NMR spectra. A chain propagation mechanism of living poly(1,5‐hexadiene) is proposed.
Synthesis of polypropylene with improved MgCl2‐supported Ziegler‐Natta catalysts, including silane compounds as external bases
Authors: Spitz Roger , Bobichon Charles , Guyot Alain
Published: April 2003

The new catalytic system comprising a diester as an internal Lewis base and a silane (triethoxyphenylsilane) as an external Lewis base presents important differences to the classical third generation catalyst with two esters in the system, i. e. a high isotacticity is obtained with a low ratio Al/Lewis base, the stereospecificity is stable with temperature and time, the sensitivity to hydrogen concerning the average molecular weight is high and the activity, which remains low without hydrogen, is greatly enhanced by the transfer agent. The selectivity of the system is controlled in a complex manner by the concentration and ratio of the cocatalytic system.
Chemical intercalation of tetraalkylammonium ions into polyacetylene
Authors: Ignatious Francis , François Bernard , Mathis Claude
Published: April 2003

A novel class of carbanionic dopant systems was developed which facilitates the intercalation of tetraalkylammonium ions into polyacetylene (PA), which was considered impossible by chemical methods so far. The chemistry of the dopant system was discussed. The presence of [R4N]+ ions in PA was verified by elemental analysis and IR spectroscopy. The maximum doping levels were determined in the case of several carbanionic systems and also by systematically varying the size of the [R4N]+ ions. A correlation between maximum doping levels and the redox‐potentials of the carbanions was established.
Partitioned polymerization, 3. On the use of inhibitors partially soluble in the aqueous phase
Authors: Bartoň Jaroslav , Juraničová Viera
Published: April 2003

The partitioned emulsion polymerization of methyl methacrylate and acrylonitrile initiated by ammonium peroxodisulfate and/or 2,2′‐azoisobutyronitrile was studied in the presence of p‐benzoquinone, 2,2‐diphenyl‐1‐picrylhydrazyl, 4‐hydroxy‐2,2,6,6‐tetramethylpiperidin‐1‐oxyl, 4‐benzoyloxy‐2,2,6,6‐tetramethylpiperidin‐1‐oxyl, 4‐methacryloyloxy‐2,2,6,6‐tetramethylpiperidin‐1‐oxyl, 4‐acetoxy‐2,2,6,6‐tetramethylpiperidin‐1‐oxyl and 4‐stearoyloxy‐2,2,6,6‐tetramethylpiperidin‐1‐oxyl radicals. These compounds with the exception of 4‐stearoyloxy‐2,2,6,6‐tetramethylpiperidin‐1‐oxyl inhibit the partitioned emulsion polymerization of methyl methacrylate. In the partitioned emulsion polymerization of acrylonitrile 4‐stearoyloxy‐2,2,6,6‐tetramethylpiperidin‐1‐oxyl was also found to be effective. This fact was ascribed to the increased water solubility of this inhibitor in an emulsion polymerization system containing acrylonitrile.
Structural variations in ethylene‐tetrafluoroethylene copolymers as a function of composition and temperature
Authors: Iuliano Mauro , De Rosa Claudio , Guerra Gaetano , Petraccone Vittorio , Corradini Paolo
Published: April 2003

Ethylene‐tetrafluoroethylene copolymers, containing 50–80 mol‐% of tetrafluoroethylene (TFE) units, were investigated by wide‐angle X‐ray scattering (WAXS) and dynamic mechanical analysis (DMA). With increasing TFE content, a shift toward low temperatures of the crystalmesophase transition is observed; only the mesophase is observed for high TFE content (e.g., the 80 mol‐% TFE copolymer). On the basis of a conformational analysis, a gradual change, with the TFE content, of the chain conformation from a planar zig‐zag conformation to a conformation built up locally of very short helical stretches is indicated. For both the crystal and the mesophase structure the size of the domains in which the ordered disposition of the chain axes is maintained is larger for copolymers with higher TFE content, where a lower degree of local order is expected.
Tacticity and dielectric relaxation around the glass transition of poly(vinyl chloride). A thermally stimulated depolarization currents (TSDC) study
Authors: del Val Juan José , Colmenero Juan , Mijangos Carmen , Martínez Gerardo , Millán José Luis
Published: April 2003

The thermally stimulated depolarization currents (TSDC) technique has been used to study molecular motions around the glass transition in three different samples of poly(vinyl chloride) (PVC) varying in the contents of isotactic triads. The α‐relaxation mode associated with cooperative molecular motions taking part in glass transition appears to be strongly dependent on tacticity. A secondary relaxation mode α′, different from the β‐relaxation, has been detected just below the α‐relaxation and at temperatures depending on the content of isotactic triads. Above the glass transition temperature the TSDC curves show a ρ‐peak corresponding to the motion of free charges in the material. This process does not seem to be affected by tacticity. The results suggest that specific conformations of isotactic triads play an important role in the motion of chain segments in the polymer.
Plastic deformation and solid‐phase transformation in β‐phase polypropylene
Authors: Shi Guan‐yi , Chu Feng , Zhou Gui‐en , Han Zhe‐wen
Published: April 2003

Tensile specimens of isotactic polypropylene, initially crystallized in the β‐form with high purity, were tested at various temperatures. It was observed by WAXD that the most important phenomenon occurring in the course of a tensile test is the β‐smectic transformation for specimens drawn at lower temperature and β‐α transformation for specimens drawn at higher temperature, which takes place in the crystalline lamellae and is induced by plastic deformation. c‐Axis oriented β‐crystals have never been found in the drawn specimens. It was also shown that the β‐smectic transformation propagates inside the spherulites from the equatorial regions, in which the chain axes are nearly parallel to the drawing direction, towards the diagonal and polar regions. Finally, it was noted that microvoids are formed simultaneously during plastic deformation, which may be due to the volume contraction induced by the β‐α or β‐smectic transformation.
Heteropolyacids — new efficient initiators of cationic polymerization
Authors: Bednarek Melania , Brzezińska Krystyna , Stasiński Jacek , Kubisa Przemysław , Penczek Stanisław
Published: April 2003

We have found, that heteropolyacids (HPA) are efficient initiators of cationic polymerizations, including polymerizations of cyclic ethers and acetals, providing high‐molecular‐weight polymers. In several systems (e. g. THF, 1,3‐dioxolane) the degree of polymerization is given by the ratio of concentrations of monomer and initiator, as for the living system. In the polymerization of cyclic formaldehyde trimer: 1,3,5‐trioxane, the comparable polymerization rates may be obtained with ≈ 25 times less an initiator consumption on weight basis (≈ 103 times less on molar basis) than for typical initiators like BF3 · OR2.
Phthalocyanines on mineral carriers, 4. Low‐molecular‐weight and polymeric phthalocyanines on SiO2, γ‐Al2O3 and active charcoal as catalysts for the oxidation of 2‐mercaptoethanol
Authors: Wöhrle Dieter , Buck Thomas , Hündorf Uwe , Schulz‐Ekloff Günter , Andreev Atanas
Published: April 2003

Low‐molecular‐weight phthalocyaninatocobalt compounds 2a–d and polymeric phthalocyaninatocobalt derivatives 4, 6a, b were prepared on the surface of the inorganic carriers SiO2 or γ‐Al2O3 and of active charcoal, the range of loading being 11,9 – 0,2 wt.‐%. The oxidation of 2‐mercaptoethanol in an aqueous solution at pH 9 was used as a model reaction for demercaptizations of petroleum fractions with phthalocyanines on carriers as heterogeneous catalysts. The catalytic activity, related to the phthalocyanine content, was found to increase with increasing dispersion of the complex on the carrier. The influence of the type of support on the activity is given by the following order: SiO2 < γ‐Al2O3 < Norit charcoal. Polymeric phthalocyanines exhibit a higher catalytic activity as compared with low‐molecular‐weight phthalocyanines. The mechanism of the oxidation of the thiol is discussed.
Rigid rod polymers with flexible side chains, 7. Synthesis and phase behaviour of polyimides prepared from pyromellitic anhydride and N,N′‐bis(1‐imidazolylcarbonyl)‐2,5‐bis(alkoxyalkoxy‐1,4‐phenylenediamines)
Authors: Helmer‐Metzmann Freddy , Ballauff Matthias , Schulz Rolf Christian , Wegner Gerhard
Published: April 2003

Polymides 3a and 3b with stiff‐chains bearing trioxaoctyl or tetraoxaundecyl side chains were synthesized and characterized. The polycondensation was done with pyromellitic anhydride and N,N′‐bis(1‐imidazolylcarbonyl)‐2,5‐(1,4,7‐trioxaoctyl)‐ or 2,5‐(1,4,7,10‐tetraoxaundecyl)‐1,4‐phenylenediamine (2a or 2b). 3b, being sufficiently soluble, was characterized by 13C NMR spectroscopy. The results of IR and 13C NMR spectroscopy prove the presence of the correct imide structure. In solid state 3a and 3b form layered structures with the side chains being in a disordered state.
Effect of monomer diffusion in the polymerization of olefins over Ziegler‐Natta catalysts
Authors: Soga Kazuo , Yanagihara Hisayoshi , Lee Dong‐ho
Published: April 2003

By using an extremely high stereospecific catalyst, three kinds of copolymerizations were carried out with combinations of monomers which differ in the crystallinity of the homopolymers. Addition of a small quantity of comonomer to the homopolymerization systems producing very high crystalline polymers was found to cause a remarkable increase in the apparent polymerization rate as well as a marked decrease in the polymer crystallinity. Such an irregular increase in the polymerization activity was, however, not observed when a small amount of comonomer was added to the homopolymerization systems producing low‐crystalline or amorphous polymers. These observations have led to the conclusion that resistance of monomer diffusion through the polymer film should be one of the significant parameters for the apparent polymerization rate when very high crystalline polymers, like high density polyethylene, isotactic polypropylene etc., are produced.
Photoconductive polymers and copolymers of N‐(2‐propynyl) carbazole and N‐(2‐propynyl)phenothiazine
Authors: Kmínek Ivan , Cimrová Věra , Nešpůrek Stanislav , Vohlídal Jiří
Published: April 2003

Homopolymers of N‐(2‐propynyl)carbazole, its copolymers with acetylene, and the homopolymer of N‐(2‐propynyl)phenothiazine were prepared using Ti(OBu)4/AIEt3 as the catalyst. The homopolymer of the carbazole derivative was also prepared by its metathetic polymerization catalyzed with the system WOCl4/Ph4Sn. Homopolymers of both monomers and the copolymer of N‐(2‐propynyl)carbazole with a small quantity of acetylene are photoconductive.
On the cationic polymerization of oxirane with triphenylmethylium salts
Authors: Libiszowski Jan , Szymanski Ryszard , Penczek Stanislaw
Published: April 2003

1,4‐Dioxanium and other trialkyloxonium ions were observed by 1H NMR in the polymerization of oxirane initiated with the triphenylmethyl cation. The major product of polymerization is 1,4‐dioxane. Thus, the kinetic data for the same system previously published by other authors, refer to the propagation in which oxirane propagates with the participation of dioxanium and/or other unstrained trialkyl oxonium cations. Our present results, together with previous data of León et al., indicate that the rate constants of propagation with these two kinds of species are very close to each other. Propagation with participation of the oxiranium ion probably takes place only at the very beginning of polymerization.
Electrochemical preparation and properties of poly(3‐aryl‐2,5‐thienylene)s
Authors: Sato Masa‐aki , Tanaka Susumu , Kaeriyama Kyoji
Published: April 2003

Films of poly(3‐phenyl‐2,5‐thienylene) (1a), poly[3‐(4‐methoxyphenyl)‐2,5‐thienylene] (1b) and poly[3‐(4‐trifluoromethylphenyl)‐2,5‐thienylene] (1c) were electrochemically prepared. The conductivities of 1a, 1b and 1c were determined to be 140, 40, and 1,8 · 10−3 S/cm, respectively. The surfaces of 1a and 1b are considerably rough. The infrared spectra of electrochemically neutralized polymers showed that they have a regular structure. Cyclic voltammograms showed that the oxidation potential increases in the order 1b < 1a < 1c (in the neutral state). The results are discussed in terms of the electronic effect of the substituents. The visible spectra of these neutral polymers showed that the π‐π*‐transition occurs at lower energy than that of poly(2,5‐thienylene) (1d). This indicates that the pendant aryl groups are conjugated with the main chain. The effect of substituents on the peak positions of the π‐π* transition is hardly discernible. 1a is highly anode‐active as compared with 1d. The spectral change of 1a upon PF doping presumably is the indication of polarons at low doping levels. The changes during Et4N+ doping shows that cation doping took place.
Hydrogels based on N‐vinyl‐2‐pyrrolidinone and 2‐hydroxyethyl methacrylate
Authors: Koßmehl Gerhard , Volkheimer Jürgen , Schäfer Horst
Published: April 2003

Hydrogels (crosslinked polymers with a defined water content) based on N‐vinyl‐2‐pyrrolidinone and 2‐hydroxyethyl methacrylate of different compositions were prepared by radical copolymerization and swollen in buffered isotonic sodium chloride solution. The linear expansion to hydration, weight‐percentage of hydration, refractive index, extractables, percentage of transmission of visible light and oxygen permeability of the resulting hydrogel samples were examined.
Photo‐induced copolymerization of cyclohexene with maleic anhydride
Authors: Li Tong , Pan Jinshi , Zhang Zhongquan
Published: April 2003

Kinetics and mechanism of photo‐induced copolymerization of cyclohexene with maleic anhydride in chloroform were studied. The UV spectra suggested the formation of a chargetransfer complex between the comonomers. This complex was excited under irradiation and then underwent hydrogen abstraction to produce two kinds of radicals for initiation. The polymerization produces an alternating copolymer in the composition range of 25 to 75 mol‐% of either comonomer. The chain‐transfer role of cyclohexene was also investigated.
Electrosynthesis of poly(N‐ethyl‐3,6‐carbazolediyl) catalyzed by a Ni(0)‐based complex
Authors: Siove Alain , Adès Dominique , Chevrot Claude , Froyer Gérard
Published: April 2003

Poly(N‐ethyl‐3,6‐carbazolediyl) was synthesized by electroreduction of the NiBr2/2,2′‐bipyridine/3,6‐dibromo‐N‐ethylcarbazole system in N,N‐dimethylacetamide. Both gel permeation chromatography analyses of the polymer formed and electrochemical studies of the system during the course of polymerization in homogeneous phase point at a constant efficiency of the catalytic complex. The latter generates potentially active species which contain the transition metal inserted into a CBr bond. Mechanisms of formation of the growing chains are proposed on the basis of the electrochemical behaviour of the catalytic system. Chemical doping of the polymer leads to a material the conductivity of which is in the range 10−4 < σ/(Ω−1 · cm−1) < 10−3.
Synthese und thermische eigenschaften von photosensiblen polyacrylsystemen mit zimtsäurehaltigen seitengruppen und deren verwendung in composite‐membranen
Authors: Koch Thomas , Ritter Helmut , Buchholz Norbert , Knöchel Friedrich
Published: April 2003

The synthesis of comb‐like polymers containing cinnamic acid derivatives in the side chains is described. The disappearance of thermal transitions after UV‐irradiation of the polymer samples was demonstrated by DSC measurements in the case of the liquid‐crystalline homopolymer poly[4‐propoxyphenyl 4‐(6‐acryloyloxyhexyloxy)cinnamate] and the side‐chain crystallizable copolymers poly[(4‐(6‐acryloyloxyhexyloxy)cinnamic acid‐co‐hexadecyl acrylate)]. A significant influence of UV‐irradiation on the permeation activation energy of 1‐butanol through polyamide composite membrance containing a film of the photosensible comb‐like polymers was observed.
Crystallization behavior of block copolyarylates synthesized via two‐step interfacial polycondensation
Authors: Lee Yu‐Der , Tsai Hong‐Bing
Published: April 2003

DSC, X‐ray diffraction and solid‐state 13C NMR were used to investigate the crystallization properties of block copolyarylates prepared via two‐step interfacial polycondensation. The block copolyarylates obtained from 1,1,2,2‐tetrachloroethane solution were found to have low crystallinity. This could be explained as the influence of amorphous blocks on the crystalline blocks. When the block copolyarylates were redissolved in dichloromethane, the annealed, cast films exhibited considerably higher crystallinity. It was concluded that the crystallization behavior of block copolyarylates is very much dependent on their sample history.
Structural models for crystallographic disorder in poly(tetrafluoroethylene)
Authors: Marega Carla , Marigo Antonio , Garbuglio Carmine , Fichera Annamaria , Martorana Antonino , Zannetti Roberto
Published: April 2003

Some structurally disordered models for poly(tetrafluoroethylene) were elaborated and the corresponding calculated X‐ray diffraction patterns compared with experimental patterns. This and differential scanning calorimetry results suggest some differences between the virgin powder and a sintered polycrystalline plate of poly(tetrafluoroethylene). These differences may be related to the crystal phase transitions that occur in a range of temperatures close to room temperature.
Ternary and partial ternary azeotropes
Authors: Quella Ferdinand
Published: April 2003

A paper in 1983 of Ham postulating the non‐existence of ternary azeotropes resulting from ternary copolymerization is contradicted on the basis of mathematical solutions and further experimental results from other authors. A broader view of the problem of ternary azeotropy must include the partial azeotropes, which are almost absent from recent literature, although they contain the potential for hundreds of polymers with still largely unknown physical properties. Ham has hitherto been supported by the apparent necessity of using comparatively complex mathematical equations. However, it will be shown that many of these can be reduced to simple relationships.
Study of polymeric photosensitizers, 3. Synthesis of multifunctional polymeric photosensitizers containing pendant 4‐nitrophenoxy moieties and various kinds of quaternary phosphonium or ammonium salts and their application to the photo‐isomerization of potassium cinnamate
Authors: Nishikubo Tadatomi , Abe Koichi , Uchida Jiro
Published: April 2003

Some multifunctional polymeric photosensitizers containing both pendant photosensitizing groups and substrate‐attracting groups were synthesized by partial substitution reaction of poly(chloromethylstyrene) with potassium 4‐nitrophenoxide under the conditions of phase transfer catalysis, followed by addition reactions of the resulting polymer with various kinds of tert‐phosphines or amines. The reactivity of tert‐phosphine was found to decrease with increasing lenght of the alkyl chain in the tert‐phosphine. However, the addition reaction of the polymer with tert‐phosphines and ‐amines proceeded quantitatively at 80°C for 48 h in DMF, respectively. The photo‐isomerization of potassium cinnamate (PCIN) was carried out using the multifunctional polymeric photosensitizers in methanolic aqueous solution. The polymeric photosensitizer (polymer 3) containing the small and hydrophilic substrate‐attacting benzyltri‐ethylphosphonium chloride moiety showed a higher efficiency than the polymers (polymers 5 and 7) containing bulky and hydrophobic substrate‐attracting moieties like benzyltributyl‐ or benzyltrioctylphosphonium chloride. Polymer 3 has the highest efficiency at a content of 10 mol‐% of pendant 4‐nitrophenoxy (NP) moieties, and polymers 5 and 7 have their highest efficiency at a content of 15 mol‐% of pendant NP moieties. Polymeric photosensitizers containing pendant quaternary phosphonium salts as the substrate‐attracting group have a higher efficiency than the polymers containing pendant quaternary ammonium salts. Further more, the rate of photo‐isomerization of PCIN was found to be strongly affected by the concentration of the polymeric photosensitizers in solution, and also by the polarity of the reaction medium.
Liquid membranes with organic polyphosphates as ionic carriers
Authors: Narȩbska Anna , Wódzki Romuald , Wyszyńska Alicja
Published: April 2003

Poly(hexylene phosphate) (1) and poly[poly(ethylene glycol)phosphate] (2) were examined as ionic carriers for concentration/separation processes, applying the liquid membrane technique. Experiments were performed with nickel and cobalt ions pertracted both from a single solution and bicomponent mixtures. 2, dissolved in 1,2‐dichloroethane, was found to be an effective carrier of nickel ions. The system seems to offer efficient separation of Ni(II)/Co(II) ions.
Synthesis of amphiphilic star‐shaped and graft copolymers based on polystyrene and poly(ethylene oxide)
Authors: Berlinova Iliyana V. , Panayotov Ivan M.
Published: April 2003

Amphiphilic block macromonomers possessing a central unsaturation were synthesized by condensation of polystyrene half‐ester of maleic acid {α‐[2‐(3‐carboxyacryloyloxy)ethyl]‐ω‐sec‐butylpoly[1‐phenylethylene]} with poly(ethylene glycol) monoether or polystyrene‐block‐poly(ethylene oxide). In the radical monomer cis‐trans‐isomerization homopolymerization of the diblock macromonomers, four‐to eight‐armed amphiphilic star‐shaped copolymers were obtained. Radical copolymerization of the diblock macromonomers with styrene led to graft copolymers with low degree of grafting. The triblock macromonomers proved to be unable to polymerize.
Synthesis and characterization of processable conducting polyazomethines
Authors: Lee Kwang‐Sup , Won Jong Chan , Jung Jin Chul
Published: April 2003

A series of the wholly aromatic polyazomethines (PAM) having flexible side chains was synthesized by solution and melt polycondensation of 2,5‐dialkoxyterephthalaldehydes and aromatic diamines. The solution polycondensation was carried out at 80°C for 24 h in 1,3‐dimethyl‐3,4,5,6‐tetrahydro‐2(1H)‐pyrimidinone (DMPU)/N‐methyl‐2‐pyrrolidone (NMP) mixtures. The melt polycondensation was conducted in N2 atmosphere at 200°C for 2,8 h. All of the polymers were soluble in CCl4, CHCl3, THF, benzene, toluene, etc. The inherent viscosity (ηinh), measured at 30°C in CHCl3, was 0,13–0,32 dL/g, and 5% weight loss in TG curves appeared at 365–390°C in N2 atmosphere. The electrical conductivities of I2‐treated dialkoxy‐substituted PAM were low, 10−4 < σ < 10−6 S/cm, compared with unsubstituted I2‐treated PAM.
Perfluoroalkylated monomers and polymers
Authors: Freund Lothar , Jung Holger , Nießner Norbert , Schmidt Hans‐Werner , Heitz Walter
Published: April 2003

Trifluoromethyl‐, pentafluoroethyl‐ and other perfluoroalkylbenzenes (2a–d, 4 and 3) were prepared by the reaction of the corresponding aromatic halides with perfluorocarboxylic acids in the presence of copper(I) iodide. These products were modified by oxidation or (and) substitution reactions and subsequently polymerized to give perfluoroalkyl‐substituted polyamides, polyesters and poly(thio‐1,4‐phenylene)s showing good solubility.
Polymers and oligomers with substituted 2,5‐thienylene units. Preparation and electrical conductivity properties
Authors: Yamamoto Takakazu , Kashiwazaki Akio , Kato Kazunori
Published: April 2003

Ni‐catalyzed dehalogenation polycondensation of 3‐formyl‐, 3‐hydroxyiminomethyl‐ and 3‐cyano‐2,5‐dibromothiophene with zinc affords oligo(3‐formyl‐2,5‐thienylene) (2a), oligo‐(3‐hydroxyiminomethyl‐2,5‐thienylene) (2b), and oligo(3‐cyano‐2,5‐thienylene) (2c). Electrochemical polymerization of 3‐methoxythiophene and 3,4‐dimethoxythiophene give blueblack films of oligo(3‐methoxy‐2,5‐thienylene) (2d) and poly(3,4‐dimethoxy‐2,5‐thienylene) (2e). Iodine adducts of 2a–2c show electrical conductivity values between 1,8 · 10−11 and 8,8 · 10−8 S · cm−1. Doped 2d shows electrical conductivity of 2 · 10−1 S · cm−1, whereas doped 2e exhibits an electrical conductivity between 1,5 and 30 S · cm−1. Doping of undoped 2d and 2e causes profound changes in their IR and NMR spectra, colour, and electrical conductivity properties.
Etude par 1H NMR des groupements chlorométhyles du poly(chlorure de vinyle), 2. Etude par écho de spin et comparaison avec des modèles moléculaires
Authors: Llauro‐Darricades Marie‐France , Pétiaud Roger
Published: April 2003

In order to assign all CH2Cl resonances observed by 1H NMR in poly(vinyl chloride), (PVC), a preliminary study of the diastereoisomers of molecular models for the groups CH2ClCHCl [II] and is used, in conjunction with spin echo experiments. The complex region [3,5–4,0 ppm] which corresponds to saturated CH2Cl chloromethyl protons is completely assigned. A separate evaluation of CHClCH2Cl [II], CH2CH2Cl [III] and is proposed and tested on raw PVC samples. The main interest of this 1H NMR determination is the fact that raw PVC can be used and that it gives the ratio [II]/[III] which is not accessible by 13C NMR on reduced samples.
An example of polymer reactivity affected by the presence of another polymer
Authors: Casinos Ismael , Fernández María Jesús
Published: April 2003

The acid hydrolysis of the cellulose portion of cellulose‐g‐poly(vinyl acetate‐co‐methyl acrylate) was carried out. The effect of the synthetic polymer in the reaction medium on the reactivity of cellulose in its acid depolymerization was studied. It could be shown that this effect is the same whether the synthetic polymer is covalently linked to cellulose or not and it was found that the hydrolysis time needed to degrade the cellulosic part of the graft copolymer is strongly dependent on the composition of the reaction mixture. This work showed that only a restricted range of graft copolymer compositions can be hydrolyzed in the shortest reaction time here established (14h). In order to hydrolyze graft copolymer samples with different compositions to those of the cited range, in the same hydrolysis time of 14h, two methods are suggested: (a) elimination of an adequate portion of cellulose from the graft copolymer and (b) addition of an appropriate amount of synthetic polymer to the graft copolymer sample. The second method is not useful from the point of view of polymer characterization. A molecular description of the reaction medium on the basis of the system components is attempted.
Synthesis, characterization and polymerization of new epoxy compounds containing azomethine linkages
Authors: Mikroyannidis John A.
Published: April 2003

New epoxy compounds bearing azomethine linkages were synthesized and characterized. A series of epoxy derivatives of bis(azomethine)s (2a – d) was synthesized by reacting an aromatic diamine with 4‐hydroxybenzaldehyde in a 1:2 mole ratio to afford the corresponding bis(azomethine)s (1a – d), and subsequent reaction with excess 1‐chloro‐2,3‐epoxypropane in presence of a quarternary ammonium bromide as catalyst. In addition, epoxy compounds 4a, b and 5b were synthesized by reacting 1,4‐benzenedicarbaldehyde with 4‐aminophenol, 4‐aminobenzoic acid or 5‐aminoisophthalic acid in a 1:2 mole ratio and then with 1‐chloro‐2,3‐epoxypropane. The epoxy compounds were characterized by elemental analyses as well as by IR and 1H NMR spectroscopy. All epoxy compounds were thermally polymerized in the presence of 4,4′‐sulfonyl dianiline (6). The polymerization was investigated by DTA. The thermal stabilities of the resulting polymers were evaluated by dynamic TG and isothermal gravimetric analysis (IGA). The polymers derived from diepoxy compounds are stable in nitrogen up to 293–340°C and afford an anaerobic char yield of 43–62% at 800°C.
A formylstyrene‐styrene‐divinylbenzene resin. Synthesis, condensation reactions, and low‐molecular‐weight model compounds
Authors: Strasdeit Henry , Friedemann Marion , Pohl Siegfried , Driessen Willem L. , Reedijk Jan
Published: April 2003

A formylated resin (1a) containing 4‐formylphenyl groups was obtained from poly[styrene‐co‐divinylbenzene (2%)] by reaction with Cl2CHOCH3/SnCl4 and subsequent hydrolysis of the intermediate. 1a reacted with N‐methyltrimethylenediamine with the formation of azomethine groups. From the nitrogen content of the product the degree of functionalization of 1a was calculated to be 50%. Condensation reactions between 1a and N‐ethylethylenediamine, cystamine, methanol, 1,2‐ethanedithiol, 2,3‐dimercapto‐1‐propanol (BAL), and 2‐aminobenzene‐thiol were also studied. A new chloromethylated resin was prepared from 1a and BAL in the presence of conc. hydrochloric acid (OH/Cl exchange). The formylation of 2,4‐diphenylpentane yielded the low‐molecular‐weight model compounds 4‐(1‐methyl‐3‐phenylbutyl)benzaldehyde (2a) and 2‐(1‐methyl‐3‐phenylbutyl)benzaldehyde (2b) in an 87:13 mole ratio, suggesting that ca. 90% of the aldehyde groups in 1a are in para‐position.
Polymers from multifunctional isocyanates, 4. Synthesis of alkylene(or arylene)bis(ω‐isocyanatocarboxamide)s and polyaddition to sequential poly(diamidodiurethane)s and poly(diamidodiurea)s
Authors: Mormann Werner , Hohn Elke
Published: April 2003

Alkylene‐ and arylenebis(ω‐isocyanatodicarboxamide)s were obtained in high yields by regioselective reaction of isocyanatoacyl chlorides with silyl protected diamines (1,2‐ethanediamine, 1,6‐hexanediamine, piperazine, p‐ and m‐phenylenediamine). 3‐Isocyanatopropanamides undergo cyclization through intramolecular attack of the amide nitrogen by the isocyanate group to form six‐membered acylureas (5,6‐dihydro‐(1 H, 3 H)‐2,4‐pyrimidinediones), which do not react further with amines or alcohols. Poly(diamidodiurethane)s and poly(diamidodiurea)s were made from bis(isocyanatobutanamide)s and bis(isocyanatohexanamide)s by polyaddition with 1,4‐butanediol or diamines. The polymers have a regular sequence of two amido and two urethane (urea) groups; they are crystalline materials. Starting from a given diisocyanatodicarboxamide the urea melts about 40 to 60°C higher than the urethane. The poly(urethane)s from piperazine‐based diisocyanatodicarboxamides have rather low melting points due to the missing possibility of the amide group to act as hydrogen bond donor. Thermogravimetric results show higher thermostability for the poly(diamidodiurea)s than for the corresponding poly(diamidodiurethane)s and increasing thermostability with increasing length of the isocyanatoalkanamide applied.
Preparation and characterization of a series of poly[oxy‐1‐(ω‐bromoalkyl)ethylene]s
Authors: Wicks Douglas A. , Tirrell David A.
Published: April 2003

2‐Bromoethyloxirane (2b), 3‐bromopropyloxirane (2c), and 4‐bromobutyloxirane (2d), were prepared by epoxidation of the corresponding bromoalkenes. Treatment of the oxiranes with a triethylaluminium/acetylacetone/water mixture afforded the polyethers 3b–d in good yield as tacky, white elastomers. Substitution of bromide by benzoate ion established essentially equal reactivities for the three polymers; each was substantially more reactive than any of the halogenated polyether elastomers available heretofore.