bluuebunny/crossref_metadata_2025 huggingface dataset:
Viscoelastic properties of mixtures of polystyrene with low‐molecular‐weight poly[oxy(2,6‐dimethyl‐1,4‐phenylene)]
Authors: de Araujo Marco Aurelio , Stadler Reimund
Published: April 2003

A series of poly[oxy(2,6‐dimethyl‐1,4‐phenylene)]s (PPE) (trivial names: polyphenylenether, polyoxyxylene, polyphenyleneoxide) with narrow molecular weight distribution were prepared by polymerization of 4‐bromo‐2,6‐dimethylphenol and subsequent fractionation. The molecular weight dependence of the glass transition temperature obeys the Fox‐Flory equation. Polystyrene (PS)/PPE blends (PS: number‐average molecular weight M̄n = 144 000, ratio of weight‐ to number‐average molecular weight M̄w/M̄n = 1,05) were prepared using PPE samples with molecular weights below the entanglement spacing of PPE, in order to obtain information about the influence of specific interactions on the linear viscoelastic properties in the plateau and terminal region. The iso‐free‐volume state turned out to be the most appropriate reference state to compare samples of various compositions. Low‐molecular‐weight PPE essentially acts as a solvent for polystyrene. The concentration dependence of the zero‐shear viscosity η0 is proportional to ϕ3,6PS, ϕPS being the volume fraction of PS, and the temperature dependence of the logarithmic shift factor log aT indicates that interactions, which are responsible for the thermodynamic miscibility in this system, do not alter the linear viscoelastic properties of PS. The concentration dependence of the plateau modulus (G(0)N ∝ ϕ1,2 for PS/PPE‐1500) blends is explained by an additional small elastic contribution of the short PPE chains to the plateau modulus at higher frequencies.
Zum Mechanismus der oxidativen Kupplung von Phenolen
Authors: Bartmann Martin , Kowalczik Udo
Published: April 2003

In order to make a decision between the quinone acetal equilibration/quinone acetal rearrangement and the so far discussed SET mechanism for the oxidative coupling of 2,6‐xylenol to poly(oxy‐2,6‐dimethyl‐1,4‐phenylene) the polymerization was carried out in the presence of 5‐(2,6‐dimethylphenoxy)‐2‐methoxy‐1,3‐xylene (1) (the methylated dimer) or α‐methyl‐ω‐phenoxypoly(oxy‐1,4‐phenylene) [O‐methylated poly(phenylene ether)] (2). GC and GPC studies indicated that neither 1 nor 2 are incorporated into the polymer. These observations exclude the SET‐mechanism according to Scheme 4.
Thermal analysis of poly(butylene terephthalate) for heat capacity, rigid‐amorphous content, and transition behavior
Authors: Cheng Stephen Z. D. , Pan Robert , Wunderlich Bernhard
Published: April 2003

Thermal analysis was performed on poly(butylene terephthalate), PBT, between 210 and 560 K. By combination of experimental heat capacities with computations with an approximate frequency spectrum of 65 group and 19 skeletal vibrations, preliminary recommended ATHAS (1988) heat capacities are proposed for the solid state from 0 to 600 K. The Tarasov parameters used for the computation of the skeletal vibrations were θ1 = 542 K and θ3 = 80 K for crystalline PBT and θ3 = 40 K for amorphous PBT. The glass transition temperature of amorphous PBT was found on efficiently quenched samples to be 248 K, much lower than for semicrystalline PBT where a 310–325 K glass transition temperature is typical. The increase in heat capacity calculated for 100% amorphous samples is 107 J/(K · mol) at 248 K and 77 J/(K · mol) at 320 K. The equilibrium melting temperature is estimated to be 518 K. The unique existence of rigid‐amorphous fractions of the semicrystalline polymers is discussed with quantitative data for samples crystallized from the glass and from the melt between 275 and 490 K. The rigidamorphous fraction varies between above 0,9 for cold‐crystallized samples to 0,3 for samples crystallized at 490 K. The crystallinity varied from below 0,1 to 0,5. The crystallinity could be separated into four parts, melting at high, medium, and low temperatures, and a part crystallized on cooling after isothermal crystallization. The sequence of crystallization of differently melting crystals was established.
Crosslinking reactions in the molten state: Interpolymeric condensation reactions
Authors: Lambla Morand , Druz Jacques , Satyanarayana Nallani
Published: April 2003

Chemical reactions leading to crosslinking were followed by rheometrical studies during curing at different temperatures and compositions of compatible species. The condensation reactions between two copolymers of styrene and maleic anhydride, and several α,ω‐dihydroxyoligostyrenes, lead to an experimental variation of the elastic modulus (G′)t. A kinetic scheme is proposed, selecting the most reliable reactions, which describes the experimental behaviour adequately. According to this scheme, the rate constants of interpolymeric condensation reactions were evaluated. It appears that the values obtained for grafting and crosslinking are quite the same. They depend mainly, in absence of a catalyst, on the molecular weight of the oligomer and on the local viscosity, which is a function of composition. In presence of a catalyst, there is a large increase of the constant, indicating that the chemical step is dominating the diffusion process.
Liquid‐crystalline aromatic polyesters with phenylalkyl side chains
Authors: Brügging Wilhelm , Kampschulte Uwe , Schmidt Hans‐Werner , Heitz Walter
Published: April 2003

Thermotropic liquid‐crystalline poly(1,4‐phenylene terephthalate)s with phenylalkyl side chains were synthesized. The influence of this novel type of substituent on the thermal properties and solubility behavior is discussed. In common solvents soluble, liquid‐crystalline polyesters with low transition temperatures were obtained when the phenylalkyl substituent was introduced in combination with a bulky substituent or when both phenyl rings were substituted with phenylalkyl side chains. When poly(1,4‐phenylene terephthalate) is only monosubstituted with a phenylalkyl substituent in the 1,4‐phenylene unit, the polyesters have melting temperatures above 310°C and are only soluble in solvents such as p‐chlorophenol.
Funktionalisierung heterogen‐vernetzter polyvinylalkohol‐gele
Authors: Schott Herbert , Bretzger Waltraud
Published: April 2003

Cross‐linked poly(vinyl alcohol) beads were functionalized by derivatization of their hydroxyl groups with succinic acid anhydride, 1,6‐hexamethylene diisocyanate, 3‐aminopropyltriethoxysilane, 2‐chlorophenylbis(1,2,4‐triazol‐4‐yl) phosphate and different sulfhydryl reagents. The resulting 8 gels carry isocyanato, carboxyl, amino, phosphate and mercapto residues in concentrations of 1 to 3 mmol per gram of polymer. The derivatives obtained from the starting poly(vinyl alcohol) beads are mechanically stable, resistent to hydrolysis in the pH range between 1 and 14 and stable up to 100°C. The functionalized, cross‐linked polymer beads, applicable in aqueous systems as well as in organic solvents, should find a wide application in chromatography, as supports in the preparative solid phase synthesis and as basic carriers for polymeric reagents.
Studies on functional diene oligomers with an amino end group, 3. Synthesis of oligoisoprenes containing a secondary amino end group
Authors: Nagasaki Yukio , Higuchi Akinori , Goan Hiroki , Yoshino Norio , Tsuruta Teiji
Published: April 2003

Lithium monoalkylamide, in the presence of monoalkylamine, was found to initiate the polymerization of isoprene to form oligoisoprenes. The molecular weight distribution of products formed in the lithium isobutylamide initiated isoprene oligomerization strongly depends on the initial mole ratio [Isoprene]0/[Amine]0/[Amide]0; with an initial mole ratio of 60/1/8, oligomers with a number‐average molecular weight of about 800 were obtained. The presence of N,N,N′,N′‐tetramethylethylenediamine in the reaction system was found to be effective for the selective formation of secondary amino‐ended oligoisoprenes.
Synthesis and transport properties of 2‐ethylhexylpoly(trimethylene phosphate) – A synthetic analogue of natural teichoic acids
Authors: Wódzki Romuald , Kałużyński Krzysztof
Published: April 2003

The paper deals with modelling the transport of magnesium and calcium ions in the cell wall of Gram‐positive bacteria. The model compound, i. e. 2‐ethylhexylpoly(trimethylene phosphate)

Structure‐based IUPAC nomenclature: α‐2‐Ethylhexyl‐ω‐hydroxypoly[oxy(hydroxyphosphonol)oxytrimethylene].

(EPTP), was synthesized in order to mimic the transport mediated by lipoteichoic acids. It was found that EPTP can transport preferentially magnesium ions in an ion exchange‐diffusion process with the counter‐transport of hydrogen ions.
Poly{[(Chloro‐2 éathyl)‐4 phéanyl]‐1 éathylène}: Synthèse, caractérisations, dégradation thermique et modifications chimiques
Authors: Boinon Bernard , Benayad Belabbas , Monthéard Jean‐Pierre
Published: April 2003

Poly{1‐[4‐(2‐chloroethyl)phenyl]ethylene} (3) was synthesized by bulk polymerization of 4‐(2‐chloroethyl)styrene (6) in two steps from commercial products. The polymer was characterized by means of GPC (weight‐average molecular weight M̄w = 85 000 and number‐average molecular weight M̄n = 63 500), 1H NMR and 13C NMR spectroscopy. The first stage of thermal degradation begins at 290°C and ends at about 410°C. The overall activation energy was calculated to be 43 kcal · mol−1 (180 kJ · mol−1). The solid residue was crosslinked and insoluble. The volatile products, identified by gas chromatography‐mass spectroscopy (GC‐MS), were chiefly hydrogen chloride, dichloromethane and monomer. In a strongly basic medium, nucleophilic substitution of chlorine was achieved without elimination.
New functional poly(ethylene oxide)s: Synthesis and application
Authors: Kazanskii Konstantin S. , Ptitsyna Nelli V.
Published: April 2003

Principles and new approaches to the synthesis of functional poly(ethylene oxide)s (PEO) are considered. It could be shown that quantitative functionalization during initiation or deactivation of living polymers cannot be reached independently of the demands to achieve a desired molecular weight of the polymer. This is illustrated by the data of the synthesis of dinitrophenyl derivatives of PEO (molecular weights from 3 · 103 to about 105) which are synthetic immunogenes. Vinyl ether macromonomers of PEO with molecular weights in the range of 750–3000 were also synthesized by anionic polymerization of ethylene oxide with trimethylamine as initiator. These macromonomers were used for effective grafting of PEO onto a solid surface, grafted PEO being able to selectively binding alkali salts from the solution. Values of binding constants were evaluated.
Functionalization of polysiloxanes by esterification of pendant epoxy groups: Cross‐linkable liquid polymers containing photo‐dimerizable ester units
Authors: Hajaiej Adel , Coqueret Xavier , Lablache‐Combier Alain , Loucheux Claude
Published: April 2003

Photo‐dimerizable carboxylic acids were grafted onto linear silicone copolymers by amine catalyzed esterification of pendant epoxypropyl groups. The epoxy‐carboxy reaction was found to surpass in experimental simplicity, chemical selectivity and reproducibility, the modification methods involving the hydrosilylation of functionalized olefins. Liquid, photo‐crosslinkable polymers (8a and 8b) were finally obtained after acetylation of the hydroxy‐ester groups resulting from the addition of functional carboxylic acids, and no unwanted side‐reaction was detected. The practical sensitivity of photo‐reactive polysiloxanes of various average molecular weights containing 5–17 mol‐% of sensitive units, was measured by photoresist type insolubilization tests. The ultimate acetylation reaction was shown to have little or no influence on the dimerization process of 2‐cyano‐5‐phenyl‐2,4‐pentadienoic derivatives (8a), but to increase the rate of disappearance of trans‐cinnamic groups (in 8b) submitted to UV light irradiation.
Stereochemistry of anionic oligomerization, 22. Effects of chain length and stereochemistry on the kinetics of addition of 1,1‐diphenylethylene to oligomeric models of living poly(2‐vinylpyridine)lithium
Authors: Helary Gerard , Fontanille Michel , Khan Ishrat M. , Hogen‐Esch Thieo E.
Published: April 2003

Rate constants and equilibrium constants were determined for the addition of 1,1‐diphenylethylene to living trimers of 2‐vinylpyridine in THF having either a meso or a racemic diad adjacent to the carbanion center. The racemic isomer was shown to be slightly more reactive (≈40%) compared with the meso isomer and slightly less than the corresponding dimer. The living dimer of 2‐vinylpyridine in turn is slightly more reactive than the meso trimer, but is five times less reactive compared to the lithio salt of 2‐ethylpyridine. The changes in equilibrium constant were quite dramatic, the constant for lithio‐2‐ethylpyridine being about 100–200 times larger than for the living oligomers and about 2 600 times larger than that of the living polymer.
Gas‐phase copolymerization of ethylene with propene and with 1‐butene using supported chromium‐ and titanium‐containing catalysts
Authors: Zakharov Vladimir A. , Yechevskaya Lyudmila G. , Bukatov Gennadii D.
Published: April 2003

The gas‐phase copolymerization of ethylene with propene and 1‐butene using supported Cr‐containing catalysts of different composition and supported Ti‐Mg catalysts was studied. Comonomer reactivity ratios for 8 different catalyst systems were determined. A lower regiospecificity of the chromium oxide catalyst as compared with the titanium‐magnesium catalyst was observed, according to 13C NMR measurements.
Small‐angle X‐ray diffraction study of the monoclinic modification of poly(3,3‐dimethyloxetane)
Authors: Pérez Ernesto , Bello Antonio , Fatou José G. , Rausell‐Colom José A.
Published: April 2003

The long spacings of several samples of poly(3,3‐dimethyloxetane) (PDMO) were determined by small‐angle X‐ray diffraction as a function of molecular weight and crystallization temperature, in the interval where only the monoclinic modification is produced. The equilibrium melting temperature and the basal interfacial free energy of the mature crystals were determined from the correlation between long spacings and melting temperatures. Finally, an estimation of the critical sizes of the nuclei was made from nucleation theory, and the results were compared with the actual sizes of the crystallites, assuming a two‐phase model. Our results show that both the nuclei and the mature crystals have rather small sizes, which is attributed to the high under‐coolings involved in the crystallization of PDMO.
Polymerisation durch [3+2]‐cycloaddition, 2. Reaktionen von hexafluoracetonazin mit substituierten diolefinen
Authors: Nuyken Oskar , Maier Gerhard , Burger Klaus
Published: April 2003

Hexafluoroacetone azine reacts with esters of 1,6‐heptadien‐4‐ol to form polymers 1 containing 4,4,8,8‐tetrakis(trifluoromethyl)‐1,5‐diazabicyclo[3.3.0]octan‐2,6‐diyl groups linked with trimethylene chains with acyloxy side groups. Due to these ester functions the polymers are completely soluble in common solvents. DSC measurements proved these polymers to be partly crystalline.
Polymere aminoschutzgruppen auf basis von tert‐butoxycarbonyl‐ und benzyloxycarbonylfunktionen enthaltenden polymethacrylamiden
Authors: Rehse Henning , Ritter Helmut
Published: April 2003

The synthesis of tert‐butoxycarbonyl‐ and benzyloxycarbonyl‐modified monomers was performed by the addition of p‐chlorophenyl isocyanate or benzyl isocyanate to the free OH groups of N‐(2‐hydroxy‐2‐methylpropyl)methacrylamide (1), N‐(2‐hydroxy‐2‐methylpropyl)‐6‐methacrylamidohexanamide (2) and N‐β‐hydroxyphenethylmethacrylamide (3). The monomers were homopolymerized and copolymerized with MMA. The kinetics of acidic‐induced amine cleavage from the new amino‐protecting groups was followed by NMR spectroscopy and it became evident that the polymers are suitable amino‐protecting groups. Ca2+ ions enhance the rate of amine cleavage considerably. Neighboring group effects, the influence of comonomers and spacer groups on the reactivity of the urethane groups are also discussed.
Activation of propene polymerization by hydrogen for improved MgCl2‐supported Ziegler‐Natta catalysts
Authors: Spitz Roger , Masson Patrick , Bobichon Charles , Guyot Alain
Published: April 2003

As in the case of the third generation MgCl2‐supported stereospecific catalysts, characterized by the use of aromatic esters as internal and external Lewis bases, the new improved family of catalysts, containing an aromatic diester as internal Lewis base and a trialkoxyphenylsilane as external Lewis base, was found to be sensitive to hydrogen. A very strong activation effect, followed by deactivation, was observed upon introduction of small amounts of hydrogen. In the present case the effect is reversible, unless rather high hydrogen pressure (2 bar) is used. The activation effect was observed with any of the cocatalysts and even in the absence of an external Lewis base. The effect is reduced or even suppressed if enough ethylene is used in the copolymerization with propene. Owing to the competition between ethylene and hydrogen for the activation, it is assumed that the step sensitive to hydrogen is that of initiation rather than propagation.
Emulsion polymerization of butadiene, 1. The effects of initiator and emulsifier concentration
Authors: Weerts Pierre A. , van der Loos Jos L. M. , German Anton L.
Published: April 2003

The kinetics of the emulsion polymerization of butadiene was investigated using Dresinate 214 as emulsifier and three dissociative initiators, viz. potassium peroxodisulfate, 4,4′‐azobis‐(4‐cyanopentanoic acid) and 2,2′‐azoisobutyronitrile. All experiments were conducted in the presence of a thiol as chain transfer agent, as usual in diene‐polymerizations. The polymerization rate in interval II, Rpol, was found to be highly insensitive to changes in the initiator concentration (Rpol ∝ [I]0,08). Primary radicals are generated in large abundance in interval I as compared with the final particle number, indicating that the initiator efficiency with regard to particle nucleation is very low. The development of particle number as a function of conversion at several emulsifier concentrations shows that limited coagulation is occurring in the present system. Rpol depends on the emulsifier concentration with an exponent of 0,61, while the final particle number after cessation of coagulation depends on the emulsifier concentration to the 1,6th power. As a consequence the average number of radicals per particle must be a function of particle size, because the monomer concentration in the latex particles is approximately constant in interval II. A certain analogy in behaviour between the emulsion polymerization of various polar monomers, kinetically dominated by radical desorption, and the emulsion polymerization of butadiene, suggests that similar events determine the kinetic course in the present system.
Emulsion copolymerization of acrylonitrile and butyl acrylate, 10. Effect of 1,1‐diphenyl‐2‐picrylhydrazyl on the polymerization process
Authors: Capek Ignác
Published: April 2003

The emulsion copolymerization of acrylonitrile with butyl acrylate, initiated by ammonium persulfate in the presence of disodium dodecylphenoxybenzenedisulfonate and 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH), was kinetically investigated at 70°C by conventional GLC and gravimetric methods. The copolymerization under batch conditions was conducted to both low and high conversion. In the presence of a small amount of DPPH the molecular weight of the copolymer is little decreased when compared with that prepared without DPPH. In addition, the rate of copolymerization unexpectedly decreases with increasing emulsifier concentration. The radical scavenger was found to decrease the average particle size. In the interval 2 the rate of polymerization is approximately proportional to the 0,35th power of the emulsifier concentration and to the 0,5th power of the initiator concentration (without DPPH). The dependence of the rate of polymerization on the final particle number and of the final particle number on the emulsifier concentration also deviates from the simple micellar theory predictions. The results can be explained by a coagulative nucleation mechanism.
Polymer diffusion and mobility in mixtures of polystyrene and polymethylstyrenes
Authors: Lang Sibylle , Sillescu Hans
Published: April 2003

Tracer diffusion coefficients D* of both components were measured in mixtures of polystyrene with poly(o‐methylstyrene), poly(p‐methylstyrene), and a commercially available random copolymer of p‐ and m‐methylstyrene, respectively. D* values were determined by applying the holographic grating technique where between 5 and 10% of the respective polymer component was labelled at the end group with a photoreactive dye. For molecular weights between 15 000 and 37 000 and temperatures between 175 and 200°C, the D* values differed relatively slightly when compared at equal molecular weight and equal temperature distance T–Tg from the glass transition temperature Tg. The differences were compared with those of monomeric friction coefficients obtained from dynamic mechanical experiments.
Nuclear magnetic resonance study on the relationship between the helicity and L‐alanine content of L‐alanine/β‐alanine random copolypeptides in connection with silk fibroin conformation
Authors: Kashiba Hitoshi , Asakura Tetsuo , Komoto Tadashi
Published: April 2003

The helicities of six kinds of L‐alanine/β‐alanine random copolypeptides having different L‐alanine contents were determined using 1H NMR. Next, the theoretical helicities of these copolypeptides were calculated on the basis of a statistical thermodynamic analysis of the helixcoil transition of the random copolypeptide — using Monte Carlo methods — as a function of the L‐alanine content. The statistical weight parameters used in the model were determined from a comparison of the observed and calculated results. The experimental and theoretical results are in agreement with the fact that Bombyx mori silk fibroin with 30,0 mol‐% L‐alanine content assumes exclusively a random‐coil conformation and that Philosamia cynthia ricini silk fibroin with 48,8 mol‐% L‐alanine content locally assumes an α‐helical conformation in the sequence of the L‐alanine residues, both in aqueous solution.
Role of polymer matrix on the conductivity of polymers doped with tetracyanoquinodimethane (TCNQ) salts of polycations
Authors: Pecherz Janusz , Kryszewski Marian
Published: April 2003

The influence of interactions with polymer matrix on the critical concentration and stability of heterogeneous conductive polymer films was investigated. These films were obtained by reticulate doping of polyacrylonitrile (PAN), poly(methyl methacrylate) (PMMA) and polycarbonate (PC) with complex salts of tetracyanoquinodimethane (TCNQ) with polycations having sulfonium groups in the main chain, Ks[4,6]. It was found that the chemical structure of the matrix influences the conductivity of such systems. The PMMA matrix is most suitable for obtaining conducting systems at low concentration of the dopant. In PMMA the absorption spectra of moleculary dispersed Ks[4,6] do not change with time. The strong influence of PAN matrix was confirmed by the study of absorbance changes of Ks[4,6] with time in this matrix and particularly by investigation of absorption of this salt in solutions containing acrylonitrile/methyl methacrylate copolymers of various composition.
Structural investigations and phase behaviour of a ternary lyotropic liquid‐crystalline cellulosic system: Cellulose tricarbanilate/3‐chlorophenylurethane of cellulose/triethylene glycol monomethyl ether
Authors: Siekmeyer Maria , Steinmeier Hans , Zugenmaier Peter
Published: April 2003

Two similar, fully substituted cellulose derivatives, phenylurethane and 3‐chlorophenylurethane of cellulose, and mixtures of various ratios thereof in a common solvent were investigated in the lyotropic liquid‐crystalline phase. Helicoidal structures of different handedness were found with regard to the two binary liquid‐crystalline systems. Compatibility of the considered ternary system may be concluded from a structural investigation in the high and low composition range with regard to one cellulose derivative component and incompatibility of the lyotropic liquid‐crystalline system in the medium composition range. Structural features of the ternary system at elevated temperatures were evaluated by a turbidimetric study.
Phase transitions and structure changes in poly[bis(phenoxy)‐λ5‐phosphazene]
Authors: Kojima Morio , Sun Del C. , Magill Joseph H.
Published: April 2003

Phase transition behavior in poly[bis(phenoxy)‐λ5‐phosphazene] (PBPP) was studied by electron microscopy, X‐ray diffraction techniques and differential scanning calorimetry. Several polymorphic forms were detected. Relative changes in enthalpy associated with the thermotropic transition, T(1), are examined as a function of heat treatment. Correspondingly, structural and morphological changes have been established in line with enthalpy results.
Preferential solvation of polystyrene by an excimer‐forming fluorophore in the system polystyrene/cyclohexane
Authors: Fuhrmann Jürgen , Wadle Armin , Krampitz Gerhard , Hennecke Manfred
Published: April 2003

Fluorescence spectroscopy is used to study the preferential solvation of the polymer and the mobility of the fluorophore in the highly diluted ternary system polystyrene/ethyl 1‐naphthoate/cyclohexane under theta‐conditions. The ratio of the excimer to monomer fluorescence intensity Iexc/Imon of the fluorophore is correlated with the concentration and the mobility of the fluorophore in the two phases, inside and outside the polymer coil; the limits of this model are discussed in detail. In the selected system preferential solvation increases the Iexc/Imon ratio whereas the reduced mobility of the fluorophore inside the coil acts in the opposite manner. The model allows to calculate the distribution coefficient K for the distribution of the fluorophore between the two phases and the ratio q of the mobilities for the fluorophore in the two phases. The values of K obtained indicate a strong preferential solvation of polystyrene by the ethyl 1‐naphthoate fluorophore. The mobility ratio q depends on the molar mass of the polymer in such a way that it reflects segmental density.
ABA triblock comb copolymers with oligo(oxyethylene) side chains as matrix for ion transport
Authors: Khan Ishrat M. , Fish Daryle , Delaviz Yadollah , Smid Johannes
Published: April 2003

ABA triblock copolymers consisting of two terminal blocks (A) of comb‐like polymethacrylate with oligo(oxyethylene) side chains (on the average eight oxyethylene units per side chain) and a middle block B of polystyrene were synthesized by anionic polymerization. The ratios A/B were varied, and the respective polymers characterized by 1H and 13C NMR, gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). The polymers were then solution‐cast from tetrahydrofuran solutions of lithium perchlorate, and the homogeneous, solvent‐free polymer electrolyte systems tested for their thermal characteristics (DSC) and conductivity. The inclusion of a polystyrene block in the comb‐like polymethacrylate electrolyte vastly improves their film‐forming and mechanical properties, but also lowers the conductivity. Addition of dimethyltetraethyleneglycol (2,5,8,11,14‐pentaoxapentadecane) enhances the ion conduction which can reach values of 10−4 Ω−1 · cm−1 at 70°C, depending on salt and styrene content.
Photon correlation spectroscopy of dilute polymer solutions: Dynamic zimm plots and scaling of molar‐mass‐dependent properties
Authors: Vancsó Gyula
Published: April 2003

Results of photon correlation spectroscopy measurements on polystyrene (PS) standards in dilute tetrahydrofuran (THF) solutions are presented. The experiments were performed at 45°C on eight different samples covering the molar mass range between 5·105 and 1,6·107 g/mol. The first cumulant of the measured dynamic structure factor of the scattered light is discussed as a function of the scattering angle and of the solution concentration. The scaling constants of the centre‐of‐mass diffusion coefficient and of the Stokes effective hydrodynamic radius with molar mass are determined. The relationship between the concentration dependence of the centre‐of‐mass diffusion coefficient and the molar mass is derived. The values of the reduced first cumulants are presented by dynamic Zimm plots. The shape of the Zimm plots shows a deviation from the theoretically predicted form. This deviation is explained by applying the results of dynamic scaling considerations.
Radikalpolymerisation von methylmethacrylat im gesamten umsatzbereich. Stationäre und instationäre experimente zur bestimmung von wachstums‐ und abbruchsgeschwindigkeit
Authors: Sack‐Kouloumbris Regina , Meyerhoff Günther
Published: April 2003

Free‐radical polymerization of methyl methacrylate in bulk at 0°C over the full range of conversion is reported. Details for stationary and non‐stationary experiments are described allowing to measure both kinetically relevant ratios fk/ka and kw/ka, f representing radical efficiency, kw rate constants of propagation and ka rate constant of termination. From these ratios the absolute rate constants kw and ka are available. The photochemical decay of the initiator 1,1′‐azodicyclohexanenitrile in connection with the rotating‐sector technique and observation of the post‐effect after stopping the initiator decay were used. The rate of polymerization and the number‐ and weight‐average molar masses were measured. Both, kw and ka, showed a strong dependence on conversion which is well known for ka but is reported here for the first time for kw since Hayden and Melville's determination of kw from measurements of the temperature increase during polymerization were reported.
Poly(2‐vinylpyridine) block copolymers. Phase separation and electric conductivity of iodine complexes
Authors: Möller Martin , Lenz Robert W.
Published: April 2003

A series of AB diblock copolymers of poly(2‐vinylpyridine) (P‐2VP) and either polybutadiene or polystyrene were prepared in a nonpolar solvent at low temperature. Well‐defined polymers with narrow molecular weight distributions were obtained and electron micrographs showed that these block copolymers form a well‐separated two‐phase morphology. Percolation of P‐2VP domains could be achieved for samples with 40 and with 60 mol‐% of P‐2VP blocks. These samples were modified by addition of various amounts of iodine in solution and in the melt. Electric conductivities of the doped composites were determined by the four‐probe method. The conductivities of the two phase systems were, in general, lower than that of P‐2VP doped with I2.
Investigation of electrical conduction of thermally treated nylon‐6 films
Authors: Bhat Narendra V. , Kelkar Deepali S.
Published: April 2003

This paper reports the variation in electrical conduction of thermally treated nylon‐6 films. The conductivity measurements were performed in vacuum over the temperature range from room temperature to 80°C. The samples of the nylon‐6 films varying in form and degree of crystallinity were prepared by heat‐setting nylon‐6 films in nitrogen atmosphere at different temperatures for one hour. The results of the variation of conductivity with temperature and the current‐voltage characteristics are used to analyze the mechanism of electrical conduction in nylon‐6 as well as for the calculations of the activation energy of electrical conduction. A change in the structure of nylon‐6 was found to affect both the mechanism of electrical conduction and the activation energy.
Strictly alternating polyamides with stiff and flexible chain segments: Effects on thermotropic liquid crystallinity of the introduction of an ethylene unit into the mesogenic group
Authors: Schmucki Marcel , Jenkins Aubrey D.
Published: April 2003

Bipolyamides containing mesogenic groups were prepared by solution polycondensation from aromatic dicarbonyl dichlorides and novel diamines. Ortho‐substitution and the aliphatic chain length of α,ω‐bis(4‐aminophenyl)alkylenes affected the thermal transitions of the resulting polyamides profoundly. Introduction of an ethylene unit into the stiff biphenylene segment not only reduced the isotropization temperatures, but also depressed the tendency to form liquid crystals.
Properties of polyacetylene obtained with (η‐Cp)2Ti(PMe3)2
Authors: Martinez Jairo R. , Rausch Marvin D. , Chien James C. W. , Alt Helmut G.
Published: April 2003

Acetylene was polymerized by (η‐Cp)2Ti(PMe3)2 at room temperature to give predominantly trans‐polyacetylene. All properties are within the ranges reported for polyacetylene produced with Ti(OBu)4/AlEt3 as catalyst.
Synthesis of polyamides by direct polycondensation with phenylphosphonic anhydride as an activating agent
Authors: Ueda Mitsuru , Honma Tsukasa
Published: April 2003

A new activating agent for amide condensations, phenylphosphonic anhydride (1), was prepared by the reaction of phenylphosphonic dichloride with water. The new activating agent was found to be useful for the preparation of amides from carboxylic acids and amines. The direct polycondensation of dicarboxylic acids with aromatic diamines using the activating agent in the presence of pyridine proceeds at 60°C to produce polyamides with inherent viscosities up to 1,1 dl/g. Furthermore, the activating agent was used for chemoselective polyamidation; that is, polyamides from dicarboxylic acids and diamines containing various functional groups were prepared without special protection of acylating‐sensitive groups.
Polymeric phthalocyanines and their precursors, 16. A structure model for polymeric phthalocyanines
Authors: Knothe Gerhard , Wöhrle Dieter
Published: April 2003

A model for describing the structural features such as degree of polymerization, size, and shape of polymeric phthalocyanines 2, 4, 6 is described. Analytical methods such as IR, titration of carboxylic end groups, and elemental analysis are used in the structure investigation. The results demonstrate that for polymeric phthalocyanines 2 with cyano end groups, prepared from 1,2,4,5‐benzenetetracarbonitrile (1), the number of macrocycles (n) in the polymer is not higher than 7–9, and that linear polymers as well as polymers with two rows are possible. Polymers 6, prepared from bridged diphthalonitriles 5, are considerably larger showing a more two‐dimensional structure. For polymeric phthalocyanines 4 with carboxylic end groups, prepared from 1,2,4,5‐benzenetetracarboxylic acid derivatives 3, a linear structure with n = 4–9 is favoured. Literature results are examined in the light of the described model.
Synthesis and properties of poly(peptide)‐wrapped unsubstituted metalophthalocyanines by polycondensation of micellar or reversed micellar aggregates
Authors: Hanabusa Kenji , Ye Xuanjing , Koyama Toshiki , Kurose Akio , Shirai Hirofusa , Hayakawa Tadao
Published: April 2003

Poly(peptide)‐wrapped unsubstituted metalophthalocyanines (Mt‐Pc's, Mt = Fe, Co) were synthesized by polycondensation of amphiphilic bifunctional active esters of amino acids (1 and 2), which form micellar or reversed micellar aggregates and solubilize Mt‐Pc's. Though Mt‐Pc's are insoluble in most organic solvents, the obtained poly(peptide)‐wrapped Mt‐Pc's are soluble in protic solvents such as formic acid, dichloroacetic acid, and trifluoroacetic acid. The wrapped Mt‐Pc's are stable, and their leakage out of the poly(peptide)s is not observed. UV‐Vis spectra revealed that the wrapped Fe‐Pc is predominantly in the monomeric state. ESR spectra confirmed the poly(peptide)‐wrapped structure of Mt‐Pc's.
Enzyme‐analogue built polymers, 25. Synthesis of macroporous copolymers from α‐amino acid based vinyl compounds
Authors: Wulff Günter , Vietmeier Jürgen
Published: April 2003

The suitability of a variety of newly prepared polymerizable a‐amino acid derivatives for the preparation of template‐imprinted polymers was investigated. The polymerizable binding sites were attached to the α‐amino acid template via azomethine, carboxylic ester or boronic ester linkages. Macroporous polymers containing these monomers were prepared. The extent to which the templates could be split off from the polymer, the degree of racemization of the a‐amino acids during polymerization and cleavage as well as the degree of rebinding to the polymers were studied.
Cationic polymerization of bis(1‐alkylvinyl)benzenes and related monomers, 1. Structure elucidation of 1,1,3‐trimethyl substituted polyindane
Authors: Dittmer Thomas , Gruber Freddy , Nuyken Oskar
Published: April 2003

1,4‐Bis(1‐chloro‐1‐methylethyl)benzene (BINIFER)/borontrichloride is known to be a very efficient initiating system for cationic polymerization of e.g. isobutene at low temperature (< −60°C). However, at higher temperature this system polymerizes by its own. The obtained polymers show a remarkable, high thermal stability and are soluble in common solvents. The analytical results indicate a very uniform structure consisting exclusively of 1,1,3‐trimethyl indane‐3,5‐diyl units. Other possible structures could be excluded. A mechanism explaining the surprisingly selective polyindane formation is discussed.
Synthesis and structure of nitro‐substituted poly(phthalidylidenebiphenyl‐4,4′‐ylene)s
Authors: Shitikov Aleksander V. , Zolotukhin Mikhail G. , Sultanova Venera S. , Panasenko Anatoly A. , Salaskin Sergei N. , Rafikov Sagid R.
Published: April 2003

Nitro‐substituted derivatives of poly(phthalidylidenebiphenyl‐4,4′‐ylene) (l), containing a controlled amount of nitro groups within 0,3 and 3,0 per mol of repeating unit, were prepared by nitrations under various conditions. The nitration was carried out either in nitric acid or by potassium nitrate and nitric acid in sulfuric acid solution. 13C NMR spectroscopy was used to study the structure of the resulting nitroderivatives. The trinitroderivative was found to contain the nitro groups in position 6 of the phthalide moiety and in positions 2 and 2′ of the biphenylylene unit. At lower degrees of nitration, some di‐, tri‐ as well as unsubstituted units are present in the polymer.
Poly(alkylene phosphate)s by polycondensation of phosphonic diamides with diols
Authors: Baran Jolanta , Klosinski Pawel , Penczek Stanislaw
Published: April 2003

Polycondensation of diols with phosphonic bis(dialkylamide)s leads to high‐molecular‐weight polyphosphites (M̄n up to 4 · 104). Model reactions of 1‐butanol, 2‐butanol and phenol with phosphonic bis(diethylamide) (1) were studied and it was established, that these reactions exhibit characteristic induction periods. Linearization of the kinetic curves after addition of amines prior to reaction enabled us to postulate the mechanism of esterification, involving activation of 1 by hydrogen‐bonding to amines. However, the major side reaction lowering the degree of polymerization was found to be dealkylation of the formed ester units by added and/or evolved amine. Therefore, in order to increase the rate of polycondensation and to prevent the formed polymer chain from breaking down by dealkylation, the process was conducted at increased temperature (90°C) in a nonsolvent for the polymer of higher molecular weight. Thus, the polymer separates from the major solution and becomes less prone to dealkylation.
Kinetic effect of radiation intensity and thermal after‐treatment in the photopolymerization of diallyl oxydiethylene dicarbonate
Authors: Bellobono Ignazio R. , Selli Elena , Righetto Luca , Rafellini Peppino , Trevisan Lucio
Published: April 2003

The influence of radiation intensity (from 1,08 · 10−7 to 2,48 · 10−4 einstein.s−1 · 1−1) on the photopolymerization of diallyl oxydiethylene dicarbonate was investigated systematically not only in the initial stages of reaction, but also at high monomer conversion (x), in order to detect possible variations in the polymerization mechanism. In some of the runs irradiation was stopped at x = 0,55–0,65 and thermal after‐treatments were carried out both in the presence and absence of air by following kinetically x‐values during the self‐decelerating cross‐linking. To rationalize experimental data a model is proposed which assumes two basically different mechanisms occurring simultaneously (bimolecular termination and radical trapping), but with different “weights” as a function of time. Long living radicals produced by irradiation continue to react in the dark. The rate of this reaction, which is enhanced in the presence of oxygen, is fitted by a relaxation model that considers double bonds, particularly of pendant groups, as traps, with increasing lifetimes, able to transfer to radical sites. The role of oxygen is also discussed.
Insoluble polymeric sulfoxides as liquid‐solid‐liquid and solid‐solid‐liquid triphase catalysts
Authors: Kondo Shuji , Yasui Haruhiko , Tsuda Kazuichi
Published: April 2003

Crosslinked polymers containing sulfinyl groups were prepared by free‐radical terpolymerization of p‐methylsulfinylstyrene, styrene, and divinylbenzene. These polymers serve as phasetransfer catalysts for the reaction of 1‐bromooctane with sodium iodide in toluene‐water system. The catalytic reaction is affected by some experimental parameters, such as stirring speed, particle size, degree of crosslinking, and solvent. The catalytic activity also depends strongly on copolymer composition, which causes differences in the adsorption of alkali metal ions and in the microenvironment around the active site. On the basis of the results of reactions of benzyl bromide with phenoxide, and of an alkyl methanesulfonate with sodium halides, it is evident that phase‐transfer reactions catalyzed by insoluble polymeric sulfoxides take place in the organic phase where a small amount of water exists. Furthermore, these polymers work as catalysts even in the absence of water.
Copolymerization of styrene with acrylonitrile initiated by 2‐methyl‐2‐undecanethiol
Authors: Cheng Haitao , Yan Deyue , Xia Ping
Published: April 2003

The copolymerization of styrene (St) with acrylonitrile (AN) initiated with 2‐methyl‐2‐undecanethiol (RSH) was investigated. Kinetic studies revealed that the initial rate of the copolymerization, which does not occur spontaneously in the absence of RSH, obeys the following expression: Rp ∝︁ [RSH]x, where x is 0,5 when [RSH] ranges from 3,4.10−4 to 3,4.10−3 mol/l and 0 when [RSH] is larger than 3,4.10−3 mol/l. The initial copolymerization rate, Rp, increases with increasing percentage of AN in the monomer feed. From the slope of ln Rp vs. 1/T, the apparent activation energy, Eapp, was calculated to be 17 kJ/mol in the temperature range of 30°C to 50°C. RSH is the only initiating species, and it also plays a role as chain‐transfer agent. The value of Mw/Mn, which varies from 1,5 to 2,0, is typical of a free‐radical poymerization. The reactivity ratios were calculated to be rSt = 0,42 ± 0,04 and rAN = 0,02 ± 0,03. It seems to be unnecessary to introduce a penultimate effect for explaining the experimental data.
Behaviour of homogenous catalysts for propene polymerization in methylene chloride
Authors: Longo Pasquale , Oliva Leone , Grassi Alfonso , Pellecchia Claudio
Published: April 2003

Propene polymerizations in the presence of the homogeneous catalytic system Cp2Ti(C6H5)2‐Al(CH3)3‐Al(CH3)2F were performed at different monomer concentrations in CH2Cl2. A relevant increase of the polymerization rate is observed, resulting in polymer productivities higher than those obtained with methylaluminoxane cocatalyst in toluene. The dependence of the monomer conversion on the propene concentration seems to support the hypothesis of a cationic catalytic site. Similar results were obtained with a homogeneous catalyst based on a chiral zirconocene and Al(CH3)3‐Al(CH3)2F.
Polymers of 1‐azabicyclo[4.2.0]octane, 2. Polystyrene‐block‐poly(1‐azabicyclo[4.2.0]octane) by mixed‐mechanism technique
Authors: Mühlbach Klaus , Schulz Rolf C.
Published: April 2003

By endcapping of living polystyrene with ethylene oxide and subsequent reaction with bromoacetyl bromide a polymer with a bromoacetoxy endgroup was obtained. This was used as a macroinitiator for the living cationic polymerization of 1‐azabicyclo[4.2.0]octane. The structure and composition of the so formed two‐block copolymer was elucidated by different methods. The ratio of the two block and their lengths were varied within broad limits.
Polymers of carbonic acid, 4. Crystalline smectic polyurethanes derived from piperazine or 4,4′‐bipiperidine and diphenols containing aliphatic spacers
Authors: Kricheldorf Hans R. , Awe Jens
Published: April 2003

4,4′‐Alkylenedioxydiphenols (3a–e), prepared from α,ω‐dibromoalkanes and hydroquinone, were converted with phosgen to the corresponding dichloroformates 4a–e, which were reacted with piperazine, trans‐2,5‐dimethylpiperazine or 4,4′‐bipiperidine under the conditions of interfacial condensation. The DSC measurements of polyurethanes derived from 2,5‐dimethylpiperazine displayed one endotherm indicating a normal melting process, whereas the polyurethanes derived from piperazine or 4,4′‐bipiperidine showed a reversible first order phase transition below the melting point. WAXS powder patterns indicate a change between two different smectic modifications. Thermomechanical analyses (penetration method) proved that also the high‐temperature smectic modification is a solid state and not a liquid‐crystalline one.
Polymers of carbonic acid, 5. Nematic polyurethanes derived from 4,4′‐dihydroxybiphenyl and 4,4′‐bipiperidine, ethylene‐4,4′‐bipiperidine or trimethylene‐4,4′‐bipiperidine
Authors: Kricheldorf Hans R. , Awe Jens
Published: April 2003

4,4′‐Bipiperidine (3a), 1,2‐bis(4‐piperidinyl)ethane (3b) and 1,3‐bis(4‐piperidinyl)propane (3c) were condensed with the dichloroformates of p‐phenylene, 2‐methyl‐1,4‐phenylene or 2,5‐biphenylylene. Furthermore, two copolyurethanes were prepared either by mixing 3a and 3c or by mixing the dichloroformates for p‐phenylene and 2,5‐biphenylylene. Inherent viscosities between of 0,6 and 1,7 dl/g were found for the polyurethanes of 3c, but only values below 0,86 dl/g for those of 3a and 3b. The polyurethanes derived from hydroquinone or methylhydroquinone are semicrystalline polymers with a short‐term thermostability up to 310°C. The polyurethanes deriving from phenylhydroquinone are amorphous with a thermostability up to 360°C. The homo‐and copolyurethanes containing 4,4′‐biphenylylene units form a smectic layer structure in the solid state and a nematic melt above the melting point.
Characteristics of rectifying devices with thin films of polyphthalocyanine
Authors: Abe Katsuya , Saito Hiroshi , Kimura Takeshi , Ohkatsu Yasukazu , Kusano Toru
Published: April 2003

Chemically and thermally stable thin films of polyphthalocyanine were prepared by a simple evaporation‐polymerization method. The rectifying characteristics of metal/semiconductor/metal (MSM) type sandwich devices with the film were studied. A Schottky type device metal (Cu, Al, Ti)/polyphthalocyanine/Cu shows reproducible rectifying characteristics when Ti is selected as a counter electrode. The reproducibility is improved by pre‐oxidation treatment of the surface of Cu substrate. Best electric parameters for the device are as follows: rectifying ratio = 14; threshold potential difference = 0,61 V; saturation current = 2,5 · 10−6 A · cm−2; barrier height = 0,75 eV; diode ideality parameter = 4,23. Doping of five kinds of quinones [p‐benzoquinone (p‐BQ), tetrabromo‐p‐benzoquinone (p‐TBBQ) tetrachloro‐p‐benzoquinone (p‐TCBQ) tetrachloro‐o‐benzoquinone (o‐TCBQ) 2,3‐dichloro‐5,6‐dicyanobenzoquinone (DDQ)] and 2,5‐cyclohexadien‐1,4‐diylidenedimalodinitrile (TNCR) in thin films of polyphthalocyanine affected electrocharacteristics in some cases. The diode ideality parameter decreases to 2,17 at 0,90 · 10−6 mol · cm−1 of p‐TBBQ, and the rectifying ratio increases to about fourteen times by doping p‐TBBQ and p‐TCBQ. The doped device shows a rectifying response up to 1 kHz.