bluuebunny/crossref_metadata_2025 huggingface dataset:
Elimination and replacement of organometallic co‐catalysts during polymerization of propene with heterogeneous Ziegler‐Natta catalysts
Authors: Kohara Tadanao , Shinoyama Masayuki , Doi Yoshiharu , Keii Tominaga
Published: April 2003

The changes in the polymerization rates induced by the elimination or replacement of soluble organometallic co‐catalysts have been examined in the course of the polymerization of propene initiated with titanium trichloride and various types of organometallic co‐catalysts. The elimination of an organometallic co‐catalyst, A, in the liquid phase during the polymerization resulted in a slow deactivation of the catalysts by the attack of a propene monomer. In contrast, the replacement of an initial organometallic co‐catalyst, A, by a different co‐catalyst, B, during the polymerization caused a rapid change in the polymerization rate from the specific rate with TiCl3 and A to that with TiCl3 and B. These results have been interpreted in terms of the bimetallic mechanism that an organometallic co‐catalyst coordinates to a titanium ion, in an exchangeable form with the co‐catalysts in the liquid phase, and regulates the catalytic activity.
On structure and temperature transformations of nascent polyethylene, produced by polymerization of ethylene in presence of a modified Ziegler‐Natta catalyst
Authors: Mihailov Marin , Minkova Lili , Nedkov Emanuil , Kircheva Radka
Published: April 2003

Nascent polyethylene with high molecular mass (Mn ≈ 105, Mw ≈ 106) produced in hydrocarbon medium in presence of TiCl4/(C2H5)2AlCl/(C6H5)2Mg catalyst was studied by means of X‐ray diffraction, electron and light microscopy, and low‐angle light scattering. It consists of porous spherulite‐fibril aggregates indicating a not very high degree of crystallinity α(α≈). Data, concerning the dependence of spherulite dimensions, degree of crystallinity and other structure parameters of nascent polyethylene on polymerization time and temperature are discussed. Using the same structure‐analytical methods some samples of nascent polyethylene were studied after annealing them in nitrogen atmosphere at different temperatures between 110–250°C with successive cooling to room temperature. Furthermore both the endo‐ and exothermal transitions occurring in the nascent and annealed structures after heating to 250°C were studied by means of DTA and DSC. The experimental information leads to the conclusion that nascent polyethylene structures consist of crystalline folded chain lamellae with an increased amount of tie molecules between them as well as of extended chain crystals.
Crosslinking statistics, 3. Relation between relative reactivity and accessibility of cellulose hydroxyl groups
Authors: Luby P. , Kuniak Ľ. , Fanter C.
Published: April 2003

From the results of a structural analysis of cellulose crosslinked by a bifunctional reagent conclusions can be drawn merely on the distribution of crosslinks among individual hydroxyl groups. No information is available to what extent this distribution is caused either by different relative reactivities of the hydroxyl groups or incomplete accessibility of glucose units. If each glucose unit had the same chance of reaction, at low levels of conversion only monosubstituted units should be present in the reaction product. If, however, some higher substituted units are present, this means that at a certain level of conversion there must have been a smaller number of units capable of reaction to which relatively more reagent had access. The relation between relative reactivity and accessibility of cellulose hydroxyl groups obeys certain statistical laws of random selection. A theory explaining these laws is developed in the present work and supported by good agreement with experimental results exemplified by microcrystalline cellulose crosslinked by epichlorohydrin (1‐chloro‐2,3‐epoxypropane). The relative reactivities of cellulose hydroxyls were found to increase in the order OH‐3, OH‐6, OH‐2 in the crosslinking reaction with epichlorohydrin.
On the dilute solution properties of styrene/methyl methacrylate copolymers
Authors: Chiantore Oscar , Casorati Ernesto , Costa Luigi , Guaita Marino
Published: April 2003

The solution properties of unfractionated styrene/methyl methacrylate copolymers were investigated over the entire range of copolymer composition. The Mark‐Houwink‐Sakurada constants Kη, and aη of the copolymers, as well as the constants KΘ and B′ from the Stockmayer‐Fixman procedure, related to the unperturbed chain dimensions and to the excluded volume, respectively, seem simply related to those of the parent homopolymers through some composition variables. In most cases, however, equations must be employed which have to be fitted to the experimental data, in order to evaluate parameters which are not otherwise predictable.
On the effect of solvent/nonsolvent combination in the column fractionation of polymers
Authors: Mencer Helena J. , Kunst Branko
Published: April 2003

The effect of some solvent/nonsolvent pairs on the efficiency of the column fractionation of polystyrene was investigated. Extensive cloud point titration experiments were shown to be needed for the correct assessment of thermodynamic qualities of a solvent/nonsolvent pair used in the column fractionation of polymers. Besides the thermodynamic suitability of solvent pairs their kinetic behavior was shown to differ. Possible reasons for the observed differences were discussed.
Exchange equilibria of anion resins, 1. Effect of physical structure of macroporous styrene‐divinylbenzene copolymers
Authors: Góźdź Antoni S. , Kolarz Bożena N.
Published: April 2003

Anion exchange equilibria on benzyltrimethylammonium resins are studied on solvent‐modified copolymer matrices prepared from styrene‐divinylbenzene suspension copolymers obtained in the presence of a series of unbranched alkanes (C7  C16) and toluene. Equilibria involving the exchange of chloride anions for bromide, iodide and perchlorate in dilute 0,01 M aqueous solutions were determined by the limited batch technique. It is found that the structure of the copolymer depends strongly on the interaction of an inert solvent with the copolymer during its formation. This structure affects the hydration of the functional groups and counter‐ions in the gel phase and consequently brings about a variation of the selectivity of the resin.
Vinyl polymerization, 366. Polymerization of methyl methacrylate initiated with a hydrolyzed product of poly[bis(2‐chloroethyl) vinylphosphonate]
Authors: Imoto Minoru , Sakae Masatoshi , Ouchi Tatsuro
Published: April 2003

PVPA, a simulated terpolymer from vinylphosphonic acid, 2‐hydroxyethyl hydrogen vinylphosphonic acid and 2‐chloroethyl hydrogen vinylphosphonic acid, was prepared by partial hydrolysis of poly[bis(2‐chloroethyl) vinylphosphonate] (2). In aqueous solution, PVPA was found to be able to polymerize methyl methacrylate (MMA) without any further initiator by a radical mechanism. The effects of the masses of water, PVPA and MMA on the polymerization were studied. The overall activation energy was found to be 77,7 kJ.mol−1. The Michaelis‐Menten equation could be applied for the relationship between the mass of MMA and the rate of polymerization (Rp). The plots of pH of aqueous solution against Rp gave a downward bell‐type curve. An initiation mechanism of the polymerization process is discussed.
Synthesis and conformational study of poly(ε‐N‐benzyloxycarbonyl‐L‐lysyl‐L‐valyl‐ε‐N‐benzyloxycarbonyl‐L‐lysine) in the solid state and in solution
Authors: Ciaschi Roberto , D'Alagni Maria
Published: April 2003

Poly(ε‐N‐benzyloxycarbonyl‐L‐lysyl‐L‐valyl‐ε‐N‐benzyloxycarbonyl‐L‐lysine) (6) was synthesized via the p‐nitrophenyl active ester method. The dipeptide and the active ester of the tripeptide were obtained by using tert‐butoxycarbonyl‐N‐ε‐benzyloxycarbonyl‐L‐lysine succinimido ester and dicyclohexylcarbodiimide as condensing agents, respectively. Polymer 6 was investigated in the solid state by IR and X‐ray diffraction measurements and in trifluoroethanol solution by UV, CD, and IR spectroscopy. The results obtained in the solid state indicate the occurrence of the β‐conformation and some other unidentified conformation. No useful information was obtained from the study of the trifluoroethanol solution of 6. Once more it was found that the introduction of valyl residues in a chain, containing residues which are α‐helix formers, seems to favour the β‐structure.
Théorie des chaîcnes de markov et distribution moléculaire dans les copolycondensats linéaires, 1. Modèle mathématique et systèmes d'ordre I
Authors: Durand Dominique , Bruneau Claude‐Marcel
Published: April 2003

Markov chain theory combined with graph theory gives a mathematical model for the description, in linear elements, of the random evolution of polymerizing macromolecular systems. Applying this mathematical model to the study of molecular distribution in linear systems of order I, i.e. systems having identical functional groups (a link being able to occur between any two sites), allows one to obtain molecular distribution functions with a general form which can be applied to many different systems. The use of matrix calculus gives simple mathematical expressions which are well suited for computer programming.
Le tétrakis[(phényl‐1 vinyl)‐4 phenyl]plumbane sa synthèse et son utilisation dans la préparation de macromolécules‐modèle
Authors: Beinert Gérard , Herz Jean
Published: April 2003

The present paper describes the synthesis of tetrakis [4‐(1‐phenylvinyl)phenyl]plumbane (1). It was found that “living” mono‐ or difunctional carbanionic polystyrenes are able to react with compound 1 to form star‐shaped polymers or tetrafunctional crosslinked networks, resp., and it could also be shown that this polyfunctional lead compound can be used to prepare starshaped copolymers containing polystyrene and poly(methyl methacrylate) branches.
Hochmolekulare makrocyclische polycarbonate
Authors: Horbach Alfred , Vernaleken Hugo , Weirauch Kurt
Published: April 2003

Interfacial condensation polymerization of bischloroformates of bisphenol A with bisphenol A results in the formation of cyclic aromatic polycarbonates of high molecular weight. Products made by this technique show a significant reduction (up to 95%) in their end group content. Also, in comparison to molecular weights determined by light scattering, these products show markedly lower molecular weights by solution viscocity measurements and by applying the Mark‐Houwink equation for linear polycarbonates. The existence of high molecular weight cyclic polycarbonates is confirmed by a controlled saponification reaction using piperidine as a basic compound. The saponification reaction causes nearly no change in the number average molecular weight of the polymer and causes an increase in the number of end groups of up to 2 end groups per molecule. The observed increase in the intrinsic viscosity data is similar to what would be expected from linear polycarbonates. It is shown that cyclic polycarbonates with molecular weights exceeding 100 000 are easily obtained.
On the interaction of styrene‐maleic anhydride copolymer with styrene
Authors: Bartoň Jaroslav , Vašková Viera
Published: April 2003

The interaction between alternating styrene/maleic anhydride copolymer as polymeric acceptor and styrene as low molecular weight donor in acetone and/or tetrahydrofuran was investigated by UV spectroscopy and polymerization technique. The equilibrium constant for the complex formation between styrene and the maleic anhydride structural unit of the styrene/maleic anhydride copolymer at 20°C was found to be 0,02 ± 0,001 dm3·mol−1 in acetone and 0,06 ± 0,003 dm3·mol−1 in tetrahydrofuran. The results of the thermally initiated polymerization of styrene in acetone in the presence of the alternating styrene/maleic anhydride copolymer indicate that the copolymer or the products of the interaction between the monomeric units of maleic anhydride in the copolymer and styrene do not initiate a radical polymerization of styrene.
Reaktionen bei der Bestrahlung von poly(N‐chloramid)en
Authors: Günster Engelbert J. , Schulz Rolf C.
Published: April 2003

On irradiating poly(N‐chloroamide)s in films or in solution in the range of 325–375 nm carboxamide groups are formed. The irradiated polymer contains chlorine which is linked to C‐atoms. This reaction can certainly not be explained with an intramolecular photorearrangement but with a sequence of photoreactions and dark reactions satisfactorily accounting for all observations.
Struktur und Eigenschaften segmentierter polyetherester, 3. Synthese definierter Oligomerer des polybutylenterephthalats
Authors: Hässlin Hans‐Walter , Dröscher Michael , Wegner Gerhard
Published: April 2003

The synthesis of some series of oligo(oxytetramethylene oxyterephthaloyl) [oligo(butylene terephthalate)s] with different but well‐defined end groups is described. The separation of artificial mixtures of the oligomers by high pressure liquid chromatography was studied under various elution and column conditions, and thus, the purity of the individual oligomers was demonstrated. The equilibrium melting point T = 236 ± 4°C and the corresponding heat of melting ΔH = 28,7 kJ·mol−1 of poly(butylene terephthalate) was determined from the analysis of the melting behaviour of the oligomers as depending on the degree of polymerization and the structure of the end groups.
Über enzymanalog gebaute Polymere, 11. Bindungsstellen im Polymer mit unterschiedlicher Zahl der Haftgruppen
Authors: Wulff Günter , Schulze Ilona , Zabrocki Karl , Vesper Wolfgang
Published: April 2003

4‐Vinylphenylboronic esters 1 and 2 of L‐1,2‐propandiol (3a) resp. D‐mannitol (4a) were polymerized under different conditions to macroporous, crosslinked copolymers. Afterwards the alcohols 3a resp. 4a were split off. The alcohols have thus been used to form chiral microcavities within the polymer, of which those prepared from 1 contain 1 and those from 2 contain 3 binding groups B(OH)2. Binding sites with 2 binding groups have been investigated before. These polymers possessed capacity for the resolution of the racemate of the template used. The kinetics of the mass transfer within polymers with three binding groups per cavity is discussed in more detail. The chromatographic investigation of the binding ability at different pH‐values of polymers from 2 for D‐mannitol showed even in acidic media a pronounced binding through neutral esters 5, whereas in alcaline media a much stronger binding through basic esters 6 occurred.
Ammonium salt catalyzed copolymerization of 2‐hydroxy‐4‐(2,3‐epoxypropoxy)benzophenone with phthalic anhydride
Authors: Lustoň Jozef , Maňásek Zdeněk
Published: April 2003

Ammonium salt catalyzed copolymerization of 2‐hydroxy‐4‐(2,3‐epoxypropoxy)benzophenone with phthalic anhydride was studied. The conversion curves could be linearized by the first order equation and the experimental rate constants kexp for the initiation by various ammonium salts were determined. The rate of copolymerization was found to depend on the size of the cation but not on the type of anion. kexp is a function of the first power initiator concentration but is independent of epoxide and anhydride concentration. The activation energy for the cetyltrimethylammonium bromide (CAB) initiated copolymerization in nitrobenzene was determined to be 73,5 kJ/mol. The kinetic scheme of copolymerization, which agrees well with the experimental results, was solved. The rate constant of the copolymerization of 2‐hydroxy‐4‐(2,3‐epoxypropoxy)benzophenone with phthalic anhydride catalyzed by CAB in nitrobenzene was found to be 2,76·10−2l.mol−1·s−1. The ratio of rate constants for both propagation steps, i.e. reaction of carboxylate anion with epoxide (k3) and reaction of alkoxide anion with anhydride (k2), was determined to be k3/k2 = 0,2 ± 0,1.
Stabile Polyphenoxyle, 4. Polymere aus sterisch gehinderten, geschützten Vinylphenolen
Authors: Braun Dietrich , Wittig Wolfgang
Published: April 2003

2,6‐Di‐tert‐butyl‐4‐vinylphenyl trimethylsilyl ether (1e) and 2,6‐di‐tert‐butyl‐4‐vinylphenyl acetate (1c) were synthesized and polymerized by cationic and free radical initiators. The protecting groups could be splitted off from the polymers by hydrolysis in acidic medium or by reduction with lithium aluminium hydride, resp., yielding high molecular sterically hindered free polyphenols.
Amorceurs radicalaires fonctionnels, 2. Macroinitiateurs à partir de l'α‐hydrogeno‐ω‐hydroxypoly(oxyéthylène) et des acides tert‐butyldioxycarbonylbenzoïques
Authors: Ladousse Alain , Maillard Bernard , Villenave Jean‐Jacques , Filliatre Claude
Published: April 2003

Modified polystyrenes were obtained by free radical polymerization of styrene using the macroinitiators α‐tert‐butyldioxyterephthaloyl(or phthaloyl)‐ωtert‐butyldioxyterephthaloyl(or phthaloyl)poly(oxyethylene) (3 and 4), which were synthetized. To examine the stability of such compounds, thermolysis kinetics of model compounds, OO‐tert‐butyl O‐methyl monoperoxyphthalate (6) and terephthalate (7) were studied by differential scanning enthalpimetry. Suspension polymerization of styrene applying the industrial method, showed that the macroinitiator is able to initiate the process. A polystyrene containing up to 4% by weight oxyethylene units was obtained.
Approche simple du problème de la distribution des séquences dans les terpolymères
Authors: Rios Léonardo , Guillot Jean
Published: April 2003

This work deals with a very simple determination of the variation limits, and to some extent, to the variation itself of the sequence distribution in a terpolymer without assistance of computer programming. A simple analytical approach is stated and shown that it is sufficient to consider only the corresponding binary copolymerizations involved in the ternary polymerization. Calculations are applied to the function Ac/L̄n(A), i.e. the ratio of the mole fraction of monomer A in the terpolymer Ac to the number average sequence length of this monomer in the terpolymer.
Synthesis of a polydithiocarbonate from carbon disulfide, alkali metal diolate and α,ω‐dihalo compound
Authors: Soga Kazuo , Toshida Yomishi , Hattori Iwakazu , Nagata Koichi , Ikeda Sakuji
Published: April 2003

Poly[thio(thiocarbonyl)oxy‐1,4‐cyclohexyleneoxy(thiocarbonyl)thiomethylene‐1,4‐phenylenemethylene] (4) was obtained from 4‐bromomethylbenzyl bromide (1), dipotassium 1,4‐cyclohexanediolate (2) and carbon disulfide at low temperature by using 1,4,7,10,13,16‐hexaoxacyclooctadecane as catalyst. At high temperatures, poly[oxy‐1,4‐ cyclohexyleneoxymethylene‐1,4‐phenylenemethylene] (8) was obtained from the reaction between 1 and 2, however. Mechanisms are proposed for these reactions.
A new route for the synthesis of polyhydroxyethers
Authors: Rokicki Gabriel , Kuran Witold
Published: April 2003

Polyhydroxyethers were synthesized from monoalkali metal salts of diphenols and 1‐halo‐2,3‐epoxyalkanes in a one‐step reaction in dipolar, aprotic solvents as reaction media. They were also synthesized from alkali metal salts of diphenols, dihalobenzoid compounds with electron‐withdrawing groups between benzene rings and 1‐halo‐2,3‐epoxyalkanes by a two‐step reaction.
β‐Carotene inhibited photooxidation of polystyrene, 1. Effect of β‐carotene on photochemical reactivity of anthracene in hexane solution
Authors: Nowakowska Maria
Published: April 2003

The effect of β‐carotene on the photochemical reactivity of anthracene in hexane solution was investigated. A kinetic scheme of photochemical and photophysical processes occurring in the system irradiated with light at λ = 365 nm is proposed. The rate constants of physical quenching process and chemical reaction between β‐carotene and singlet oxygen molecule were determined.
β‐Carotene inhibited photooxidation of polystyrene, 2. Effect of β‐carotene on anthracene sensitized photooxidation of polystyrene films
Authors: Nowakowska Maria
Published: April 2003

The inhibiting effect of β‐carotene on anthracene sensitized photooxidation of polystyrene was observed and a kinetic scheme of the photophysical and photochemical processes in the system was proposed. The rate constants of several processes occurring in the system were evaluated. The indexes of reactivity for anthracene and β‐carotene in polystyrene were determined.
Haupt‐ und seitenkettenkristallinität bei isotaktischen poly(alkylethylen)en, 4. Die abhängigkeit des kristallinitätsgrades bei den höheren homologen von der thermischen vorbehandlung
Authors: Blum Klaus , Trafara Gundolf
Published: April 2003

Crystallization of the higher homologues of poly(alkylethylene)s containing 12, 13, 14, 16 and 20 C‐atoms in the side chains is investigated varying the temperature and duration of crystallization. On cooling the samples slowly from the melt to about 5 to 10 K below the melting temperature, the modification is formed which was first reported by Turner‐Jones: The main chain conformation is a quaternary helix, the side‐chains crystallize by forming the orthorhombic polyethylene structure. Degrees of crystallinity were determined by X‐rays using the method of Hermans and Weidinger. The degree of crystallinity increases up to a limiting value with increasing duration of crystallization at constant temperature. The limiting value grows by increasing the number of C‐atoms in the side‐chains.
The angular distribution of crystallinity in a stretched rubberlike polymer
Authors: Allegra Giuseppe
Published: April 2003

The distribution of crystallinity around the axis of elongation in a rubberlike polymer stretched above its normal melting temperature is calculated. Although most of the basic assumptions are identical with those adopted by Flory in 1947, the model of rubber elasticity proposed by Ronca and Allegra in 1975 is explicitly adopted, and the assumption of parallelism among the crystallites is avoided. According to some experimental observations, only the extended chain crystallization mechanism is taken into consideration. The incipient crystallization temperature and the equilibrium retractile force are also obtained. The X‐ray intensity distribution for the general reflection on a stretched fiber diagram is formally derived as a function of crystallite orientation. Agreement with several experimental data obtained by Cesari, Perego, Zazzetta and Gargani, from crosslinked cis‐1,4‐polybutadiene may be regarded as satisfactory, considering the simplifying assumptions. According to the theoretical predictions, the crystallites formed at incipient crystallization are quite narrowly aligned around the direction of elongation. Unlike Flory's theory, the present formalism leads to no discontinuity in the derivative of the retractile force vs. the stretch ratio at the incipient crystallization point, in agreement with observation.
Redox polymerization, 4. Kinetics of the polymerization of acrylic acid derivatives initiated by the system cyanoacetic acid/Mn(OCOCH3)3 in dimethylformamide
Authors: Haragopal Mahadevan , Mahadevan Venkatanarayana
Published: April 2003

The kinetics of the polymerization of acrylonitrile, methyl methacrylate, and acrylamide initiated by the redox system cyanoacetic acid/manganese triacetate in dimethylformamide solution were investigated in the temperature range of 25 – 40°C. It was found that an initial complexation between the reactants followed by an electron transfer yields radicals. In contrast to acrylamide, acrylonitrile and methyl methacrylate effectively suppress further oxidation of the primary radicals. Exclusively the mutual termination accounts for the kinetics of these polymerizations. Data on the average degrees of the polymerizations support the suggested mechanisms. Rate and equilibrium constants were evaluated and their significance is discussed.
Chainlength dependence of thermodynamic properties of poly(ethylene glycol)
Authors: Klein Joachim , Jeberien Hans‐Edwin
Published: April 2003

Investigations of ten poly(ethylene glycol) samples with molecular weights of 62 to 20 000 showed that inverse gas chromatography is a sensitive tool to determine molecular weight dependent variations of thermodynamic parameters like specific retention volume, activity coefficient, and Flory‐Huggins interaction parameter. As mobile phase 27 probe molecules with various functional groups could be characterized with respect to their solubility behaviour for the oligomers and polymers due to the ability to form hydrogen bonds. By application of the factor analysis technique two factors could be extracted from the data matrix of retention values. The best fit of the corresponding simple structure was achieved with a combination of group concentrations of the terminal OH‐group and the repeating ether unit of the poly(ethylene glycol)s.
Free radical polymerization in the presence of non‐solvents, 1. Styrene
Authors: Bartoň Jaroslav , Capek Ignác , Juraničová Viera , Mlynárová Mária
Published: April 2003

During styrene (STY) polymerization, initiated by radicals formed by thermal or photochemical decomposition of 2,2′‐azoisobutyronitrile (AIBN) the overall polymerization rate constant K defined by relation K = Rp/([AIBN]0,5 [STY] η) and the ratio kp/(2kt0) increase with decreasing styrene concentration by hexane or benzene (Rp is the polymerization rate and ηMIX the viscosity of the reaction system). In the thermally initiated polymerization K = kp (2f kd/(2kt0))0,5 and in the photochemically initiated polymerization K = kp (2,303 ϕ I0ϵ d/(2kt0))0,5 where kd, kp, and kt0 are respectively, the rate constants of AIBN decomposition, of propagation, and of termination (for a system of the viscosity 1 mPa·s) reactions, ϕ is the quantum yield of radicals entering into reaction with the monomer, I0 the intensity of the incident light, ϵ the molar absorption coefficient of AIBN, and d the path length of the light. The increase of K and of kp/(2kt0) with decreasing monomer concentration is more marked for the system styrene/hexane than for styrene/benzene and this increase is greater at 30°C than at 60°C. For Θ‐systems formed by binary mixtures like styrene/hexane, styrene/decane and styrene/C1 – C4 alcohols the values of kp and kt0 at 30°C range between 57 and 91 dm3·mol−1·s−1 and (0,9 to 2,2)·107 dm3·mPa·mol−1, i.e. they are in principle identical with the tabulated values of these rate constants for styrene bulk polymerization.
A new method for the estimation of random chain branching from viscosity measurements in two solvents
Authors: Bohdanecký Miloslav
Published: April 2003

A method for the evidence of random chain branching (or for the estimation of its degree) is suggested, based on the determination of intrinsic viscosity in two solvents with a very different “solvent power”. Conditions under which the method can be employed are examined (effect of solvent power on the viscosity parameter of branching, effect of polydispersity). The method is verified using reported data for six polymers, mainly with three‐functional random branching. It is less sensitive than the classical method (determination of parameter g′), but does not require the knowledge of molecular weight of the branched polymer, and may therefore be useful in cases where the molecular weight determination of a branched polymer by the light scattering method is not accurate.
Thermotropic liquid crystalline polymers, 3. Comb‐like polymers with side chains simulating the smectic type of liquid crystals
Authors: Shibaev Valery P. , Moiseenko Victor M. , Platé Nikolai A.
Published: April 2003

The syntheses of a number of new comb‐like polymers are described, which contain mesogenic groups as side branches presenting models of low‐molecular liquid crystals of smectic type. The resulting polymers are capable to form an enantiotropic liquid crystalline phase, which may be defined as smectic, according to the terminology used for low‐molecular liquid crystalline substances. The thermodynamic limits of the liquid crystalline state in these polymers were determined, which made it possible to define the liquid crystalline state as a thermodynamically stable phase with spontaneously appearing anisotropy of properties (in particular, the optical anisotropy). The characteristic feature of the structure of these polymers was found to be the layer order of side groups providing — in combination with the packing of the mesogenic groups — the possibility of liquid crystalline properties. Only the mesogenic groups take part in the formation of the crystalline packing in these polymers, whereas the methylene chains are in the amorphous phase together with the backbone chain.
Synthesis and properties of polymers with conjugated double bonds with nitro‐substituted acenaphthenediylidene repeating units
Authors: Schopov Ivan , Kirowa Plumka
Published: April 2003

Three new conjugated polymers with nitro‐substituted acenaphthenediylidene repeating units were prepared. The polymers which exhibit semiconductive and paramagnetic properties, differ in number and location of the nitro groups. The comparison of the polymer properties leads to the conclusion that in one of the polymers an intermolecular charge transfer complex could exist, thus improving its semiconductive properties.
Oligomérisation anionique de l'éthylène, 5. Fonctionalisation des oligomères vivants par action directe de l'oxygène
Authors: Aldissi Matt , Schué François , Geckeler Kurt , Abadie Marc
Published: April 2003

Living oligomers of ethylene obtained by sec‐butyllithium complexed with tetramethylethylenediamine (TMEDA) were deactived by oxygen. NMR and mass spectrometry, coupled with gas chromatography of the resulting product allowed us to follow the influence of TMEDA towards functionalization. The two products

equation image

were characterized. Apparently the ratio [TMEDA]/[sec‐BuLi] does not seem to influence the functionalization reaction.
Polymere charge‐transfer‐Komplexe auf der basis von polyvinylalkoholacetalen, 3
Authors: Geißler Ulrich , Schulz Rolf C.
Published: April 2003

A new fluorene containing polymer, poly[2‐(2‐fluorenyl)‐1,3‐dioxan‐4,6‐diylmethylene] (3 or 4), and the corresponding model compound, 2‐fluorenecarbaldehydetrimethyleneacetal (6) were synthesized. The fluorescence spectroscopy of the polymer in dilute solution indicates the formation of an intramolecular excimer. Charge‐transfer complex formation with tetracyanoethylene (TCNE), 2,5‐cyclohexadien‐1,4‐diylidenedimalonodinitrile (TCNQ), and 2,4,5,7‐tetranitro‐9‐fluorenone (TENF) was studied by means of absorption spectroscopy.
Copolymerisation von 4‐(1,1‐dicyanoethylazo)benzylmethacrylat mit styrol, methacrylonitril und methylmethacrylat mit anschließender Pfropfung der Azocopolymere
Authors: Nuyken Oskar , Rengel Reinhard , Kerber Robert
Published: April 2003

4‐(1,1‐Dicyanoethylazo)benzyl methacrylate (3), a new azo‐monomer, was copolymerized with styrene, methacrylonitrile, and methyl methacrylate (MMA) giving azo‐copolymers. The compositions of the copolymers from 3 and MMA were nearly identical with those of the monomer mixtures. Thus allowing 100% conversion leading to copolymers of almost identical chemical composition. These azo‐copolymers were used as initiators for different monomers in either emulsion or solution, resulting in graft‐copolymers. The graft‐copolymers were characterized by IR and GPC. In one case the raw graft‐copolymer was separated into ungrafted backbone‐polymer, grafted copolymer, and homopolymer of the component to be grafted.
Borverbindungen, 11. Die Metathese der 2‐ethyl‐1,3,2‐dioxaboracycloalkane mittlerer Ringgröuße
Authors: Gerwarth Ulrich W.
Published: April 2003

2‐Ethyl‐1,3,2‐dioxaboracycloalkanes polymerize more slowly than the analogous 2‐aryl compounds. This is due to a difference in the bond type of the O—B—O group as shown by IR spectra and mass spectra. For the polymerization of 2‐aryl‐1,3,2‐dioxaboracycloalkanes the metathetic mechanism, postulated and proved in a foregoing paper, was confirmed.
Elektron‐Donor‐Akzeptor‐Komplexe und copolymere mit difluormaleinsäureanhydrid
Authors: Regel Walter , Canessa Guido
Published: April 2003

The formation constants of electron donor acceptor complexes formed by p‐dioxene, α‐methylstyrene, phenanthrene, phenyl vinyl ether and styrene as donor molecules and difluoromaleic anhydride as acceptor are much larger compared to those formed by maleic anhydride and the same donor molecules. However, no relation can be established between the numerical value of the formation constant and the tendency of alternating copolymerization induced by radical initiators. Symmetry considerations lead to the conclusion that electron donor acceptor complexes have no significant involvement in this copolymerization. The result of our kinetic investigations in the system phenyl vinyl ether/difluoromaleic anhydride supports the above statement: The formation of the electron donor acceptor complex is not the rate determining step of copolymerization.
Polymerization of ethylene initiated by homogeneous polybutadienyllithium/TiCl4 complexes
Authors: Siove Alain , Fontanille Michel
Published: April 2003

The chemical structure of polybutadienyllithium/TiCl4 complexes was studied for several values of r = [Li]/[Ti], using spectroscopic methods, gravimetry, and the elemental analysis. Dependent on the molecular weight of the polybutadienyl chain, the complexes are soluble or insoluble in hexane. The soluble systems were used for the initiation of the polymerization of ethylene, leading to a mixture of homopolybutadiene and block copolymers, slightly reticulated. The efficacity of such systems can be estimated to be 0,8.
Study on the complex formation of cobalt chelates with polymer ligands
Authors: Shigehara Kiyotaka , Yamada Akira , Sano Hiroshi , Tsuchida Eishun
Published: April 2003

Variously composed copolymers from styrene and 4‐vinylpyridine (4‐VP) were prepared and their complex formation reactions with benzylbis(dimethylglyoximato)Co(III) [BzCo(III)(DMG)2] and N,N′‐ethylenebis(salicylideneiminato)Co(II) (Co(II)salen) were studied kinetically by the stopped‐flow rapid scanning spectroscopy. For the complex formation reaction with BzCo(III)(DMG)2, the relationship between the complex formation constant K and the content of 4‐pyridylethylene units in the copolymers showed an unusual bell‐type curve, and the K values were higher than the K value of complexation with pyridine. From the correlation between K, k (complex formation rate constant), and k′ (complex dissociation rate constant), it resulted that (1) the higher K values of the polymer systems are due to the lower k′ values compared with the pyridine system, and (2) the bell‐type change of the K values is also caused by the k′ values. In the case of Co(II)salen‐copolymer systems, two species of the complex, i.e., mono‐ and diaxial coordinated complexes were clearly identified by spectrometric kinetics, whereas the pyridine system gave only a mono‐axial coordinated complex. The diaxial coordination seems to lead to a much more favorable structure than the monoaxial one, due to the entropic gain or to the polymer chelate effect.
Synthetic polymers containing sugar residues, 7. Synthesis and properties of polyurethanes from D‐cellobiose and diisocyanates
Authors: Kurita Keisuke , Hirakawa Nobuhiko , Iwakura Yoshio
Published: April 2003

Polyurethanes containing D‐cellobiose residues in the main chain were synthesized from D‐cellobiose and diisocyanates. The direct addition polymerization without blocking the excess hydroxy groups afforded soluble polyurethanes with inherent viscosities up to 1,08 dl · g−1. The pendant hydroxy groups in these polyurethanes were utilized for polymer reactions such as acetylation and crosslinking. Water absorption values of polyurethane films were confirmed to be very high. Acetylation decreased the values drastically, although the degrees of acetylation were not high. Thermal stability and crystallinity were also studied.
Esterolytic action of poly[p‐vinyl(thiophenol)‐co‐acrylic acid]
Authors: Hayama Shigeru , Takeishi Makoto , Takahashi Kanju , Niino Shogo
Published: April 2003

Hydrolyses of p‐nitrophenyl acetate (PNPA) and 3‐acetoxy‐N,N,N‐trimethylanilinium iodide (ANTI) catalyzed by poly[p‐vinyl(thiophenol)‐co‐acrylic acid] (PSH) were studied in the pH range of 8 – 9,5. The reaction of PNPA followed pseudo‐first‐order kinetics and was found to be catalyzed by the thiophenolate ions on the polymer backbone. In the case of positively charged ANTI, the rate of catalysis showed substrate saturation phenomena and could be described by a Michaelis‐Menten kinetics. This indicates that this reaction proceeds via a complex formed by electrostatic interaction between the substrate and the negatively charged polymer catalyst. When ionic strength was increased to 0,12 mol/l the reaction did not further follow the Michaelis‐Menten kinetics, suggesting that the complexation constant or the reaction rate of the complex might vary with the amount of the substrate incorporated in the polymer domain. Positively charged N,N,N‐trimethylanilinium iodide competively inhibited the PSH‐catalyzed hydrolysis of ANTI.
Donor acceptor interactions in polymeric systems, 6. Effects of the molecular weight of carbazolyl containing polyesters and the length of spacer between donor groups on the complex formation with 2,4,7‐trinitrofluorenone
Authors: Tazuke Shigeo , Nagahara Hajime
Published: April 2003

EDA complex formation between 2,4,7‐trinitrofluorenone (TNF) and polyesters bearing pendant 9‐carbazolyl groups was studied in ethylene dichloride. The formation constant (K) decreases with increasing length of the main chain repeating units separating pendant donor groups and with decreasing degree of polycondensation. In all cases, the values of K in polymeric systems are larger than those for the monomer model system by factors less than three. Thermodynamic parameters for complex formation were also determined. The general trend of the polymer effect is to increase − ΔH, while the entropy term is not much different from the monomer model system. The origin of polymer effects is interpreted as due not only to neighbouring group effects but also to remote group effects, and simultaneous participation of more than one carbazolyl group in complexing an acceptor molecule is considered. The results are compared with the EDA complex formation by ethylenic polymers and polyurethanes with pendant carbazolyl groups.
Donor acceptor interactions in polymeric systems, 7. Structure matching effect in interpolymer EDA complex formation
Authors: Tazuke Shigeo , Nagahara Hajime
Published: April 2003

Interpolymer EDA complex formation between polyesters bearing pendant carbazolyl groups and polyurethanes bearing pendant trinitrofluorenonyl groups was investigated in dioxane at 25°C. Complex formation depends on the degree of polycondensation (DP) as well as on structure matching of polymeric D and polymeric A. With increasing DP, the solubility of the D polymer‐A polymer mixture trends to decrease. Even when the polymer complexes do not precipitate, the Ketelaar's plots do not always fall on a straight line. These phenomena were interpreted as due to higher order complex formation and/or dependence of the formation constant on the fraction of saturation. It was found that polymeric donor acceptor pairs in which the number of atoms in a repeating main chain unit are identical for D and A polymers form a stronger complex than other combinations. It was concluded that structure matching of an interacting pair is a favourable condition to form tight complexes as in the case of antigenantibody interactions.
Syntheses and properties of poly(iminoethylene) derivatives containing nucleoside moieties
Authors: Murakami Akira , Konishi Yoshiyuki , Shimidzu Takeo
Published: April 2003

Cationic polynucleotide model compounds such as poly[N‐(adenosin‐5′‐yl)iminoethylene hydrochloride‐co‐N‐(5‐ribosyl)iminoethylene hydrochloride‐co‐iminoethylene] (1a) and poly‐[N‐(uridin‐5′‐yl)iminoethylene hydrobromide‐co‐N‐(5‐ribosyl)iminoethylene hydrobromide‐co‐iminoethylene] (1b) were synthesized by alkylation of linear poly(iminoethylene) with 5′‐chloro‐5′‐deoxyadenosine and 5′‐bromo‐5′‐deoxyuridine, respectively. In aqueous solution the adenine moieties of 1a are stacked one above the other, whereas the uracil moieties of 1b are scarcely stacked. These model compounds interact with mononucleotides at relatively low concentration (0,5 mmol.dm−3). The magnitudes of UV hypochromicities are decreasing for the various systems in the order of purine/purine > purine/pyrimidine > pyrimidine/pyrimidine. Stacking is the dominant mode of base‐base interaction.
Syntheses and properties of polysaccharide‐type polymers, 4. Synthetic polysaccharides containing amino groups
Authors: Komada Hajime , Okada Masahiko , Sumitomo Hiroshi
Published: April 2003

New Polysaccharide‐type polymers containing amino groups in their main chains were synthesized by chemical modification of poly(5,6‐dihydro‐2H‐pyran‐6,2‐diyloxymethylene) (2). Thus, the unsaturated polyacetal 2, having a dihydropyran ring in the repeating unit, was obtained by ring‐opening polymerization of 6,8‐dioxabicyclo[3.2.1]oct‐3‐ene (1), and it was epoxidized with m‐chloroperoxybenzoic acid followed by the reaction of the epoxide with ammonia or dimethylamine in aqueous solutions to yield polysaccharides containing the corresponding β‐aminoalcohol groups (4a and 4b). Visible spectroscopy revealed that 4a and 4b interacted with copper(II) ion in aqueous solutions. A qualitative biological test showed that both 4a and 4b inhibited the growth of microorganisms. Sulfated derivatives of 4a and 4b were prepared by reaction of 4a and 4b with chlorosulfuric acid in formamide. Their anticoagulant activities were evaluated by the “Activated Partial Thromboplastin Time (APTT) method” and compared with that of dextran sulfate.
Structure and properties of segmented poly(ether esters), 4. Compatibility of oligo(tetramethylene terephthalate)s with oligoethers and block copoly(ether ester)s
Authors: Hässlin Hans‐Walter , Dröscher Michael
Published: April 2003

The mutual compatibility of oligo(tetramethylene terephthalate)s 1a—d and their compatibility with oligoethers 2, 3, and 4 and block copoly(ether ester)s 5a—c based on poly(tetramethylene terephthalate) and poly(oxytetramethylene) is reported. From the binary phase diagrams of the oligoesters it is concluded that the oligoesters do not cocrystallize and the melt of the lower melting compound is not a good solvent for the higher melting homologue. For the trimer/pentamer (1b/1c)‐blend the eutectic composition contains 3 mole‐% of the pentamer 1c. Oligo(oxytetramethylene) (3) is a better solvent for the oligoesters than oligo(oxyethylene) (2). The addition of an oligoester to the block copoly(ether ester) induces a change in the phase behaviour of the polymer, resulting in a melting point of the blend higher than for the pure polymer or oligomer.
Helix‐coil transition of poly(γ‐benzyl‐L‐glutamate) in a mixture of dichloroacetic acid/1,2‐dichloroethane
Authors: Roots Jaan , Edsman Katarina , Nyström Bo
Published: April 2003

The thermally induced inverted helix‐coil transition of poly(γ‐benzyl‐L‐glutamate) (M̄w ≈ 320 000) in a mixture of dichloroacetic acid/1,2‐dichloroethane (80/20 w/w) has been observed by the temperature dependence of both the refractive index increment and the partial specific volume; the transition is centered around 31°C. A correlation of the refractive index increment and the partial specific volume data, utilizing an equation based on the Onsager‐Böttcher theory, had no significant success.
Influence of sensitisers on the photostabilising action of a hindered piperidine compound in polypropylene
Authors: Allen Norman S.
Published: April 2003

The influence of prior thermally generated hydroperoxides and added anthraquinone have been examined on the photostabilising action of a hindered piperidine compound, bis(2,2,6,6‐tetramethyl‐4‐piperidinyl) sebacate, in polypropylene film using ESR spectroscopy and flash photolysis techniques. The hindered piperidine compound was found to effectively inhibit both the hydroperoxide and carbonyl group sensitised photooxidation of the polymer. Using ESR spectroscopy evidence is presented to show that the hindered piperidine compound reacts stoichiometrically with the hydroperoxide groups generated by thermal oxidation to give a stable nitroxyl radical. On flash photolysis of anthraquinone in hexane transient formation due to the semi‐quinone radical and subsequent formation of the hydroquinone were found to be effectively inhibited by a stable N‐oxyl radical compound but not the amine. It is concluded that the nitroxyl radical is the effective stabilising species and operates by a radical scavenging mechanism to form the hydroxylamine.
Biosoluble polymers for drug delivery
Authors: Singh Maninder , Vasudevan Padma , Ray Alok R. , Guha Sujoy K.
Published: April 2003

The immobilization of α‐chymotrypsin on periodate oxidized cellulose as a biocompatible carrier was investigated. The properties and release of the enzyme from the polymer were studied. It was found that after an initial spurt, the amount of the released enzyme attains a practically constant value and the released enzyme retains its activity and shows increased heat stability. Such systems may be useful for a slow delivery of drugs and enzymes in the body.
Micellisation de copolymères séquencés polystyrène‐polyvinylpyridinium, 1. Méthodes d'études. Influence de la nature du solvant
Authors: Selb Joseph , Gallot Yves
Published: April 2003

The dilute solution properties of polystyrene‐poly(4‐vinyl‐N‐ethylpyridinium bromide) block copolymers (PS‐PVPQ) are studied in solvents selectively solvating polyelectrolytic moieties (mixtures: water‐methanol‐0,1 M LiBr). For these multicomponent systems, the validity of the data given by light scattering, viscosity and sedimentation velocity measurements, is discussed. Diblock copolymers exhibit four different types of behaviours, depending on solvent composition. The macromolecules are dissolved singly in methanol, but they are associated when water is present. When the water content increases, the association degree passes through a maximum. Since the solutions may contain two species of particles, i.e. the single molecules and the multimers with a narrow weight distribution, the term of micellization for this association phenomenon is correct. Despite their high “molecular weight”, the micelles are small and hence they are very compact. Unlike results from other micellar polymeric systems, the micelle occurrence is accompanied by an increase of the intrinsic viscosity. The hydrodynamic volume of a micelle does not depend on the micellar weights; this can be explained by a star‐like micellar model. Thus, the parameter determining the size of a micelle is not the number of molecules per micelle, but the length of the “branches”, i.e., the “soluble” blocks.
The structures of poly(vinyl fluoride) at elevated temperatures and after heavy rolling
Authors: Preedy John E. , Wheeler Ernest J.
Published: April 2003

The structures of poly(vinyl fluoride), (P(VF)), were investigated at elevated temperatures and after heavy rolling at various temperatures. In the former case the marked increases in both crystallite size and the unit cell a‐dimension above 140°C were accompanied by a reduction in crystallinity, indicating a melting and recrystallization process. When compared to the polyethylenes, thermal behavioural differences may be attributed to the polarity of the P(VF) molecules. Notable changes in deformation structure were obtained upon varying the rolling temperature. Above 60°C heavy rolling produced a hexagonal {1010} 〈0001〉 texture, the paracrystallites having a clearly oriented lamellar structure. At 60°C and below more complex textures were produced, the microparacrystallites of the predominant component having a platy morphology. At −80°C, the deformation structure also showed extensive voiding.