bluuebunny/crossref_metadata_2025 huggingface dataset:
Liquid‐crystalline polymers containing heterocycloalkanediyl groups as mesogens, 6. Liquid‐crystalline poly[trans‐11‐{4‐[5‐(4‐methoxyphenyl)‐1,3‐dioxan‐2‐yl]‐2,6‐dimethylphenoxy}undecyl methacrylate] and poly[trans‐11‐{4‐[5‐(4‐methoxyphenyl)‐1,3‐dioxan‐2‐yl]‐2,6‐dimethylphenoxy}undecyl acrylate]
Authors: Hsu Chain Shu , Percec Virgil
Published: April 2003

The synthesis and characterization of poly[trans‐11‐{4‐[5‐(4‐methoxyphenyl)‐1,3‐dioxan‐2‐yl]‐2,6‐dimethylphenoxy}undecyl methacrylate] and poly[trans‐11‐{4‐[5‐(4‐methoxyphenyl)‐1,3‐dioxan‐2‐yl]‐2,6‐dimethylphenoxy}undecyl acrylate] is presented. Both polymers exhibit nematic mesophases and do not present side‐chain crystallization. At temperatures higher than 160°C the 1,3‐dioxane‐2,5‐diyl groups undergo a thermally induced trans‐cis isomerization. A radical mechanism is proposed for this isomerization.
On the structure of radically obtained maleic anhydride/C4‐alkene copolymers
Authors: Bortel Edgar , Stysło Maria
Published: April 2003

The radical heterophase copolymerization of maleic anhydride (1) with isobutene (2), 1‐butene (3) or with a petrochemical C4‐fraction free from butadiene (C4) yielded copolymers with a molecular weight of 424 · 103, 291 · 103 and 190 · 103 g/mol, respectively. The structures of poly(1‐co‐2), poly(1‐co‐3) and poly(1‐co‐C4) obtained were elucidated by 13C NMR, 1H NMR and IR spectroscopy. Irrespective of whether 2, 3 or C4 was used as comonomer, the appropriate 13C NMR, 1H NMR and IR spectra proved to be essentially identical. These spectra confirm the presence of the 1,1‐dimethylethylene structural units in the repeating units of each of the copolymers investigated. Thus, the radical copolymerization of 1‐butene with maleic anhydride is accompanied by a rearrangement within the 1‐butene molecule due to hydrogen and methyl shift.
X‐ray diffraction studies of monomeric and polymeric 5,7‐dodecadiynylene bis(N‐ethylcarbamate) (ETCD)
Authors: Downey Milton J. , Hamill Gregory P. , Rubner Michael , Sandman Daniel J. , Velazquez Christopher S.
Published: April 2003

Crystals of the monomer and polymer of the bis‐ethylurethane of 5,7‐dodecadiyne‐l, 12‐diol (1 a, ETCD), systematic name: 5,7‐dodecadiynylene bis(N‐ethylcarbamate) have been studied by X‐ray powder and single‐crystal photographic techniques. Lattice constants at 20°C were obtained from both single‐crystal and powder data and are in satisfactory agreement with a previous report. Lattice constants at 130–135°C were obtained from powder data and reveal that the lattice expands in volume by 4% on heating from 20°C, in contrast to a previous report which indicated a volume contraction on heating. Rotation photographs of poly(ETCD) crystals before and after extraction of unpolymerized monomer with boiling methanol reveal that solvent extraction renders many reflections more diffuse. Weissenberg h0l‐photographs of the polymer reveal sufficient disorder so as to preclude a high‐precision structural determination. Rotation and Weissenberg photographs of monomeric ETCD at 20°C manifest the major reflections of the polymer.
Polymeric phthalocyanines and their precursors, 15. Syntheses of alkylenedioxy bridged polymeric phthalocyanines and their absorption capacities for organic solvents in comparison to other phthalocyanines
Authors: Wöhrle Dieter , Schulte Bernd
Published: April 2003

Alkylenedioxy bridged polymeric phthalocyanines 3a – d were synthesized by the reaction of the tetracarbonitriles 2a–d with copper(II) chloride or copper in bulk. As compared with other tetracarbonitriles the reactions applying 2a – d, which contain a flexible alkylene chain, run at relatively low reaction temperatures leading to good yields of polymers with a high degree of anelation of phthalocyanine rings (Pc > 100). In contrast to their low swelling factors and their low surface areas, polymeric phthalocyanines, with different bridging units between the chelate rings in the solid state exhibit good absorption capacities for organic solvents, mainly from the liquid state.
Drawing of ultra‐high‐molecular‐weight polyethylene in the melt. Influence of crystallization history
Authors: van Aerle Nick A. J. M. , Lemstra Piet J.
Published: April 2003

Ultra‐high‐molecular‐weight polyethylene (UHMW‐PE) can be drawn in the melt in a limited temperature range between the melting point of lamellar crystals, appr. 135°C, and the orthorhombic → hexagonal phase transition temperature, at appr. 155°C. In this particular temperature range, referred to as region 2, drawing results in the formation of a composite structure composed of fibrous crystals as a result of strain‐induced crystallization of the high molecular weight fraction, embedded in a melt of lower molecular weight material. After cooling to room temperature, this latter fraction crystallizes using the fibrous crystals as crystallization nuclei. The resulting structure exhibits a shish‐kebab morphology. Solution‐crystallized as well as melt‐crystallized UHMW‐PE samples were studied with respect to draw efficiency and structure formation during deformation in the melt.
Polymeric chiral crown ethers, 2. Syntheses and chiral recognition of polymers consisting of (S)‐ or (R)‐2,2′‐binaphthyl‐21‐crown‐6 units through cyclopolymerization of divinyl ethers
Authors: Kakuchi Toyoji , Sasaki Hiroshi , Yokota Kazuaki
Published: April 2003

Optically active divinyl ethers, (−)‐(S)‐ and (+)‐(R)‐2,2′‐bis[2‐(2‐ vinyloxyethoxy)ethoxy]‐1,1′‐binaphthyl [(S)‐1 and (R)‐1], were synthesized and polymerized with cationic catalysts. The resulting polymers are composed of only cyclic constitutional units, (S)‐ and (R)‐dinaphtho‐[2,1‐r:1,2‐t]‐1,4,7,11,14,17‐hexaoxaperhydrocyclohenicosen‐8,10‐ylene. Both (S)‐ and (R)‐polymers show nearly equal values of optical rotation, but in opposite directions. The ability of chiral recognition of the (R)‐polymer towards racemic primary alkylammonium salts was investigated with salts of 1‐phenylethylamine, valine, phenylalanine and phenylglycine, and found to be very similar to that of the corresponding model crown ether.
Influence of inter‐turn hydrogen bonding on the stabilization of the helical inclusion complex of amylose
Authors: Hui Yongzheng , Gai Yonghua
Published: April 2003

Two different modes of interaction between 2‐chloro‐N‐dodecylpyridinium iodide (CDPI) and randomly substituted methylamylose (MA), which is mainly composed of 2,3‐O‐methylamylose or 6‐O‐methylamylose (6‐MA), are reported. The fluorescence intensity of CDPI is enhanced and its reactivity toward alkaline hydrolysis is retarded upon the addition of MA. Both cases show a saturation‐type relationship with increasing concentration in the case of MA, indicating the formation of an inclusion complex. In addition to the contribution of hydrophobic‐lipophilic interaction, the intramolecular hydrogen bonding of the host may also play an important role in stabilizing its helical conformation, as proved by the fact that the dissociation equilibrium constant, Kd, evaluated from kinetic data, increases with increasing degree of substitution of MA. This deduction is confirmed by experiments using 6‐MA as the host instead of MA. With increasing concentration of added 6‐MA, a linear relationship for the fluorescence and a bell‐type profile for the hydrolysis of CDPI are found. These results can be interpreted by the solubilization of CDPI in 6‐MA micelles. As in the case of cyclodextrin, in each turn of the amylose helix, the primary hydroxyl groups are located on one side and the secondary groups on the other side. Therefore, in the case of 6‐MA, where the primary hydroxyl groups are completely blocked, the macromolecules lose the ability to adopt a helical conformation. In conclusion, inter‐turn hydrogen bonding is an important factor contributing to the formation and stabilization of the helical inclusion complex of amylose.
(5,10,15,20‐Tetraphenylporphyrinato)manganese acetate as a novel initiator for the ring‐opening polymerization of 1,2‐epoxypropane
Authors: Kuroki Masakatsu , Aida Takuzo , Inoue Shohei
Published: April 2003

(5,10,15,20‐Tetraphenylporphyrinat o)manganese acetate (2) was found to bring about the ring‐opening polymerization of 1,2‐epoxypropane (3) (R2 = CH3) under mild conditions to give the polymer with a bimodal molecular weight distribution consisting of a sharp main peak and a small shoulder on the higher molecular weight side. The polymerization was found to proceed even in the presence of a protic compound such as an alcohol or a carboxylic acid to give the polymer with a unimodal very narrow molecular weight distribution. The number of the polymer molecules is in good agreement with the sum of those of 2 and the protic compound, demonstrating the “immortal” nature of polymerization.
Synthesis of amorphous films from phenylsilanes by plasma chemical vapor deposition
Authors: Nakamura Takashi , Sinigersky Vesselin A. , Hirano Tsuneo , Fueki Kazuo , Koinuma Hideomi
Published: April 2003

Phenylsilane and methylphenylsilane were decomposed by an rf (radio frequency) glow discharge to investigate the effect of aromatic substitution on the reactivity of the silanes as well as on the structures and properties of the deposited films. The spectral analyses and the optical band gaps of the films indicate that the films deposited at low rf‐powers have polysilane‐like chains with pendant phenyl groups, and that the films deposited at high rf‐powers are substantially silicon carbon alloys containing unsaturated carbon clusters. Although all the as‐deposited films are nearly insulators, the conductivities were improved by as such as six orders of magnitude by either a substitutional doping with diborane or a chemical doping with iodine.
Azo polymers — syntheses and reactions, 1. Terpolymers from styrene, butadiene and azo monomers
Authors: Nuyken Oskar , Weidner Richard
Published: April 2003

Terpolymerization of styrene, butadiene and azo monomers yield polymeric azo initiators. The incorporation of the azo monomers into the terpolymers is almost ideal under “cold rubber” conditions, meaning that the composition of the products does not change with conversion. The retarding effect of some of the azo monomers is explained by the formation of hydrazyl radicals. This view is supported by experiments in which the azo monomers were replaced by model azo compounds.
Ordered and disordered glasses: A comparison of thermodynamical and dynamical properties
Authors: Jungbauer Dietmar A. , Wendorff Joachim H. , Kreuder Willi , Reck Bernd , Urban Claus , Ringsdorf Helmut
Published: April 2003

Characteristic dynamical properties of the glassy state were studied for side‐chain polymers in which either an isotropic glassy state or a nematic glassy state could be induced at will. The dynamical properties of such ordered and disordered glasses were found to be identical. This may indicate that the decrease of the volume taking place at the isotropic‐nematic transition leaves the free volume unchanged. It was furthermore observed that the glassy state is able to stabilize a given structure both with respect to a first‐ and second‐order phase transition for kinetic reasons.
Copolymerization reactivities, electron structure and nuclear magnetic resonance spectra of vinylazoles
Authors: Ivashkevich Oleg A. , Gaponik Pavel N. , Bubel Oleg N. , Kovalyova Tamara B.
Published: April 2003

Data obtained on the electronic structure of a series of C‐ and N‐vinylazoles using the SCF MO method in MNDO approximation and analysis of the 13C and 1H NMR data as well as their copolymerization reactivity ratios in the copolymerization with styrene have shown individual correlations between the relative activity 1/r (r is the copolymerization reactivity ratio of styrene) and the chemical shifts of the terminal vinyl carbon atoms in 13 C NMR spectra, between 1/r and chemical shifts of the protons in trans‐position towards the substituent in 1H NMR spectra, and between 1/r and the net effective charges on the terminal vinyl carbon atoms for each type of monomers considered. The correlations obtained and the analyses obtained from the monomers studied within the modified Alfrey‐Price scheme indicate that the reactivity of vinylazoles in copolymerization is mainly influenced by two factors: the acceptor inductive effect of a substituent in the vinyl bond and the conjugation effect. These factors operate in a different manner for C‐ and N‐vinylazoles and determine their different reactivity in radical copolymerization with styrene.
Stereoassociation of poly(methyl methacrylate): Study on the complexation stoichiometry and structural characteristics of the aggregates
Authors: Katime Issa A. , Quintana José R.
Published: April 2003

A study of the composition of a poly(methyl methacrylate) (PMMA) stereocomplex and the structure of the stereocomplex particles is described. The study was conducted in dilute solutions of tetrahydrofuran (THF), using polymer pairs of an isotactic (ISO) and two syndiotactic (SYN) poly(methyl methacrylate)s of different tacticity. Gel permeation chromatography measurements of the stereocomplex obtained from mixing ISO and SYN‐1 give an optimum ratio of 1:1,5, while for the other polymer pair (ISO/SYN‐2) this relation ranges between 1:2,5 and 1:4. As the tacticity of the syndio‐PMMA samples decreases the optimum ratio increases. The study of the structure of the particles was performed by light scattering measurements of the stereocomplex fractions obtained at the outflow of the chromatographic system. The stereocomplex particles show an exponential relationship between the radius of gyration RG and the molecular weight M, viz. RG = K · Ma which is not very far from that of the linear unperturbed dimensions of PMMA. The numerical value of the exponent a being lower than 0,5 suggests a slight tendency towards the spherical shape of pseudobranched structures expected for these aggregates.
New polymer syntheses, 30. Thermotropic polyesters of 2‐(2‐naphthylthio)terephthalic acid
Authors: Kricheldorf Hans R. , Döring Volker , Beuermann Ilka , Eckhardt Volker
Published: April 2003

2‐(2‐Naphthylthio)terephthalic acid (3 b) was synthesized from 2‐naphthalenethiol and dimethyl 2‐nitroterephthalate. Homopolyesters of this diacid were prepared by thermal condensation with the diacetates of hydroquinone or 4,4′‐biphenyldiol. Copolyesters were obtained by concondensation with 4‐acetoxybenzoic acid. For comparison a homopolyester was prepared from 2‐(2‐naphthyloxy)terephthalic acid and hydroquinone. DSC measurements and microscopic observation under polarized light revealed that the homopolyesters are semicrystalline and form a nematic mesophase above their melting points. The polyester from 3 b and hydroquinone crystallizes significantly more rapidly than the polyester of 2‐(2‐naphthyloxy)terephthalic acid. All copolyesters are amorphous and form a nematic phase between the glass‐transition temperature (130 –140°C) and the temperature at which rapid thermal decomposition takes place (470 ± 10°C). The polyesters were also characterized by elemental analyses, viscosity measurements, thermomechanical analyses and thermogravimetry.
Copolymerisation von acetylen mit acetylenderivaten, 2. Copolymerisation von acetylen mit 3,3‐dimethyl‐1‐butin
Authors: Kanischka Gerd , Höcker Hartwig
Published: April 2003

The coordinative copolymerization of acetylene with 3,3‐dimethylbutyne in toluene with MoCl5 was investigated. The copolymers were characterized spectroscopically as well as by means of gel permeation chromatography and differential scanning calorimetry. The copolymer composition was determined by means of the absorption coefficient of characteristic IR bands of 3,3‐dimethyl‐1‐butin. Planar polyen sequences can be determined by means of UV spectroscopy. The transformation temperatures for the copolymers are below the temperature obtained for the cis‐trans isomerization of pure polyacetylene. The molecular weight of the copolymers is lower than that of the copolymers of acetylene with phenylacetylene. The dependence of solubility and stability of the copolymers on the content of vinylene units shows the same tendency as observed for copolymers from acetylene and phenylacetylene; with increasing acetylene content the solubility decreases, while the instability increases. Increasing temperatures and light irradiation favour oxidation and degradation reactions. The oligomer fractions contain tert‐butylbenzene, 1,3‐ and 1,4‐di‐tert‐butylbenzene as well as 1,2,4,‐ and 1,3,5‐tri‐tert‐butylbenzene.
Synthesis and rheological study of some maleic acid and fumaric acid stereoregular polyesters, 3. Synthesis of a series of configurationally pure aliphatic polymaleates
Authors: Djonlagić Jasna , Sepulchre Marie‐Odile , Sepulchre Maurice , Spassky Nicolas , Jaćović Mihailo S.
Published: April 2003

A series of aliphatic polymaleates was prepared by polycondensation of potassium maleate with α,ω‐dibromoalkanes Br(CH2)n Br (n = 1, 2, 3, 4, 5, 6, 8 and 10) in 1‐methyl‐2‐pyrrolidone. In practically all cases the formation of high‐molecular‐weight polyesters is accompanied by the production of substantial amounts of cyclic oligomers. This polycondensation reaction, carried out at moderate temperature, allows to obtain configurationally pure polymaleates. The resulting unsaturated polyesters are highly viscous liquids with glass transition temperatures below room temperature.
Synthesis and structural study of an ABA block copolymer consisting of poly(γ‐benzyl l‐glutamate) as the A component and poly(propylene glycol) as the B component
Authors: Cho Chong‐Su , Kim Seon‐Woong , Sung Yong‐Kiel , Kim Kae‐Yong
Published: April 2003

ABA type block copolymers composed of poly(γ‐benzyl L‐glutamate) (PBLG) as the A component and poly(propylene glycol) as the B component were obtained by polymerization of γ‐benzyl L‐glutamate N‐carboxyanhydride, initiated by amine groups at both ends of poly(propylene glycol). From circular dichroism measurements in ethylene dichloride solution as well as from infrared spectra measurements in the solid state, it was found that the polypeptide block exists in the α‐helical conformation, as in PBLG homopolymer. Wide‐angle X‐ray diffraction patterns for the block copolymers depend on the casting solvent and show basically similar reflections as the PBLG homopolymer.
Light scattering as tool for the determination of adiabatically performed temperature changes
Authors: Kiepen Friedheinz , Borchard Werner
Published: April 2003

The temperature changes caused by adiabatic pressure changes were studied in a polymersolvent system at high pressures. It is shown that the temperature determination by means of light scattering measurements is in good agreement with thermodynamic calculations of the temperature change for adiabatic pressure changes. The directly measured temperature changes by use of a thermocouple are found to be far too small.
Macrocyclization equilibria in polycycloolefins
Authors: Suter Ulrich W. , Höcker Hartwig
Published: April 2003

Macrocyclization equilibrium data from metathesis reactions of cycloolefins (cyclobutene, cyclooctene, and cyclododecene) are compared with predictions of a novel, simple rotational isomeric state (RIS) scheme for polyalkenes with at least three single bonds between adjacent double bonds. The predictions agree with experiment within the combined experimental errors, supporting the conformational models and confirming that macrocyclization equilibrium has indeed been established in the metathesis reactions.
Urea‐induced “denaturation” of a polymer membrane with poly(L‐glutamic acid) domains for permeation
Authors: Chung Dae‐won , Maeda Mizuo , Inoue Shohei
Published: April 2003

The effect of urea on the permeability was investigated for potassium ion, phenyl‐1,2‐ethanediol, and sugars for a membrane from the graft copolymer 3a containing poly(butyl methacrylate) and poly(L‐glutamic acid) moieties and having polypeptide domains for permeation. The membrane treated with urea shows an increase in permeability and diminishes its ability to recognize the molecular size of permeating sugars, owing to a conformational change of the poly(L‐glutamic acid) chains induced by urea.
Unperturbed dimensions of polymers in binary and ternary systems
Authors: Tejero Roberto , Gómez Clara , Celda Bernardo , Gavara Rafael , Campos Agustin
Published: April 2003

The unperturbed dimensions parameter KΘ is one of the most important characteristics of a polymer chain. For binary systems (polymer/solvent) and mostly for ternary systems (polymer/solvent(1)/solvent(2)) the KΘ values show large discrepancies with respect to those under thetaconditions in a single solvent. These discrepancies can be explained by considering that the interaction parameter χ (and consequently the coil dimensions or the number of intramolecular contacts between polymer segments) changes with molecular weight M. Assuming this dependency, a modified Stockmayer‐Fixman equation is proposed from which a unique value of KΘ for a given polymer, independent of M, is obtained. The use for ternary polymer systems of an interaction parameter between polymer and the solvent mixture (χ3M) which depends on M, allows to calculate a single KΘ value for a polymer in different mixtures of solvents and justifies the proportionality found between KΘ deviations and the excess Gibbs free energy between both solvents of the solvent mixture.
Prediction of second virial coefficients from intrinsic viscosities in ternary polymer systems
Authors: Celda Bernardo , Gavara Rafael , Gómez Clara , Tejero Roberto , Campos Agustin
Published: April 2003

Deviations in the determination of the unperturbed dimensions of polymers arising in ternary polymer systems (solvent (1)/solvent (2)/polymer) can be explained by the inaccurate use of an interaction parameter independent of polymer molecular weight. On this basis, a new formalism for the calculation of the second virial coefficient from intrinsic viscosity is proposed. This formalism was tested (and compared with well established formalisms) for all ternary polymer systems with simultaneous intrinsic viscosity and second virial coefficient data in the literature.
EPR spectrum of radicals produced in the thermal decomposition of tetrakis(p‐methoxyphenyl)succinonitrile
Authors: Szőcs Ferenc , Plaček Jan , Eichholz Hermann , Braun Dietrich
Published: April 2003

The thermal decomposition of tetrakis(p‐methoxyphenyl)succinonitrile (1) results in two identical cyanobis(p‐methoxyphenyl)methyl radicals (2). The hyperfine structure constants of the EPR spectrum of 2 were determined and a computer simulated spectrum was found to be in good agreement with the experimental one. The spin density at the central carbon atom is some‐what lower than that of the cyanodiphenylmethyl radical.
Polyuréthannes à propriétés émulsifiantes et électrolytiques, 1. Cinétique de condensation des alkylimino‐2,2′ diéthanols et de leurs dérivés sulfobétaïniques avec divers monoisocyanates
Authors: Gerard Jean‐François , Perchec Pierre Le , Pham Quang Tho
Published: April 2003

This work deals with model reactions allowing the synthesis of low‐molecular‐weight polyurethanes with electrolytic and emulsifier properties. The kinetics of addition reactions of 2,2′‐alkyliminodiethanols (3a – c) and their ammonium sulfonate derivatives 5 and 6 with propyl (8a) and cyclohexyl isocyanate (8b) were studied in DMSO and in the bulk. The tertiary amino groups of 3 exhibit catalytic effects, whereas the ammonium sulfonate internal salts inhibit the reaction. 8a is 2 – 3 times more reactive than 8b and the addition rates decrease with increasing R. Autoassociations (OH ··· OH) should mainly be intramolecular because of the proximity of the alcohol groups. In bulk the 8a + 3 additions apparently follow second order kinetics. On the other hand, the third order law must be taken into account with 8b. In contrast, in DMSO, due to the strong (solvent, OH and/or NCO) complexations, the kinetics do neither follow the simple second order, nor the third order law. By the use of two successive second order kinetics, diols were found more reactive than their monoalcohol‐monocarbamate derivatives. However, the difference in reactivity decreases with increasing reaction temperatures. Sulfobetaine units may be inserted into the polyurethane chains if diols with ammonium sulfonate groups are used as comonomer, but their weak reactivity must be taken into account.
A carbonyl‐olefin exchange reaction. New route to conjugated polymers, 3. Influence of the reaction conditions
Authors: Schopov Ivan , Mladenova Lyudmila , Kovachev Georgi
Published: April 2003

The reaction conditions influencing the carbonyl‐olefin exchange reaction were studied. It could be established that highest yields and molecular weights are obtained for a mole ratio catalyst/monomer of 1 : 1, the former being introduced in several portions. The observed slowdown of the reaction is explained by deactivation of WCI6, due to complex formation with the resulting polymer. Increase of solvent polarity, temperature and duration also leads to higher yields and molecular weights.
Cyclopolymerization, 14. Influence of temperature on free‐radical cyclopolymerization of N‐allylmethacrylamide and N‐allylacrylamide
Authors: Kodaira Toshiyuki , Sakaki Shuzo
Published: April 2003

Cyclopolymerizations of N‐allylmethacrylamide (1a) and N‐allylacrylamide (1b) are conducted over the temperature range below and above the ceiling temperature (Tc) of N‐propylmethacrylamide (2a), one of the monofunctional counterparts of 1a. Increasing the polymerization temperature extensively enhances the cyclopolymerizability of 1a at temperatures in the vicinity of the Tc of 2a, while the cyclopolymerizability of 1b increases slightly with temperature. The polymerization tendency of N‐propylacrylamide (2b), one of the monofunctional counterparts of 1b, is lying high above the temperature range investigated and both monoallyl counterparts of 1a and 1b showed similar polymerizabilities. The differences between the cyclopolymerizabilities of 1a and 1b are interpreted by applying the hypothesis that the lower the polymerizability of the corresponding monofunctional counterparts of the unconjugated dienes, the higher their cyclopolymerizabilities. Another point focused on the reversibility of intramolecular cyclization, because polymerization of 1a was carried out in the vicinity of the Tc of 2a. It appears that the cyclic structure of poly(1a) consists exclusively of a 5‐membered ring whereas poly(1b) contains 5‐ and 6‐membered rings. The polymerization temperature does not affect the proportion of these two cyclic structures for both polymers. These results suggest that reversibility of intramolecular cyclization need not be taken into consideration to explain the cyclopolymerization behavior of 1a and 1b.
Stereochemical configuration of polyfumarates as studied by 13C nuclear magnetic resonance spectroscopy
Authors: Wang Xiaogong , Komoto Tadashi , Ando Isao , Otsu Takayuki
Published: April 2003

The 125 MHz 13C NMR spectra of some poly(dialkyl fumarates) (PDAF) and poly(dicycloalkyl fumarates) (PDCF) prepared by radical polymerization are measured in CDCl3 solution at 60°C. The multiplet resonances of the main‐chain carbon atoms and the ester carbonyl carbon atoms are assigned to stereochemical triad and pentad sequences, respectively, using model compounds as well as computer simulation. From these results it is found that PDAF and PDCF exhibit essentially atactic structures with meso addition favoured over racemic addition, and that the ratio of meso to racemic content varies with different kinds of alkyl and cycloalkyl groups. The tactic sequence proportions of the polymers cannot be explained by one‐parameter Bernoullian statistics, but can be successfully explained by modified Bernoullian trial.
Characterization of the surface morphology in carboxylated methyl methacrylate‐butyl acrylate emulsion copolymers
Authors: Emelie Brigitte , Pichot Christian , Guillot Jean
Published: April 2003

A series of carboxylated methyl methacrylate (MMA)‐butyl acrylate (BuA) (weight ratio 1 : 1) copolymer latexes were prepared by emulsion polymerization with varying the nature of carboxylic acid (acrylic (AA), or methacrylic acid (MAA)), the type of emulsifier (sodium dodecyl sulfate (SDS) or nonylphenyl polyoxyethylene ether (HV25®) surfactants), or the polymerization method (batch or shot process). Results of surface characterization and rheological behavior of the latexes were found to provide information on the carboxylic acid location and the interfacial layer thickness, respectively. Stability studies against different types of electrolyte and temperature showed that the surface morphology is strongly dependent upon the nature of oligomers formed during the synthesis, especially the presence of sequences rich of poly‐(carboxylic acid)s, and how they are anchored onto the particle. According to the type of emulsifier and polymerization process, stability is predominantly determined either by electrostatic or steric forces. In some cases, when surfactant HV25® is used, enhanced steric stabilization prevails.
The mechanism of copolymerization of maleic anhydride with methyl methacrylate and with methyl acrylate
Authors: Brown Anthony Stuart , Fujimori Kiyohisa , Craven Ian
Published: April 2003

Composition diagrams for the copolymerization of maleic anhydride with methyl methacrylate and with methyl acrylate in ethyl methyl ketone at 50°C were determined using a non‐aqueous potentiometric direct titration method. The data were analysed using non‐linear least squares minimization procedures to test the applicability of terminal, penultimate and complex models for both systems. In both systems, the penultimate model was an improvement over the terminal model, though the penultimate effect was more pronounced in the methyl methacrylate system. No evidence could be found for complex participation in either system.
Molecular structure of 2,6‐bis[2‐(heptamethylcyclotetrasiloxan‐2‐yl)ethyl]hexamethylcyclotetrasiloxane as a model of poly(hexamethylcyclotetrasiloxane‐2,6‐diylethylene)
Authors: Ovchinnikov Yu. E. , Shklover V. E. , Struchkov Yu. T. , Astapova T. V. , Zhdanov A. A.
Published: April 2003

The molecular and crystal structure of 2,6‐bis[2‐(heptamethylcyclotetrasiloxan‐2‐yl)ethyl]hexamethylcyclotetrasiloxane (1) representing a three‐unit oligomer (“trimer”) of the corresponding poly(hexamethylcyclotetrasiloxane‐2,6‐diylethylene) (3) was determined. A similarity of the crystal packings of 1 and the earlier studied “dimer” 2 allows to establish the parameters of the “subcell” of polymer 3, which are in a good agreement with the data of its wide‐angle X‐ray study.
The molecular structure of 4‐(dimethylmaleimido)phenyl methacrylate
Authors: Puranik Vedavati G. , Tavale Sudam S. , Row Tayur N. Guru , Sehra Jagdish C.
Published: April 2003

The molecular structure of 4‐(dimethylmaleimido)phenyl methacrylate was determined by means of X‐ray diffraction. Crystals are orthorhombic, space group F2dd, a = 3,993(1) Å, b = 36,650(6) Å, c = 39,460(8) Å and Z = 16; dcalc = 1,360 g · cm−3, V = 5774,7 Å3, M = 285,3, λ = 0,7107 Å, μ (MoKα) = 1,06 cm−1, F(000) = 2400. The structure was solved by direct methods and refined to R = 0,062 for 304 observed reflections. The molecule has a synperiplanar conformation as to the CC and CO double bonds about C(7)C(8) and also as to the CO and CO bonds about C(7)O(1).
Small angle X‐ray scattering investigations on cold‐drawn nylon 6
Authors: Ferracini Elena , Ferrero Adele
Published: April 2003

Small angle X‐ray scattering (SAXS) on cold‐stretched nylon 6 supports the model of fully extended chains as a consequence of mechanical deformation. There is no evidence for the persistence of lamellar fragments. The ordered zones present before cold‐stretching exhibit a dimension of 4,7 nm and those formed after cold‐stretching and annealing one of 6,3 nm in fibre direction. The long period of the as‐extruded samples is 11,5 nm, and that of the coldstretched and annealed samples is 8,3 nm. The reduction of the long period and the increase of particle dimensions in the annealed samples support the hypothesis that a new lamellar system is formed.
Morphologie der segmentierten polyetheresteramide auf der basis von polyamid 12 und oligotetrahydrofuran
Authors: Lohmar Jörg , Meyer Kurt , Goldbach Günther
Published: April 2003

Polyetheresteramides (PEEA) on the basis of polyamide 12 and oligotetrahydrofuran (OTHF) may be referred to as intrinsically plasticized and intrinsically impact strength toughened thermoplastic elastomers. This is due to their special 4‐phase morphology consisting of two pure crystalline and two mixed amorphous phases, which was completely analysed by various TEM preparation techniques. PEEA containing more than 50% PA 12 hard segments exhibit a space filling dendritic superstructure of lamellar crystallized hard segments. In the range of 50 – 30% PA 12, the dendrites become more and more isolated, and below 30% PA 12 only single lamellae can be observed. The matrix in all PEEA is an amorphous, PA 12‐rich mixed phase (“OTHF‐plasticized PA 12”) located between the hard segment lamellae. An amorphous OTHF‐rich mixed phase is very finely dispersed in PEEA and acts as an intrinsically impact strength toughening modifier. Lamellar crystallized soft segments could be imaged by TEM in this dispersed phase, but only in PEEA products with a higher molecular OTHF and at sufficient low temperatures.
An easy calculation of the expected n‐ad sequence proportions in polymers obeying first‐order markov statistics and being prepared by ring‐opening polymerization of chiral heterocyclic monomers
Authors: Sepulchre Maurice
Published: April 2003

An easy and fast calculation method of the normalized n‐ad sequence proportions in optically active polymers which derive from heterocyclic monomers and which obey first‐order Markov statistics is developed. The proposed method does not require any computer calculation and provides very accurate values up to high conversions in polymer. It can be applied over a wide range of enantiomeric excess of the initial monomer, and of copolymerization reactivity ratios. This is useful for testing whether a polymer fits the first‐order Markov propagation model.
Molecular design of block and graft copolymers by vinyl‐substituted xanthates
Authors: Niwa Masazo , Higashi Nobuyuki , Shimizu Motoyuki , Matsumoto Takahiro
Published: April 2003

The selective polymerization behavior of O‐ethyl S‐4‐vinylbenzyl xanthate (1) was investigated on the basis of polymerization kinetics in the dark and in the presence of UV‐light. S‐Benzyl O‐ethyl xanthate (2) was used as a non‐polymerizable model compound of 1 to evaluate chain transfer constants. In the homopolymerization and the copolymerization of 1 initiated with AIBN in the dark, styryl groups selectively take part in the polymerization, and xanthate groups are not responsible for it. The monomer reactivity ratios (r1 = 0,51 and rMMA = 0,41) of 1 with methyl methacrylate (MMA) are very close to those of styrene with MMA. The photolysis of 2 was investigated by 1H NMR. It was found that photodecomposition of 2 takes place at CH2S (a) and SC( = S) bonds (b) with the ratio: a/b = 1/5. The polymerization of MMA was carried out with 1 upon photoirradiation. Number‐average degrees of polymerization of the polymers obtained increase linearly with conversion. Block and graft copolymers were prepared by using these macrophotoinitiators.
New polymer syntheses, 27. Syntheses of aromatic polyethers from 2,6‐difluoropyridine and silylated aromatic diols
Authors: Kricheldorf Hans R. , Schwarz Gert , Erxleben Jörg
Published: April 2003

Aromatic polyethers were prepared by bulk condensation of 2,6‐difluoropyridine (1) with various silyalated diphenols and benzelnediols at temperatures between 140 and 240°C. Colorless products were obtained with inherent viscosities in the range of 0,4–1,4 dl/g. DSC measurements revealed that the polyethers derived from bisphenol‐A, phenolphthalein, 4,4′‐oxydiphenol and phenylhydroquinone are amorphous with glass‐transition temperatures in the range of 90–190°C. Polyethers derived from hydroquinone or 4,4′‐biphenyldiol are crystalline with melting points in the range of 200–270°C. Thermogravimetry in air indicates thermostabilities up to 450°C (at 5% loss of weight). Poly(pyridinediylether‐co‐ketoether)s (4) and poly(pyridinediylether‐co‐arylsulfoether)s (5) were obtained by cocondensation of 1 with 4,4′‐difluorobenzophenone or 4,4′‐difluorodiphenyl sulfone and various silylated aromatic diols. For these copolyethers inherent viscosities in the range of 0,6–1,0 dl/g were found, and tough films could be cast from solution. Incorporation of the pyridinediyl units was found to significantly lower the glass‐transition temperatures. The copolyethers obtained from 1, 4,4′‐difluorobenzophenone and hydroquinone or 4,4′‐biphenyldiol are crystalline. Thermodynamical analyses indicate high heat‐distortion temperatures (>200°C) for annealed samples of these crystalline polyethers. Thermogravimetry conducted at a heating rate of 10°C/min in air only indicates a moderate thermostability.
Greffage de monomères acryliques induit par un plasma froid sur un polypropylène
Authors: Epaillard Fabienne , Brosse Jean‐Claude , Legeay Gilbert
Published: April 2003

Cold plasma can be applied to polymer chemistry especially when grafting is to be achieved. Multifunctional acrylate monomers could be grafted onto polypropylene after its surface was activated. Grafting, the final stage of this plasma‐induced polymerization, is the consequence of a reaction of a macroradical, which has diffused to the surface of the substrate, with a reactive species created on the polypropylene surface. The rate of grafting was found to be smaller than the rate of monomer disappearance. The rate increases with the power, but no relation could be established between both.
Poly(oxyethylene) terminated with tertiary amino or quaternary ammonium groups
Authors: Masař Bohumil , Janout Václav , Čefelín Pavel
Published: April 2003

α‐(3‐Dimethylaminopropyl)‐ω‐dimethylaminomethylpoly(oxyethylene)s (2a–e) were prepared from α‐(3‐aminopropyl)‐ω‐aminomethylpoly(oxyethylene)s (1a–e) (M̄n = 430–2300 g·mol−1), by the Wallach‐Leuckart reaction, with a degree of transformation of NH2 into N(CH3)2 groups of 70–98%. The samples were characterized by means of IR spectrometry and Siggia's acylation method, adjusted for microdetermination. The polymers terminated with 3‐dimethylaminopropoxy groups were transformed into the corresponding derivatives bearing quaternary ammonium end groups, and characterized both as dihydroxides and dichlorides. The content of the quaternary ammonium groups was found to differ considerably for the individual samples in the range of 19–97%. The reason for this variability was found not to be a low efficiency of the quaternization reaction, but the Hofmann‐degradation giving rise to terminal vinyl groups of the polyether chain.
Solution properties of ultrahigh‐molecular‐weight polymers, 16. Unperturbed dimensions of poly(isobutyl methacrylate)
Authors: Simionescu Cristofor I. , Ioan Silvia , Flondor Aurelia , Simionescu Bogadan C.
Published: April 2003

Three techniques, i. e., the Lenka extrapolation method, the Stockmayer‐Fixman method, and the extrapolation of the Mark‐Houwink constants to a = 0,5 were applied to determine the unperturbed dimensions of ultrahigh‐molecular‐weight poly(isobutyl methacrylate). A correction term, depending on the exponent a of the Mark‐Houwink relation, is suggested to be introduced into the Stockmayer‐Fixman‐Burchard equation.
Correlation of viscoelastic properties with the molar mass distribution for aqueous polyacrylamide solutions
Authors: Müller Rolf‐Joachim , Klein Joachim
Published: April 2003

The dependence of viscous and elastic rheological functions on molar mass and molar mass distribution was investigated under shear flow conditions using concentrated solutions of polyacrylamides and polyacrylamide mixtures. The zero‐shear viscosity η0 correlates with the weight‐average molar mass M̄w; with increasing shear rate the corresponding controlling molar mass average tends to change to the number‐average molar mass M̄n. It is shown that the analysis of the shape of the whole flow curve is a simple way to obtain qualitative information about molar mass distribution. Elastic forces are influenced mainly by the high‐molar‐mass tail of a molar mass distribution. The zero normal stress coefficient ψ0 depends on a molar mass average between M̄w and z‐average molar mass M̄z·ψ0 increases with the 7,4th power of the molar mass for the polyacrylamides (not for the mixtures). The steady‐state compliance Je(0) is, for the investigated system, independent of the absolute molar mass, but increases with the 5,5th power of the ratio M̄z/M̄w. The elasticity modulus G0(A) can be correlated with M̄n of the polyacrylamide samples and their mixtures. These investigations show that the analysis of various rheological functions can lead to a wealth of information about the molar mass distribution of a polymer.
Interaction effects on linear dimensions of polymer chains in polymer mixtures
Authors: Sariban Alla , Binder Kurt
Published: April 2003

Monte Carlo simulations are presented for binary (AB) symmetric polymer mixtures (chain lengths NANBN) for the case that an attractive interaction ϵ exists between monomers of the same kind, and the limiting case that one species (B) is very diluted. It is shown that with increasing interaction strength ϵ/(kB · T), T being the absolute temperature, the minority chains collapse to a very dense configuration, while the majority chains stay nearly Gaussian. Both chain radii, structure factors and numbers of nearest neighbour contacts are discussed.
Dioxygen sensitivity of a photoexcited thin film of phthalocyanine dispersed in poly(N‐vinylcarbazole)
Authors: Kaneko Masao , Wöhrle Dieter , Schlettwein Derck , Schmidt Volker
Published: April 2003

Thin films (thickness 0,3 μm) of a mixture of phthalocyaninatozinc(II) (1) and poly(1‐vinylcarbazole) (2) are prepared by coating from a solution on ITO glass. The blue coloured films are investigated in an electrochemical cell under irradiation with visible light. In the presence of dioxygen from air the films exhibit an intensive cathodic photocurrent. The action spectrum of the photocurrent corresponds to the absorption spectrum of the phthalocyanine. The results show a device which can be switched by air and visible light.
Effect of secondary structure on salt permeability of poly(γ‐methyl‐L‐glutamate) membranes
Authors: Minoura Norihiko
Published: April 2003

Poly(γ‐methyl‐L‐glutamate) membranes with α‐helix structure and with ß‐sheet structure were prepared by casting. The electrical membrane potentials of the membranes in LiCl, NaCl, and KCl solutions were measured in order to obtain information on the mobility of ions within the membranes. In the membranes with α‐helix structure the relative ionic mobilities of Na+ and Li+ to K+ are larger than in aqueous solutions. In the membranes with ß‐sheet structure the mobility of cations within the membrane is extremely restricted. The partition coefficient of KCl in this membrane at low concentrations is greater than 10. The permeability and diffusion coefficients of KCl depend on the concentration of KCl, and the values are higher, when compared with those for the membrane with α‐helix structure. These results reflect the differences between the secondary structures of the polymers. The specific behaviour of the partition coefficient and of the permeability found in the membranes with ß‐sheet structure is explained by an interaction between the carbonyl groups of the main chain and the cations.
Le phényl‐1 éthylpotassium, amorceur de polymérisation anionique: Préparation par clivage de l'oxyde de bis(phényl‐1 éthyle); étude du milieu réactionnel
Authors: Beinert Gérard , Zilliox Jean‐Georges , Herz Jean
Published: April 2003

1‐Phenylethylpotassium (5), an efficient anionic polymerization initiator in tetrahydrofuran (THF) solution serving as a substitute for 1‐methyl‐1‐phenylethylpotassium in most of its applications, was obtained by cleavage of bis(1‐phenylethyl) ether (1) with potassium. Ether cleavage reactions were carried out in THF at mole ratios potassium/1 = 2/1 and 1/1, and the resulting solutions were submitted to careful analysis. All by‐products formed in the reaction media were unambiguously identified and their mole fractions in the resulting mixture determined. The presence of these by‐products was found not to influence the initiator efficiency.
Synthesis and properties of (18‐crown‐6)‐bridged phthalocyanine network polymers
Authors: Ahsen Vefa , Yilmazer Emel , Bekâroǧlu Özer
Published: April 2003

(18‐Crown‐6)‐bridged phthalocyanine network polymers 4–8 as well as a low‐molecular‐weight model compounds with only one phthalocyanine unit (3a, b) were prepared from tetracyanodibenzo‐18‐crown‐6 (2a). The cyano end groups were partially converted into imido groups during the cyclotetramerization reaction, as detected from the IR spectra. In order to obtain structurally uniform compounds with the same end groups, the C  N groups were hydrolyzed into imido groups with conc. sulfuric acid. The metal‐free phthalocyanine polymer 4a was obtained by the reaction of 2a either with hydroquinone or PbO in ethylene glycol. The chlorides of Cu(II), Ni(II), and Co(II) were empolyed in order to synthesize the corresponding metal‐phthalocyanine polymer, and Fe(CO)5 was used for the preparation of the Fe‐analog 7a. For the preparation of the Co‐containing polymer 8a ammonium molybdate has to be added as catalyst. The selectivity of 7a for Rb+ was found to be highest in the heterogeneous phase extraction experiments. Polymers 4–8 are also capable of binding silver from aqueous and methanolic solutions.
Mechanisms of the thermal degradation of polyesters based on 1,2‐propanediol, phthalic anhydride, maleic anhydride and 1,4,5,6,7,7‐hexachlorobicyclo[2.2.1]hept‐5‐ene‐2,3‐dicarboxylic acid
Authors: Vijayakumar Chinnaswamy Thangavel , Lederer Klaus
Published: April 2003

Six different linear polyesters based on phthalic anhydride, maleic anhydride, 1,4,5,6,7,7‐hexachlorobicyclo[2.2.1]hept‐5‐ene‐2,3‐dicarboxylic acid (HET‐acid) and 1,2‐propanediol were synthesized. The polyesters were pyrolysed by heating dynamically at a rate of 10 K · min−1 from 40 to 440°C. Apart from the dynamic pyrolysis, the standard unsaturated polyester was isothermally pyrolysed at five different temperatures (200, 250, 300, 350 and 400°C) for 60 min. The pyrolysis products obtained were separated in a capillary gas chromatograph and identified using a mass‐selective detector. In all the polyesters investigated, the corresponding anhydride was formed in major quantities. A variety of low‐molecular‐weight compounds such as propanoi isomers, isomeric dimethyldioxanes, 1,2‐propanediol, 5‐hydroxy‐2‐pyrone and its 6‐alkyl substituted derivatives, polychlorocyclopentadienes and considerable quantities of complex mono‐ and diesters of the diacid component were identified. The presence of HET‐acid units in the polyester chain alters the course of the degradation of the diol units considerably by suppressing the formation of 1,2‐propanediol and increasing the formation of isomeric dimethyl‐dioxanes, 1‐propanol and 2‐propanol. In the thermal degradation of HET‐acid containing polyesters, the formation of HET‐anhydride is favoured in comparison to the retro‐Diels‐Alder reaction in chain. The mode of formation of the products identified by gas chromatography/mass spectrometry analysis is discussed in the light of the general polyester degradation mechanism.
Determination of primary crystallite size of TiCl3 catalysts by small angle x‐ray scattering
Authors: Kakugo Masahiro , Sadatoshi Hajime , Sakai Jiro , Yokoyama Masakazu
Published: April 2003

Small‐angle X‐ray scattering (SAXS) analysis using MoKα radiation is successfully applied to a determination of the crystallite sizes of TiCl3 catalysts. The sizes of TiCl3 catalysts dispersed in nascent polypropylenes differing in polymer yield are determined by using this technique. It is shown that the original catalyst size does not change during the course of polymerization. This result agrees with the observation by transmission electron microscopy (TEM).