bluuebunny/crossref_metadata_2025 huggingface dataset:
The polymerisation of styrene by trifluoroacetic acid
Authors: Obrecht Werner , Plesch Peter H.
Published: April 2003

The polymerisation of styrene (St) by trifluoroacetic acid (TFA) in methylene chloride was studied by high‐vacuum dilatometry at 40°C with specially purified reagents. Drying increases rates, changes the internal orders, and changes the MWD in that with undried TFA the MWD is bimodal, with the driest TFA it is unimodal. For undried TFA, the whole reaction cannot be represented by a single, simple equation; with dried TFA, —d[St]/dt = kv [St]2[TFA]3. When polymerisation is complete the solutions contain free TFA and polystyryl trifluoroacetates. 1‐Phenylethyl trifluoroacetate itself is not an initiator, it yields oligostyrene if treated with TFA, and if present in a reaction mix of St + TFA it retards the polymerisation, is consumed, and causes a distinctly bimodal MWD. The relation of our results to those of Sawamoto et al is discussed.
Thermodynamic studies of DNA‐dye complexes, 2. DNA‐methylene blue and DNA‐thionine systems
Authors: Tanaka Shigeyuki , Baba Yoshihiro , Kagemoto Akihiro
Published: April 2003

The interaction between DNA and various dyes (methylene blue (1), and thionine (2)) was studied by means of the heat of mixing. From the results, the thermodynamic quantities were estimated for the DNA‐dye system by an intercalation process. The free energy change of the system DNA‐2 was found to be nearly equal to that of the system DNA‐1, but the absolute value of the heat of interaction of the system DNA‐2, which has amino groups, is higher than that of the system DNA‐1. These facts are comparable with those previously found for the systems DNA‐proflavine and DNA‐acridine orange. However, the locations of 1 and 2 intercalated into DNA may be different from those of acridine orange and proflavine because the enthalpy changes for the systems DNA‐1 and DNA‐2 are higher than those of the systems DNA‐acridine orange and DNA‐proflavine, respectively. These facts showed that the location of the intercalated dye depends on the presence of amino groups in 3‐position of the dye.
Der einfluß von D‐alanin auf das konformative verhalten von kollagenmodellpeptiden
Authors: Roth Werner , Heidemann Eckhart
Published: April 2003

With the help of equilibrium measurements on covalently bridged collagen model peptides of the sequence D,L‐Ala‐Gly‐L‐Pro it was shown that the thermostability of the tertiary structure of these peptides is strongly influenced by the D‐Ala contents. The conformational behaviour of the peptides was studied by measurements of circular dichroism in methanol at various temperatures.
Préparation et identification de copolyamides alternés du type ω‐aminoacide
Authors: Tran Ngoc‐Mai , Carrière François , Sekiguchi Hikaru
Published: April 2003

The hydrochlorides of p‐nitrophenyl 6‐aminocaproate (4a), p‐nitrophenyl 12‐aminododecanoate (4b), and p‐nitrophenyl 12‐(6‐aminocaproylamino)dodecanoate (6) were prepared and polycondensed in 1,2,4‐trichlorobenzene in the presence of tributylamine under different conditions. The polycondensation of 6 at 128°C gave the alternating copolyamide (PA 6, 12). The polymers were identified by DTA and by 13C NMR.
Etude 13C NMR d'alcanes ramifiés, 1. n‐alkyl‐12 tricosanes. Application aux polyéthylènes basses densités
Authors: Freche Patrick , Grenier‐Loustalot Marie‐Florence , Metras Franck , Gascoin Alain
Published: April 2003

A series (8 compounds) of mono‐branched alkanes (12‐n‐alkyl‐tricosanes) as models for polyethylene was prepared. The results obtained from 13C NMR show in particular the dependence of the chemical shifts (Δδ ≈ 0,05 p.p.m.) on T in the temperature range 37°C ≤ T ≤ 100°C but that the branches remain identifiable in this range of temperature. By mixing different tricosanes we simulated various branched polyethylenes. The chemical shifts observed at 100°C with some corrections complete the incremental system of Grant and Paul as modified by Randall for the effect of temperature.
A functional styrene monomer having a hexylamino group. Synthesis and polymerization
Authors: Li Xue‐fen , Maeda Mizuo , Tsuruta Teiji
Published: April 2003

Synthesis and polymerization of N‐hexyl‐N‐[2‐(4‐vinylphenyl)ethyl]amine (5) are reported. To elucidate the reaction mechanism for the monomer synthesis, kinetic studies are carried out on the lithium catalyzed amination reaction of styrene (3) and of 1,4‐divinylbenzene (1) with hexylamine (2). The reaction rate, v, was found to be expressed as v = k [3] [2] [CH3(CH2)5NHLi], where k is the rate constant. Methods for selective synthesis of 5 are considered on the basis of results of the kinetic studies. Polymerization and copolymerization behavior of 5 shows that 5 has characteristics similar to 3 in radical polymerization.
Versuche zur copolymerisation deuterierter monomerer copolymerisation styrol/deuterostyrol und methylmethacrylat/deuteromethylmethacrylat
Authors: Wittmer Paul , Böck Harald , Naarmann Herbert , Schmitt Burghard J.
Published: April 2003

In free radical copolymerization of styrene with completely deuterated styrene and methyl methacrylate with completely deuterated methyl methacrylate no isotope effects upon the copolymerization parameters were observed. However, isotope effects were found in the rates of copolymerization Rp. In the case of styrene Rp decreases monotonically from a higher level for the deuterated monomer to a lower level for the [1H]‐monomer. For the case of methyl methacrylate Rp again is higher for the deuterated monomer than for the [1H]‐monomer, but there is a minimum in the curve Rp vs. monomer mixture composition.
Dégradation photochimique de polymères cétoniques, 2. Etude sur modèles de la photodégradation de copolymères cétoniques à groupes carbonyles en chaǐne
Authors: Bonnans‐Plaisance Chantal , Casals Pierre‐François , Levesque Guy
Published: April 2003

Three linear phenyl ketones, 4‐methyl‐1,7‐diphenyl‐3‐heptanone (6a), 2,8‐diphenyl‐4‐nonanone (6b), and 5‐methyl‐2,8‐diphenyl‐4‐nonanone (6c), and four cyclic ketones, 1‐phenethyl‐2‐(3‐phenylpropionyl)cyclopentane (4a), 1‐(3‐phenylbutyryl)‐2‐(2‐phenylpropyl)cyclopentane (4b) and their cyclohexane homologues (5a and 5b), were synthesized as models of styrene copolymers bearing carbonyl groups in the chain, and their photochemical degradation was studied in various solvants at wavelengths > 280 nm. This study has shown that both Norrish mechanisms, i.e., the type I scission in α‐position of the carbonyl and the type II photoelimination, which occur with the models, take place in a similar fashion with the copolymers. The relative part and the efficiency of each photodegradation depend on the solvent, the linear or cyclic character of the chain, as well as on the substitution. Photodegradation studies of the models have also allowed us to explain the photochemical behaviour of the particular copolymers and especially the faster fragmentation of linear chains, and to elucidate the mechanisms involved in the degradation of these polymers.
Darstellung von Oligo[(hydroxy‐1,3‐phenylen)methylen]en mit Hydroxynitrophenylen‐ und Alkylhydroxyphenyleneinheiten
Authors: Böhmer Volker , Lotz Werner , Pachta Jiri , Tütüncü Suat
Published: April 2003

Possibilities to synthesize substituted oligo[(hydroxy‐1,3‐phenylene)methylene]s containing hydroxynitrophenylene and alkylhydroxyphenylene units are discussed. The only successful way to introduce the hydroxynitrophenylene unit consists in the condensation of chloromethylated nitrophenols with an excess of alkylphenols. The resulting compounds can be prolonged stepwise at the alkylhydroxyphenylene end group by alternating hydroxymethylation and further condensation with alkylphenols. Thus, including the hydroxymethylated compounds, 11 dinuclear, 17 trinuclear, and 5 tetranuclear compounds were obtained for the first time. Some of them were characterized by their acetyl derivatives.
Molecular association in aqueous solutions of high molecular weight poly(N‐vinyl‐2‐pyrrolidone)
Authors: Güven Olgun , Eltan Ender
Published: April 2003

A viscosimetric method was used to investigate the molecular association in aqueous solutions of poly(N‐vinyl‐2‐pyrrolidone), (PVP), of molecular weight 700 000. Limiting viscosity numbers [η] and Huggins constants kH of the polymer solutions were observed to decrease upon addition of denaturing agents such as thiourea and guanidinium sulfate. Guanidinium sulfate was found to be even more effective in its denaturing action as compared to urea and thiourea. The decrease in [η] and kH values increased with increasing concentrations of the denaturing agents. This behaviour was explained on the basis of the rupture of bridges formed by water molecules among different PVP chains, hydrogen bonding being responsible for these intermolecular associations. While no change in the [η] values was observed for PVP in 2 M thiourea solutions upon increasing the temperature from 25°C to 35 and 45°C, for the same increase in temperature the [η] values of aqueous PVP solutions showed substantial decreases. This is also attributed to the breaking of hydrogen bonds existing between PVP molecules.
Photochromic polymers: Photoinduced conformational changes and effect of polymeric matrix on the isomerization of photochromes
Authors: Matějka L. , Dušek K.
Published: April 2003

Two types of photochromic polymers were prepared and studied: a copolymer of maleic anhydride with styrene containing aromatic azo groups P(MAH‐STY‐AAB) and a copolymer of methacrylic acid with methacryloylamidoazobenzene, P(MA‐MAAB). The effects of the polymeric carrier, the solution viscosity, and the position of the photochrome in the chain on photochrome isomerization were determined. Investigation of the effect of radiation on the conformation of the polymer chain revealed that the copolymer P(MAH‐STY‐AAB) exhibited a pronounced photoviscosity effect in 1,4‐dioxane solution, i.e., a reversible decrease by 24–30% in the reduced viscosity of the solution after irradiation. In the case of the copolymer P(MA‐MAAB), radiation causes a destabilization of the compact conformation.
Synthèse par voie radicalaire de polymères à extrémités hydroxylées, 8. Synthèse de polybutadiènes: Etude de différents paramètres influençant la polymolécularité
Authors: Brosse Jean‐Claude , Bonnier Maryvonne , Legeay Gilbert
Published: April 2003

It was shown that radical polymerization of butadiene in 1‐butanol and 2‐butanol, initiated by hydrogen peroxide cleaved into two hydroxyl radicals by heat, leads to three types of polymers according to their respective polydispersity. It was found that the formation of these products — oligomers, polymers, and high polymers — can be influenced by modifying the experimental conditions. Thus, it is possible to obtain selectively oligomers free of polymers and polymers free of low molecular weight oligomers.
The morphology of semicrystalline segmented poly(ether ester) thermoplastic elastomers
Authors: Zhu Li‐Lan , Wegner Gerhard
Published: April 2003

The supermolecular structure of melt‐crystallized segmented copoly(ether ester)s based on poly(tetramethylene terephthalate) and poly(tetramethylene oxide) is investigated by polarizing microscopy and electron microscopic techniques. Spherulites are formed on isothermal crystallization at supercoolings ΔTu < 30°C. The spherulites recrystallize to form dendritic structures on further annealing at higher temperatures. The spherulites and dendrites are builtup from lamellae which exhibit little variation concerning the thickness of their crystalline core. The internal phase boundaries in these systems are made visible with a newly developed staining method. A network of interlocked individual lamellae is formed on rapid quenching of the melt films. Row crystallization (shish‐kebabs) is observed, if the melt is sheared during the crystallization. It is concluded from these observations that the chemical structure of the segmented copolymers bears little relevance for the supermolecular structure of these materials except for the thickness of the crystalline core of the lamellae which seems to be related to the molecular length of the hard segment sequences occurring with the highest concentration in the sample.
The crystallization behavior and the mechanical properties of segmented poly(ether ester) thermoplastic elastomers
Authors: Zhu Li‐Lan , Wegner Gerhard , Bandara Upali
Published: April 2003

The isothermal melt crystallization of three segmented copoly(ether ester)s based on PBT as the hard and PTMO as the soft segments differing in their hard segment content was investigated. The kinetics of crystallization was studied using polarizing microscopy and DSC. Two regimes of crystallization were observed. Spherulitic structures of low crystallinity are formed via predominantly athermal nucleation in regime I at supercoolings ΔTu < 30°C. Ill‐defined aggregations of lamellae grow at ΔTu > 30°C. The crystallization follows an apparent Avrami‐equation; the Avrami‐constants cannot be explained in terms of a simple model. The structure of the samples was investigated by SAXS and compared to the structure of samples crystallized by rapid quenching and subsequent annealing. Much higher long spacings are obtained on isothermal crystallization. The long spacing increases with decreasing ΔTu. It increases at constant ΔTu with decreasing average hard segment length contrary to the samples crystallized by subsequent annealing of the quenched melt. In this case polymers differing in composition do not differ with regard to the long spacing obtained at constant ΔTu. The modulus in the Hookean‐range as derived from stress‐strain curves at T > Tg does not reflect the details of the morphology or chain architecture but it is found to depend logarithmically on the volume fraction of crystallinity in the sample. Data of pure PBT are described by the same relationship.
Chain folding in α‐methyl‐ω‐alkoxypoly(oxyethylene)
Authors: Al Kafaji Jawad K. H. , Booth Colin
Published: April 2003

Samples of α‐methyl‐ω‐alkoxypoly(oxyethylene), with an oxyethylene block of number average molar mass M̄n = 2300 g · mol−1 and with n‐alkoxy end groups ranging from methoxy to octadecyloxy, have been prepared and characterised. Lamella spacings have been investigated by small‐angle X‐ray scattering and by Raman scattering. Melting behaviour has been investigated by differential scanning calorimetry. Crystallisation is affected by the length of the n‐alkoxy end group (nc carbon atoms) and the crystallisation temperature (Tc). Samples with small nc form extended chain lamella crystals. The formation of folded chain lamella crystals is favoured by large nc and small Tc. Folded chain lamella crystals are unstable with respect to chain unfolding above a given temperature (Tx). Annealing at temperatures lower than Tx increases the stability of the lamella crystals. All samples have been obtained in extended chain lamella crystalline form by annealing at 43,5°C. The melting points of these annealed crystals show a shallow minimum at nc ≈ 5. This effect can be explained if alkyl and oxyethylene segments are well mixed in non‐crystalline lamella‐surface layers.
Ring‐opening copolymerization of cycloalkenes investigated by 13C NMR spectroscopy
Authors: Ivin Kenneth J. , Lapienis Grzegorz , Rooney John J.
Published: April 2003

Ring‐opening copolymerization studies were made on the systems cyclopentene (CPE)/ norbornene (NBE), cyclooctene (COE)/ norbornene, 1,5‐cyclooctadiene (COD)/norbornene, cyclopentene/cycloheptene (CHP), and cyclopentene/ 1,5‐cyclooctadiene using olefin metathesis catalysts.13C NMR spectra of the copolymers permit direct determination of the reactivity ratios in most cases, as well as the proportion of cis double bonds in each type of dyad. For CPE/NBE, COD/NBE and CPE/CHP the reactivity ratios vary widely with the catalyst system and sometimes with the catalyst/cocatalyst ratio and method of mixing. There is no correlation between composition of the copolymer and cis content. The copolymers show either a random or blocky distribution of monomeric units. The results are discussed in terms of a mechanism in which the metal carbenes formed in the propagation processes are initially coordinated to the polymer chain and can add further monomeric units stereospecifically while in this form. These propagation processes compete with a relaxation process leading to a metal carbene in which the polymer chain is no longer coordinated at the vacant site and which adds monomer in a less stereospecific fashion.
Synthesis of poly(oxovinyl sulfide)s by vinylogous nucleophilic substitution polymerizations of bis(3‐chloroacryloyl) derivatives of benzene with 4, 4′‐oxydibenzenethiol
Authors: Ueda Mitsuru , Sakai Naoyuki , Komatsu Masanobu , Imai Yoshio
Published: April 2003

Poly(oxovinyl sulfide)s 3 were prepared by vinylogous nucleophilic substitution polymerization of bis(3‐chloroacryloyl) derivatives of benzenes (1a and 1b) with 4,4′‐oxydibenzenethiol (2). The synthesis involves solution polycondensation and two‐phase polycondensation with phase transfer catalysts. Polymers having inherent viscosities in the range of 0,2–0,7 dl·g−1 were obtained quantitatively by both methods. They are soluble in concentrated sulfuric acid, dichloroacetic acid, and m‐cresol, and practically insoluble in polar aprotic solvents and common organic solvents. Thermogravimetric studies in both air and nitrogen atmospheres indicated that the decomposition temperatures for 10% weight loss of the polymers were about 400°C.
The effect of preaveraging of hydrodynamic interaction on the intrinsic viscosity and intrinsic flow birefringence of gaussian polymer chains
Authors: Fortelný Ivan
Published: April 2003

The intrinsic viscosities of a Gaussian chain with and without hydrodynamic interaction preaveraging and with the identification of the centre of gravity of the Gaussian coil with the chain center were calculated using Tsuda's theory. It appears that the value of the Flory constant is more affected by approximations used in the derivation of Tsuda's theory than by preaveraging of hydrodynamic interaction. Svetlov's theory was used in the calculation of the ratio of intrinsic flow birefringence to intrinsic viscosity. For unpreaveraged hydrodynamic interaction this quantity is lower by some 15–20% than for a free‐draining coil.
Polymere azomethine mit azobenzol‐einheiten
Authors: Koßmehl Gerhard , Wallis Jan
Published: April 2003

Condensation of 4‐aminoazobenzene (1), respectively 4, 4′‐diaminoazobenzene (2), with mono‐ and dialdehydes of the benzene and thiophene series yields intensive coloured polymeric azomethines (polymeric Schiff bases) with azobenzene units, respectively model compounds. The structure of these polymers and model compounds were confirmed by elemental analyses, IR‐and electronic spectra and — in the case of the model compounds — by MS and 1H NMR spectra. The electrical conductivities of the polymers and model compounds and the thermo oxidative degradations of the polymers were studied.
Anionic polymerization of isopropenyl methyl ketone, 1. IR‐spectroscopic study of the nature of alkali derivatives of acetone and of the active centres in the anionic polymerization of isopropenyl methyl ketone
Authors: Tsvetanov Christo B. , Petrova Dobrinka T. , Panayotov Ivan M.
Published: April 2003

The nature of alkali derivatives of acetone (ADA) and active centres (AC) in the anionic polymerization of isopropenyl methyl ket one (IMK) was studied by means of IR spectroscopy. Solutions of ADA and of the AC of IMK in tetrahydrofuran show a characteristic absorption at 1560 – 1610 cm−1, due to the stretching vibrations of the delocalized isopropenyl oxide group. Two kinds of equimolar complexes are formed between acetone and ADA, depending on the nature of the counterion (Li+, Na+, K+, Cs+). The same interaction is observed between the AC of oligo (IMK) and the carbonyl group of the last but one monomeric unit (penultimate effect).
Aliphatic‐aromatic polyamide‐imides from diisocyanates, 1. 1H and 13C NMR study of polymer structure
Authors: Nieto José L. , de la Campa José G. , de Abajo Javier
Published: April 2003

The reaction of a diisocyanate and an asymmetric aliphatic‐aromatic diacid containing a preformed imide group was studied in order to obtain polyamide‐imides. It is shown in this paper that combined 1H and 13C NMR spectrometry will permit the quantitative evaluation of the proportions of head‐tail, head‐head, tail‐tail additions, provided the content of urea in the polymer is low. In order to obtain unequivocal assignments and to thoroughly characterize the NMR spectra of the polymer, several model compounds resembling the polymer backbone were synthesized. A model polymer was synthesized with the same purpose, and its 1H and 13C NMR spectra fully assigned. Unexpected chemical functions in the polymer, like urea and carboxylic acid, can also be easily detected and quantified by NMR.
Approche de la microstructure d'une résine copolymère de monomères vinyliques et diéniques
Authors: Guillot Jean
Published: April 2003

The present work deals with a general framework of the kinetics and the microstructure (sequence distribution of monomeric units, network parameters…) of resins constituted of vinyl and diene monomers based on the theory of Markov chain propagation. As a matter of example, calculations were applied to the copolymerization of styrene with p‐ and m‐divinylbenzene.
Determination of rate constants for elementary reactions in cyclopolymerization of N‐propyldimethacrylamide
Authors: Yamada Bunichiro , Saya Toshiaki , Otsu Takayuki
Published: April 2003

Radical cyclopolymerization of N‐propyldimethacrylamide (PDMA) was investigated. Kinetic orders of polymerization rate with respect to the monomer and the initiator were 1,0 and 0,5, respectively, at a monomer concentration greater than 1,6 mol/l. Absolute values of rate constants of propagation and termination reactions were determined by the rotating sector method in bulk and in 50% propionitrile solution at 30°C. Poly(PDMA) consists of 5‐membered cyclic repeating units almost exclusively. The rate constants for addition of poly(PDMA) radical to vinyl monomers and those for addition of polymer radicals to PDMA were also evaluated. One the basis of the rate constants obtained, the rate determining step of PDMA propagation was deduced to be the intermolecular addition of the growing radical to PDMA monomer. The growing radical of PDMA, formed by intramolecular addition to the carbon‐carbon double bond of the same molecule, was found to be as reactive as polymer radicals from reasonance stabilized monomers. The 5‐membered ring formation was highly favored by the conformation of PDMA in which coplanarity of the newly formed bond and the semi‐occupied orbital of the new radical center is readily achieved. Relatively low reactivity of poly(PDMA) radical was accounted for by delocalization of the unpaired electron on the coplanar three carbon atoms. Radical addition of a 2‐tertiary thiol to PDMA solely yielded the substituted succinimide. The 5‐membered ring formation in PDMA polymerization and in the addition reaction was ascribable to the favorable conformation of PDMA.
Study of photopolymers, 15. Polymerization of ethylene glycol divinyl ether and photocrosslinking reaction of its polymer
Authors: Nishikubo Tadatomi , Iizawa Takashi , Yoshinaga Akira , Nitta Masayuki
Published: April 2003

Soluble polymer with methylene‐1,4‐dioxane‐2,3‐diymethylene (75 − 65 mole‐%) and 2‐[(vinyloxy)ethoxy]ethylene structural units (25 − 35 mole‐%) were obtained in the radical polymerization of ethylene glycol divinly ether (EGVE) in benzene at conversions of about 30 – 45%. It was found that in the radical polymerization of EGVE the rate of polymerization is proportional to the 1,5th power of monomer concentration and to the 0, 6th power of initiator concentration. On the other hand, a soluble polymer with 1,4‐dioxepane‐5,7‐diylmethylene units was obtained from cationic polymerization of EGVE in dichloromethane by using iodine as as catalyst. Moreover, the photocrosslinking reactions by irradiation with UV light of the radically obtained polymer having pendant vinyloxy groups with dithiols or by diazonium tetrafluroborates were investigated.
Polymethacrylic acid derivatives, 2. Spectroscopic study of the compact conformation to coil transition
Authors: Morcellet‐Sauvage Joëlle , Morcellet Michel , Loucheux Claude
Published: April 2003

The compact → coil conformational transition of hydrophilic‐hydrophobic copolymers derived from poly(methacrylic acid) was studied by UV Spectroscopy. Two copolymers were used in this study: a Poly(N‐methacryloylalanine‐co‐N‐phenylmethacrylamide) (P50) and a poly(methacrylic acid‐co‐benzyl methacrylate) (S25). Both samples exhibit hypochromism in the absorption band of the aromatic chromophore when they are under the compact conformation: 7% and 30% hypochromism for P50 and S25, respectively. This difference is explained by differences in the hydrophobic side chain‐side chain interactions between the aromatic residues. Increasing the temperature was found to increase strongly the hypochromism of S25 and to have little effect on P50.
Odd‐even effects in polymeric liquid crystals
Authors: Roviello Antonio , Sirigu Augusto
Published: April 2003

Semiflexible mesophasic polymers of the general formula \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} [{\rm OOC(CH}_{\rm 2} {\rm )}_{n - 2} - {\rm COO} - {\rm R}^1 \rlap{--} ]_{\rm X} ,n = 9,11,13,\rlap{--} [{\rm OOC(CH}_{\rm 2} )_{n - 2} - {\rm COO} - {\rm R}^2 \rlap{--} ]_{\rm X} ,n = 9,11,13,14, $\end{document}
and
\documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} [{\rm OOCO} - {\rm (CH}_{\rm 2} {\rm )}_{n - 4} - {\rm OCOO} - {\rm R}^2 \rlap{--} ]_{\rm X} ,n = 9,11,13, $\end{document}
where
\documentclass{article}\pagestyle{empty}\begin{document}$ {\rm R}^{\rm 1} = - {\rm C}_{\rm 6} {\rm H}_{\rm 5} - {\rm C}({\rm CH}_3 ) = {\rm CH} - {\rm C}_6 {\rm H}_5 - $\end{document}
and
\documentclass{article}\pagestyle{empty}\begin{document}$ {\rm R}^{\rm 2} = {\rm C}_{\rm 6} {\rm H}_{\rm 5} - {\rm C}({\rm CH}_3 ) = {\rm N} - {\rm N} = ({\rm CH}_3 ){\rm C} - {\rm C}_6 {\rm H}_5 - $\end{document} are prepared and their solid and liquid crystalline behaviour examined and compared to that of the corresponding homologues with n even. Evidence is given of relevant odd‐even effects in the thermodynamic parameters of the clearing transition. The conclusion is drawn in favour of an anisotropic structuration also of the flexible parts of the polymer chain in the liquid crystal phase.
Modification des condensats phénoliques par des groupes phtalimides. Résines dérivées des phtalimidométhylphénols. Synthèse et caractérisation
Authors: Guyot Alain , Revillon André , Sallé Robert , Sillion Bernard
Published: April 2003

By reacting N‐hydroxymethylphthalimide (5a) or N‐chloromethylphthalimide (5b) with an excess of phenol, a mixture of 2‐phthalimidomethylphenol (6) and 4‐phthalimidomethylphenol (7) was obtained. The ratio 6/7 was found to be 2:3 for the reaction with 5a and 3:2 with 5b, as determined by 1H NMR at 250 MHz. The condensation of 6 with hexamethyleneteraamine (3) at the mole ratio 6/3 equal to 2 and 7,5 was performed at 190°C. The resulting resins (HPP) were compared to those prepared from o‐cresol and 3 (HOC), and GPC of the resulting products was made. A higher thermal stability of the resins HPP was evidenced by thermogravimetric analysis. This improvement of the thermal stability was also observed for the condensation products of the ortho and para isomers 6 and 7 with phenol and formaldehyde, leading to modified novolacs FPP, although the amount of incorporated 6 and 7 was found to be less than the original amount in the reaction mixture.
Estimation of chain molecular dimension of poly(2‐methylpent‐1‐ene sulfone) at critical polymer contents by dielectric measurements
Authors: Araki Kazuo , Imamura Yoshio
Published: April 2003

Dielectric measurements were made in the frequency range from 30 Hz to 3 MHz for a series of the solutions of poly(2‐methylpent‐1‐ene sulfone) (PMPS) having two different molecular weights in benzene at 30°C. The unperturbed chain molecular dimension was estimated from dielectric relaxation time at the critical polymer contents, Ccr. This value of the unperturbed dimension was much higher than that from the intrinsic viscosity measurement. The dielectric motion at Ccr involves simultaneous co‐operative reorientations of about three spheres. The number of the spheres of reorientation may be related to the flexibility of the molecular chain of the polymer. The ratio of two effective volumes of the polymer obtained from the unperturbed chain molecular dimension and from the dielectric relaxation time, τm agreed with that of the two effective volumes obtained from the K value in Onogi's treatment and from the τm value.
Absolute determination of molecular weights of standard polystyrenes by means of sedimentation‐diffusion measurements in toluene
Authors: Petrus Vladimír , Porsch Bedřich , Nyström Bo , Sundelöf Lars‐Olof
Published: April 2003

Sedimentation coefficients, s0c, diffusion coefficients, Dc, and specific viscosities have been determined for eleven samples of commercial narrow‐molecular‐weight distribution polystyrenes Pressure Chemicals Co. and Waters Ass., 5 · 104 g · mol−1 < weight average molecular weight Mw < 2 · 106 g · mol−1 at different concentrations in toluene (25°C). From the Svedberg equation the values of the MsD averages have been calculated from the sedimentation and diffusion coefficients extrapolated to infinite dilution. The reproducibility of the measured values of s00, D0 and [η] was better than 3%. The parameters determined for the same samples in Prague and in Uppsala (using different instruments and different data evaluation techniques) were in good agreement (the maximum deviation 6%). The plots of log s00 vs. log D0 and log [η] vs. MsD are linear without any systematic deviations; all experimental hydrodynamic data are consistent within the interval of experimental error, i.e. ±3%. However, when plotted versus the nominal molecular weights the scatter is considerably increased. Furthermore, the calculated average molecular weights, MsD, differ in several instances from the nominal ones.
Polymer‐solvent interactions in mixed solvents, 4. Ethyl‐ and butyl vinyl ether‐maleic acid alternating copolymers in water/2‐chloroethanol mixtures
Authors: Apostolopoulos Michel , Morcellet Michel , Loucheux Claude
Published: April 2003

Viscosity and preferential solvation measurements were carried out on maleic acid‐ethyl‐ and ‐butyl vinyl ether alternating copolymers (MA‐EVE and MA‐BVE, respectively) in watermethanol and water‐2‐chloroethanol mixtures. The conformational transition of MA‐BVE was found to be strongly related to the solvation of the polymer by 2‐chloroethanol. Comparison of experimental results on MA‐BVE, MA‐EVE, and poly(methacrylic acid) (PMA) in water‐2‐chloroethanol mixtures indicates that the behaviour of MA‐EVE is different from that of MA‐BVE and PMA because it does not undergo any conformational transition.
Darstellung und eigenschaften von copolyamiden mit oxyethylengruppen in definierter sequenz
Authors: Iwabuchi Susumu , Nakahira Takayuki , Tsuchiya Atsushi , Kojima Kuniharu , Böhmer Volker
Published: April 2003

The polyamides 3–5 were synthesized from α,ω‐diamino‐substituted oligo(oxyethylene)s (1) and bis‐chlorides of dicarboxylic acids (2). As copolymers with defined sequences they contain up to five oxyethylene units per repeating unit. Hereby properties like solubility, thermal stability and complexing ability towards alkali metal cations are influenced.
Stereochemistry of the acetal addition of a β‐deuterated vinyl ether as a model reaction for the polymerization of vinyl ethers
Authors: Morii Hisayuki , Fujishige Shoei , Matsuzaki Kei , Uryu Toshiyuki
Published: April 2003

As a model reaction for the homogeneous cationic polymerization of vinyl ethers, cis‐ethyl vinyl ether‐β‐d (1a) was reacted with 1,1‐diethoxyethane in presence of BF3O(C2H5)2 as a catalyst. The steric structures of the adducts, mainly 1,1,3‐triethoxybutane‐2‐d (3a) and 1,1,3,5‐tetraethoxyhexane‐2, 4‐d2 (4a, equivalent to the dimer) were determined by means of 1H NMR spectroscopy, taking into account the conformational characteristics based on energy calculation. The predominant stereoisomer of 3a was proved to be the erythro‐form. The assignments of the methylene proton resonances to erythro‐ and threo‐configurations were applied to the analysis of the spectra of 4a which enabled us to elucidate the molecular aspects of the opening of the double bond and the mode of approach of the monomer to the cationic reactive site. It was also concluded that the stereospecific reaction might be attributed to the repulsive forces between the ethoxy group of vinyl ether and that of the carbonium ion derived from the acetal.
Stereoregularity of polystyrene derivatives, 4. Poly(α‐methylstyrene) obtained by anionic catalysts
Authors: Kawamura Tokiji , Uryu Toshiyuki , Seki Toshiyuki , Matsuzaki Kei
Published: April 2003

The stereoregularity of poly(α‐methylstyrene)s prepared by anionic initiators was determined from the peak area of α‐methyl proton absorptions and aromatic C1 carbon absorptions. Highly syndiotactic polymers were obtained at 0°C in both toluene and tetrahydrofuran (THF). Sodium, potassium, and cesium naphthalenes gave polymers with the same syndiotacticity in THF. The syndiotacticity of polymers prepared by sodium and potassium naphthalenes as catalyst in both toluene and THF decreased at low temperatures. This behavior is similar to that of o‐methylstyrene and m‐methylstyrene in THF. The stereoregulation mechanism in the anionic polymerization of α‐methylstyrene is discussed and compared with that of polystyrene and ring substituted polystyrenes.
Thermolyse einiger azoalkylacetate und azochloralkane
Authors: Nuyken Oskar , Schuster Herbert , Kerber Robert
Published: April 2003

The kinetic results (from DSC and 1H NMR) of the thermolysis of symmetric azochloroalkanes and azoalkyl acetates with the general structure R1 R2 (X) C—N=N—C(X) R1 R2 (X=OCOCH3, Cl; R1, R2=CH3, C6H5) and of asymmetric phenylazoalkyl acetates with the general structure R1 R2(H3COCO) C—N=N—C6H5(R1 R2=CH3, C6H5) are described. The suitability of the asymmetric compounds as initiators for radical polymerization is demonstrated with (diphenyl)phenylazomethyl acetate (7c). Quantitative measurements of the thermolysis products from 1,1′‐azo(methylethyl) diacetate (4a) showed that the ratio for the disproportionation to combination reaction of the resulting substituted alkyl radikals is 4,3.
Configurational statistics of poly(dimethylsiloxane) accounting for all rotational states
Authors: Brückner Sergio , Malpezzi Luciana
Published: April 2003

Some configuration‐dependent properties of poly(dimethylsiloxane) are evaluated by taking into account the full rotational range around skeletal bounds (ars model). Allocation of fractional electronic charges to Si, O and C atoms and consequent coulombic interactions give an essential contribution to the interpretation of experimental data. A comparison is drawn with the rotational isomeric state (ris) model adopted by many authors. A substantial equivalence between the two models is detected in the study of long polymer chains while some detectable difference arises in the description of short sequences.
13C NMR sequence analysis, 22. Stereoselectivity of the polymerization of D,L‐leucine and D,L‐valine N‐Thiocarboxy anhydrides
Authors: Kricheldorf Hans R. , Mang Thomas
Published: April 2003

Two kinds of N‐thiocarboxyanhydrides of D,L‐L and D,L‐L were synthesized, 5‐oxo‐2‐thioxo‐1,3‐oxazolidones 1a, 1b and 1,3‐thiozolidine‐2,5‐diones 2a, 2b. Their polymerizations were conducted at 20°C with primary, secondary, and tertiary amines or with potassium tert‐butylate as initiators. The tacticity of the resulting poly(D,L‐L)s and poly(D,L‐L)s was investigated by means of 13C NMR spectra. It was found that under all conditions the formation of isotactic sequences is favoured. The stereoselectivities of all polymerizations were low; the average lengths of isotactic blocks never exceeded 6 monomeric units. The chain growth deviates slightly from the Bernoullian statistics favoring the formation of longer isotactic blocks. While D,L‐4‐isopropyl‐2,5‐thiazolidindione (2a) did not polymerize, the polymerization of D,L‐4‐isopropyl‐5‐oxo‐2‐thioxooxazolidine (1a) (D,L‐L‐NTA) showed under all conditions lower stereoselectivities than those of the two D,L‐L‐NTAs.
Immobilisierung von salmin an CNBr‐sepharose 4B
Authors: Zeitz Klaus , Schott Herbert
Published: April 2003

The protamine salmine was immobilized on CNBr‐Sepharose 4B without involving the arginine side‐groups. The optimum conditions for the immobilization on a preparative scale were investigated in a series of analytical experiments. A Maximum yield (206 mg salmine/g dry salmine‐sepharose) was achieved at a pH‐value of 8, a gel concentration of 10 mg/ml suspension volume and a salmine sulfate concentration of 5 mg/ml reaction solution. An equation was developed to calculate the maximum immobilization of peptides on CNBr‐Sepharose 4B assuming known molecular weights of the ligand.
Polysiloxane‐based activators in the anionic block copolymerization of ϵ‐caprolactam
Authors: Lefebvre Pierre Marie , Jerome Robert , Teyssié Philippe
Published: April 2003

The activator used in the anionic polymerization of ϵ‐caprolactam is systematically anchored onto the growing polyamide chain. The use of a macromolecular activator, as an isocyanate‐terminated polymer, provides an attractive pathway to block copolymerization. However, this procedure is not compatible with a polysiloxane activator, because of the degradtion of the siloxane backbone under conditions needed for ϵ‐caprolactam polymerization. The degradation process was unambiguously evidenced through model‐reactions. This conclusion is in contradiction with a previously published report on this subject.
Über ternäre azeotrope — zur frage der existenz eines ternären azeotroppunktes ohne binäres azeotrop
Authors: Quella Ferdinand , Braun Dietrich
Published: April 2003

The terpolymerization equations of Alfrey‐Goldfinger and Ring for calculation of ternary azeotropes are compared. It is shown that the equation of Alfrey and Goldfinger can be transformed into that of Ring. Possible copolymerization ratios for the existence of ternary azeotropes without a binary one are discussed. Copolymerization ratios taken from literature show that there is a chance to find such and azeotrope, but and existing example was not found. So copolymerization ratios were arbitrarily chosen to give a range wherein such and azeotrope could exist.
Configurational characteristics of the polysulfides, . Dipole moments and gauche effects in poly (1,3‐dithiocane)
Authors: Welsh W. J. , Mark J. E. , Guzman J. , Riande E.
Published: April 2003

Several earlier studies of poly(alkylene sulfides) have not yielded evidence for a sulfur gauche effect, in contrast to the large attractive gauche effect found particularly in the lower members of the poly(alkylene oxides). In this study the dipole moments at 25°C and the corresponding temperature coefficient of poly(1,3‐dithiocane)

Structure based name: poly(thiomethylonethiopentamethylene).

[SCH2S(CH2)5]x are calculated in the rotational isomeric‐state approximation, and the results compared to the values determined by experiment. In the calculations the energy Eσ′ = [Eg± − Et] associated with S. . .CH2 interactions in the SCH2SCH2 segment is adjusted to attain agreement between theory and experiment. The results indicate that an extra stabilization energy of ca. 0,9 kcal . mol−1 must be added to these gauche states relative to the trans state (beyond that determined by conformational energy calculations based on semiempirical potential energy functions). This provides the first evidence of a large attractive sulfur gauche effect in the polysulfides, about equal in magnitude to that found for the analogous poly(methylene oxide).
The copolymerization of unsaturated carboxylic acids with styrene and an unsaturated tertiary amine in benzene
Authors: Harbák František , Bezděk Milan , Hynková Vlasta , Svobodová Jarmila
Published: April 2003

The copolymerization parameters of 2‐acryloyoxybenzoic (AOB) and 2‐methacryloyloxybenzoic (MOB) acids, methyl 2‐methacryloyloxybenzoate (MMOB), and N‐methyl‐N‐phenyl‐2‐aminoethyl methacrylate (MPAM) with styrene in benzene solution were determined and used in the calculation of the Alfrey‐Price copolymerization constants e and Q for AOB, MOB, MMOB, and MPAM. Using e Q thus determined and the corresponding tabulated values for methacrylic acid (MAA), the copolymerization parameters of pairs AOB‐MPAM, MOB‐MPAM, MMOB‐MPAM, and MAA‐MPAM were calculated. They are compared with those determined by the copolymerization of these pairs in which the interaction of functional groups on comonomers plays a role.
Miscibility of poly(vinyl chloride) with ethylene/N,N‐dimethylacrylamide copolymers.
Authors: Matzner M. , Robeson L. M. , Wise E. W. , McGrath J. E.
Published: April 2003

The incorporation of N,N‐dimethylacrylamide (DMA) as a comonomer in polyethylene yields a material possessing dramatically improved mechanical compatibility with poly(vinyl chloride) (PVC). At increased levels of DMA (25–30 wt.‐%) miscibility with PVC is achieved. This behavior is believed to be due to the specific interaction of the tertiary hydrogen of poly(vinyl chloride) (weak “acid” or proton donor) with the disubstituted amide in the ethylene copolymer (weak “base” or proton acceptor). Dynamic mechanical characterization of the ethylene/DMA copolymer (EDMA)/PVC blends reveals separate glass transitions temperatures at DMA levels below 20 wt.‐%; they merge into a single Tg when the DMA content reaches a value above 25 wt.‐% in the ethylene copolymer. The secondary loss transition for PVC (−40°C) is lowered in temperature and greatly suppressed in magnitude. This is further evidence of molecular miscibility. Mechanical property data obtained on the EDMA/PVC blends are consistent with the foregoing considerations.
Grafting of styrene onto carbon fibers having pendant thiol groups
Authors: Fujisawa Takao , Tanaka Akira , Yosomiya Ryutoku
Published: April 2003

Carbon fibers containing thiol groups were produced by reacting carbon fiber oxidized by nitric acid, with excess thiirane. Then, graft polymerization with styrene was carried out in a sealed tube under nitrogen. The following order of initiating ability of the investigated initiators was found: di‐tert‐butyl peroxide > p‐cumenyl hydroperoxide (CHPO) > dodecyl peroxide > benzoyl peroxide > 2,2′‐azoisobutyronitrile. When CHPO was used as initiator, the rate of graft polymerization was maximum at [CHPO] = 0,01 mol/1. Chain transfer constant and grafting efficiency, both calculated from the equations of Fox and others, were compared with the experimental results.
Limiting viscosity number and sedimentation coefficient of solutions of cellulose acetates
Authors: Ishida Shin‐Ichiro , Komatsu Hideki , Katoh Hiroyuki , Saito Masatoshi , Miyazaki Yukio , Kamide Kenji
Published: April 2003

Viscosity and sedimentation experiments were made for fractions of cellulose acetate CA (degree of substitution, D.S. = 2,46) in acetone and CA (D.S. = 2,92) in N,N‐dimethylacetamide (DMAc) at 25°C. The following empirical relations were established between the sedimentation coefficient at infinite dilution s0 and the weight average molecular weight M̄w: s0 = 1,02 · 10−14 M̄w0,39 (s) for CA (D.S. = 2,46) in acetone and s0 = 1,83 · 10−14 M̄0,24w (s) for CA (D.S. = 2,92) in DMAc. From the analysis of the molecular weight dependence of s0 and the limiting viscosity number [η] (method 1B) and the concentration‐dependence parameter ks and [η] (method 1E), the solvent draining parameter X was estimated to be less than 1, indicating that the free draining effect cannot be ignored. The unperturbed chain dimension parameter A was determined from data on s0 and M̄w to be between 1,72 · 10−8 and 1,80 · 10−8 cm for CA (D.S. = 2,46) in acetone and between 1,63 · 10−8 and 1,68 · 10−8 cm for CA (D.S. = 2,92) in DMAc. These values are in good agreement with those estimated by thermodynamic and viscometric approaches.
Studies of siloxane‐acid model system: Hexamethyldisiloxane‐trifluoroacetic acid
Authors: Wilczek L. , Chojnowski J.
Published: April 2003

The equilibrium in the system containing hexamethyldisiloxane, trifluoroacetic acid, and the inert solvent methylene chloride is studied. The system may serve as a model of reactions which play an important role in the cationic polymerization of cyclic siloxanes. The kinetic studies confirm that analogous reactions control the concentrations of silanol and silyl ester end groups as well as of acid and water during the polymerization. Allowing for some hydrogen bonding formation in the analysis of these equilibria the respective equilibrium constants can be obtained preserving almost constant values in the total range of concentrations studied.
Untersuchung der teilschritte der ethylen‐hochdruck‐polymerisation, 1. Druckabhängigkeit der einzelnen geschwindigkeitskonstanten
Authors: Luft Gerhard , Lim Pe‐Chin , Yokawa Masaru
Published: April 2003

In order to calculate the average molecular weight, the molecular weight distribution or the branching of low density polyethylene, the individual values of the rate constants of the different reactions involved in the free radical polymerization are required. The method of rotating sector was applied to determine the rate constants of chain propagation and chain termination in a wide range of temperatures and pressures. This first part of the work reports the influence of the pressure. It was found that the rate constant kp of the chain propagation increases with rising pressure whereas the rate constant kt of chain termination decreases. The effect of the pressure on kp can be explained in terms of the activation volume. The decrease of kt with pressure is caused by a diffusion controlled termination reaction.
On the mechanism of the flow process of poly(ethylene terephthalate)
Authors: Sasano Haruko , Kawai Tohru
Published: April 2003

The mechanism of “flow process” defined as drawing by which neither crystallization nor molecular orientation takes place was clarified on the basis of its direct experimental evidences on drawing of “amorphous” poly(ethylene terephthalate) films. In a certain temperature range above Tg, the polymer molecules are deformed and oriented on drawing, “inter‐molecular secondary linkage” playing an important role in the transmission of the applied force. When this intermolecular linkage breaks down above a certain critical temperature, the polymer molecules may slip past each other and flow independently, resulting in a large deformation without inducing any molecular orientation and crystallization. At higher temperatures crystallization occurs inducing the orientation as well.