bluuebunny/crossref_metadata_2025_split huggingface dataset:
Changes of the polymerization mechanism depending on the monomer and solvent for a homogeneous Ziegler‐type initiating system
Authors: Barthelemy Pascal , Deffieux Alain , Sigwalt Pierre 
Published: April 2003

AbstractThe homogeneous system resulting from the reaction between tetrabenzylzirconium and triethylaluminium is an active catalyst for the polymerization of styrene, and p‐methyl‐, α‐methyl and p‐chlorostyrenes. The molecular weights and the structures of the resulting polymers are highly dependent on the nature of the monomer and on the reaction medium. In toluene, styrene and p‐methylstyrene give essentially linear unsaturated dimers, whereas p‐chlorostyrene leads to a polymer with a high molecular weight. In methylene dichloride higher oligomers and a polymer are obtained simultaneously from all the monomers. The comparative behaviour of the styrene derivatives was examined in copolymerization experiments under various experimental conditions. The ratios of monomer incorporation were compared with those reported in the literature for related systems. The results show that, according to the monomer and the reacting medium, the same catalytic system is able to induce polymerizations of the “coordinated anionic”, radical and cationic type.
Relaxation processes in a block copoly(ether‐ester) elastomer investigated by the spin probe method
Authors: Lembicz Franciszek , Ukielski Ryszard 
Published: April 2003

AbstractRelaxation processes in the soft segment phase of a block copoly(ether‐ester) elastomer were investigated using the spin probe method. Rotational mobility of the two probes, differing in sizes, were analysed and the results were interpreted based on the relaxation diagram. It was found that the change in mobility of the probes, as detected by the change in ESR line shape, in the slow rotation region corresponds to the β‐relaxation, whereas that in the rapid rotation region corresponds to the α + β‐relaxation. The analysis of probe mobilities, including the way they rotate, indicates the necessity of inclusion of rotational anisotropy in the interpretation of the behaviour of probes of different size.
Cinétique de la diffusion de l'eau dans un film mince de photoresist
Authors: Sebillote Franc̨ois , Weill André , Paniez Patrick 
Published: April 2003

AbstractDiffusion of water molecules in novolak‐based photoresist films commonly used in microelectronics is investigated. Thermogravimetry was used, in order to measure the diffusion constants of water molecules for temperatures ranging from 30 to 80°C. It is shown that the time to reach equilibrium with the surrounding atmosphere is only a few seconds for a dry 1 μm thick film of novolak‐based positive photoresist.
Asymmetric addition of hydrogen cyanide to aliphatic aldehydes catalyzed by a synthetic cyclic peptide, cyclo[(S)‐phenylalanyl‐(S)‐histidyl]
Authors: Asada Shoichi , Kobayashi Yoshiyuki , Inoue Shohei 
Published: April 2003

AbstractThe asymmetric addition of hydrogen cyanide to an aliphatic aldehyde, catalyzed by a synthetic dipeptide, cyclo[(S)‐phenylalanyl‐(S)‐histidyl] (1), leads to a product having a higher optical yield than that reported for the reaction using an enzyme (D‐oxynitrilase) as catalyst.
Reductions with the lithium aluminium hydride‐poly(N‐methylethyleneimine) complex suspended in hydrocarbon media
Authors: Tanaka Ryuichi , Kataoka Kazuya , Ueoka Isao , Saito Shogo 
Published: April 2003

AbstractA variant of the reduction with lithium aluminium hydride (LAH), involving the complex of LAH with a high‐molecular‐weight, linear poly(N‐methylethyleneimine) (PMEI), is described. The reduction of simple aldehydes, ketones, or esters was found to proceed essentially within the solid LAH‐PMEI complex suspended in pentane and the resulting pure alcohols can be isolated by working up only the separated solid phase.
Polymerization of lactams, 74. Behaviour of the polymerization mixture prepared by the non‐activated polymerization of 2‐pyrrolidone above the limit polymerization temperature, 1
Authors: Fries Tomáš , Ciekerová Blanka , Roda Jan , Králíček Jaroslav 
Published: April 2003

AbstractPolymerization mixtures of 2‐pyrrolidone, i.e. the mixtures of monomer, polymer and their potassium salts, prepared by non‐activated polymerization under optimal conditions (45°C), exhibit in the temperature interval between the ceiling temperature (70°C) and 110°C an increase in the polymer yield, whereas the yield and intrinsic viscosity [η] of the polymer decrease at higher temperatures (up to 160°C). The polymerization mixtures, heat stressed in this way, have an increased polymerization activity in comparison with the non‐activated polymerization, if exposed again to the optimal polymerization temperature. A controlling effect of the present semicrystalline poly(2‐pyrrolidone) and the stability of a part of growth centres, even at high temperature, are concluded from the investigated behaviour.
Acid curing of epoxy resins. A comparison between the polymerization of diepoxide‐diacid and monoepoxide‐cyclic anhydride systems
Authors: Matějka Libor , Pokorný Svatopluk , Dušek Karel 
Published: April 2003

AbstractThe molar masses of linear polyesters formed in the polymerization of stoichiometric mixtures of 1,7‐heptanedicarboxylic acid (4) with 2,2‐bis[4‐(2,3‐epoxypropoxy)phenyl]propane (2) (the diglycidyl ether of Bisphenol A), and of 1,2‐cyclohexanedicarboxylic anhydride (3) with 2,3‐epoxypropyl phenyl ether (1), catalyzed with tertiary amines, and the effect of the concentration of the tertiary amine catalysts were compared. In the reaction between anhydride 3 and epoxide 1 the molar mass of polyester, determined by GPC, was found to decrease with increasing concentration of the tertiary amine, whereas in the reaction of the acid it is independent of the catalyst content. The molar mass distribution is much narrower in the reaction of the anhydride. These results correspond to the mechanisms determined earlier: a stepwise mechanism in the reaction between epoxide and acid, and an “initiation” mechanism in the case of anhydride. In the polymerization of the dicarboxylic acid 4 with the diepoxide 2 good agreement was observed with the theoretical dependences, calculated by using the theory of branching processes.
Dégradation contrôlée des polyisoprènes‐1,4 par le couple phénylhydrazine/oxygène, 1. Etude sur molécules Modèles
Authors: de Barros Lobo Filho Eurico , Reyx Danièle , Campistron Irène , Casals Pierre‐François 
Published: April 2003

AbstractSome constituents and structures in the mixtures obtained by reaction of oxygen with model compounds of 1,4‐polyisoprene in the presence of phenylhydrazine (1) could be identified. Accelerated oxidation of monomeric units 2 of 1,4‐polyisoprene by phenyl radical generation (reaction of 1 with oxygen) and in situ decomposition of hydroperoxides, allow to explain the formation of epoxidized and hydroxylated units which were identified. Identification of phenylsubstituted alcohols and phenyl ketones leads to the proposition of a chain cleavage process involving the addition of phenyl radicals to the double bonds of 2. No more carbonyl compounds or structures resulting from peroxide decompositions by carbon‐carbon bond cleavage could be detected. The hypothesis of their transformation into phenylhydrazones, followed by oxidation and decompositions, is supported by indications of phenylazo structures, but has to be confirmed.
13C NMR studies of the conformation of cyclic paraffins, n‐paraffins and polyethylene in solution
Authors: Yamanobe Takeshi , Sorita Tetsushi , Ando Isao , Sato Hisaya 
Published: April 2003

AbstractHigh‐resolution 13C NMR spectra of cyclic paraffins, n‐paraffins and polyethylene were measured in 1,2,4‐trichlorobenzene solution, and the results were compared with the solid state 13C high resolution NMR data measured previously. It is proposed that in cyclic paraffins up to C32, the conformation in the solid state is retained even in solution, all the methylene carbons within the cyclic paraffin exhibiting identical gauche‐trans population with fast transition between the conformers in the ring plane, whereas in cyclic paraffins of larger carbon number, the conformation in the solid state is not retained in solution, the gauche‐trans populations being different in this case. The conformation of n‐paraffins and polyethylene is also discussed.
Structural study of compounds modelling elementary polymer units, 2. Molecular and crystal structures of bis[(3‐pentafluorophenoxy)phenyl] 4,4′‐oxydibenzoate and octafluorobiphenyl‐4,4′‐diylbis(oxy‐1,3‐phenylene) dibenzoate
Authors: Lindeman Sergey V. , Struchkov Yury T. , Malichenko Boris F. , Shklover Valerii E. , Vasnev Valerii A. , Kameneva Tatiana M. , Sheludko Evgenii V. 
Published: April 2003

AbstractThis paper discusses the synthesis and X‐ray studied of bis[(3‐pentafluorophenoxy)phenyl] 4,4′‐oxydibenzoate (10) and octafluorobiphenyl‐4,4′‐diylbis(oxy‐1,3‐phenylene) dibenzoate (11). These compounds are differently chosen models of the elementary unit of a polyarylate based on fluorinated bisphenols and aromatic dicarboxylic acids. Structures of 10 and 11 provide data on the conformational flexibility and the predominant was of arrangement of polyarylate chains.
Polymeric phthalocyanines and their precursors, 10. Thermal stability of polymeric phthalocyanines and their low molecular analogues
Authors: Wöhrle Dieter , Schulte Bernd 
Published: April 2003

AbstractThe thermal stabilities of structurally uniform polymeric phthalocyanines 2 and their lowmolecular‐weight model compounds 5 were examined. Thermal analyses under inert and oxidative conditions showed that the nature of the metal as well as that of the substituents and end groups has a decisive influence on the thermal stability. Polymers 2 turned out to be less stable as compared to their low‐molecular‐weight analogues 5. Generally, the stability under inert conditions was found to be higher than under oxidative conditions. For polymer 2b (Mt = Cu) it could be shown that 400°C must not be exceeded during its synthesis, whereas the polymer withstands isothermic temperatures of up to 500°C without decomposition.
Electroinitiated polymerization of p‐diethynylbenzene
Authors: Grovu‐Ivanoiu Maria , Bulacovschi Victor , Simionescu Cristofor I. 
Published: April 2003

AbstractThe electroinitiated anionic polymerization of p‐diethynylbenzene was carried out in various solvents with different solvation capacity using various electrolytes. The latter were classified depending on their efficiency for the polymerization which was found to be in good agreement with polarographic measurements. IR and H NMR spectral analyses of the polymers obtained showed the formation of extended π‐conjugated systems with only one of the two acetylenic bonds having reacted, thus giving soluble products suitable for structural studies.
Formation of the intermediate cyclic six‐membered oxonium ion in the cationic polymerization of β‐propiolactone initiated with CH3CO⊕SbF
Authors: Słomkowski Stanisław , Szymański Ryszard , Hofman Andrzej 
Published: April 2003

AbstractAnalysis of the 1H NMR spectra of \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 3} \mathop {\rm C}\limits^ \oplus {\rm OSbF}_{\rm 6}^ \ominus $\end{document} /β‐propiolactone and of the model systems \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 3} \mathop {\rm C}\limits^ \oplus {\rm OSbF}_{\rm 6}^ \ominus $\end{document}/(CH3)2O and \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 3} \mathop {\rm C}\limits^ \oplus {\rm OSbF}_{\rm 6}^ \ominus $\end{document}/CH3COOCH3 in liquid SO2 in the temperature region −70 to −20°C revealed that the reaction of the acetylium cation with β‐propiolactone leads to the cyclic six‐membered oxonium ion 4, participating as an intermediate in the initial stage of polymerization.
Viscous properties of butadiene/styrene triblock copolymer solutions
Authors: Żuchowska Danuta , Meissner Wanda 
Published: April 2003

AbstractViscosities of dilute and concentrated solutions of a styrene‐butadiene‐styrene triblock copolymer in solvents of different thermodynamic quality and at different temperatures were studied. In 1,4‐dioxane (theta solvent for butadiene blocks) the viscosity derived polymer‐polymer interaction parameter has been found to be much smaller than in decalin (theta solvent for styrene blocks) or in tetralin (good solvent for both blocks). The dynamic viscosity and the enthalpy of activation of viscous flow, ΔH, increase much faster for 1,4‐dioxane solutions with increasing concentration than those for decalin or tetralin. The different properties of solutions in different solvents are discussed in terms of the physical structure of the systems.
Synthesis and characterization of polyamides deriving from 2,2′‐[sulfonylbis(1,4‐phenyleneoxy)]diacetic acid
Authors: Scariah Koonamparampil J. , Krishnamurthy Valadi N. , Rao Kalur V. C. , Srinivasan Mahalingam 
Published: April 2003

AbstractSix semi‐aromatic polyamides (3a–f) were synthesized by low temperature solution polycondensation of aromatic diamines (1a–;f), containing flexible groups such as CH2, CH2CH2, O, S, and SO2, with 2,′2‐[sulfonylbis(1,4‐phenyleneoxy)]‐diacetyl chloride (2) in a solvent mixture of NMP and HMPT (vol. ratio 2 : 1). All the polyamides posses inherent viscosities in the range of 0,31 to 0,73 dl/g. They are soluble in polar amides and DMSO. The molecular weights, molecular weight distributions, thermal stabilities, thermal degradation kinetics and percentages of crystallinity were determined.
Formation of crosslinked polymers in the copolymerization of 9,10‐anthrylenedimethyl dimethacrylate and methyl methacrylate
Authors: Krakovyak Mark , Ananieva Tatiana , Anufrieva Elisaveta 
Published: April 2003

AbstractThe formation of a crosslinked polymer during the copolymerization of mono‐and bifunctional monomers was investigated choosing as an example the free‐radical copolymerization of methyl methacrylate (MMA) and 9,10‐anthrylenedimethyl dimethacrylate (1). The anthracenecontaining crosslinks permit the determination of the topological structure of soluble MMA‐1 copolymers containing bridge bonds. This copolymer is formed first and characterized by a considerable structural heterogeneity. The intrinsic viscosity of the soluble copolymer increases sharply in a certain reaction stage and, at the same time, an insoluble copolymer fraction appears. In the formation of the gel fraction those branched macromolecules which consist of a greater number of linear components and contain a greater number of “pendent” double bonds participate first.
Chain folding in oligo(oxyethylene)s. A study of the C1, C10, C13, C15, C18 and C21 dialkyl ethers of pentatetracontaethylene glycol
Authors: Yeates Stephen G. , Booth Colin 
Published: April 2003

AbstractOligomers of general formulaH(CH2)n(OCH2CH2)45O(CH2)nH, with n in the range 1 to 21, were prepared. Both the oxyethylene and the alkyl blocks are homogeneous. It was shown (by X‐ray scattering, IR spectroscopy and differential scanning calorimetry) that annealed crystalline samples have structures in which the oxyethylene blocks are normal to their end‐group planes and are either once‐folded (n = 18, 21) or unfolded (n = 10, 13, 15). It was also shown that rapidly crystallised samples with n = 10, 13, 15 and 18 have long spacings (by SAXS) intermediate in value between those of the unfolded and once‐folded forms.
Synthesis and polymerization of N‐acryloyl‐ and N‐methacryloylaminomethyl crown ethers
Authors: Nakatsuji Yohji , Furuyoshi Shigeo , Okahara Mitsuo , Takemoto Kiichi 
Published: April 2003

AbstractPolymerizable crown ethers, N‐acryloyl‐ and N‐methacryloyl‐N‐ethylaminomethyl crown ethers (4a,b and 5a, b), were prepared from N‐ethylaminomethyl crown ethers (1 and 2). Their polymerization and copolymerization with styrene afforded the new poly(crown ether)s (6), in which the crown rings are attached to the polymer chain by an amide linkage.
Functional polymers and sequential copolymers by phase transfer catalysis, 20. Synthesis of copolymers and alternating block copolymers containing thermotropic liquid crystalline polyethers and aromatic poly(ether sulfone) segments
Authors: Shaffer Timothy D. , Percec Virgil 
Published: April 2003

AbstractCopolymers and alternating block copolymers were prepared both containing a liquid crystalline (LC) polyether segment, based on 4,4′‐biphenyldiol (3) and 1,5‐dibromopentane (2), and a thermoplastic segment, deriving from an aromatic poly(ether sulfone) (PSU) (1). The alternating block copolymer was prepared by the phase transfer catalyzed (PTC) polyetherification of mesogenic α,ω‐bis(5‐bromopentoxy)polyether (5) with α,ω‐bis(hydroxyphenyl)PSU (1). Copolymers containing mesogenic segments were prepared utilizing α,ω‐bis(hydroxyphenyl)‐PSU as another diphenol in the PTC polyetherification of 5 with 2 and 3. The thermal behavior, as characterized by differential scanning calorimetry (DSC), revealed phase separation for all prepared copolymers as well as liquid crystalline behavior down to a content of mesogenic units deriving from 5 as low as 30 wt.‐%. Optical polarization microscopy, however, revealed significant differences in textures of the copolymers with the textures observed for homopolymer 5. Textures of a 5/PSU blend clearly show phase separation.
Lichtinitiierte polymer‐ und polymerisationsreaktionen, 26. Elektrophile ringöffnungsreaktionen zwischen glycidylethern und ketonen oder aldehyden initiiert durch photoinitiatorsysteme
Authors: Timpe Hans‐Joachim , Merckel Carsten , Baumann Harald 
Published: April 2003

AbstractBy the irradiation of benzoin derivatives in the presence of arene diazonium salts or aryl iodonium salts cationic species are formed, which initiate ring‐opening reactions of 2,3‐epoxy‐propyl (glycidyl) ethers in the presence of ketones or aldehydes. 1,3‐Dioxolane formation dominates over homopolyaddition reactions of glycidyl ethers. This method forms dioxolane in satisfactory preparative yields. The quantum yields of disappearance of phenyl glycidyl ether in acetone (ΦPGE) were measured in dependence of some system parameters. By the photolysis of benzil dimethyl ketal more catalytic species are produced as in the case of benzoin isopropyl ether or α‐phenylbenzoin. The ΦPGE values for diazonium salts are higher than for iodonium salts, with triphenylsulfonium salts the reaction failed. With the anions of iodonium salts the following sequence for ΦPGE is observed: SbF6− > PF6− ≫ SbCl6− = BF4− = 0. Because the key step of the catalyst formation is an electron transfer reaction between radicals produced by the photolysis and the onium ions, the concentration of the salts influences ΦPGE. Phenyl glycidyl ether reacts more rapidly than 2,2‐bis(4‐hydroxyphenyl)trimethylene diglycidyl ether and isobutyl glycidyl ether.
Polymeric phospholipid analogues, 19. Synthesis and polymerization of 10‐(11‐methacryloyloxyundecyloxycarbonyl)decyl 2‐(trimethylammonio)ethyl phosphate
Authors: Furukawa Akio , Nakaya Tadao , Imoto Minoru 
Published: April 2003

Abstract10‐(11‐Methacryloyloxyundecyloxycarbonyl)decyl 2‐(trimethylammonio)ethyl phosphate was prepared, characterized, and polymerized with 2,2′‐azoisobutyronitrile (AIBN). The polymer exhibits liquid crystalline behaviour from room temperature up to ca. 280°C and is soluble in methanol and hot ethanol.
Complexation of alkali‐ and alkaline‐earth cations by poly(oxyethylene)s in methanol
Authors: Buschmann Hans‐Jürgen 
Published: April 2003

AbstractStability constants and thermodynamic values for the reaction of alkali and alkaline‐earth cations with poly(oxyethylene)s in methanol were measured by means of calorimetric titration. The apparent molecular weights of the ligands were determined by means of calorimetric end point titration. This method gives direct information on the composition of the complex formed in solution. The measured stability constants for a given ligand with K+, Rb+, Cs+, and Ba2+ ions are all of the same order of magnitude. Poly(oxyethylene)s with high molecular weight are able to surround cations completely. The reaction enthalpies for the reaction with poly(oxyethylene)s reach higher values as compared to crown ethers. From these data, the bond energies between a complexed cation and a single donor atom of the ligand were calculated for the first time.
New amphipathic lipopeptides, 1. Synthesis and mesomorphic structures of lipopeptides with polysarcosine peptidic chains
Authors: Douy André , Gallot Bernard 
Published: April 2003

AbstractAmphipathic lipopeptides CnSarp with a hydrophobic aliphatic chain, Cn, and a hydrophilic peptidic chain of polysarcosine, Sarp, were synthesized by two methods, a step‐by‐step method and a polymerization method. In the step‐by‐step method, the sarcosine residues are added one by one at the end of a fatty amine (n‐alkylamine, n = 12,14,16,17,18). In the polymerization method, sarcosine N‐carboxyanhydride is polymerized initiated by the amino end of a fatty amine. In concentrated water solution, lipopeptides CnSarp exhibit mesophases whose structure was determined by means of X‐ray diffraction. Three types of mesomorphic structures (lamellar, cylindrical hexagonal, and body‐centred cubic) and two types of polymorphism (one as a function of the length of the peptidic chains, the other as a function of the water content of the mesophases) were established. Furthermore, the respective influence of the factors, governing the type of structure of the mesophases and the values of their geometrical parameters, were analysed.
Metal salt catalysed transesterifications of thioesters and their application to polyester syntheses
Authors: Sasakawa Tomoyoshi , Takasaki Haruhiko , Ikeda Tomiki , Tazuke Shigeo 
Published: April 2003

AbstractThe transesterification of S‐phenyl thiobenzoate with 1‐butanol, catalysed with metal salts, was studied as a model reaction for the polyester synthesis. The metal salts were found to interact with both the alcohol and the thioester. Mn(OCOCH3)2 · 4H2O, the most active catalyst, shows a higher kinetic order as well as a greater temperature dependence than the less active catalyst LiOCOCH3 · 2H2O, whereas the uncatalysed reaction shows the smallest temperature dependence. The application of the catalysts for polyester formation was examined with S,S‐diphenyl 1,4‐benzenedicarbothioate and triethyleneglycol. The molecular weight of the resulting polyester was found to increase with increasing catalytic activity of the metal salt in the corresponding monofunctional model reaction.
Anionic polymerization of fluorine‐containing vinyl monomers, 5. Polymerization of fluoroalkyl acrylates and methacrylates with delocalized carbanionic initiators
Authors: Narita Tadashi , Hagiwara Tokio , Hamana Hiroshi , Yanagisawa Hayato , Akazawa Yoshimi 
Published: April 2003

AbstractAnionic polymerizations of 2,2,2‐trifluoroethyl acrylate (1a), 2,2,2‐trifluoroethyl methacrylate (1b), 2,2,2‐trifluoro‐1‐trifluoromethylethyl acrylate (2a), and 2,2,2‐trifluoro‐1‐trifluoromethylethyl methacrylate (2b) showing low reactivity toward alkyllithium and alkylmagnesium compounds, were examined with several delocalized anionic initiators. 1,1‐Diphenylhexyllithium, disodium salt of living α‐methylstyrene oligomer, and sodium dihydronaphthylide were found to yield the corresponding polymers of 1b and 2b with appreciably high conversions. On the contrary, no polymerization conditions were found to produce polymers of 1a and 2a. The polymerization reactions follow an anionic addition polymerization mechanism, according to the results of 1H NMR and GPC measurements.