bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymerisation of N‐vinylcarbazole in pyridine using free radical initiators
Authors: Sengupta P. K. , Mukhopadhyay G. 
Published: April 2003

AbstractN‐Vinylcarbazole (NVC) is polymerised in the presence of pyridine at 60°C by using azodiisobutyronitrile (AIBN) and benzoyl peroxide (Bz2O2) as initiators and the results are compared with those obtained when benzene is used as the solvent. In the AIBN‐initiated system using pyridine as the solvent the rates of polymerisation follow an usual linear relationship with respect to monomer concentration and a square root dependence with respect to the initiator concentration. In the Bz2O2‐initiated system, however, deviations from these ideal behaviours are observed when benzene and pyridine, respectively, are used as the solvent. Initiation occurs through the complexation of the monomer with Bz2O2 and degradative transfer is thought to be mainly responsible for this unusual kinetic behaviour.
Effects of photoselection on the kinetics of colour decay in a photochromic spiropyran/poly(alkyl methacrylate) matrix
Authors: Kryszewski M. , Nadolski B. , Imhof R. E. , North A. M. , Pethrick R. A. 
Published: April 2003

AbstractPhotochromic measurements are reported on the decay of the coloured form of 1′,3′,3′‐trimethyl‐6‐nitro[2H‐(1)‐benzospiropyran‐2,2′‐indoline] dispersed in poly(methyl methacrylate) and poly(ethyl methacrylate) matrices. Polarized light was used to photoselect molecules in specific orientations, and the data are analysed in terms of a free volume distribution controlling the kinetic matrix effect. A time correlation function is obtained which characterizes both the rotation and the isomerization of the molecule.
Mathematical properties of polydisperse systems, 4. Calculation of molecular weight distribution from light scattering on gaussian polymer coils. Purely numerical inversion methods
Authors: Greschner Georg S. 
Published: April 2003

AbstractThe molecular weight distribution (MWD) of a high polymer is calculated from a weakly perturbed Zimm‐plot of the classical light scattering on dilute solutions of Gaussian polymer coils (theta state). A typical Zimm‐plot is simulated corresponding to the measurements of high accuracy as would be obtained by using the laser photometer described by Hack and Meyerhoff. The accuracy as published by these authors for small dissymmetries is used. Two inversion procedures are described in detail and tested, both of them avoiding the use of an empirical formula for the Laplace image of the calculated MWD. A complete numerical analysis of the results is given. The results are compared with those of the previous paper.
Application de la réaction de métathèse à la synthèse de prépolymères α,ω‐bifonctionnels, 2. Etude de possibilitiés d'application à la synthèse de prépolymères α,ω‐dichlorés
Authors: Reyx Danièle , Croissandeau Marie‐Christine 
Published: April 2003

AbstractThe capability of chloroalkenes to undergo cometathesis with alkenes was investigated with the intention to check the possibility of applying the principle of the synthesis of α,omega;‐difunctional polybutadienes to α,omega;‐dichloropolybutadienes. The results obtained from the analysis of the reaction products resulting from 1,6‐dichloro‐3‐hexene (1)/4‐octene (2) systems and WCl6/EtAlCl2 were compared with those obtained from 1‐chloro‐3‐hexene (8) alone, 1/1,5‐cyclooctadiène (13), 5‐chloro‐1‐pentene (6)/2, and 1,4‐dichloro‐2‐butene (10)/2 systems in the presence of WCl6/EtAlCl2. It was found that it is possible to apply the synthetic principle to α,omega;‐bis‐(δ‐chloroalkenyl)polybutadienes.
Die Veresterung von p‐kresol und oligo [(hydroxyphenylen)methylen]‐verbindungen mit acrylsäure‐ und propionsäurechlorid
Authors: Kämmerer Hermann , Hegemann Günter , Önder Nurhan 
Published: April 2003

Abstractp‐Cresol and eight oligo[(hydroxyphenylene)methylene] compounds 1b–e and 4a–d could be esterified with good yields with acryloyl chloride or propionyl chloride, respectively, in the presence of triethylamine. The simple and multiple acrylates and propionates were characterized by determination of their molar masses, elemental analyses, hydrogenation of the CC double bonds in the acrylate groups, and by their IR‐ and UV‐spectra. No steric hindrance could be ascertained. Acrylates with more than three phenolic units in their molecules were found to have a range of melting, whereas all the propionates possess sharp melting points. This can be explained by polymerization of the acrylates which proceeds at room temperature without changing the appearance of the sample. The decadic molar absorption coefficients from the UV‐spectra of the different homologous series were found to be proportional to the number of the phenolic units in their molecules.
Asymmetric copolymerization of styrene homologues with oxygen
Authors: Nukui Masahiro , Ohkatsu Yasukazu , Tsuruta Teiji 
Published: April 2003

AbstractStyrene homologues (styrene, α‐methylstyrene, and β‐methylstyrene) were copolymerized with oxygen to produce optically active copolymers in the presence of a chiral Co(II) (Schiffbase) complex. The absolute configuration of the carbon atom in the copolymer chain was determined by hydrogenolysis of the copolymer to phenylethanediol derivatives. In the cases of styrene and α‐methylstyrene, (R)‐(+)‐1‐phenylethanediol and (R)‐(+)‐2‐phenyl‐1,2‐propanediol were preferentially formed, respectively. In the reaction of β‐methylstyrene, the preferential formation of (1S, 2R)‐(−)‐ and/or (1R, 2R)‐(−)‐1‐phenyl‐1,2‐propanediol was observed. The chiral Co(II) (Schiff‐base) complex seems to stabilize both the peroxy‐and the peroxyalkyl radical.
Zur synthese und morphologie von 1,3,5‐trioxan‐blockcopolymeren
Authors: Kloos Friedrich , Sextro Günter , Burg Karlheinz , Cherdron Harald 
Published: April 2003

Abstract1,3,5‐Trioxane and 1,3‐Dioxolane were polymerized in the melt in presence of different polyethylene glycols using BF3‐etherate as catalyst. Thereby the polyethers are incorporated as blocks via a chain transfer reaction with their terminal hydroxyl groups. The addition of the polyethers drastically reduces the rate of polymerization. An investigation of the morphology of the melt‐crystallized block copolymer by visible light microscopy was carried out. It could be shown that, in contrast to homopolymers and blends, not only the normal spherulitic crystallization occurs but also spiral type spherulites are formed. The latter depends on the molar mass of the total polymer and on the amount and chain‐length of the polyether blocks.
Über enzymanalog gebaute polymere, 14. Stereospezifische haftungen über amidbindung oder elektrostatische wechselwirkung
Authors: Sarhan Ali , Wulff Günter 
Published: April 2003

AbstractD‐N‐(4‐vinylphenyl)carbamoylethylenedioxy(4‐vinylphenyl)borane (1) with D‐glyceric acid as template was copolymerized with technical divinylbenzene by a radical mechanism in the presence of various amounts of acetonitrile as an inert solvent. The resulting differences in the structure and swellability of the polymers are discussed in relation to the specificity of the polymers for the racemic resolution of D,L‐glyceric acid. Some of these polymers were found to be able to bind glyceric acid with high optical enrichment by a covalent amide bond. To prevent the formation of the covalent amide bond during the intake reaction, the amide bond in the monomer is replaced by an ion pair relation. For this intention, the synthesis of an appropriate monomer 4‐vinyltrimethylanilinium 2‐(4‐vinylphenyl)‐1,3,2‐dioxaborolan‐4‐carboxylate (2) and the investigation of the resulting polymers are described.
Specific features of styrene polymerization on 1,3‐bis(1‐lithio‐1‐methylhexyl)benzene in the presence of tetrahydrofuran
Authors: Murav'Eva L. S. , Mushina E. A. , Kubasova N. A. , Chernova M. V. , Krentsel B. A. 
Published: April 2003

AbstractBasic feature of styrene polymerization under the action of 1,3‐bis(1‐lithio‐1‐methylhexyl)‐benzene (1) in the presence of tetrahydrofuran were studied. UV spectra of 1 and dilithiumpolystyrene in a benzene solution with an without THF were investigated. A comparison of the results of the UV spectra with the data of cryoscopy and viscometric measurements of “living” and deactivated polystyrene allows the conclusion that polystyrene chains propagating on the dilithium catalyst are in monomeric form.
Block copolymers by radical polymerization 3. Block copolymers of styrene, methyl acrylate, n‐methyl‐n‐vinylacetamide, 1‐vinyl‐2‐pyrrolidone
Authors: Anand Pritt Singh , Stahl Hans George , Heitz Walter , Weber Gerhard , Bottenbruch Ludwig 
Published: April 2003

AbstractA polyazoinitiator obtained from 2,2′‐azoisobutyronitrile (AIBN) and a diol is used to prepare block copolymers according to the Smets procedure. Partial decomposition of the polyazoinitiator in presence of a monomer results in an azogroup‐containing prepolymer. Block copolymers are obtained decomposing the remaining azo groups in presence of a second monomer. Examples investigated are styrene/methyl acrylate, styrene/N‐methyl‐N‐vinylacetamide, methyl acrylate/N‐methyl‐N‐vinylacetamide, 1‐vinyl‐2‐pyrrolidone/acrylonitrile. Homopolymers are produced simultaneously. Up to 70% of block copolymers are formed in these reactions. Block copolymers of styrene/methyl acrylate have hard/soft segmented molecules. It is an elastic material with spherical, cylindrical and lamellar, resp. domain structures, depending on the composition.
Effect of octadecyl 3‐(3,5‐di‐tert‐butyl‐4‐hydroxyphenyl)‐propionate on the course of polystyrene photo‐oxidation initiated by dicumyl peroxide
Authors: Kowal Joanna , Nowakowska Maria 
Published: April 2003

AbstractPhotochemical processes occurring in polystyrene films containing dicumyl peroxide (DCP), in the presence of octadecyl 3‐(3,5‐di‐tert‐butyl‐4‐hydroxyphenyl)propionate (Irganox 1076) were investigated. It was found, that Irganox 1076 reduces the photo‐oxidation and photo‐degradation of polystyrene when DCP is used as an initiator of the processes and polymer samples are irradiated with light of λ = 313 nm in air.
Radical‐initiated curing of unsaturated polyesters with styrene. role of polymer‐bound versus free tertiary amine accelerators
Authors: Jada Sivananda S. 
Published: April 2003

AbstractPolyester prepolymers, prepared from maleic anhydride and diethylene glycol were cured with styrene using benzoyl peroxide as the catalyst and tertiary amines as accelerators. The effect of the accelerators on curing rates and efficiencies and resin properties was studied when the accelerators were chemically incorporated into the polyester prepolymer versus when the same accelerators were free. The accelerators employed were diethylaniline (1); N,N‐bis‐(2‐hydroxyethyl)aniline (2); N,N‐bis(2‐hydroxyethyl)propylamine (3); N,N‐bis(2‐hydroxyethyl)‐isopropylamine (4); N,N‐bis(2‐hydroxyethyl)butylamine (5); and dimethylaniline. The efficiency of the free accelerators decreased in the order dimethylaniline > 1 > 2 > 4 > 3 > 5. Each of the accelerators, 2–5, were significantly more efficient when incorporated into the polymer chain than when they were used free according to measured curing times, pot life, and gel times. Furthermore, the initiation energies for polymer‐bound accelerators 3, 4, and 5 are significantly lower than those obtained when these same accelerators are added free. Polymerbound accelerators 2, 3, 4, and 5 gave resins with higher Brinell's hardness, higher tensile strengths, higher softening points, and lower extractable fractions than were obtained for resins prepared with identical amounts of the corresponding free accelerators. Mechanisms to account for these results are suggested.
Polymere mit phosphor‐stickstoff‐bindungen, 5. Zu reaktion und polymerisation von (NPCI2)3 in gegenwart von elementhalogeniden und borsäureestern
Authors: Horn Hans‐Georg , Kolkmann Friedrich 
Published: April 2003

AbstractHexachlorocyclotriphosphazene (1) reacts with SbCl5 or BCl3 to produce long chain polymers, whereas AlCl 3 gives phosphazenyl cations. TiCl4 does not react and boric acid esters lead to an exchange of one ester group for one chlorine. 31P NMR‐spectra were used to identify the reaction products. The molecular weights of the polymeric compounds were measured.
Änderungen der struktur von flüssing‐kristallinen polymeren mit mesogenen seitengruppen durch temperaturänderung
Authors: Tsukruk Vladimir V. , Shilov Valery V. , Lipatov Yury S. 
Published: April 2003

AbstractPoly(1‐[4‐(4‐alkoxyphenoxycarbonyl)phenoxycarbonyl]‐1‐methylethylene) (1) which exhibits liquid crystalline structures was investigated by X‐ray diffraction. It was found that an increase of the intensity of the low‐angle maxima with increasing temperature is caused by a variation of the dimensions of the liquid crystal regions and their concentration.
Study of polymer compatibilization in solution through polymer/polymer interactions: Ternary systems poly(ethylene oxide)/styrene‐methacrylic acid copolymers/solvent
Authors: Lecourtier Jacqueline , Lafuma Françoise , Quivoron Claude 
Published: April 2003

AbstractIntroduction of about 8 wt.‐% methacrylic acid units in a styrene backbone considerably increases its compatibility with poly(ethylene oxide) in benzene solutions. A Similar, but less important effect, is observed in tetrahydrofuran while no compatibility occurs in chloroform for this copolymer composition. In Order to explain the phase equilibria of these polymer 1/polymer 2/solvent systems, the respective roles of the solvent and of the acid‐ether hydrogen bond were investigated by viscometry and spectroscopy.
Stereoselective solvolyses of amino acid p‐nitrophenyl esters by optically active imidazole‐containing polymers
Authors: Cho Iwhan , Shin Jae‐Sup 
Published: April 2003

AbstractSolvolytic reactions of N‐methoxycarbonyl‐D‐ and L‐phenylalanine p‐nitrophenyl ester (D‐2 and L‐2) by poly(N‐methacryloyl‐L‐histidine) and poly(N‐methacryloyl‐L‐histidine methyl ester) were carried out. However, no significant difference between the solvolytic rates of the two enantiomeric substrates was observed. To investigate the effect of hydrophobic interaction, N‐acetyl‐, N‐pentanoyl‐ and N‐octanoyl‐L‐histidine were prepared and their effect on the ester solvolyses was studied. The rates were generally enhanced as the alkanoyl group became larger. Furthermore N‐octanoyl‐L‐histidine showed some degree of stereoselective catalysis. Accordingly, when polymers with increased hydrophobicity were prepared by copolymerizing N‐methacryloyl‐L‐histidine and its methyl ester with dodecyl methacrylate and were subjected to catalyze the solvolyses of optically active esters, the apparent catalytic rate constant for L‐2 was observed to be 1,3 times larger than that for the D‐2. The enantio‐selectivity became more pronounced as the hydrophobic character of polymer catalysts was enhanced.
Functional polycarbonate by copolymerization of carbon dioxide and epoxide: Synthesis and hydrolysis
Authors: Takanashi Midori , Nomura Yoshihiro , Yoshida Yasuhiko , Inoue Shohei 
Published: April 2003

AbstractPolycarbonates with pendant carbonate groups were synthesized by copolymerization of carbon dioxide and epoxides containing a carbonate substituent using the diethylzinc/water system as catalyst. The polycarbonates underwent acidic and basic hydrolysis to release slowly the compound attached as the pendant group via the carbonate linkage. Other hydrolysis products were glycerol and CO2, but no oligomeric products were formed.
13C NMR sequence analysis, 21. Stereoselectivity of oligopeptide syntheses
Authors: Kricheldorf Hans R. , Mang Thomas 
Published: April 2003

AbstractVarious diastereomeric N‐protected dipeptide methyl esters were synthesized from N‐protected racemic amino acids and racemic amino acid methyl esters. Derivatives of alanine, valine, leucine, and phenylalanine were condensed in various solvents including optically active solvents such as O‐acetyl lactic acid ethyl ester, N‐acetyl lactic acid ethyl ester, or N‐acetyl L‐alanine methyl ester. The N‐protected amino acids were activated by means of 2‐ethoxy‐1‐ethoxycarbonyl‐1,2‐dihydroquinoline (EEDQ), dicyclohexylcarbodiimide and 4‐chlorothiophenol, 1,1‐carbonyldiimidazole, 1‐diethoxyphosphino‐1,3,4‐triazole, chloroacetonitrile, and isobutyl chloroformate. The reaction mixtures containing four stereoisomers were analyzed by means of 13C NMR spectroscopy with respect to the mole ratios of the diastereomeric dipeptides. The stereoselectivity of all experiments was low. The number of experiments favoring the formation of L‐L (D‐D) sequences exceeded by far the number of those favoring L‐D (D‐L) sequences. Tripeptide syntheses, conducted under the reaction conditions of various dipeptide syntheses, revealed that the stereoselectivity is influenced by chiral neighboring groups. However, these “penultimate effects” are not stronger than solvent effects.
The radiation crosslinking of block copolymers of butadiene and styrene
Authors: Basheer Rafil , Dole Malcolm 
Published: April 2003

AbstractBlock copolymers of butadiene and styrene containing 21 and 61 wt.‐% styrene as well as pure polybutadiene have been investigated with respect to the extent of crosslinking produced by the irradiation with 60Co γ‐rays. The free radical yield at 77 K, G(R.), has also been measured. Addition of the styrene blocks to the butadiene chains causes a rapid decrease in both G(X), the G‐value for crosslink formation, and the free radical yield in nearly the same proportion for both, but G(X) is about twice as high as expected if crosslinks arose only from free radical recombination reactions. The effect of the styrene segments in the block copolymers on G(X) is approximately the same as in random copolymers of butadiene and styrene up to 21 wt.‐% styrene compositions.
Preparation and application of ion exchangers with azacrown‐ether and cryptands to alkali and alkaline‐earth cation separation
Authors: Frère Yves , Gramain Philippe 
Published: April 2003

AbstractThree macrocyclic exchangers are prepared and characterized by grafting on chloromethylated styrene‐divinylbenzene resin, one diazacrown‐ether (7,16‐bis(2‐hydroxyethyl)‐1,4,10,13‐tetraoxa‐7,16‐diazacyclooctadecane (1)), one cryptand (21‐(2‐aminoethyl)‐4,7,13,16‐tetraoxa‐1,10,21‐triazabicyclo[8.8.5]tricosane (2b)), and one polymeric cryptand (poly(4,7,13,16‐tetraoxa‐1,10,21,24‐tetraazabicyclo[8.8.8]hexacos‐21,24‐ylene‐2,7‐dihydroxyoctamethylene (3)). Separation of alkali and alkaline‐earth cations is studied by liquid column chromatography with these exchangers in water. The separations occur according to the binding properties of the ligands in solution with an increase of the binding constants in the resin. The resolutions obtained are limited by relatively low capacities of the resins (0,4–0,9 mmol Mn+/g) and mainly by slow diffusion of the cations inside the resins.
Determination of network structure by extraction and random degradation, 1. Theory
Authors: Hoffmann Martin 
Published: April 2003

AbstractThe weight fraction and the molecular mass“Relative molecular mass” (systematic IUPAC name) is shortened to “molecular mass” throughout this paper.
of polymeric material extracted from a polymer network, the time needed for the dissolution of the network during random degradation, and the molecular mass of the high molecular mass degradation products can be utilised for the determination of previously inaccessible structural details of the network, e.g. the value of the molecular mass of network chains, the chain end correction term, the functionality of the crosslinks, and the inhomogeneity of crosslinking, i.e. the amount, the diameter, and the crosslink concentration of anomalously and highly crosslinked regions.
Determination of network structure by extraction and random degradation, 3. Comparison with elastometry and equilibrium swelling
Authors: Hoffmann Martin 
Published: April 2003

AbstractExtraction and random degradation of networks make it possible to determine the molecular mass“Relative molecular mass” (systematic IUPAC name) is shortened to “molecular mass” throughout this paper.
of the network chains, the amount of chain ends, the spatial inhomogeneity of crosslinking, the surprisingly high functionality of the crosslinks, and the efficiency and the transfer of crosslinking radicals. These results are compared with the stress‐strain behaviour at low and high extensions, the stress optical coefficient, and the equilibrium swelling degree. A value of the memory term relative to that of crosslinked melts may be deduced from the swelling degree at a given modulus. With this value an “analytical” modulus may be calculated from the analytical results. It corresponds roughly to the Mooney‐Rivlin modulus if one neglects the influence of functionality, but there remain deviations which suggest that another method should be developed for determining the modulus of the covalent network. The modulus measured at low extensions cannot be used to calculate the crosslink density in weakly crosslinked polymers.
Polymerization of lactams, 51. Heterogeneous hydrolysis of poly(2‐pyrrolidone)
Authors: Roda Jan , Trí H. T. Minh , Zilvar Václav , Šubr Vladimír , Králíček Jaroslav 
Published: April 2003

AbstractThe heterogeneous hydrolysis of poly(2‐pyrrolidone) with 1,1 M and 0,5 M KOH and HCI solutions in the temperature range 30–60°C was investigated. The course of the reaction was characterized by the decrease of weight of insoluble polymer and by the number of split bonds in the chain. The reaction proceeds in two stages different in rate; the possible reasons of the initial higher reaction rate are discussed.
Polymères thiocarboxyliques, 3. Réaction avec les dérivés amines: ammoniac, amines, diamines, amino‐acides, dipeptides, colorants
Authors: Haraoubia Rachid , Bonnans Chantal , Gressier Jean‐Claude , Levesque Guy 
Published: April 2003

AbstractDithiocarboxylic groups as side groups on linear or crosslinked polymers were transformed quantitatively into the corresponding thioamides by ammonia and primary or secondary amines, whereas reaction with 1,2‐diaminoethane led to poly(Δ2‐imidazoline)s. Due to the high reactivity of carboxymethyl diethioesters [(2‐thioacylthio)acetic acid] the fixation of amino acids, dipeptides, and amino dyes on macromolecular chains was realized with high yields.
The cationic polymerization of 2‐alkenylfurans, 2. A side reaction leading to polyunsaturated products
Authors: Alvarez Rubén , Gandini Alessandro , Martínez Ricardo 
Published: April 2003

AbstractA spectroscopic and conductimetric study of the cationic polymerization of 2‐vinylfuran (1) and 2‐methyl‐5‐venylfuran (2) showed the existence of an important side reaction originating from a hydride‐ion shift from an unsaturated polymer molecule to an active species. The resulting allylic carbocation, in equilibrium with a doubly unsaturated polymer molecule, can react further and the repetition of the mechanism on progressively more conjugated species leads to the formation of a series of highly charge‐delocalized carbenium ions absorbing throughout the visible region of the spectrum (and giving high electrical conductivity) and of neutral polyconjugated polymer molecules. Since the hydride‐ion abstraction occurs from the tertiary carbon atom of the vinylic chain, vinylidene polymers of monomers such as 2‐isopropenylfuran (3) and 2‐isopropenyl‐5‐methylfuran (4) are not susceptible to it. Indeed, their cationic polymerization proceeds without colour formation and conductivity increase.