bluuebunny/crossref_metadata_2025_split huggingface dataset:
Postirradiation polymerization and ESR studies of γ‐irradiated N‐tert‐butylacrylamide
Authors: Kiliç Soner , Baysal Bahattin M. 
Published: April 2003

AbstractPostirradiation polymerization of γ‐irradiated N‐tert‐butylacrylamide was studied at 80, 85, 90, and 100°C, and the activation energy was found to be 183 kJ · mol−1. By ESR spectroscopy, the half‐life for the second order decay of the irradiated monomer was found to be 13,8 h at 25°C with a decay rate constant of 4,5 · 106 g · mol−1 · h−1. The effect of oxygen and sulfur dioxide on γ‐irradiated N‐tert‐butylacrylamide was also studied. It was observed that oxygen reacts with N‐tert‐butylacrylamide free radicals resulting in a characteristic peroxyl radical spectrum. The signal decays rapidly and disappears in about 100 h. The decay was found to be of second order with a rate constant of 1,3 · 107 g · mol−1 · h−1 and a half‐life of 3,8 h at 25°C. In contrast to the situation with atmospheric oxygen, an appreciable fraction of the free radicals does not react rapidly with sulfur dioxide. The changes in the ESR spectra indicate that at least a large fraction of the original N‐tert‐butylacrylamide radicals, generated in the irradiated sample, react with sulfur dioxide rapidly to give sulfonyl radicals. Their decay is second order with a rate constant of 4,5 · 106 g · mol−1 · h−1 and a half‐life of 8,3 h.
Cationic polymerization of 1‐azabicyclo[4.2.0]octane, 2. Reactivities of ions and ion‐pairs
Authors: Matyjaszewski Krzysztof 
Published: April 2003

AbstractThe cationic ring‐opening polymerization of 1‐azabicyclo[4.2.0]octane (1) was studied with initiators providing small and large anions, namely F⊖, Br⊖, I⊖, picryl(Pic⊖), CF3SO3⊖. In nitrobenzene as solvent the macroions and macroion‐pairs, independently of the anion size, propagate with the same rate constant kp+ = kp± = 7,0 · 10−3 mol−1 · l · S−1 at 35°C ( Δ HP≠ = 55 ± 5kj· mol−1, Δ SP≠ = 105 ± 11 j · mol−1 · K−1). This result strongly indicates that it is not the large size of anoins which is exclusively responsible for the equality kP+ = kP±. The structure of the onium ions, their strong solvation, and the resulting weak interactions with anions are primarily responsible for the observed equalities. In methanol as solvent polymerization proceeds 30 times slowlier than in nitrobenzene and ion‐pairs are more reactive by 40% than ions, in agreement with Enikolopyan's findings.
Structure of active centers and mechanism of the anionic polymerization of lactones
Authors: Hofman Andrej , Słomkowski Stanistaw , Penczek Stanistaw 
Published: April 2003

AbstractThe anionic polymerization of β‐propiolactone (βPL) in DMF initiated with CH3COO−K+ or CH3O−K+ has been found to proceed via the carboxylate ion as growing species. This is valid for all polymerization steps in the former system, starting from the first monomer addition, whereas in the latter CH3O−K+ was found to produce in the initiation reaction both alcoholate and carboxylate anions in almost equal properties. The alcoholate reproduces approximately half of itself in each subsequent step; thus, after a few addition steps all of the active species have become carboxylate ones. The anionic polymerization of ε‐caprolactone (εCL), on the other hand, can only be induced by alcoholates and the growing species are alcoholate anions. Carboxylate anions, even with crowed cations, are inactive as initiators of εCL. These conclusions are based on NMR studies of the end‐groups originating from the initiator and on UV‐VIs studies of the reaction products of the active species with 2,4,6‐trinitroanisole. The difference between the polymerizations of βPL and εCL are explained in terms of ring strain and conformation.
Oligomères amphiphiles obtenus par voie radicalaire, 3. Simulation et contrôle de la synthèse d'oligomères de i'acide acrylique et de i'acrylamide à extrémité thio
Authors: Pichot Christian , Pellicer Raymond , Grossetete Pierre , Guillot Jean 
Published: April 2003

AbstractThe synthesis of amphiphilic oligomers through radical initiated polymerization of hydrophilic monomers in the presence of long hydrocarbon chain thiols as transfer agents was simulated using a model based on a kinetic scheme similar to that proposed by Ikada. Taking into account the solvent as a secondary transfer agent, the weight fractions of different oligomer molecules and the average degrees of polymerization versus conversion were determined as a function of the mole ratio [thiol]/[monomer] and the solvent transfer constant. A relatively good agreement was found between the theoretical and the experimental values for acrylic acid (AA) and acrylamide (Am) oligomerizations. Oligomers terminated by the solvent could complete with thiol‐terminated oligomers. It is interesting that by modifying the simulation model, it is possible to estimate the amount of thiol necessary to keep the composition of the reactant mixture constant during synthesis, thereby eliminating the drift in the oligomer composition at high conversion.
Viscosity behavior of the polyelectrolyte poly(vinyl alcohol) having some intrachain crosslinks
Authors: Ochiai Hiroshi , Kurita Yuji , Murakami Ichiro 
Published: April 2003

AbstractThe viscosity behavior of aqueous poly(vinyl alcohol) (PVA)‐borax‐NaCl systems was investigated. The intrinsic viscosity [η] of PVA in borax solution increases with increasing borax concentration. In solutions containing both borax and NaCl, on the other hand, [η] decreases with increasing concentration of NaCl, and at high NaCl concentration phase separation is observed. In the absence of borax, [η] is nearly independent of the NaCl concentration. These results are interpreted in terms of a limited chain expansion due to charges and intrachain crosslinks simultaneously introduced in the PVA chain when the chain is complexed with negatively charged tetrahedral borate ions. The crosslinking density was estimated from the intrinsic viscosity [η]∞ at infinite ionic strength using the Kuhn and Majer equation.
The crystal structure of α‐TiCl3 and the reticular disorder introduced by ball‐milling
Authors: Gerbasi Rosalba , Marigo Antonio , Martorana Antonino , Zannetti Roberto , Guidetti Gian Pietro , Cojazzi Gianna 
Published: April 2003

AbstractBy X‐ray powder diffraction methods the crystal structures of α‐TiCl3 and of the products obtained by dry ball‐milling activation of this form were studied. TiCl3 microcrystals show initially a structural disorder in the positions of titanium atoms and the successive mechanical activation introduces into the structure some stacking faults, mainly associated to ±60° rotations of the triple layers ClTiCl. The structural investigation has been carried out by an accurate fit of observed X‐ray patterns to those calculated in correspondence of structures containing well‐defined disordered sequences and of likewise well‐defined crystallite sizes. Like γ‐TiCl3 and MgCl2, α‐TiCl3 is very sensitive to mechanical activation, which improves the performances of these three compounds when they are employed as catalysts, or supports for catalysts, in Ziegler‐Natta polymerization processes.
Polymere ammoniumsalze aus N,N,N′,N′‐tetramethylalkylendiaminen und N,N′‐alkylenbis(chloracetamid)en
Authors: Schindlbauer Hellmuth , Gusbeth Helmut 
Published: April 2003

AbstractLong chain polymeric ammonium salts 3a–g and 4a were prepared in DMF/H2O from N,N,N′,N′‐tetramethylalkylenediamines 2a and 2b and N,N′‐alkylenebis(chlorocetamide)s 1a–g. Some of them can be casted to clear transparent sheets. The chlorine atoms in 1a – g are activated by the adjacent carbonyl amino group. The polymer from N,N′‐tetramethylenebis(chloroacetamide) (1d) and N,N,N′,N′‐tetramethylhexamethylenediamine (2b) shows an intrinsic viscosity of 61 ml/g, the highest value known for polyelectrolytes so far. The intrinsic viscosity decreases with increasing numbers of CH2‐groups in the monomers. The polymeric ammonium salts 3a – g and 4a give sheets from DMF solutions, which are soluble in water and stable under normal conditions. Polymers which are best suitable for the preparation of sheets show less hygroscopicity than the others, due to their structure. Intrinsic viscosities were calculated from the reduced specific viscosities measured in 0,4 M KCl but may be also determined in water by the method of Yuan et al., plotting the reduced specific viscosities as a function of 1/√c.
Synthesis of an acryloyl‐type polymer pending D‐glucose analog of N‐acetylmuramyl‐L‐alanyl‐D‐isoglutamine
Authors: Ouchi Tatsuro , Sakamoto Yoshiomi , Jokei Satoshi , Chikashita Hidenori 
Published: April 2003

AbstractPoly{1‐{3‐[O‐1‐(1‐carboxyethylaminocarbonyl)ethyl]‐6‐O‐D‐glucopyranosylcarbonyl}ethylene} (3b) was synthesized as the lipophilic and polymeric model of 1‐{N‐[2‐(2‐acetylamino‐2‐deoxy‐3‐O‐D‐glucopyranosyl)propionyl]‐L‐alanylamino}glutamic acid (1) to the minimum required structure for the eimmunoadjuvant activity of bacterial cell wall. N‐[2‐(6‐O‐acryloyl‐1,2‐O‐isopropylidene‐α‐D‐3‐O‐glucofuranosyl)propionyl]‐L‐alanine benzyl ester (6) was prepared as a key monomer in the synthesis. The homopolymerization of this monomer was carried out in benzene at 50°C using 2, 2′‐azoisobutyronitrile as radical initiator to give polymer 7. From the results of copolymerization with styrene, the values of Q and e for the acryloyl type monomer 6 were estimated to be 2,0 and 0,11, respectively. The removal of isopropylidene and benzyl protecting groups from homopolymer 7 was carried out by acidic treatment with trifluoroacetic acid/water (vol. ratio 6:1) and by catalytic hydrogenolysis with palladium carbon in acetone, respectively, to afford the homopolymer 3b.
Etude du prépolymère époxyde par chromatographie et 1H NMR à 350 mhz, 2
Authors: Gulino Danièle , Galy Jocelyne , Pascault Jean Pierre , Pham Quang Tho 
Published: April 2003

AbstractThe epoxy resins (TGMDA) obtained from 4,4′‐methylenedianilic (2) and 1‐chloro‐2,3‐epoxypropane (epichlorohydrin) were found to consist of oligomers with large distribution of molecular weights and functionalities. The structure of the main components separated by preparative gel permeation chromatography and by high pressure liquid chromatography (HPLC) was studied by 1H NMR. The best separation was obtained by HPLC on a preparected TGMDA with tert‐butyl isocyanate at 60°C. For the impurities, as found with DGEBA prepolymers, we identified primary and secondary alcohol groups on chain ends but also secondary amino groups inside the oligomer chains.
The influence of molecular interaction on polymerization, 8. Copolymerization of monomethyl itaconate with 2‐naphthyl methacrylate
Authors: Boudevska Hrissanta , Todorova Olga 
Published: April 2003

AbstractThe copolymerization of monomethyl itaconate (monomethyl 2‐methylenesuccinate, MMI) with 2‐naphthyl methacrylate (2‐NM) initiated with 2, 2′‐azoisobutyronitrile (AIBN) in solvents of different dielectric constants and capability to form hydrogen bonds was investigated. The reactivity ratios of the monomer pairs in the different solvents are as follows:

IR and 1H NMR spectroscopy studies show the influence of the solvent on the capability of the monomers to form hydrogen bonds and donor‐acceptor associates. The changes in the reactivity ratios of both monomers are attributed to the interaction observed between the monomer molecules as well as between the molecules of the monomers ad the respective solvent.
Préparation de polystyrène de masse éalevée à chaîcne aliphatique ou noyaux aromatiques deuteriés
Authors: Lapp Alain , Beinert Gérard , Picot Claude 
Published: April 2003

AbstractIsotopically substituted styrene, (phenyl‐2H5) styrene (3), and selectively labled styrene, [alpha;, beta;‐2H2] styrene (6), were prepared by the classical two step synthesis, starting with the correspondingly labeled compounds. By anionic polymerization in an inert atmosphere labeled high molecular weight polystyrences 10 and 11 were prepared.
HPLC analysis of cyclo‐oligoamides 6 and 66
Authors: Guaita Cesare 
Published: April 2003

AbstractA new HPLC method for cyclo‐oligoamides 6 and 66 separation is proposed. Using an RP 8 column and an H2O/CF3CH2OH mixtures, all cyclic amides up to the decamer were separated and quantitative results were obtained using an internal standard.
Examples of triphase reactions involving a crosslinked polymer, a solid, and a liquid phase
Authors: Hodge Philip , Khoshdel Ezzatollah , Waterhouse Janette 
Published: April 2003

AbstractSeveral reactions involving crosslinked polymers, a solid, and a liquid phase were investigated. Witting reactions between crosslinked polymers (1 and 5) contaning phosphonium salt residues, solid potassium carbonate, and aldehydes in tetrahydrofuran were found to proceed satisfactorily, even in the absence of a phase transfer catalyst. The Oxidation of 2‐phenyl‐1,2‐propanediol in methylene chloride by solid sodium periodate (but not postassium periodate) is catalysed by the periodate form (9a) of an anion exchange resin. The reaction of 1‐bromooctane in benzene, tetrahydrofuran, or acetonitrile with potassium cyanide or sodium cyanide and of benzyl bromide in tetrahydrofuran or acetonitrile with potassium acetate or sodium acetate are catalysed only slightly, if at all, by the cyanide or acetate forms (9e and 9f) of an anion exchange resin. Crosslinked polymers containing crown ether residues catalyse the reaction of 1‐bromooctane in toluene with sodium iodide. It is not clear how the crosslinked polymers and solid reagents manage to react with each other, but possible mechanisms are discussed. The importance of carrying out control reactions in such studies is stressed.
Functionalized polyionenes, 3. Polyionenes with pendant l‐menthyloxymethyl groups and chiral recognition by means of hydrophobic domains
Authors: Suzuki Yasuzo , Tazuke Shigeo 
Published: April 2003

AbstractTo understand hydrophobic interaction as a function of polymer structure, the binding of 1‐anilino‐8‐napthalenesulfonic acid magnesium salt (ANS) by polyionenes was investigated by means of fluorescence spectroscopy. Three ionenes having ammonium groups in the main chain and pendant l‐menthyloxymethyl (PIPM‐6, OIM‐6)PIPM‐6: poly[(dimethyliminio)hexamethylene(dimethyliminio)methylene‐5‐(l‐menthyloxy‐methyl)‐l,3‐phenylenemethylene dibromide]. OIM‐6: poly[(dimethyliminio)hexamethylene‐(dimethyliminio)‐5‐ethyl‐5‐(l‐menthyloxymethyl)‐2,8‐dioxo‐3,7‐dioxanonamethylene dichloride]. PIA‐6: poly[(dimethyliminio)hexamethylene(dimethyliMINIO)‐5‐(9‐anthryl‐methyl)‐2,8‐dioxo‐3,7‐dioxanonamethylene dichloride].
OR 9‐anthryl groups (PIA‐6) were used together with their model compounds. The emission intensity of aqueous solution of ANS in the presence of PIPM‐6 an OIM‐6 is about 40 and 90 times that in pure water, respectively, indicating that a hydrophobic domain is effeciently formed in water. The corresponding emission increment in the presence of PIA‐6 is only 8 times larger than that in pure water. These results suggest that the hydrophobic domains formed by OIM‐6 and PIPM‐6 are less polar than those formed by PIA‐6 and, consequently, the l‐menthyloxymethyl group is more hydrophobic than the anthryl group. The reduction of viscosity in salt solution runs parallel with the strength of hydrophobic interaction. The emission intensity of dansyl‐D‐phenylalanine is 1,3 times higher than that of dansyl‐L‐phenylalanine in the presence of PIPM‐6. These results indicate that the hydrophobic domains formed by PIPM‐6 have some ability of chiral recognition.
Synthesis and X‐ray photoelectron spectroscopy of poly(α‐ethyl‐α‐methyl‐β‐propiolactone) terminated with a perfluoroalkyl group
Authors: Albert Brigitte , Jérôme Robert , Teyssié Philippe , Pireaux Jean‐Jacques , Verbist Jacques Joseph 
Published: April 2003

AbstractPerfluorinated carboxylates are efficient initiators of the α‐ethyl‐α‐methyl‐β‐propiolactone polymerization resulting in perfluoroalkyl‐terminated polyester. The X‐ray photoelectron spectra of the C8F17‐end‐capped polyester agree with an enrichment in fluorine atoms of the surface layer corresponding to an average number of 7 perfluoro groups per chain or to 36,6 wt.‐% of C8F17‐groups instead of 8,4 wt.‐% as calculated for a random distribution.
Polymeric schiff's base chelates and their precursors, 7. Dioxygen binding and catalytic oxidation of 2,6‐di‐tert‐butylphenol
Authors: Wöhrel Dieter , Bohlen Heike , Aeinger Christa , Pohl Dieter 
Published: April 2003

AbstractDioxygen binding and catalytic oxidation of 2,6‐di‐tert‐butylphenol(9) were investigated by employing various low molecular chelates (1 and 2), covalently or coordinatively bound polymeric chelates (3, 4, 5, 6, and 7), and polymeric Schiff's base chelates (8). Particularly the covalently bound polymeric chelates 3 and 4 were found to exhibit activities similar to low molecular 1 in regard to dioxygen binding. It is suggested that these polymers can reversibly form mononuclear superoxo‐complexes. In the oxidation of 9 the covalently bound polymeric chelates 3 – 5 exhibit good activity which does not decrease after repeated use.
Polymers from renewable sources, 1. Diamines and diisocyanates containing difurylalkane moieties
Authors: Cawse John L. , Stanford John L. , Still Richard H. 
Published: April 2003

AbstractFuran‐based diisocyanates and diamines were prepared unambiguously as potential monomers for polyurethane and polyamide production, starting from methyl furoate and furfurylamine, respectively. The syntheses were optimized and the product identity was confirmed by elemental analysis, IR and NMR spectroscopy, and also by preparation of derivatives which were similarly characterized.
Untersuchungen zur klärung der sensibilisierten photodegradation von polystyrol in lösungen, 2. Energieübertragungsphänomene
Authors: Woliński Leszek , Wilkowski Konrad , Turzyński Zbigniew 
Published: April 2003

AbstractA new approach is presented to explain “the sensitized photodegradation effect”, which was observed in polystyrene solutions irradiated with the light of a mercury lamp of wavelength λ ≥ 270 nm. The radiationless electronic excitation energy transfer from solvent molecules as energy donors to polystyrene (PS) macromolecules is considered to be the main factor influencing the polymer photodegradation rate in solution. Possible mechanisms of the energy transfer are discussed, the total energy transfer rate in eight investigated PS‐solvent systems is evaluated and compared with PS photodegradation rates, determined by light scattering in the first part of this series.
Temperature dependence of the viscosity of dilute poly(N‐vinylcarbazole) solutions in 1,4‐dioxane
Authors: Urizar Mercedes , Rodriguez Matilde , León Luis Manuel , Gonzalez M. Carmen , Zamora Fernando 
Published: April 2003

AbstractThe dependence of the viscosity of dilute solutions of poly(N‐vinylcarbazole) in 1,4‐dioxane on the temperature is studied by Moore's treatment. The numerical values of the constants from this treatment Ke, Kβ, and β indicate that this polymer in 1,4‐dioxane assumes the characteristic behaviour of flexible polymers. The numerical values of the parameters KΘ and B from the Stockmayer‐Fixman plot and the Mark‐Houwink constants K and a are determined and the temperature coefficient of the unperturbed dimensions is evaluated for this system.
Enantioselective hydrolysis of dipeptide amino acid esters by di‐ and tripeptide‐type L‐histidine derivatives in a bilayer vesicular system
Authors: Ohkubo Katsutoshi , Ogata Harumi , Yamaki Kazuhiro , Yamashita Kohichi 
Published: April 2003

AbstractThe enantioselective hydrolysis of dipeptide‐type amino acid esters (Z‐(L)‐Ala‐(L or D)‐Ala‐PNP (5a), Z‐(L)‐Ala‐(L or D)‐Leu‐PNP (5b), and Z‐(L)‐Ala‐(L or D)‐Phe‐PNP (5c)) by di‐ or tri‐peptide nucleophiles (Z‐(L)‐Leu‐(L)‐His (2a), Z‐(L)‐Phe‐(L)‐His (2b), and Z‐(L)‐Leu‐(L)‐His (3)) in the bilayer vesicular aggregates of didodecyldimethylammonium bromide (6) resulted in the enantiomer rate ratio of LL/LD = 1, 1 to 18, the value of which was considerably higher than that (L/D = 1,0 to 4,6) in the hydrolysis of Z‐(L or D)‐Ala‐PNP (4a), Z‐(L or D)‐Leu‐PNP (4b), and Z‐(L or D)‐Phe‐PNP (4c) by the identical vesicular system and that (L/D = 0,7 to 3,1) in the hydrolysis of the dipeptide substrates 5a – c by Z‐(L)‐His (1) and 6. The high enantioselectivity (LL/LD = 18) in the hydrolysis of 5c by the system of 2a and 6 was enhanced to be LL/LD = 36 by lowering the temperature from 25 to 10°C.
Thermodynamische verträglichkeit und wechselwirkungsparameter des systems oligoethylenglycol‐oligopropylenglycol
Authors: Shilov Valeri V. , Gomza Yuri P. , Kovernik Grigori P. , Lipatov Yuri S. 
Published: April 2003

AbstractThe thermodynamics of the binary system oligo(ethylene glycol) (OEG) ‐ oligo(propylene glycol) (OPG) is investigated by lightscattering. The Flory‐Huggins interaction parameter χ12 for this system is determined by the decrease of the OEG melting point in a mixture with OPG. At 310,8 K the system is compatible in the concentration range between 0 and 30 vol.‐% of OPG in the mixture. The analysis of the temperature dependence of χ12 according to the novel Flory theory leads to the assumption that mixing in this system occurs at a lower critical mixing temperature.
The molecular structures of methacrylates with bulky ester substituents, (RS)‐1,2,2,2‐tetraphenylethyl methacrylate and (1S, 2R)‐(+)‐1‐benzyl‐3‐dimethylamino‐2‐methyl‐1‐phenylpropyl methacrylate
Authors: Kageyama Hiroyuki , Yanagisawa Yoshihiko , Kasai Nobutami , Okamoto Yoshio , Yashima Eiji , Takeda Takahiro , Hatada Koichi 
Published: April 2003

AbstractThe molecular structures of (RS)‐1,2,2,2‐tetraphenylethyl methacrylate (TrBzMA) and (1S, 2R)‐(+)‐1‐benzyl‐3‐dimethylamino‐2‐methyl‐1‐phenylpropyl methacrylate (ChMA) were determined by means of X‐ray diffraction: (RS)‐TrBzMA .0,5C6H6; triclinic, space group P1, a = 9,271(2), b = 33,965(4), c = 9,167(2) Å, α = 90,26(2), β = 118,80(2), γ = 88,03(2)°, and Z = 4; ChMA; monoclinic, space group P21, a = 12,482(1), b = 9,184(1), c = 9,246(1) Å, β = 93,49(1)°, and Z = 2. Both structures were solved by the direct method and refined by the block‐diagonal least‐squares procedure to R = 0,054 and 0,057 for non‐zero reflections, respectively. Both of the two crystallographically independent molecules of TrBzMA have the same structure; each molecule has a synperiplanar (sp) conformation as to the CC and CO double bonds about the C(1)C(2) bond and also an sp conformation as to the CO and CO bonds about the C(1)O(1) bond. The ChMA molecule has an antiperiplanar (ap) and a sp conformation about the C(1)C(2) and C(1)O(1) bonds, respectively.