bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oligo(thiophénylènes‐1,4) α,ω‐difonctionnalisés, 4. Effects de la structure sur la miscibilité avec le polyundécanamide. Propriétés des mélanges
Authors: Daccord Gérard , Sillion Bernard , Thibert Cyrille 
Published: April 2003

AbstractFrom several types of polyamides (3, 4, 5, and 6) containing blocs of 2, 4, 6, and 14, 7 thio‐1,4‐phenylene units blends with polyundecanamide (2) were prepared. Their miscibility, thermal properties, mechanical properties, and methane permeability were studied and related to the chemical structure of the additives. The thermal stability of the polyamide was found to be improved for all kinds of blends. The miscibility of the thio‐1,4‐phenylene blocs incorporated into the copolymers is higher than the theoretical prediction for the unmodified blocs. Increasing of Young's modulus and decreasing of methane permeability were observed when the thio‐1,4‐phenylene blocs are partially miscible.
Propriétés physicochimiques d'une série de polystyrènes deutériés en solution dans le tétrahydrofuranne
Authors: Lapp Alain , Strazielle Claude 
Published: April 2003

AbstractThe physicochemical properties of a series of deuterated polystyrenes were investigated in tetrahydrofuran by viscosity, light scattering (LS), on line LS‐GPC, and size exclusion chromatography (GPC). The viscosity laws and unperturbed dimensions of deuterated (PSD) and “hydrogenated” (PSH) polystyrene were compared. There are small but distinct differences in the solution behaviour of PSH and PSD. Some optical properties of partially D‐labelled polystyrenes were investigated.
Studies on the adiabatic polymerisation of acrylamide
Authors: Thomson Ross A. M. , Ong Chin Kee , Rosser Christine M. , Holt John M. 
Published: April 2003

AbstractKinetic parameters, obtained isothermally, have been used in the quantitative description of the polymerisation of acrylamide under virtually adiabatic conditions. The equations which have been derived relate the temperature rise on reaction to the decrease in reactant concentration during the course of reaction, taking account of the various energies of activation and frequency factors involved, whose values may be chosen as required. The approach used has been to find the value of the overall activation energy which gives the best agreement between theoretical and experimental temperature‐time plots. Good agreement has been obtained between these when a value of 74,5 ± 0,9 kJ · mol−1 was chosen for the overall activation energy for the persulfate‐initiated polymerisation of acrylamide using a wide range of initiator and monomer concentrations. This gives a value of 135,5 kJ · mol−1 for the activation energy for the thermal decomposition of the persulfate ion, which is in good agreement with the literature. Interesting implications are discussed in the context of the nature of the product formed during the course of the polymerisation.
Kinetics of the addition reaction of sec‐butyllithium onto bis(1‐phenylvinyl)benzenes
Authors: Leitz Edgar , Höcker Hartwig 
Published: April 2003

AbstractDivinylidene compounds such as bis(1‐phenylvinyl)benzenes not being anionically homopolymerizable add sec‐butyllithium (sBuLi) to form biscarbonionic species. The reaction can be treated as a consecutive addition reaction. For 1,3‐bis(1‐phenylvinyl)benzene the rate constants of the first and second addition step of sBuLi are both 1,98 · 10−2 1/(mol · s); for 1,4‐bis(1‐phenylvinyl)benzene the rate constant for the first step is 2,06 · 10−2 1/(mol · s) and that for the second step is 1,51 · 10−3 1/(mol · s) (in toluene as solvent, with an excess of sBuLi at 20°C). The overall activation energy of the individual steps is 60 kJ/mol, the frequency exponent being between 8 and 9.
Lamellar crystalline structure of star‐shaped block copolymers with an amorphous block of polystyrene and two crystallizable blocks of poly(ethylene oxide)
Authors: Gervais Monique , Gallot Bernard , Jérǒme Robert , Teyssié Philippe 
Published: April 2003

AbstractStar‐shaped block copolymers S(EO)2 with two poly(ethylene oxide) chains (PEO) linked to the same end of a polystyrene chain (PS) exhibit a lamellar liquid crystalline structure, with crystallized and folded PEO chains, in the dry state as well as in the presence of a preferential solvent of the PS block at temperatures below about 50°C. Refolding of the PEO chains was studied in terms of the PS swelling degree and in terms of the PEO content of the copolymers. A difference in length of the PEO chains was suggested, probably resulting from the different nature of the sites that initiate the EO chain polymerization. To investigate the effect of the number of the PEO chains fixed to the PS block, two block copolymers S(EO)2 and SEO of the same relative molecular mass and composition were studied.
Gruneisen parameter for polyamides
Authors: Warfield R. W. , Kayser Eleonore G. , Hartmann Bruce 
Published: April 2003

AbstractFor the five aliphatic polyamides, poly(caprolactam), poly(ω‐aminoundecanoic acid), poly(ω‐aminododecanoic acid), poly(hexamethylene adipamide), and poly(hexamethylene sebacamide), experimental values were obtained of the thermodynamic properties: molar volume, volume thermal expansion coefficient, isothermal bulk modulus, and molar heat capacity. These properties were combined to form the dimensionless ratio known as the Gruneisen parameter. All of the experimental properties were analyzed in terms of molecular components using the method of additive properties. It was concluded that the hydrogen bonding found in polyamides produces a highly localized region of very low Gruneisen parameter.
The solid‐state polymerization, physical properties, and crystal structures of diacetylene mixed crystals
Authors: Enkelmann Volker 
Published: April 2003

AbstractSuitable substituted diacetylenes, 2,4‐hexadiynylene di‐p‐toluenesulfonate (1a) and 2,4‐hexadiynylene di‐p‐fluorobenzenesulfonate (1b), were cocrystallized to form substitutional solid solutions. By solid state polymerization of mixed crystals of 1a and 1b single crystals of the corresponding copolymers were obtained. The polymerization rate can be varied over a wide range by admixture of the comonomer 1b in the lattice of 1a. The crystal structures of monomer 1b and of the corresponding polymer, 2b, were determined. It was found that the packing of the reactive triple bond systems is identical in both monomers. Comonomer 1b acts as a defect site with a high probability of chain termination.
Synthesis of macromolecular antioxidants by reaction of aromatic amines with epoxidized polyisoprenes, 2. Kinetics and mechanism of model reactions
Authors: Jayawardena Shanthilal , Reyx Danièle , Durand Dominique , Pinazzi Christian Pierre 
Published: April 2003

AbstractKinetic and thermodynamic parameters were determined for the reaction of the unsymmetrical oxiranes 3,4‐epoxy‐methylheptane (1) and 1,2‐epoxy‐3‐ethyl‐2‐methylpentane (4) with aniline in o‐dichlorobenzene. A kinetic scheme involving two elementary reactions agrees well with the experimental results obtained for the phenol catalysed reactions. The thermodynamic parameters, especially the entropy, lead to the proposal of a concerted transfer mechanism allowing for the observed normal and abnormal addition reactions.
The propagation rate‐constants for the cationic polymerisation of acenaphthylene and styrene in nitrobenzene
Authors: Holdcroft Geoffrey E. , Plesch Peter H. 
Published: April 2003

AbstractRate measurements of the polymerisation of acenaphthylene in nitrobenzene at 298 K by PhCO+ SbF6− gave kp+ = 23,2 ± 2 dm3 · mol−1 · s−1 which confirmed our previous value with yet another initiator. Under the same conditions we obtained kp+ = 188 ± 9 dm3 · mol−1 · s−1 for styrene. The completeness of initiation was indicated by a count of carbonyl groups by spectroscopy. The conductivity measurements indicated that [Pn+] is independent of time and that there is no ion‐pairing. The DPD of the polymers was unimodal and the DP independent of m0 and c0. Exploratory experiments showed that HClO4 and CF3SO3H in nitrobenzene are not useful for kp+ determinations. In an Appendix a detailed treatment is given of how the impurity content of solvent and monomer can be determined by kinetic measurements.
Cationic polymerization of 1‐azabicyclo[4.2.0]octane, 1 alkylation
Authors: Matyjaszewski Krzysztof 
Published: April 2003

AbstractThe rate constants of the reaction of 1‐azabicyclo[4.2.0]octane (1) with different alkyl esters or halides were measured using 1H NMR and UV spectroscopy as well as conductometric methods. The reactivities of the alkylating agents were found to decrease with increasing nucleophilicity of the derived anions (CF3SO⊖3 > I⊖ > Br⊖ > picryl⊖ > Cl⊖). Reactivities of all ethyl derivatives, except ethyl chloride, are higher than the reactivity of the 1‐alkyl‐1‐azoniabicyclo[4.2.0]octane cation (2), which means that for these compounds the rate constant of initiation is higher than that of propagation. The reactions proceed much slower in methanol than in nitrobenzene due to the strong donor‐acceptor interactions between methanol and 1. Attempts to observe covalent active centers directly by NMR spectroscopy in the polymerization mixture or to detect them kinetically, were unsuccessfull. The reactivity of ethyl triflate, modelling the hypothetical active center, was found to be 2.104 times higher than the reactivity of ions 2. This is ascribed to the high strength of the bond in the cation 2, not sufficiently compensated by the strain of the four‐membered ring.
Investigation of the structure of polymers of the polyphenylene type by 13C NMR spectroscopy
Authors: Urman Yakov G. , Teplyakov Mikhail M. , Alekseeva Swetlana G. , Khotina Irina A. , Slonim Izrael Ya. , Korshak Vasilii V. 
Published: April 2003

AbstractThe structure of a number of polymers of the polyphenylene type, prepared by polycyclocondensation of aromatic diketones and their acetals was investigated by 13C NMR spectroscopy. The spectra provide a means to determine the content of 1,3,5‐trisubstituted benzene rings and defective β‐methylchalcone fragments, as well as the endgroups.
Initiation mechanism of free‐radical polymerization of methyl methacrylate by p‐substituted N, N‐dimethylanilines
Authors: Tsuda Kazuichi , Kondo Shuji , Yamashita Keiji , Ito Kiyohiko 
Published: April 2003

AbstractIn order to investigate the initiation mechanism of the polymerization of MMA by N, N‐dimethylaniline (DMA), p‐substituted DMA's were prepared and used for a kinetic study. Electron donating groups increase and electron withdrawing substituents decrease the over‐all rate of polymerization. Moreover, different kinds of amines were examined as initiators. The results were related with the Hammett equation and the ionization potential of the amines. The solvent effect and the composition of the initiator complex were investigated. From these results, it is concluded that the initiating species is a 1:1 electron transfer complex of DMA with the monomer methyl methacrylate.
Evaluation of kinetic parameters resulting from photostabilized degradation of poly(2,6‐dimethyl‐1,4‐phenylene oxide) films in the absence and presence of zinc bis(O,O′‐diisopropyldithiophosphate)
Authors: Chandra Ramesh 
Published: April 2003

AbstractLight scattering was used to evaluate the resulting changes in molecular weight, root‐mean‐square radius of gyration, degree of polymerization, number of chain scissions per single chain kngth, degree of degradation, specific rate constant, energy of activation, enthalpy, entropy and free energy of activation for the photo‐oxidative degradation of poly(2,6‐dimethyl‐1,4‐phenylene oxide) (poly(oxy‐2,6‐dimethyl‐1,4‐phenylene)) film, both in the presence and absence of 0,1 wt.‐% zinc bis(O,O'‐diisopropyldithiophosphate) (ZnDTP) as photostabilizer, undergoing random chain scission and crosslinking processes in the temperature range 313–363 K with light of wavelength 365 nm. The inhibitive action of ZnDTP was discussed from the viewpoint of the amount of gel fraction.
Investigation of exothermic polymer blends by neutron scattering
Authors: Jelenič Jernej , Kriste Rudolf G. , Oberthür Radulf C. , Schmitt‐Strecker Sigrid , Schmitt Burghard J. 
Published: April 2003

AbstractProvided a polymer is soluble, i. e., molecularly dispersed in another polymer irrespective of the molecular weight of the components, the solution is exothermic. By increasing the temperature two effects, both unfavourable to mixing become larger: (i) the excess entropy of mixing caused by contact interaction and (ii) the total effect from the difference of the free volumes of the pure components. So, an upper miscibility gap occurs. The thermodynamic properties of the mixture cannot be derived from the properties of the pure components. They can be described by the corresponding states theory of Prigogine, Flory, and Patterson with suitable values for the contact energy and contact entropy parameters X12 and Q12. The temperature of separation can be predicted from measurements on the mixture at low temperatures.
Catalytic effects of cationic polymeric liposomes on the alkaline hydrolysis of aniomic phenyl esters
Authors: Kitano Hiromi , Katsukawa Makoto , Ise Norio , Dorn Klaus , Ringsdorf Helmut 
Published: April 2003

AbstractAlkaline hydrolyses of anionic phenyl esters such as 4‐acetoxy‐3‐nitrobenzoic acid and 4‐butyryloxy‐3‐nitrobenzoic acid were examined in the presence of cationic and polymeric liposomes, liposomes of low molecular weight compounds, and micelles. All the additives accelerate the reaction due to the hydrophobic interaction between substrates and additives and the electrostatic interaction both between substrates and additives and between OH− and additives. In the Arrhenius plots of the reactions catalyzed by the liposomes, discontinuous regions were observed due to the phase transition of liposomes from the gel state to the liquid crystal state. Activation parameters ΔH≠, ΔS≠ and ΔV≠ for these reaction systems were evaluated. Both ΔS≠ and ΔV≠ values increase upon the addition of cationic liposomes and micelles. These results were attributed to the desolvation of the activated complex by the strong electrostatic affinity to the cationic colloidal additives.
Etude systématique des «microémulsions;» obtenues avec des copolymères séquencés poly(vinyl‐2 pyridine)/poly(oxyéthylène), 1. Domaine d'existence; Nature et composition des phases continue et dispersée
Authors: Marie Pascal , Gallot Yves 
Published: April 2003

AbstractA systematic investigation of transparent systems (“polymeric microemulsions”), obtained with amphiphilic block copolymers in the presence of water, toluene, and alcohol, was carried out. Their domain of existence in the pseudo‐ternary phase diagram is limited compared to that observed for microemulsions with classical surfactants and located in the vicinity of the miscibility curve of the ternary solvents mixture. From dialysis equilibrium and viscosity measurements, it has been established that, whatever the respective lengths of the sequences are, these stable systems consist of a dispersed “phase” — containing the compolymer molecules — surrounded by an continuous “phase”. Both “phases” are composed of a mixture of the three considered solvents, the continuous phase being constituted by a ternary solvent mixture located on the mutual solubility curve. As a consequence, all water or oil is not trapped within the dispersed particles as in the case of classical micromulsions, but there is a preferential obsorption of the solvents by each type of blocks of the copolymer.
Kinetische untersuchungen zur reaktionsfähighkeit von chlormethylgruppen in methylendiphenolen
Authors: Böhmer Volker , Stein Günter 
Published: April 2003

AbstractThe chloromethyl derivatives of 16 differently substituted methylenediphenols were synthesized for the first time. To compare their reactivity, the solvolysis in methanol and the animolysis with an excess of p‐nitroaniline in dimethyl sulfoxide were studied kinetically at 25°C. The rate constants for the methanolysis do not differ very much, beside of the fact that para‐chloromethyl derivatives react about 100 times faster than ortho‐chloromethyl derivatives. However, for the aminolysis a large acceleration up to 103 was found for compounds having both hydroxyl groups in ortho‐position to the methylene bridge. Obviously, the cleavage of the OH bond, which occurs in the rate determining step of the aminolysis, is strongly favoured by an intramolecular hydrogen bond between the phenolic hydroxyl groups.
Systèmes réactifs polyuréthannes bloqués, 1. Dissociation thérmique en fonction du type d'isocyanate et du type d'agent de blocage. etude par DSC et IRTF
Authors: Phaï Le Thi , Viollaz François , Camberlin Yves , Lam Thanh My , Pascault Jean‐Pierre 
Published: April 2003

AbstractThe preparation of blocked isocyanates and their thermal dissociation into isocyanate and blocking agent was studied by DSC and IR spectroscopy. Thermal deblocking was found to be possible only with isocyanates blocked with ε‐caprolactame or 2‐butanone oxime, but not with β‐ketoesters. With 2‐butanone oxime — the most convenient blocking agent — the dissociation of blocked aromatic isocyanates starts at ≈ 80°C and is fast at 120°C. With blocked aliphatic isocyanates, the temperature of dissociation (Td) is higher (≈ 120°C). Ether or tertiary amines have only a poor catalytic effect on the dissociation, and metal naphthenates have no apparent effect. The thermal and viscosity properties of prepolymers with terminal blocked isocyanate groups were investigated. The molecular interactions decrease in the order 1,4‐phenylene diisocyanate (7) ≫ 4,4′‐methylenediphenylene diisocyanate > trans‐1,4‐cyclohexylene diisocyanate ≈ 2,4‐ and 2,6‐toluene diisocyanate.
Changes in segmental motion of the membrane‐composing molecules of dimyristoyl phosphatidyl choline liposomes by incorporation of polypeptides
Authors: Ohno Hiroyuki , Seki Noriko , Tsuchida Eishun 
Published: April 2003

AbstractThe interaction of glycoprotein and polypeptides with phospholipid liposomes was investigated by means of the fluorescence polarization technique. Poly(L‐glutamic acid) was incorporated into the bilayer of dimyristyol phosphatidyl choline liposomes by sonication. It reduces the segmental motion of the lipids especially in the hydrophobic region close to the hydrophilic surface. On the contrary, poly(L‐leucine), on incorporation into the lipids, strongly suppresses the molecular motion of hydrocarbon chains. Glycoprotein from bovine serum brings about a remarkable decrease in the molecular motion of hydrocarbon chains. In this case the molecular motion of the lipid for liposomes with 20% glycoprotein incorporation is comparable to that of the human erythrocyte ghost. The interaction of polypeptides with liposomes was also observed with an optical microscope by using gaint liposomes (∅︁ ca. 100 μm).
Liquid‐liquid phase separation in multicomponent polymer systems, 21. Deuterium isotope effect in polymer compatibility
Authors: Atkin Elizabeth L. , Kleintjens Ludo A. , Koningsveld Ronald , Fetters Lew J. 
Published: April 2003

AbstractThe spinodal and, hence, the miscibility gap of relatively short chain polystyrene/polybutadiene (PS/PB) mixtures is shifted by 14°C towards higher temperatures, if the hydrogen in PB is replaced by deuterium. The shift corresponds to a difference in the heat of mixing of about 0,2 kJ per mole of styrene units for a 1:1 PS/PB mixture. The effect has been observed by means of Gordon's Pulse Induced Critical Scattering method and the resulting spinodals are found to differ also with respect to the location of their maximum which indicates disparity in the entropy of mixing. For the prediction of the spinodal in a polystyrene/polybutadiene/perdeutereous polybutadiene (PS/PBH/PBD6) system the assumption of non‐athermal mixing in PBH/PBD6 is needed. The value estimated for the PBH/PBD6 interaction parameter involves the second viral coefficient for solutions of PBD6 in PBH to be very close to zero. Expressions are presented for the second virial coefficient in quasiternary systems by scattering methods.
A neutron diffraction study on the doping of polyacetylene by AsF5
Authors: Hässlin Hans W. , Riekel Christian , Menke Klaus , Roth Sigmar 
Published: April 2003

AbstractThe doping of deuterated polyacetylene (cis and trans) with AsF5 was studied by neutron diffractometry. A method of optimize the crystallinity of the doped material is described. Evidence for the presence of two species in the doped polymer which are probably AsF6− and AsF3 is presented. Model calculations based on a series of [CDxH1‐x(AsF5)y]n samples support a “first‐stage” intercalation structure with a graphitic structure.
Polymer synthesis based on 2‐(hydroxyphenyl)‐2‐oxazolines
Authors: Kobayashi Shiro , Mizutani Tsutomu , Saegusa Takeo 
Published: April 2003

Abstract2‐(Hydroxyphenyl)‐2oxazolines(p‐ and n‐isomers 1a and 1b) were used for the synthesis of various polymers. Cationic polymerization of 2‐methyl‐2‐oxazoline initiated with the N‐methyl2‐oxazolinium species 3, Derived from 1, Gave telechelic poly(N‐acetylethylenimine) (5) having a hydroxyl group of different reactivity at both ends. Anionic polymerization of ethylene oxide induced by the lithium salt of 1, 7, produced a poly(ethylene oxide) macromer, 9, having a ringopening polymerizable 2‐oxazoline group. The copolymer from 9 and 2‐phenyl‐2oxazoline, 10, has been shown to have good properties as a nonionic polymeric surfactant in which the N‐benzoylethylenimine main‐chain behaves as a lipophilic group whereas the oxyethylene graftchains act as a hydrophilic group. Di‐salt 11 derived from 1 was polymerized to give polymide 13 (“amphi‐ionic polymerization”).
Syntheses of N‐(4‐substituted phenyl)isocitraconimides and reactivities in their radical copolymerizations with styrene
Authors: Oishi Tsutomu , Maruyama Shoji , Momoi Masaaki , Fujimoto Minoru , Kimura Tadashi 
Published: April 2003

AbstractRadical copolymerizations of isomeric N‐(4‐substituted phenyl)isocitraconimides 7a–f and 9a–f (M1) with styrene (ST) (M2) were performed at 60°C, using 2,2′‐azoisobutyronitrile as initiator in tetrahydrofuran, in order to study the substitutent effect on the copolymerization parameters. From the results, the monomer reactivity rations were determined as r1 = 0,0,81 ≤ r2 = 1,76 in the 7/ST systems, and r1 = 0, 0,27 ≤ r2 ≤ 0,42 in the system 9/ST. It was found that the relative reactivities (1/r2) of 7 toward the polystyrly radical cannot be correlated by the polar‐substituent constant (σ) but by the resonance‐substituent constant (ER) in the modified Hammett equation: log(1/r2) = ρσ + γER. Furthermore, the monomer reactivity ratios considering the influence of the penultimate effect were also determined, and the substituent effect of 7 and 9 was studied according to the above equation.
IR‐und UV‐spektroskopische Eigenschaften einer homologen Reihe von molekulareinheitlichen, 12gliedrige Ringe enthaltenden Leiteroligomeren
Authors: Kämmerer Hermann , Hegemann Günter 
Published: April 2003

AbstractThe reactions of multiple acrylates of oligo[(hydroxyphenylene)methylene] s (2a–2f), strongly diluted in boiling benzene, with 2,2′‐azoisobutyronitrile in a mole ratio of 1:10, were investigated. The elemental analysis and the determination of relative molar masses of the resulting products (3, 4, 5, 6a, 6b, 7a and 7b) demonstrate that their molecules contain two nitrile groups. These data, together with the IR and UV spectra, show that the products are molecularly uniform ladder oligomers with two 1‐cyano‐1‐methylethyl groups on both ends.