bluuebunny/crossref_metadata_2025 huggingface dataset:
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

A 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

The 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

The 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

The 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

The 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

The 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

2‐(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

Radical 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

The 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.
The influence of molecular interaction on polymerization, 9. Copolymerization of 2‐naphthyl methacrylate with acrylonitrile
Authors: Boudevska Hrissanta , Sinigersky Vesselin
Published: April 2003

The copolymerization of 2‐naphthyl methacrylate (2‐NM) with acrylonitrile (AN) initiated by 2,2′‐azoisobutyronitrile (AIBN) was carried out in solvents with different dielectric constants. The relative reactivity ratios of the monomers determined by the Fineman‐Ross method in the solvents used are as follows:

in chloroform: r2‐NM = 0,96 ± 0,05; rAN = 0,00 ± 0,02

in benzene: r2‐NM = 0,84 ± 0,09; rAN = 0,01 ± 0,04

in acetone: r2‐NM = 0,52 ± 0,09; rAN = 0,00 ± 0,02

in acetonitrile: r2‐NM = 0,51 ± 0,06; rAN = 0,00 ± 0,03

The capability of the monomers to form donor‐acceptor associates was shown by means of 1H NMR spectroscopy. The observed interactions between the monomer molecules on one side and between the molecules of the monomers and the solvent on the other side were used to explain the changes in the reactivity ratios of both monomers obtained in different solvents.
Solution behaviour of polyacrylamides in 0,12 M NaCl
Authors: Kulkarni Rajendra A. , Gundiah Subbaraya
Published: April 2003

Seven unfractionated samples of polyacrylamide have been investigated in 0,12 M NaCl by viscosity, osmotic pressure, and light scattering techniques. Viscosity‐molecular weight and 〈,s2〉w‐M̄w relationships have been established and the unperturbed dimensions were estimated from the Stockmayer‐Fixman relationship.
The spontaneous polymerization of methyl methacrylate, 7. External heavy atom effect on the initiation
Authors: Lingnau Jürgen , Meyerhoff Günther
Published: April 2003

A dimeric biradical •M plays a central role in the initiation of the spontancous polymerization of methyl methacrylate (M1). Besides the initiation step by chain transfer reaction, a change of the multiplicity of ˙M seems to be of importance. Evidence is given by heavy atoms in the solvent or in an inert gas atmosphere, leading to an acceleration of the overall polymerization rate. The observed effect is related to the atomic number of the respective heavy atom. Measurements of the temperature dependence of the effect for carbon tetrachloride show that — as expected — no activation energy is needed for this reaction step. The results are summarized in a reaction scheme for the initiation mechanism of the spontaneous polymerization of methyl methacrylate.
Polymer‐linked acycloguanosine
Authors: Rosemeyer Helmut , Seela Frank
Published: April 2003

Polymer‐linked 9‐(2‐hydroxyethoxymethyl)guanine (1) (acycloguanosine, acyclovir®) was prepared. Condensation of 1 with succinic anhydride gave in 77% yield 2‐(9‐guanylmethoxy)‐ethyl hydrogen succinate (2), which was coupled through its carboxylic group either to poly(L‐lysine) (M̄r = 55000) or to N‐(6‐aminohexyl)carbamoylmethylated dextran T80 to yield the polymers 3 and 4 (ligand concentrations in 3: 30 – 48 μmol of 2/g, in 4: 100 – 171 μmol of 2/g). From both polymers the antiviral 1 could be released by controlled saponification; the rate of drug delivery was found to be a function of pH and temperature. The polymeric carrier system 3 was degraded by endo‐dextranase, and the carrier system 4 by trypsin, yielding low‐molecular‐weight derivatives of the pharmacon.
A peculiar temperature‐dependent behavior of iodine species at the formation of chromophore between iodine and aqueous poly(vinyl alcohol)
Authors: Yokota Toshio , Kimura Yoshiharu
Published: April 2003

The blue colored complex between poly(vinyl alcohol) (PVA) and iodine was prepared at 5°C by mixing an aqueous solution of PVA with an aqueous ethanolic solution of iodine containing boric acid. The absorption spectrum of the system shows bands at 226 nm (A), 290 nm (B), 355 nm (C), and 650 nm (D). Their relative absorbances change largely depending on temperature. When the system is gradually warmed, the chromophoric band D decays and the intensity of band A increases. By lowering the temperature again to 5°C the concentration of chromophore increases. It was found that the decay and the re‐formation of the chromophore are reversible in the temperature range 5 to 15°C. Above 15°C, contrarily, hysteresis effects are encountered for the re‐formation. Thus, when the chromophore is re‐formed at 5°C, the spectra shows an isosbestic point at 420 nm, between bands C and D. The dependence on temperature of bands B and C is quite independent from each other, which strongly indicates that the latter band should be assigned to another iodide species than the I−3 ion (band B) and the I− ion (band A). Based on these experimental data a new mechanism is proposed involving the complex ion I−3 · I2 which is supposed to be a precursor of the chromophoric pentaiodide ion I5−.
Macroion‐counterions interactions in dilute aqueous solution of iota‐ and kappa‐carrageenan segments
Authors: Rizzo Roberto , Paradossi Gaio , Crescenzi Vittorio
Published: April 2003

Interactions of counterions with segmented kappa‐ and iota‐carrageenan sulfated polysaccharides were investigated by means of microcalorimetric and potentiometric measurements in dilute aqueous solution. The condensation of counterions onto the charged polymer chains leads, in general, to conformational transitions of the disorder‐to‐order type. A difference in the ability of different pairs of ionic species (monovalent/divalent counterions) to induce conformational transitions of carrageenate salts is demonstrated.
Structure of poly[(ethylene glycol)‐(diethylene glycol) terephthalate] as determined by chemical degradation
Authors: Fakirov Stoyko , Seganov Ilija , Prangowa Lilijana
Published: April 2003

The influence of preliminary thermal treatment and diethylene glycol (DEG) content on the rate of degradation, DEG amount in the degradation products, WAXS, relative viscosity, and density of the understructed poly(ethylene terephthalate) (PET) is studied upon aminolysis with hydrazine hydrate at 60 and 85°C. The results indicate that (i) the aminolysis is a two‐stage process, corresponding to the degradation of the amorphous and crystalline regions and (ii) the phase boundary is not sharp. A model is proposed, describing the comonomer distribution in the semicrystalline copolyesters. The comonomer units are concentrated mainly in the amorphous regions. The effect of degradation conditions like temperature, concentration, duration, particle size, deposition of low molecular products on the polymer surface, etc. is also discussed.
Crystal and molecular structure of a new spiro phosphorane monomer, 7‐oxo‐5‐phenyl‐5λ5‐phospha‐1,4,6‐trioxaspiro[4.4]nonane
Authors: Higuchi Taiichi , Fukuyo Makoto , Saegusa Takeo , Kobayashi Shiro
Published: April 2003

7‐oxo‐5‐phenyl‐5λ‐5‐phospha‐1,4,6‐trioxaspiro[4.4]nonane (3a) (C11H13O4P, monoclinic, P21/n, a = 14,751(2), b = 5,577(1), c = 14,490(3) Å, β = 106,91(2)°, V = 1140,5 Å3, Dx(Z = 4) = 1,398 g · cm−3, MW = 240,20, mp = 80°C) forms hygroscopic white needle‐like crystals. The structure was solved by direct methods and the final R value is 0,068. The geometry around the phosphorus is trigonal bipyramidal with two five‐membered rings in the apical‐equatorial planes. The three P‐O bond lengths are 1,615(5) (equatorial), 1,670(4) and, 1,808(4) Å (apical).
Modification au deuxième degré de polymères époxydés, 2. Addition de l'acide benzoïque sur polyènes époxydés
Authors: Soutif Jean‐Claude , Brosse Jean‐Claude
Published: April 2003

The addition of benzoic acid to the oxirane ring of epoxidized polymers of dienes is limited by side reactions which are promoted by increase of time, temperature, or epoxide concentration. Only high [Acid]/[Epoxide] ratios afford good yields of modification of the epoxidized polymers.
Biologically active polycations, 4. Synthesis and antimicrobial activity of poly(trialkylvinylbenzylammonium chloride)s
Authors: Ikeda Tomiki , Tazuke Shigeo , Suzuki Yasuzo
Published: April 2003

Various poly(trialkyl‐3‐(and 4‐)vinylbenzylammonium chloride)s were prepared and their antibacterial activities were assessed by the conventional spread plate method and the viable counting method. They are in general more active against Gram‐positive bacteria such as Bacillus subtilis and Staphylococcus aureus than against Gram‐negative bacteria such as Escherichia coli, Aerobacter aerogenes and Pseudomonas aeruginosa. Compounds with the longest alkyl chain studied (dodecyl) were found to exhibit particularly high activity, and this was ascribed to the contribution of the increased hydrophobicity of the compounds to the activity. The most significant finding was that the polymers was discussed and interpreted in terms of their greater contribution to each elementary process in the cidal action: their favored adsorption onto the bacterial cell surface and the cytoplasmic membrane with subsequent disruption of its integrity.
The molecular structures of (RS)‐1,2‐diphenylethyl methacrylate and (RS)‐α‐tert‐butylbenzyl methacrylate
Authors: Kageyama Hiroyuki , Miki Kunio , Kasai Nobutami , Okamoto Yoshio , Yashima Eiji , Hatada Koichi , Yuki Heimei
Published: April 2003

The molecular structures of (RS)‐1,2‐diphenylethyl methacrylate (DPEMA) and (RS)‐α‐tert‐butylbenzyl methacrylate (t‐BBMA) were determined by means of X‐ray diffraction. Crystals of (RS)‐DPEMA are monoclinic, space group C2/c, a = 33,341(3), b = 5,916(1), c = 15,911(2) Å, β = 106,42(1)°, and Z = 8. Crystals of (RS)‐t‐BBMA are also monoclinic, space group P21/c, a = 6,028(1), b = 31,009(3), c = 15,207(1) Å, β = 96,780(8)°, and Z = 8. Both structures were solved by the direct method and refined by the block‐diagonal least‐squares procedure: DPEMA, R = 0,113 for 1 100 observed reflections and t‐BBMA, R = 0,081 for 2206 non‐zero reflections, respectively. The molecule of DPEMA has an antiperiplanar conformation as to the CC and CO double bonds about the C(1)C(2) bond, a synperiplanar conformation as to the CO and CO bond about the C(1)O(1) bond, and an anticlinal conformation about the O(1)C(5) bond. One of the two t‐BBMA molecules in an asymmetric unit has an antiperiplanar conformation as to the CC and CO double bonds about the C(1)C(2) bond, whereas the other antiperiplanar molecule may contain some synperiplanar conformation. Both molecules have a synperiplanar conformation as to the CO and CO bonds about the C(1)O(1) bond and an anticlinal conformation about the O(1)C(5).
Solution behaviour of hydrolysed polyacrylamides in 0,12 M NaCl
Authors: Kulkarni Rajendra A. , Gundiah Subbaraya
Published: April 2003

Six unfractionated samples of polyacrylamide were hydrolysed to varying extents. The partially hydrolysed polyacrylamides were investigated by viscosity, osmatic pressure and light scattering techniques in 0,12 M NaCl. The molecular weights of the hydrolysed polyacrylamides confirmed the absence of main chain degradation during hydrolysis. Intrinsic viscosities and dimensions increased with increasing extent of hydrolysis. On correlating the intrinisic viscosities with the extent of hydrolysis, a linear relationship between intrinsic viscosities and the square root of the extent of hydrolysis was obtained.
Expansion coefficients of hydrolysed polyacrylamides from light scattering measurements
Authors: Kulkarni Rajendra A. , Gundiah Subbaraya
Published: April 2003

The dimensions of partially hydrolysed polyacrylamides with varying molecular weights and extents of hydrolysis determined by light scattering were used to verify the relative applicability of the various macroion expansion theories. Expansions attributable solely to the presence of electrostatic charges were evaluated with references to the dimensions of the polyacrylamides used for hydrolysis. Total expansions and expansions due to long‐range interactions were evaluated with reference to the estimated unperturbed dimensions of the strating polyacrylamides and the hydrolysed polyacrylamide samples, respectively. The expansion coefficients obtained from light scattering measurements were higher than those evaluated from intrinsic viscosities. The differences were maximum (30 – 100%) for the total expansion coefficients. Considering the variation of the Flory viscosity constant Φ with molecular weight and charge density, these differences were ascribed to the uncertainty in the applicability of the light scattering method for the determination of the dimensions of polyelectrolytes. However, the variation of the expansion coefficients with the extent of hydrolysis and molecular weight were similar to those of the expansion coefficients obtained from viscosity measurements. The total expansion coefficient was qualitatively in confirmity with the theory of Chien and Ishihara with reference to its dependence on charge density.
Quantitative structural analysis of graft copolymers by light scattering measurements in mixed solvents
Authors: Kuhn Rainker
Published: April 2003

Theoretical calculations have shown that it should be possible to determine the molar mass of the grafted chains of graft copolymers by light scattering measurements in suitable mixed solvents, and moreover, that this should be possible without the backbone having to be degraded, without the ungrafted backbone having to be isolated, and without the refractive index increment having to be determined after dialysis. Among the conditions that have to be met are the requirements that the mixed solvent must be isorefractive with respect to the backbone and that the preferential solvation of the grafted chains must be independent of their molar mass. The method is applied to fractions of graft copolymers with styrene or styreneacrylonitrile (SAN) being grafted onto ethylene/vinyl acetate copolymers, from which ungrafted polystyrene or SAN copolymer has been removed by solvent demixing. With this method the molar mass and the number of grafted chains, the coupling of backbone molecules via grafted chains, the shrinking and segregation of the individual grafted chains and the incompatibility of the grafted chains with the backbone polymer can be determined.
Morphology, crystallization, and thermal behaviour of isotactic polypropylene/low density polyethylene blends
Authors: Martuscelli Ezio , Pracella Mariano , Volpe Gaetano Della , Greco Pietro
Published: April 2003

The morphology, the crystallization and thermal behaviour of isotactic polypropylene (IPP) in its blends with two different samples of low density polyethylene (LDPE) was investigated at temperatures high enough to prevent any solidification of LDPE. It is found that pre‐existing liquid LDPE domains are incorporated in intra‐spherulitic regions during the isothermal crystallization of iPP. The radial growth rate of spherulites is almost unaffected by the LDPE content. The overall rate of crystallization of iPP, on the contrary, is strongly depressed by the addtion of LDPE. A depression of the equilibrium melting temperature of iPP, due to kinetic and morphological effects, is also observed. The depression of the overal kinetic rate constant is accounted for by the negative effect (decrease in the number of nuclei) that the addition of LDPE has on the primary nucleation process of iPP.
Dynamic viscoelasticity of polyacetylene during oxidation
Authors: Chen Show‐An , Li Liang‐Shun
Published: April 2003

Dynamic viscoelasticity measurements at 90°C suggest an oxidation process for pristine polyacetylenes (PA's). For cis‐rich PA, the oxidation can be divided into three regions: surface oxidation, bulk oxidation, and crosslinking. Crosslinking also occurs at the end of the surface oxidation period but does not occur in the bulk reaction period. For trans‐rich PA, oxygen doping was complete after the first 15 min and occurred to a smaller extent than that of the cis‐rich PA. The rate of reaction of trans PA chains with oxygen is slow in comparision to that of crosslinking by radical combination or addition reactions with the PA chains. In the case of trans PA the concentration of radical chains formed by reaction with oxygen retains a steady value after the initial period up to the end of oxidation.
Hydroperoxydation primaire de terpolymères d'éthylène/propylène/éthylidene‐5 norbornène‐2
Authors: Coiffier Francis , Arnaud René , Lemaire Jacques
Published: April 2003

Ethylene/propylene/5‐ethylidene‐2‐norbornene terpolymers (1) are very sensitive to photooxidation. In the early stages, hydroperoxidation occurs specifically at the carbon atom in α‐position to the ethylidene group. Isolated and hydrogen‐bonded hydroperoxides can be detected by IR spectrophotometry at 3550 and 3380 cm−1, respectively. In post‐thermolysis experiments at temperatures above 60°C the associated hydroperoxides were found to be less stable than the isolated hydroperoxides. Saturation of the ethylidene groups is concomitant with the decomposition of associated hydroperoxides, which are transformed thermally and photochemically into alcohols and cyclic saturated ketones. The lack of vinyl groups shows that hydroperoxidation proceeds only at the norbornene cycle.
Caractérisation texturale par thermoporométrie, à l'état gonflé par l'eau, de résines échangeuses d'anions
Authors: Quinson Jean‐François , Brun Maurice , Spitz Roger , Bartholin Michel
Published: April 2003

Thermoporometry is used to determine the size and the volume of the cavities of anion exchange resins swollen in water. The conditions of the application of thermoporometry are different of those met with non‐functionalised resins. An important fraction of the water remains bond to the polymer and does not change its state when cooling. Nevertheless, it is possible to deduce from the freezing of the non‐bound water the geometrical characteristics of the cavities of the resin which determine the fluid inside circulation. In most cases it is possible to confirm the pore size distribution by nitrogen adsorption and mercury porosimetry on resins partly swollen with water.
The influence of the valence state of titanium in MgCl2‐supported titanium catalysts on olefin polymerization
Authors: Kashiwa Norio , Yoshitake Junichi
Published: April 2003

The relationships between the valence state of titanium in MgCl2‐supported titanium catalysts and polymerization performances for ethylene and propylene were studied. When the titanium species of the supported titanium catalyst 1 was preliminarily reduced by treating it with AlEt3, the resulting catalyst system 2 had lost the activity for propylene polymerization completely. The catalyst activity for ethylene polymerization was found to be reduced to 20% of that of the original catalyst 1. In the AlEt3‐pretreated catalyst 2 no Ti4+ is found and 80% of the total titanium is present as Ti2+. The catalyst system 2 plus AlEt3, however, does exhibit activity towards ethylene‐propylene copolymerization, propylene insertion being possible if the end of the growing polymer chain is an ethylene unit. The titanium in the AlEt3‐reduced catalyst 2 could be oxidized again by treatment with various agents. The oxidized catalysts 3, in conjunction with freshly added AlEt3 as cocatalyst, are active for propylene polymerization and show increased activity for ethylene polymerization in relation to the extent of oxidation.
Polymerization of methyl methacrylate initiated by manganese(III) acetate
Authors: Reddy A. Venkatarami , Rao A. Kameswara
Published: April 2003

The kinetics of thermal polymerization of methyl methacrylate (MMA) initiated by manganese(III) in sulfuric acid is studied in the temperature range between 40 and 607deg;C. The rate of monomer consumption is found to be dependent on [MMA]2, [H+]−1 but independent of [Mn3+]. The rate of manganic ion consumption is directly proportional to [MMA], [Mn3+] and inversely proportional to [H+]. The chain length is directly proportional to [MMA] and inversely proportional to [Mn3+] and [H+]. A plausible reaction mechanism with initiation by Mn3+ OH− species and termination by the interaction of Mn3+ with the polymer radical is proposed.
Microdomain structure of poly(styrene‐4‐vinylpyridine) diblock copolymers
Authors: Ishizu Koji , Inagaki Katsumi , Bessho Keiichi , Fukutomi Takashi
Published: April 2003

A series of AB and BAB type poly(styrene‐4‐vinylpyridine) diblock copolymers with a sharp distribution of molecular weights were synthesized to study relationships between the molecular weight and domain size of lamellar and spherical microdomains. The domain sizes of diblock copolymer specimens cast from chloroform or 1,1,2‐trichloroethane were estimated from transmission electron micrographs. As a result, the lameller domain spacings, predicted from Halfand's theory, agree well with the experimental results. The radius of spherical domains is far below the theoretical values predicted from Helfand's theory, though.
The interaction of comonomers in the solution copolymerization of N, N‐dimethyl‐2‐aminoethyl methacrylate with methacrylic acid
Authors: Lokaj Jan , Doskočilová Danica , Hrabák František
Published: April 2003

The copolymerization parameters of N,N‐dimethyl‐2‐aminoethyl methacrylate (DAMA) with methacrylic acid (MAA) were determined at 50°C in benzene, dimethylformamide, and pyridine solutions. The Alfrey‐Price constants e and Q of the two monomers were determined by copolymerization of DAMA and MAA with styrene in the same solvents. Using these constants, the copolymerization diagrams of the pair DAMA‐MAA were calculated and compared with the experimentally determined ones. The mutual interaction between the comonomers is discussed.
Mikrokalorimetrische untersuchungen der enthalpischen wechselwirkungen von polymethylmethacrylaten verschiedener taktizität in lösung
Authors: Killmann Erwin , Graun Karl
Published: April 2003

Enthalpies of dilution, dissolution, and complex formation of atactic and tactic poly(methyl methacrylate)s (PMMA) were measured at 30°C with a heat flux microcalorimeter of TianCalvet. The enthalpies of dilution in 4‐methyl‐2‐pentanone, toluene, and carbon tetrachloride are positive (endothermic). Because of different mutual interactions between the solvent molecules and the polymer segments they are dependent on the polarity of the solvent, on the concentration, the molar mass and the tacticity of PMMA, and on the temperature and time of annealing. The solution enthalpies are negative due to the enthalpy of the amorphous state of the polymer. They are also influenced by the parameters just mentioned and by the pretreatment of the PMMA probes. The exothermic stereocomplex formation between the iso‐and syndiotactic triads can be determind quantitatively by the enthalpies of mixing of iso‐ and syndiotactic PMMA‐samples. The enthalpy of complex formation is related to the mass of the isotactic triads and increases with growing excess of the syndiotactic triads in the sense of a completion of the complex formation of the isotactic triads.
Polyene sequence distribution in modified poly(vinyl chloride) after thermal degradation
Authors: Martinez Gerardo , Mijangos Carmen , Millan José‐Luis , Gerrard Donald L. , Maddams William F.
Published: April 2003

The products resulting from the reaction of PVC with sodium benzenethiolate were degraded to 0,3% at 180°C in the solid state and at 160°C in solution in trichlorobenzene. The polyene distribution of the polymers after degradation was studied by both UV‐visible and resonance Raman spectroscopies, as a function of the degree of substitution. The results show that there are two types of behaviour: that of the PVC sample prior to the substitution reaction together with the samples modified up to a definite degree of substitution which depends on the starting isotactic content, and that of samples with higher degrees of substitution. The former group exhibits not only a steady improvement in thermal stability but also a preferential formation of polyenes of 7 – 9 double bonds whose concentration decreases with increasing degree of substitution. Conversely, for the second group of samples the thermal stability decreases with the degree of substitution and no specific absorption bands are observed. On the basis of earlier work on the selective substitution of the isotactic GTTG and heterotactic TTTG triads during the first stage of the reaction, the present results show that the bands at 393, 416, and 437 nm are related to specific polyenes which result from initiation by the above quoted conformations in PVC, a conclusion for which confirmatory evidence was obtained by resonance Raman spectroscopic examination of the samples. There is, therefore, clear evidence for the occurrence of two distinct degradation mechanisms, one involving initiation by the unstable triad conformations and the other via random initiation at stable and normal structures. To this may be added the initiation by defect structures, which have been extensively documented in the literature.
Electrochemical preparation and characterization of poly(2,5‐thiophenediyl)
Authors: Tanaka Susumu , Sato Masa‐aki , Kaeriyama Kyoji
Published: April 2003

A highly conductive poly(2,5‐thiophenydily) film was obtained when thiophene was electrochemically polymerized at 5°C in nitrobenzene with Bu4NBF4 or Bu4NClO4 as a supporting electrolyte. A platinum plate or indium oxide glass was used as an electrode. The current efficiency was 62%. The IR, UV, and ESR spectra were compared with those of a poly(2,5‐thiophenediyl) obtained from 2,5‐dibromothiophene by polycondensation. The electrochemically prepared poly(2,5‐thiophenediyl) was identified by its IR spectrum. In its UV spectrum, two bands are observed at 440 nm and 740 nm. The band at 740 nm disappears in an undoped film of poly(2,5‐thiophenediyl), which resembles that of the polymer obtained by polycondensation. The ESR spectra were also measured for undoped and partly undoped films. The undoped film shows an asymmetrical signal, Whereas the signal of the polymer resulting from polycondensation is symmetrical. In the air the conductivity decreases by a factor of 10−2 of the initial value in about 70 days, but an undoped film is quite stable. The undoped film can be re‐doped with iodine or sulfur trioxide and attains higher conductivity than the pellets of polymers obtained by polycondensation. This may be attributed to the difference in morphology.
Stereospecific polymerization of methylthiirane in homogeneous phase, 1. Oligomerization step and change in stereocontrol with molecular weight
Authors: Dumas Philippe , Sigwalt Pierre , Guérin Philippe
Published: April 2003

The polymerization of methylthiirane in homogeneous phase initiated by bis(isopropylcysteinato)cadmium is a living process. For low conversions, oligomers (essentially heptamers and octamers) are formed, apparently using one valency of cadmium, the main propagation taking place by using the other one. However, the size of the oligomers may still grow for higher conversions. The mechanism of the oligomer formation depends on the temperature. A “normal” insertion of the monomer is observed at −23°C, whereas at 20°C a disulfide bond is formed. The preferential choice of a different enantiomer in the main propagation reaction may depend on the presence of a particular type of oligomer, in the vicinity of cadmium, linked to the cysteine group. However, stereospecificity (stereoselection and stereoelection) appears only with molecular weights higher than 6000 and also depends on the temperature of propagation: with decreasing temperature, the stereoregularity increases and the stereoelection can be inverted (for a definite oligomer structure).
Segmented block copolymer models of uniform chain length and defined structure, 1. Synthesis and characterization
Authors: Seliger Hartmut , Bitar Mohammed Bassam , Nguyen‐Trong Hao , Marx Alexander , Roberts Rolf , Krüger Jan‐Kristian , Unruh Hans‐Günther
Published: April 2003

Segmented block copolymer models of defined structure with molecular weights up to ca. 4000 were synthesized by specific condensation of monofunctional derivatives of oligo condensation products of 4,4′‐isopropylidenediphenol (Bisphenol A) with terephthalic acid and oligomethylenes of uniform chain length. The oligo(arylester) blocks were prepared by stepwise addition of oxyterephthaloyloxy‐1,4‐phenyleneisopropylidene‐1,4‐phenylene units using a suitable protection and activation scheme. Similarly, oligo(arylester)s containing isophthaloyl and phthaloyl units were obtained. Telechelic oligomethylene segments were prepared analogously by combining functional derivatives of decane. All compounds were characterized by chemical, spectroscopic, and chromatographic methods.
Super fast polymerization under high pressure and plastic flow
Authors: Enikolopian Nikolay S.
Published: April 2003

Simultaneous action of high pressure and shear deformation on various organic compounds is studied using an apparatus of Bridgeman anvil type. This apparatus allows to work in a temperature range from −196°C to 200°C at different shear forces. It is established that under these conditions the investigated materials are in the plastic flow state. Chemical transformations of more than 300 organic compounds of different chemical classes are observed. Reactions such as polymerization, polycondensation, polyaddition etc. are realized under plastic flow. In addition, copolymerization reactions with the formation of random copolymers occur for some substances. Kinetic peculiarities of the polymerization process under plastic flow are investigated on the example of acrylamide.
Complexation between quaternary ammonium salts and high molecular weight poly(ethylene oxide)
Authors: Bortel Edgar , Kochanowski Andrzej
Published: April 2003

Complexation between tetrabutylammonium bromide, or oligomeric tetramethyl‐2,6‐ionene bromide (1), and high molecular weight poly(ethylene oxide) (PEO) was studied viscometrically, using the following media as solvents: water; 0,1 M aq. KCl; 2 M aq. KCl and 0,1 M aq. HCl. It was found that tetrabutylammonium bromide as well as the ionene 1 convert the initially linear ηred vs. cPOE relationships into bent and hunchbacked curves, thus suggesting the formation of water soluble complexes. In aqueous KCl and HCl solutions these complexes behave as typical polyelectrolytes. Contrary to cations of alkali metals, however, protons do not influence the linear ηred vs. cPOE relation, so that it is possible to determine intrinsic viscosities by use of 0,1 M aq. HCl as solvent. These viscosities are rising if the complexation between POE and ammonium salt is accomplished by the polyfunctional ionene. The increase of [η] depends on the unit mole ratio (u.m.r.) of the ionene to POE. With increasing unit mole ratio from 0 to 7 [η] increases from 9 up to 21 dl · g−1. In water the complexation between one unit mole of POE and two unit moles of ionene 1 causes an increase of the reduced viscosity ηred from 11,2 up to 80,2 dl · g−1.
Solution properties of a polydiacetylene with pyridine substituents. Formation of pyridinium salts and complexes with transition metal salts in solution
Authors: Tieke Bernd
Published: April 2003

The solution properties of polymeric 10,12‐pentacosadinyl 4‐pyridinecarboxylate (polymer 1), obtained by UV‐ or γ‐ray initiated solid state polymerization, are described, as studied by UV/VIS‐ and 13C‐NMR spectroscopy, and by viscosity measurements. Treatment of the polymer solution with non‐solvents of the polymer, protic acids, or transition metal halides induces a colour change from yellow to red, accompanied by a protonation or metal complex formation of the pyridine substituent groups, respectively. Reverse colour changes occur, if bases (e.g. triethylamine) or complexing agents, able to form metal complexes more stable than those of the polymer (e.g. 2,2′‐bipyridine), are added to the red polymer solutions. The origin of the colour changes and the structures of the protonated polymer and of the polymer‐metal complexes are discussed.
Metal‐containing initiator systems, 34. Polymerization of vinyl monomers initiated by the binary system cobaltocene/bis(ethyl acetoacetato)copper (II)
Authors: Mun Yang‐Un , Sato Tsuneyuki , Otsu Takayuki
Published: April 2003

The effect of some metallocenes such as ferrocene (Fe(C5H5)2), nickelocene (Ni(C5H5)2), and cobaltocene (Co(C5H5)2), on the vinyl polymerization initiated with bis(ethyl acetoacetato)‐copper(II) (Cu(eacac)2) was investigated. Co(C5H5)2 was found to exert a markedly accelerating effect on the polymerization of methyl methacrylate (MMA) with Cu(eacac)2. The polymerization of MMA with the system Co(C5H5)2/Cu(eacac)2 at 50°C was found to be fairly affected by the solvent used. The results of copolymerization of MMA with styrene (St) and the effect of hydroquinone (HQ) on the polymerization of MMA with Co(C5H5)2/Cu(eacac)2 showed that the polymerization proceeds via a radical mechanism. The polymerization of MMA with Co(C5H5)2/Cu(eacac)2 was studied kinetically in acetone. The overall activation energy of the polymerization was calculated to be 86,3 kJ/mol (20,6 kcal/mol). This value was somewhat higher than that (17,6 kcal/mol) obtained for the polymerization of MMA with Cu(eacac)2 alone. The polymerization rate (Rp) is represented by the following equation: Rp = k[Co(C5H5)2]0,5 [Cu(eacac)2]0,2 [MMA]1,3. The high order in monomer concentration suggests a participation of the monomer in the initiation process of this polymerization. This is supported by the examination of the ESR spectrum of the system Co(C5H5)2/Cu(eacac)2/MMA/acetone, where reduction of Cu(II) to Cu(I) occurs. To elucidate the initiation mechanism, the spin trapping technique was applied to the system Co(C5H5)2/Cu(eacac)2/methyl acrylate. From these results, an initiation mechanism for the binary initiator system Co(C5H5)2/Cu(eacac)2 is proposed and discussed.
Metal‐containing initiator systems, 35. Synthesis of block copolymers by using the binary initiator system cobaltocene/bis(ethyl acetoacetato)copper(II)
Authors: Mun Yan‐Un , Sato Tsuneyuki , Otsu Takayuki
Published: April 2003

Polymerization of methyl methacrylate (MMA) with the binary initiator system cobalt‐ocene (Co(C5H5)2)/bis(ethyl acetoacetato)copper(II)(Cu(eacac)2), was studied kinetically at 25°C in acetonitrile. The relationship between yield and molecular weight of the resulting poly(MMA) was suggestive of a living polymerization character in this system. The synthesis of block copolymers of MMA with styrene (St) was attempted by adding St as the second monomer to the polymerization system of MMA. The block copolymer was formed in a yield of 20% when MMA was polymerized for 1 day, while the yield went up to 80% when the MMA polymerization was carried out for 3 days. The resulting block copolymer was characterized by IR spectroscopy and gel‐permeation chromatography.
Polyarylenealkenylenes and polyheteroarylenealkenylenes, 16. Syntheses and electrical conductivities of poly[(alkoxy‐1,4‐phenylene)vinylene‐1,4‐phenylenevinylene]s
Authors: Koßmehl Gerhard , Samandari Massoud
Published: April 2003

Poly[(2‐alkoxy (or 2,5‐dialkoxy)‐1,4‐phenylenevinylene‐1,4‐phenylene)vinylene]s containing alkyl groups of different lengths (8a, b or 9a – c), were prepared by Wittig‐reaction of terephthalaldehyde with “bis(Wittig‐salt)s”. To establish the structure of the polymers, alkoxy(and dialkoxy)di‐α‐styrylbenzenes 10a, b and 11a – c were prepared as model compounds under similar conditions. Electrical conductivities, σ288K, of the polymers and their charge transfer (donor‐acceptor) complexes with iodine were studied. The doped polymers show increased room temperature conductivities by several orders of magnitude.
Télomérisation du chlorure de vinylidène, 2. Réaction avec des télogènes du type RCCL3et préparation de composés dérivés
Authors: Belbachir Mohamed , Boutevin Bernard , Piétrasanta Yves , Rigal Gérard
Published: April 2003

The telomerization of vinylidene chloride with CHCl3, CCl3Br, Cl3CCO2CH3, Cl3CCF3, Cl3CCF2CFClX (X = Cl, Br), and CCl3CF2CCl3 was carried out by redox catalysis. The first adducts of each reaction were isolated and identified. The hydrolysis of these telomers containing a CCl3 group at the chain‐end by means of oleum led to a series of halogenated acids, some of them being olefinic ones.
Effect of the temperature on the chemical healing of poly(ethylene terephthalate)
Authors: Fakirov Stoyko
Published: April 2003

The effect of temperature on the chemical healing of poly(ethylene terephthalate) (PET) – healing as a result of chemical reactions between neighboring macromolecules located in the interface surface — was studied. The healing process was carried out in vacuum on pressed partially overlapped strips of commercial PET, previously annealed at 258°C, at temperatures between 140 and 250°C for 24 h. It is demonstrated that the fracture behavior of the welded samples depends strongly on the healing temperatureTh. AtTh> 200°C the strips break beyond the contact area, at 160 <Th< 200°C debonding occurs, and atTh< 160°C no bonding is observed. It is assumed that the bonding effect is mainly a result of chemical reactions (solid state postcondensation and transreactions) taking place during the healing procedure.
Chiral interaction of chitosan with azo dyes
Authors: Yamamoto Hiroyuki
Published: April 2003

Absorption and circular dichroism (CD) spectra were measured on complexes of highly deacetylated chitosans with azo dyes in 0,08% acetic acid. Blue and red shifts of the absorption peaks in the visible region were observed. The induced CD results suggest two different chiral configurations of the transition dipole moments of the dyes. Since the random sequence of amino and acetamido groups in deacetylated chitosan does not affect the induced CD per amino side‐chain, intermolecular interactions of the dye molecules are most probable in these chitosan/dye systems.
Kinetics of free radical polymerization of ortho‐ and para‐alkylaryl esters of methacrylic acid
Authors: Vrhovac Ljubica , Veličković Jovan , Filipović Dragoljub
Published: April 2003

The kinetics of free radical polymerization in bulk of alkylphenyl methacrylates with ethyl‐,isopropyl and tert‐butyl groups in the ortho‐ and para‐positions of the phenyl ring with dilauroyl peroxide as initiator were investigated. For comparison and completion of the investigation, ortho‐ and para‐tolyl methacrylates were reinvestigated with this particular initiator. Most of the results obtained do not obey classical kinetics of polymerization. The results were treated according to the concept of degradative chain transfer and it was concluded that this mechanism is responsible for the non‐ideality. The ortho‐substitution with increasing size of the substituents decreases the overall rate of polymerization and strengthens chain transfer to monomer.