bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel chain polymers by condensation of metal(II) coordinated salicylaldehyde with diamines
Authors: Maurya Pyare L. , Agarwala Badri V. , Dey Arun K.
Published: April 2003

Coordination polymers, \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm \rlap{--} (MtL\rlap{--} )}_{\rm n} $\end{document} were synthesized by condensation of bis(salicylaldehydo)‐metal(II) (metal = Co, Ni, and Cu) with diamines (1, 4‐diaminobenzene and 4,4′‐diaminobiphenyl). Their composition, structure, thermal stability, and physical properties were investigated by analytical, magnetic, spectral (IR and DRS), the thermogravimetric studies. It was found that in the bis(salicylaldehydo)metal(II)‐chelates, two salicylaldehyde molecules are linked to each metal ion through the oxygen atoms of the phenolic and aldehydic groups and in the polymeric complexes the nitrogen atoms of the amino groups replace the aldehyde oxygens. The diamine molecule is thus acting as a bridging unit between two salicylaldehydometal(II) units, forming structures 1 and 2. The polymers obtained from 4,4′‐diaminobiphenyl (2a−c) are thermally more stable than those from 1, 4‐diaminobenzene (1a−c), the order of thermal stability in both cases being Ni(II) > Cu(II) > Co(II). Co(II) and Cu(II)‐complexes are paramagnetic, whereas Ni(II)‐complexes are diamagnetic. The reflectance spectra along with the magnetic data suggest a square planar structure for Cu(II) and Ni(II)‐complexes, and a tetrahedral one for the Co(II)‐complexes.
Viscosity/temperature relationships for dilute solutions of poly(2,4,5‐trichlorophenyl methacrylate)
Authors: Hadjichristidis Nikos , Touloupis Costas , Karvounis Sotiris
Published: April 2003

The actual viscosity η of six fractions of poly(2,4,5‐trichlorophenyl methacrylate) (PTCPh) with weight‐average molecular weight M̄w, ranging from 9,11 · 104 to 94,8 · 104, was determined in benzene at a number of temperatures from 22 to 60°C. The variation of the pre‐exponential term A and the apparent activation energy of viscous flow Q, with molecular weight and concentration was studied. Moore's equations are valid for PTCPh. The temperature coefficient of the unperturbed dimensions dln 〈r20〉/dT estimated from the intrinsic viscosity data by using the Burchard‐Stockmayer‐Fixman relation, is −3 . 10‐3 (from 22 to 40°C) and −0,87 . 10‐3 (from 40 to 60°C). These negative values indicate that extended configurations of PTCPh in benzene must be associated with lower energies.
Complexation between polyions and hydrous inorganic oxides and adsorption properties of complex
Authors: Kurokawa Yōichi , Sasaki Mitsuru
Published: April 2003

Complexation between polyelectrolytes and hydrous inorganic oxides was investigated by turbidity and conductance measurements. Vapor (water and organic) adsorption isotherms on the complex were determined as a function of relative humidity with a gravimetric method. The adsorptivity increases in the order benzene < acetone < methanol < water, which corresponded to the order of polarity of the adsorbate. This result may be primarily attributed to the ion site of the complex, because each complex has relative low specific area (1–30 m2/g). However, it has higher surface area compared to the polyelectrolyte complex (<1 m2/g) reported in a previous paper. Adsorption of heavy metals and amino acids on the complex was also examined.
Radiation induced molecular size changes in native and denatured deoxyribonucleic acid under anoxic conditions. A pulse radiolysis study
Authors: Washino Komei , Schnabel Wolfram
Published: April 2003

Native DNA (M̄w: 5 · 106 and 2 · 107) was irradiated at a concentration of 0,l g/l in Ar‐ or N2O‐saturated solutions. Emphasis was given to reactions induced by OH radicals. The solutions were irradiated with single 16MeV electron pulses (100 ns pulse length) in conjunction with time‐resolved Rayleigh light scattering measurements. It turned out that crosslinking and double strand breakage (dsb) can be clearly separated, the former proceeding faster than the latter. The extent to which the two processes—which counteract with respect to changes of the light scattering intensity (LSI)—occur, depends strongly on the ionic strength of the solution. At [NaClO4] > 10−1 mol/l crosslinking is the predominant process, which is assumed to be caused by the fact that hcrit, the critical length for the accomplishment of dsb, is strongly reduced. Thus, up to several hundred single strand breaks (ssb) per chain can remian ineffective with respect to the generation of dsb at high ionic strength. Crosslinking can occur both as an inter‐ and an intramolecular process. As inferred from light scattering measurements singlestranded DNA did not crosslink at a concentration of 0,l g/l and at low ionic strength, but underwent main‐chain rupture. The rate of LSI decrease is correlated to the rate of fragment diffusion. The half‐life time of the LSI decrease depends on M̄w as τ½ ∝︁ M̄. It was concluded that the lifetime of the species responsible for ssb is shorter than a few ms.
Small‐angle X‐ray scattering studies of L‐leucine dehydrogenase
Authors: Hiragi Yuzuru , Soda Kenji , Ohshima Toshihisa
Published: April 2003

The small‐angle X‐ray scattering of L‐leucine dehydrogenase (EC 1.4.1.9) from Bacillus sphaericus in 0,2 M sodium phosphate buffer (pH 7,28) was investigated. The following molecular parameters were determined: radius of gyration, as 50,8 Å from the Guinier plot and 48,5 Å from the distance distribution function; molecular weight, as 267 000; volume, as 623 000 Å3; and degree of hydration, as 0,95 g H2O/g of enzyme. By comparing the observed scattering curve with those calculated with a number of models, a hollow cylinder with 47,0 Å of outer radius, 10,3 Å of inner radius and 119,0 Å of length was proposed as a most plausible model for the enzyme.
Polyelectrolyte complexes, 3. The interaction between heparin and protamine
Authors: Cundall Robert B. , Jones Gareth R. , Murray David
Published: April 2003

The interaction of heparin with salmine protamine was investigated using the electrostatically bound fluorescent probes acridine orange and eosin Y and the 1‐(dimethylamino)‐5‐naphthalene sulfonyl group which is covalently bound to the protamine molecule. Dye displacement experiments indicate a 1 : 1 pairing of anionic heparin sites with cationic protamine sites. Further binding of heparin occurs, after all the cationic sites of protamine are bound up with heparin. This is thought to occur as a result of the different affinities of the sulfate and carboxyl groups of heparin for guanidino groups; the sulfate groups binding preferentially to the complex releasing some of the bound carboxyl groups. Fluorescence polarisation measurements suggest a heparin‐protamine complex greater in volume than would be expected from a simple pairing of heparin and protamine molecules, indicating some degree of cross‐linking. The limiting salt concentrations for the heparin‐protamine complex were determined in the prescence of a number of Group IA and IIA metal chlorides.
Effect of cooling rate on the structural relaxation of poly(oxy‐2,6‐dimethoxy‐1,4‐phenylene) and poly(oxy‐2,6‐dimethyl‐1,4‐phenylene)
Authors: Jauhiainen Tuure‐Pekka
Published: April 2003

The activation enthalpies for the structural relaxation of poly(oxy‐2,6‐dimethoxy‐1,4‐phenylene) and poly(oxy‐2,6‐dimethyl‐1,4‐phenylene) were determined by studying the dependence of the limiting fictive temperature on the cooling rate, using a differential scanning calorimeter (DSC) interfaced to a computer. The molar mass dependence of the activation enthalpies complied with the empirical equation, ΔH˙ = ΔH − A/M, where ΔH is the activation enthalpy of an infinite chain length polymer, Mv is the viscosity‐average molar mass, a = 0,64, and A is a constant that depends on the free volume of the chain ends of the polymers. The values of ΔH are 433 kJ/mol for poly(oxy‐2,6‐dimethoxy‐1,4‐phenylene) and 449 kJ/mol for poly(oxy‐2,6‐dimethyl‐1,4‐phenylene).
Allowance for polymolecularity in polymer structure‐property relationships
Authors: Bareiss Rolf E. , Chiantore Oscar , Guaita Marino
Published: April 2003

Relations between molar mass M and molar mass dependent properties E of polymers are mostly strictly valid only for monomolecular samples i:

For polymolecular polymer samples the corresponding averages Mav and Eav must be applied:

Provided the kind of average (number‐, weight‐ or any general average) of e.g. Mav is known, the corresponding average Eav is given by. Eqs. (1a, b). This is demonstrated for the relationships of van't Hoff and Mark‐Houwink, frequently used for the determination of molar masses of polymers. It is also shown that the four different relations for the expansion factor α by Flory‐Stockmayer, Fixman, Ptitsyn, and by Yamakawa‐Tanaka can be applied to polymolecular polymer samples (i.e. without fractionation), provided the corresponding averages[η]av and Mav from the Mark‐Houwink relationship are taken for the evaluation of the parameters KΘ and B′.
Induced circular dichroism in cholesteric and twisted smectic mesophases
Authors: Sato Yukio , Hatano Masahiro
Published: April 2003

A new twisted smectic mesophase formed in Tween 80 (1) (monooleate of the ether of sorbitan with 4 mol of polyethyleneglycol)‐water system was found. The induced circular dichroism (CD) spectra of achiral molecules dissolved in this twisted smectic mesophase are compared with those in the thermotropic cholesteric mesophase. Pyrene and fluorene and their derivatives, acridine, phenazine, and phenothiazine were used as achiral molecules (solute molecules). It was found that the signs and shape of the induced CD bands observed in the twisted smectic mesophase were dependent on the solute concentration. The magnitude of the induced CD bands was dependent on the symmetry of the solute molecules and the value of the geometrical ratio of short‐axis to long‐axis of the solute molecules. Furthermore, it was demonstrated that the relative polarization directions of the solute molecules could be determined by means of the induced CD in the Tween 80‐water system using a simple modified C2‐symmetry rule.
Induced circular dichroism of biphenyl and its derivatives in mesophase
Authors: Sato Yukio , Tajiri Akio , Hatano Masahiro
Published: April 2003

The mesophase induced circular dichroism (CD) of biphenyl and its derivatives was investigated using the Tween 80 (monooleate of the ether of sorbitan with 4 mol of polyethyleneglycol)‐water system, which can form a twisted smectic mesophase. The sign of CD bands in this mesophase is explained by a modified C2‐symmetry rule, since it can be considered that alignment of the solute molecules in this mesophase can be elucidated in terms of a pseudo‐C2 symmetry, when the concentration of the solute is comparatively high. The assignments of the electronic transitions of the solute molecules show a good accordance with results of magnetic circular dichroism study.
Statistics of random macromolecular networks, 1. Stepwise polymerization of polyfunctional monomers bearing identical reactive groups
Authors: Durand Dominique , Bruneau Claude‐Marcel
Published: April 2003

The molecular parameters of macromolecular networks made by stepwise polymerization of polyfunctional monomers bearing identical reactive groups are established from the calculation of the probability that a functional group leads to a finite chain. The determination of this finite chain probability as a function of reaction extent and characteristics of the system is computed directly from very simple implicit equations. Thus, sol fraction, cross‐link density, effective network chains numbers, dangling trees numbers, and cycle rank are derived easily in very general systems.
Polymerisation of N‐vinylcarbazole in pyridine using free radical initiators
Authors: Sengupta P. K. , Mukhopadhyay G.
Published: April 2003

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

The weight fraction and the molecular mass

“Relative molecular mass” (systematic IUPAC name) is shortened to “molecular mass” throughout this paper.

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

Extraction and random degradation of networks make it possible to determine the molecular mass

“Relative molecular mass” (systematic IUPAC name) is shortened to “molecular mass” throughout this paper.

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

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

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

A spectroscopic and conductimetric study of the cationic polymerization of 2‐vinylfuran (1) and 2‐methyl‐5‐venylfuran (2) showed the existence of an important side reaction originating from a hydride‐ion shift from an unsaturated polymer molecule to an active species. The resulting allylic carbocation, in equilibrium with a doubly unsaturated polymer molecule, can react further and the repetition of the mechanism on progressively more conjugated species leads to the formation of a series of highly charge‐delocalized carbenium ions absorbing throughout the visible region of the spectrum (and giving high electrical conductivity) and of neutral polyconjugated polymer molecules. Since the hydride‐ion abstraction occurs from the tertiary carbon atom of the vinylic chain, vinylidene polymers of monomers such as 2‐isopropenylfuran (3) and 2‐isopropenyl‐5‐methylfuran (4) are not susceptible to it. Indeed, their cationic polymerization proceeds without colour formation and conductivity increase.
Vinylpolymerisation mit reduzierenden Übergangsmetallverbindungen, 3. Polymerisation in gegenwart von initiatorsystemen aus vanadium(II)‐ und vanadium (III)‐chlorid sowie organischen halogenverbindungen
Authors: Moszner Norbert , Hartmann Manfred
Published: April 2003

The polymerization of methyl methacrylate initiated by the redox system vanadium(III) chloride/carbon tetrachloride was studied. The rate of polymerization can be described by the equation Rp = k · [VCl3]0,5·[CCl4]0,5·[MMA]1,0. The overall activation energies were estimated to be 74,5 kJ·mol−1 for VCl3/CCl4 and 59,5 kJ·mol−1 for VCl2/CCl4. Vanadium (II) chloride acts as a retarder in the polymerization of styrene initiated by 2,2′‐azoisobutyronitrile (AIBN). The polymerization of acrylonitrile and methyl methacrylate is inhibited by vanadium (II) chloride. The polymerization of acrylonitrile initiated by AIBN is retarded by vanadium (III) chloride.
Über enzymanalog gebaute polymer, 16. Über den Einfluß der flexibilität der haftgruppen auf die racemattrennungsfähigkeit
Authors: Wulff Günter , Gimpel Jürgen
Published: April 2003

The influence of the binding group flexibility on the ability for racemic resolution was investigated for binding groups situated in chiral cavities of enzyme‐analogously built polymers. D‐Glyceric acid was used as a template to introduce dihydroxyborylphenyl‐, 4‐(2‐hydroxyborylethyl)phenyl‐, or 5‐dihydroxyhoryl‐1,2‐indanediyl groups into chiral cavities of macroporous polymers. Investigations on the ability for racemic resolution revealed a lower specificity with higher binding group flexibility. On increasing the rigidity compared to the dihydroxyborylphenyl group the specificity is diminished to some extent. This may be attributable to a hindrance of the embedding of the substrate.
Ionic conductivity of polyether‐polyurethane networks containing NaBPh4: A free volume analysis
Authors: Killis Andreas , LeNest Jean‐François , Cheradame Hervé , Gandini Alessandro
Published: April 2003

The ionic conductivity of polyoxyethylene‐ and polyoxypropylene‐polyurethane networks containing sodium tetraphenylborate was studied as a function of temperature and salt concentration. The results can be rationalised in terms of free volume considerations. The fact that the WLF equation applies to the conductivity of these materials demonstrates that there exists a direct relationship between the ion conduction process and the viscoelastic properties of the networks.
Contribution à l'étude de la métallation de structures polyisoprène, . Etude sur polymères
Authors: Brosse Jean‐Claude , Abdin Bin Maidunny Zainul , Soutif Jean‐Claude
Published: April 2003

Metalation of polyisoprene by the complex sec‐butyllithium‐N,N,N′,N′‐tetramethylethylenediamine (secBuLi‐TMEDA) is strongly affected by the conditions of reaction. In certain cases, a first order rate constant with respect to each reagent is observed. The mole ratio secBuLi/TMEDA has a preponderant effect on the rate of metalation. A maximum yield is observed when the mole ratio secBuLi/TMEDA is 1/0,5. Addition of a cocomplexing reagent, potassium tert‐butoxide (tertBuOK), to the complex secBuLi‐TMEDA yields a higher rate of metalation. A good yield can be obtained when polysioprene is treated with the metalating complex secBuLi‐TMEDA‐tertBuOK in a mole ratio of 1/0,5/1.
Processable heat‐resistant polymers, 10. Synthesis and characterization of an unsaturated polyesterimide containing 1,5‐dioxoisoindoline‐2,5‐diyl units
Authors: Maiti Sukumar , Ray Atanu , Maiti Manoranjan
Published: April 2003

A new polyesterimide containg CC‐double bonds was prepared by reacting an unsaturated diacid chloride containing a cyclic imido group with ethylene glycol at low temperature. The solubility, thermal, electrical and cross‐linking properties of the polymer were studied. The polymer was found to be thermostable and soluble in highly polar solvents. X‐ray diffraction data revealed that the polymer is crystalline. The unsaturation sites of the polymer chain could be exploited for crosslinking reactions. The swelling behavior of the crosslinked polymer was studied as well as the thermal and electrical properties. The overall thermal stability of the crosslinked polymer was found to be higher than that of the uncrosslinked polymer.
Télomères monofonctionnels du chlorure de vinyle, 2. Cinétique par amorçage radicalaire
Authors: Boutevin Bernard , Piétrasanta Yves , Taha Mohamed
Published: April 2003

Radical telomerizations of vinyl chloride with telogens RCCl3, containing alcohol and acid functions in the R group, were carried out. The molecular weights of the obtained products are between 1000 and 10 000. Transfer constants (CT) were calculated for each case by studying the DPn (10 to 50) variation as a function of the mole ratio (R) of telogen to monomer. In addition, the functionality of the resulting poly(vinyl chloride) was evaluated from the values of CT and R.
Photolytisch induzierte umsetzungen chlorhaltiger systeme in lösungen mit polystyrol
Authors: Woliński Leszek , Turzyński Zbigniew , Zaleska Wiesława
Published: April 2003

UV spectroscopic measurements to identify the products of photolysis in polystyrene solutions of CCl4 and CHCl3 as a function of the atmospheric oxygen concentration are conducted. In polystyrene chains CC bonds are formed, thus changing the absorption properties in the long wave length range. The concentration of induced CC bonds is higher in CCl4 solution than in CHCl3 solution. The effect of O2 is observable for pressures p ≥ 2 · 10−1 mmHg; it is of minor importance for the formation of CC bonds, however. On the low‐molecular‐weight side COCl2, Cl2, and HCl are the photolysis products in the presence of O2. Observable changes in the absorption of the solvent at 280 nm were attributed to the electronic n ← π* transition of the carbonyl groups of COCl2, whereas the newly created broad band in the UV spectrum of the solvent was attributed to the electronic 1 Π1u ←1Σ g+ and 3Π+ou ← 1Σg+ transitions in Cl2. The first of these transitions is responsible for the dissociation of Cl2 molecules. A hypothesis has been set forth that molecular oxygen affects the probability density of the electronic 3Πou+ ← 1Σg+ transition. The concentration of O2 has a substantial effect on the concentration of the COCl2 photoproducts, which is best displayed by the molar absorption coefficient of this compound.
Biomimetic approach to the design of a pyridoxal enzyme model, 3. Synthesis of 4‐formyl‐3‐hydroxy‐5‐methacryloylaminomethyl‐2‐methylpyridine and its 5′‐N‐methylated analogue
Authors: Belokon' Yuri N. , Tararov Vitali I. , Bakhmutov Vladimir I. , Belikov Vasili M.
Published: April 2003

The synthesis of 4‐formyl‐3‐hydroxy‐5‐methacryloylaminomethyl‐2‐methylpyridine (7a) and 4‐formyl‐3‐hydroxy‐5‐(N‐methacryloyl‐N‐methyl)aminomethyl‐2‐methylpyridine (7b) is reported. The intermediate products 5‐aminomethyl‐2,2,8‐trimethyl‐2H,4H‐[1,3]‐dioxino[4,5‐c]‐pyridine hydrochloride (3a), 2,2,8‐trimethyl‐5‐methylaminomethyl‐2H,4H‐[1,3]‐dioxino[4,5‐c]‐pyridine hydrochloride (3b), 5‐methacryloylaminomethyl‐2,2,8‐trimethyl‐2H,4H‐[1,3]‐dioxino‐[4,5‐c]pyridine hydrochloride (5a), 5‐(N‐methacryloyl‐N‐methyl)aminomethyl‐2,2,8‐trimethyl‐2H,4H‐[1,3]‐dioxino‐[4,5‐c]pyridine hydrochloride (5b), 3‐hydroxy‐4‐hydroxymethyl‐5‐metha‐cryloylaminomethyl‐2‐methylpyridine (6a) and 3‐hydroxy‐4‐hydroxymethyl‐5‐(N‐methacryloyl‐N‐methyl)aminomethyl‐2‐methylpyridine (6b) were isolated and identified.
Hydrolyse énantiosélective d'α‐aminoesters catalysée par des complexes chiraux de métaux de transition immobilisés sur supports macromoléculaires
Authors: Spassky Nicolas , Reix Michel , Sepulchre Marie‐Odile , Guetté Jean‐Paul
Published: April 2003

The kinetics of hydrolysis of D‐ and L‐histidine methyl ester were studied in the presence of crosslinked hydrophilic polymeric supports bearing L‐histidine moieties complexed with Ni2+ salt. The selectivity of hydrolysis (kD/kL ratio) rises with the increase of the hydrophilic character (content of monomeric units of 2‐hydroxyethyl methacrylate) of the resin. It varies with the ratio ester / catalytic moiety, the best result being obtained when the latter is close to 1. The selectivity depends on the temperature and an inversion of this selectivity is observed at 31°C. The optimization of all the parameters studied allowed to reach the same enantioselectivity and comparable rates of hydrolysis as observed in a model reaction carried out under homogeneous conditions.
Effect of zinc chloride on the radical polymerization of cyclohexyl acrylate
Authors: Liaw Der‐Jang , Chung Kwang‐Chih
Published: April 2003

The paper presents a study of the radical polymerization of cyclohexyl acrylate (CHA) in the presence of ZnCl2. It was found by IR, 1H NMR, and 13C NMR spectroscopy that a complex of ZnCl2 with CHA is formed. For copolymerization of CHA with vinylidene chloride, both the Q‐ and e‐value of CHA increased with the ZnCl2 concentration. The initiation rate and k/kt were determined using DPPH as an inhibitor. It was found that ZnCl2 did not affect the initiation rate. The kp value of CHA was determined to be about 2720 1 · mol−1 · s−1 in the absence and 4710 1 · mol−1 · s−1 in the presence of ZnCl2 by the rotating sector method. The enhanced polymerization rate of CHA in the presence of ZnCl2 can be ascribed to the large kp value. The termination rate constant is not significantly affected by the presence of ZnCl2.
Polymerisationsauslösung mit substituierten ethanen, 5. Polymerisation von verschiedenen methacrylmonomeren
Authors: Błedzki Andrzej , Braun Dietrich , Menzel Wolfgang , Titzschkau Klaus
Published: April 2003

Methyl methacrylate, benzyl methacrylate, butyl methacrylate, and methacrylic acid can be polymerized by 1,1,2,2‐tetraphenyl‐1,2‐diphenoxyethane and 1,1,2,2‐tetraphenyl‐1,2‐dicyanoethane. In the first period of the polymerization with both initiators oligomers are formed which can initiate the polymerization of other vinyl monomers yielding block‐copolymers besides the resp. homopolymers.
Hydrodynamic constants and frictional properties of polystyrene in dilute solution
Authors: Bohdanecký Miloslav , Petrus Vladimír , Porsch Bedřich , Sundelöf Lars‐Olof
Published: April 2003

Experimental data from hydrodynamic measurements on eleven standard polystyrene samples in a poor and a good solvent (cyclohexane at theta‐temperature 34,5°C, toluene at 25°C) are analyzed in terms of the two‐parameter theory of the hydrodynamic properties of random coils. The discussion is focussed on the expansion factors of hydrodynamic radii αf and αμ, evaluated from the translation friction coefficients and the intrinsic viscosity, and on the hydrodynamic‐interaction parameters P and Φ. The expansion factors αf and αη are shown to assume nearly equal values (at 1,15 ≤αη ≤ 1,5). That implies that the dependences on coil expansion must be very similar for P and Φ1/3. The value of the P parameter in the unperturbed state (i.e. P0) is shown to be close to that recently calculated by Zimm and to be significantly higher than the results of previous theoretical calculations.
Study of step‐growth polymerizations using epoxy‐carboxy reaction, 2. Study of the epoxy‐carboxy reaction on models in nitrobenzene
Authors: Madec Pierre‐Jean , Maréchal Ernest
Published: April 2003

In the first part of this series devoted to epoxy‐carboxy polycondensation, we showed that the overall mechanism of the amine catalyzed epoxy‐carboxy reaction is complex. The present article studies the reaction of benzoic acid with 1‐phenoxy‐2,3‐epoxypropane carried out in nitrobenzene and in the presence of N,N‐dimethyldodecylamine as catalyst. In contrast to the results obtained in low polar solvents, where two equivalent reactions take place, the studies carried out in nitrobenzene show that, in this solvent, one of these two reactions is largely predominant. Its rate equation is: υ = k [epoxy][amine]. However, in the last steps of the reaction (conversion above 75% ), the system behaves as in low polar solvents. These results were obtained from studies carried out under stoichiometric and non‐stoichiometric conditions. The overall rate constant depends only very slightly on the stoichiometric balance. This is in agreement with a major contribution of one of two competitive reactions.
Study of step‐growth polymerizations using epoxy‐carboxy reaction, 4. Study of the epoxy‐carboxy reaction carried out in the melt on high molecular weight models
Authors: Madec Pierre‐Jean , Maréchal Ernest
Published: April 2003

Epoxy‐Carboxy polycondensation is studied in the melt by use of the octadecanoic acid/1‐dodecyloxy‐2,3‐epoxypropane reaction as a model. The catalyst is N,N‐dimethyldodecylamine. The results obtained from these high molecular weight models show that, as for the studies performed in a solvent, two main reactions take place. The experiments are carried out under stoichiometric and non‐stoichiometric conditions. It appers that, due to the strong interaction between epoxy compound and amine, a polymerization of oxirane takes place to a small extent, being a side reaction of the system. As a consequence, epoxy groups are consumed more rapidly than acid groups. Nevertheless, an approximation allowed the determination of the rate constants relative to the two main reactions. Activation parameters of these reactions are reported.