bluuebunny/crossref_metadata_2025 huggingface dataset:
Syndiotactic poly(leucine)
Authors: Fick Fritz‐Georg , Semen John , Elias Hans‐Georg
Published: April 2003

N‐(tert‐Butoxycarbonyl)‐L‐leucyl‐D‐leucyl‐L‐leucyl‐D‐leucine tetrapeptide was synthesized from L‐ and D‐leucine α‐amino acids by conventional coupling methods. This tetrapeptide was transformed into an activated (polymerizable) tetrapeptide by conversion to the pentachlorophenyl ester and subsequent removal of the tert‐butoxycarbonyl group. Condensation polymerizations of the activated tetrapeptide were performed in various solvents with triethylamine and N,N‐diethyl‐1‐amino‐2‐propanol bases. Molar masses (“molecular weights”) of the resulting polymers were estimated to be in excess of 34000 g/mol. From optical rotation measurements in trifluoroacetic acid solution, it was found that the polymers were highly syndiotactic, although a small amount of isomerization (0,9–2,1%) occurred to yield polymers with a small excess of L‐leucine residues. The degree of isomerization decreased with decreasing base strength and concentration and with decreasing polarity of the solvent; these effects were explained in terms of the simultaneous enolization and/or oxazolone‐formation reactions.

Preliminary studies of the conformation of syndiotactic poly(leucine) were performed with X‐ray diffraction, NMR, IR and optical rotation methods. It was concluded that syndiotactic poly(leucine) most probably exists in a π‐helical conformation with a preferred screw sense in both the solid state and in chloroform solution. NMR and optical rotation data on solutions in trifluoroacetic acid/chloroform showed that the polymer exhibits a conformational transition in the region of 4–10% trifluoroacetic acid content.
Synthesis of dithiocarbamates from linear poly(iminoethylene) and some model compounds
Authors: Ivin Kenneth J. , Lillie Edwin D.
Published: April 2003

Reaction of linear poly(iminoethylene) with carbon disulfide in the presence of sodium hydroxide gives a product in which every NH group is replaced by NCS⊖Na⊕. In the absence of sodium hydroxide about one NH group in two is replaced by NCS2H and there is a random distribution of such groups. Evidence for these reactions was obtained from 13C NMR spectra, which were interpreted on the basis of the chemical shifts of dithiocarbamates derived from three model diamines.
Mutarotation of α‐D‐glucose catalyzed by poly(4‐vinylpyridine) and poly(4‐vinylpyridinium hydrochloride) in N,N‐dimethylformamide solutions
Authors: Fujimori Kiyohisa
Published: April 2003

The rate of mutarotation of α‐D‐glucopyranose catalyzed by polymers of 4‐vinylpyridine (4VP) was observed in N,N‐dimethylformamide (DMF) solutions. Poly(styrene‐co‐4VP·HCI) and poly(4VP·HCl) were active while poly(4VP) of various average molecular weights showed little catalytic activity. p‐Chlorophenol‐poly(4VP) catalyst pair in DMF and poly(4VP·HCl)‐poly(4VP) catalyst pair in DMF/methanol mixed solvent showed a catalysis of bifunctional mechanism.
Asymmetric synthesis catalyzed by oligo((S)‐alanine)
Authors: Ueyanagi Kaoru , Inoue Shohei
Published: April 2003

In the asymmetric addition of 1‐dodecanethiol to isopropenyl methyl ketone catalyzed by the terminal primary amino group of oligo((S)‐alanine) (1c), the trimer and the tetramer in β‐conformation gave much higher optical yield than the monomer and the dimer in random conformation. A similar result was obtained in the catalysis by β‐alanyl‐poly((S)‐alanine) (3).
Einfluß von hydrazinderivaten auf die radikalische styrolpolymerisation
Authors: Hallensleben Manfred L. , Hoser Wolfram F.
Published: April 2003

The radical polymerization of styrene was investigated in the presence of six different hydrazine derivatives. These compounds were selected in view of the nitrogen radicals, either from the aminyl or the hydrazyl type, resulting upon carbon radical attack. A distinct dependence of the rate of polymerization on the nature of hydrazine substituents was detected in thermally as well as radically (AIBN) induced polymerization. 1,2‐Diacetylhydrazine (13), 1,2‐bis(p‐nitrophenyl)hydrazine (16), 1,2‐diacetyl‐1,2‐diphenylhydrazine (15), and 1,2‐dimethylhydrazine (12) act as retarding compounds whereas 1,2‐diphenylhydrazine (14) and tetraphenylhydrazine (1) are inhibitors. The transfer constants were calculated from the Mayo equation to be 0,02 for 12, 0,06 for 13, 0,1 for 15, 0,8 for 16, 0,9 for 14, and 5,6 for 1. Any influence of polymerization temperature on the chain transfer constant was not observed. From model reactions only hydrazyl radicals were detected.
Segmental motions of spin‐labelled poly(ethylene oxide) in dilute solution
Authors: Braun Dietrich , Törmälä Pertti
Published: April 2003

The rotational correlation times (τ) of spin‐labelled poly(ethylene oxide), (Mw=20 000) were measured in benzene, pyridine and water. It was found that τ is independent of polymer concentration (c) when c<0,15 g/(ml solvent). In dilute solutions τ values of 49 ps, 43 ps and 100 ps in benzene, pyridine and water at 293 K were obtained. A comparison with results of dielectric relaxation and nuclear magnetic resonance measurements indicated that τdiel. < τ13CNMR < τspin‐labelling < τ1H NMR. Values 17.7±2,2 kJ/mol and 17,3kJ/mol for the potential barrier of local conformational changes of PEO in pyridine and water solutions were obtained.

The apparent hydrodynamic radii (0,35–0,46 nm) indicated the loosely arranged random coil state of the polymer molecules in solution at 293 K.
Kinetische und morphologische untersuchungen zur polymerisation von oxacyclischen monomeren im festen zustand, 2. Zur morphologie der bei der straheleninduzierten polymerisation von trioxan und tetroxan entstehenden poly(oxymethylene)
Authors: Muñoz‐Escalona Antonio
Published: April 2003

In order to clarify the reaction mechanism of the solid‐state polymerisation of 1,3,5‐trioxane and 1,3,5,7‐tetroxane as induced by gamma‐radiation, the nascent textures and morphology of poly(oxymethylene) crystals were studied with light and transmission electron microscopy, X‐ray scattering and differential thermal analysis techniques. In both cases poly(oxymethylene) crystals with fibrous morphology and “twin‐structure” are obtained. The polymerization of 1,3,5,7‐tetroxane gives rise to the formation of crystals where the preferred orientation of the polymer chain is the monomer b‐axis; however, the fibrils showed ripples perpendicular to the main chain direction at a 70–240Å long period that depends extremely on the polymerization temperature. In the polymerization of 1,3,5‐trioxane, POM crystals with 60% of the polymer chains in the direction of the monomer c‐axis are obtained. The remaining chains are found in the “twin sub‐crystals”. Dark field electron micrographs showed the sub‐crystals to be an integral part of the fibrils. The material in the twin direction decreases, when the polymerization temperature or the yields increases; it never amounts to less than 30%. These results and the misfit between the lattices of the monomers and the nascent polymer indicate that the reactions which take place occur according to a simultaneous polymerization and crystallization mechanism through the gasphase. The polymerization process occurs easier at higher temperatures near the monomers' melting point due to the increase of monomer vapor pressure and diffusion processes in the monomer crystals. Molecular models of the chain growth are developed on the basis of the morphological observations.
Influence de la nature du solvant sur les propriétés physico‐chimiques des polyamides aromatiques en solution diluée
Authors: Millaud Bernard , Strazielle Claude
Published: April 2003

The dilute solution properties of some aromatic polyamides like: poly(1,4‐phenyleneterephthalamide), (or poly(imino‐1,4‐phenyleneiminoterephthaloyl)), poly(parabenzamide), (or poly(imino‐1,4‐phenylenecarbonyl)), and some chlorinated derivatives of poly(1,4‐phenyleneterephthalamide) have been investigated. Solvents like 96% sulfuric acid, methanesulfonic and chlorosulfonic acid and also N,N‐dimethylacetamide + LiCl have been used. An increase of the intrinsic viscosity and of the exponent of the viscosity law when we use methanesulfonic and chlorosulfonic acids has been observed and is explained by an increase of the rigidity and hydrodynamic diameter of the molecule. The measurements of the radius of gyration, and optical anisotropy confirm this. In N,N‐dimethylacetamide, the molecules of poly(parabenzamide) exhibit an association which depends on parameters such as percentage of LiCl and temperature.
Catalysis of olefin transformation by tungsten complexes, 6. Equilibrium oligomer concentration in the polymerization of 1,5‐cyclooctadiene
Authors: Chauvin Yves , Commereuc Dominique , Zaborowski Georges
Published: April 2003

Depending on the concentration, the ring‐opening polymerization of 1,5‐cyclooctadiene, or the metathesis of poly(2‐butynylene), affords either cyclic oligomers or a mixture of cyclic oligomers and high molecular weight polymer, the 1,5‐cyclooctadiene being not involved in the equilibrium. The concentration of oligomers at the equilibrium depends only on the nature of the solvent, and in the case of an aromatic solvent also on the total concentration of the reactants. The thermodynamic and kinetic pathways of the reaction are discussed.
Non‐ideality in vinyl polymerisation, 2. Free‐radical polymerisation of styrene with azoisobutyronitrile
Authors: Deb Pramil C. , Gaba Ishwar D.
Published: April 2003

Polymerisation of styrene in benzene initiated by azoisobutyronitrile (AIBN) was carried out at 60°C covering a wide range of concentrations of both monomer and initiator. It is found that the monomer concentration has only little effect on the characteristic constant of primary radical termination, kprt/(kikp). This is explained on the basis of the fact that the secondary dissociation of the initial primary radicals occurs very quickly (ca. 10−11 s), thus allowing no chance of competition for the initiation process. This is in sharp contrast to the secondary dissociation of the benzoyloxyl radical which has a much longer life‐time (ca. 10−9 s). However, it is found that the polymerisation constant 2fkkdk/kt is dependent on monomer concentration and increases with the latter. The characteristic constant has also been determined at 40, 50, 70, and 80°C and the energy of activation corresponding to the initiation process obtained therefrom is about 66kJ/mol. This is appreciably higher than the value generally assumed (Ei≈Ep = 32,6kJ/mol) and could not be explained on the basis of experimental error. Ei is moreover very near to the value obtained for benzoyl peroxide initiated polymerisation of styrene determined earlier. Thus it seems that the initiation and propagation processes involve different activation energies and not the same as has hitherto been assumed.
Phosphorescence quenching and photostabilising efficiencies of ultraviolet stabilisers in commercial polypropylene
Authors: Allen Norman S. , Homer John , McKellar John F.
Published: April 2003

The phosphorescence quenching efficiency of a wide range of ultraviolet stabilisers has been studied in polypropylene and their performance compared with their photostabilising action in the polymer. It is concluded that the quenching of photoactive triplet carbonyl impurities may contribute, to a greater or lesser degree, towards their stabilising action. However, individually no direct correlation between quenching efficiency and stabilising action was observed. Indeed the very interesting observation is made that a highly efficient stabiliser of the hindered amine type shows no phosphorescence quenching at all.
Über die Druckabhängigkeit der viskoelastischen und physikalisch‐chemischen Eigenschaften von Polymeren, 7. Einfluß des Lösungsmittels para‐Xylol auf das Schmelzen und Kristallisieren von Polyethylen
Authors: Karl Veit‐Holger , Asmussen Frithjof , Ueberreiter Kurt
Published: April 2003

Melting and crystallization of polyethylene (PE) with various amounts of xylene is investigated by pressure dependent volume‐temperature curves. These can be calculated by a reduction formula described earlier. Flory's formula for lowering of the melting point of polymers by solvents proves to be applicable also for high pressures.
The synthesis of epoxy resins in dipolar, aprotic solvents
Authors: Rokicki Gabriel , Kuran Witold , Nowiński Andrzej
Published: April 2003

The snythesis of low molecular weight epoxy resins from various alkali metal diphenolates and 1‐halo‐2,3‐epoxyalkanes in dipolar, aprotic solvents is described. The resulting epoxy resins have no oxy‐(2‐hydroxytrimethylene)oxy groups as a consequence of a lack of mobile protons in the reaction system. The effect of various factors on the reaction course was determined by kinetic measurements.
Free radical polymerization kinetics of n‐lauryl methacrylate
Authors: Mahabadi Hadi Kh. , O'Driscoll Kenneth F.
Published: April 2003

The kinetics of free radical polymerization of n‐lauryl methacrylate (dodecyl methacrylate) were studied at 60 and 80°C in bulk and in benzene solution. The analysis of the data showed the kinetic results deviated from classical behaviour and that this deviation could be explained by the chain length dependence of the diffusion controlled termination rate constant, Kt. Primary radical termination is explicitly considered and rejected as being insignificant in this work. Because of its lessened flexibility poly(n‐lauryl methacrylate) shows a greater chain length dependence for Kt than does poly(methylmethacrylate).
Comparative study of the hydrodynamic properties of cellulose and amylose tricarbanilates in dilute solutions viscosity, sedimentation and diffusion measurements in 1,4‐dioxane in the molecular weight range of 500 ≤M≤ 5·106
Authors: Sutter Wolfgang , Burchard Walther
Published: April 2003

Comparative hydrodynamic measurements were performed for cellulose tricarbanilates (CTC) and amylose tricarbanilates (ATC)—covering the whole region from the monomer up to the highest available molecular weight of 3,6 . 106.

The intrinsic viscosity vs. molecular weight relationships exhibit in both cases characteristic S‐shaped curves. In the region of oligomers the intrinsic viscosities remain almost constant; it follows then a steep increase with molecular weight which finally flattens out to constant slopes for high molecular weights. In the high molecular weight region the curves may be approximated by Kuhn‐Mark‐Houwink equations with exponents of 0,90 and 0,88 for CTC and ATC, respectively. The intrinsic viscosities are by a factor two smaller for ATC than for CTC. The S‐shaped curves are interpreted as a result of the finite cross‐section of the chains and a certain chain stiffness. Stockmayer‐Fixman plots gave strongly bent curves which is shown to be due to chain rigidity.

Sedimentation coefficients and diffusion constants as functions of the molecular weight approach straight lines in a double logarithmic plot for large molecular weights; for shorter chains characteristically bent curves are obtained which are ascribed to chain stiffness and finite chain cross‐section.

The origin of chain stiffness in CTC is discussed to be due to H‐bond formation between the NH‐group of the substituent in C2 position of the sugar ring and a CO‐group of the substituent in C6 of a neighbouring repeating unit. This interpretation is supported by the low viscosity of mannan tricarbanilate (MTC), in which the facility of H‐bond formation is lost and higher flexibility is obtained.
On the polymerization of crystalline 1,4‐diethynylnaphthalene, 2 The reaction mechanism
Authors: Rohde Ottmar , Wegner Gerhard
Published: April 2003

Crystalline 1,4‐diethynylnaphthalene (1) is photochemically polymerized in the solid state by a radical mechanism. Only the chain initiation step is induced by light, whereas chain propagation also occurs in the dark. The polymerization is controlled by diffusion processes within partially melted domains of the crystal, ultimately leading to a completely disordered system. The reaction rate, however, also depends on the packing of the monomer in the crystal lattice and—in the beginning of the reaction—the polymer chains have a preferential orientation with regard to the crystal axes of the monomer. Radical polymerization in solution indicates that—due to the lack of effective chain termination steps—1 can be polymerized rather effectively as compared to other acetylenes. The photochemically induced polymerization is approximately of second order with regard to monomer concentration.
Ligand‐exchange chromatography of racemates, 9. Ligand‐exchange chromatography of amino acid enantiomers on asymmetric sorbents with polydentate sulfur containing groupings
Authors: Yamskov Igor A. , Berezin Boris B. , Davankov Vadim A.
Published: April 2003

The paper describes the syntheses of four asymmetric sorbents, which contain S‐(2‐aminoethyl)‐L‐cysteine (1a), S‐(carboxymethyl)‐L‐cysteine (1c), S,S′‐(ethylene)‐bis(L‐cysteine) (2a), and N,N′‐(ethylene)‐bis(D‐methionine) (3a) groupings as the chiral fixed ligands in a cross‐linked polystyrene matrix. The sorbents were used for ligand‐exchange chromatography of amino acid enantiomers in the presence of Cu(II) and Ni(II) ions. Enantioselective effects in the formation of mixed‐ligand complexes consisting of a fixed ligand, a metal ion, and an amino acid enantiomer were determined. The highest values of enantioselectivity reaching 1 300 to 1 890J/mol were found in mixed‐ligand complexes containing histidine or β‐phenyl‐α‐alanine.
Solution properties and unperturbed dimensions of poly(pentachlorophenyl methacrylate)
Authors: Becerra Melvyn , Radic Deodato , Gargallo Ligia
Published: April 2003

The properties of dilute solutions of poly(pentachlorophenyl methacrylate) in various solvents are studied by measurements of viscosity and osmotic pressure.

The unperturbed dimensions are determined in two Θ‐solvents: benzene at 40°C, ethylbenzene at 25°C, and several other solvents such as toluene, chlorobenzene, o‐xylene and o‐dichlorobenzene at 25°C.

The results show a variation of the unperturbed dimensions with the solvent nature in good solvents. The flexibility factor, σ, calculated on the basis on the unperturbed dimensions in a Θ‐solvent and the dimensions of a freely rotating chain is higher than that of other polymethacrylates with chlorinated aromatic side groups. The polymer‐solvent interactions are discussed in relation to some other polymethacrylates.
Heterogeneous nucleation of isotactic polypropylene
Authors: Goldfarb Louis
Published: April 2003

The present work was undertaken to establish rates of primary nucleation for isotactic polypropylene and to put forth a modified classical model for the secondary nucleation process in isotactic polypropylene systems.
Temperature changes of poly(oxymethylene) structures studied by infrared spectroscopy
Authors: Terlemezyan Levon , Mihailov Marin , Schmidt Pavel , Schneider Bohdan
Published: April 2003

Temperature changes of infrared spectra of poly(oxymethylene) samples in the hexagonal crystalline form were measured; in the nascent state, these samples contained either long (type A) or short (type B) sequences of monomeric units in the G conformation. It was found that up to the temperature of “solid crystal‐plastic crystal” transition, the original structure of both types remains essentially unchanged. Only in the melt the original structure is completely destroyed. The composition of the melt is the same for both cases.
Polymeric phospholipid analogs, 11. Synthesis and polymerization of 2‐aminoethyl 2‐(p‐methacryloyloxybenzoyloxy)ethyl hydrogen phosphate
Authors: Nakai Shiro , Nakaya Tadao , Imoto Minoru
Published: April 2003

The preparation and characterization of 2‐aminoethyl 2‐(p‐methacryloyloxybenzoyloxy)ethyl hydrogen phosphate (7) are described. This monomer was polymerized with 2,2′‐azoisobutyronitrile (AIBN) and the properties of the resultant polymer are described.
Circular dichroism of poly{γ‐[2‐(9‐carbazolyl)ethyl] L‐glutamate} in dilute solution and in solid state
Authors: Yoshikawa Masao , Nomori Hiroiyuki , Hatano Masahiro
Published: April 2003

Circular dichroism (CD) and ultraviolet absorption (UV) spectra were measured for poly{γ‐[2‐(9‐carbazolyl)ethyl] L‐glutamate} (PCLG), whose side chain chromophore has three π – π* transitions in a wavelength region not overlapping with the n – π* transition of the main chain peptide group. For the dilute solution in any given helicogenic solvent, the observed CD sign had a good correlation to the polarization direction of the π – π* transitions. On the other hand, a concentrated solution with a concentration of ca. 15 wt.‐% was found to form a liquid crystalline phase, which was probably nematic at room temperature. The CD spectral profiles of the cast film of the polypeptide were quite different from that of the dilute solution. Origins of the optical activity are discussed.
Cationic polymerization of anethole by triphenylmethyl hexafluoroantimonate
Authors: Rooney John M.
Published: April 2003

Cationic polymerizations of anethole in methylene dichloride initiated by triphenylmethyl hexafluoroantimonate were studied by dilatometry and UV‐visible spectroscopy at temperatures between 0 and 35°C. Initiator consumption continued throughout polymerization, reaching 85–95%. Monomer conversion ranged from 75 to 98%. Reaction half‐lives were on the order of 15 to 60 min at 25°C. Polymer molecular weights were bimodal with some evidence of branching and cross‐linking. The principal termination reaction appeared to involve formation of a chromophore absorbing at 501 nm. Rate constants on the order of 10−3 dm3·mol−1·s−1 for initiation and 1 dm3·mol−1·s−1 for propagation at 25°C were estimated.
Zur theoretischen deutung der temperaturabhängigkeit der relaxationszeiten von polymeren
Authors: Havlíček Ivan , Vojta Vladimír , Kästner Siegfried , Schlosser Eckard
Published: April 2003

The free volume theory of Cohen and Turnbull, the results of which are identical with the empirical relationship of Williams, Landel and Ferry (WLF), was compared with the theory of conformational entropy of Adam and Gibbs (AG) using experimental results of measurements of the temperature dependence of the relaxation times of poly(vinyl acetate). In spite of being different in their mathematical form, both theories were found to describe the experiment with similar adequacy. A procedure was also suggested permitting to obtain the AG parameters if the WLF parameters are known. The procedure was applied to 59 compounds, the WLF parameters of which were found in the literature. The results are tabulated.
Temperature effect of 1H NMR chemical shifts of poly(vinyl chloride)
Authors: Ando Isao
Published: April 2003

The 1H NMR chemical shift difference of the CH2 protons of meso and racemic dyads in poly(vinyl chloride) was measured as a function of temperature and was found to decrease linearly with increasing temperature. On the other hand, the temperature dependence of the chemical shift difference was calculated by taking into account the statistical weights of the preferred conformations of any specified stereochemical configuration. The experimental behavior could be verified by this calculation by considering the four‐bond interaction.
Conformational studies on polypeptides containing L‐alanine and ω‐amino acids
Authors: Pra Antonio Del , Spadon Paola , Boni Renzo , Bonora Gian Maria , Scatturin Angelo
Published: April 2003

The synthesis and the conformational studies of the following sequential polypeptides are reported: poly(alanyl‐3‐aminopropanoic acid), poly(alanyl‐4‐aminobutanoic acid), poly(alanyl‐5‐aminopentanoic acid), and poly(alanyl‐6‐aminohexanoic acid). These compounds were examined in the solid state by X‐ray diffraction and in solution by circular dichroism spectroscopy. X‐ray diffraction patterns indicate that all copolymers assume an antiparallel pleated‐sheet conformation. The results in solution suggest that the synthetic polypeptides, in 2,2,2‐trifluoroethanol (TFE)/methanol exhibit a β‐conformation. The addition of water to a solution of copolymers in TFE destabilize this ordered structure except in the case of poly(alanyl‐6‐aminohexanoic acid).
Über die Eigenschaften einiger wasserlöslicher Azo‐Initiatoren
Authors: Nuyken Oskar , Kerber Robert
Published: April 2003

Water soluble azo compounds of the structure 1a, b, 2a, b, 3, 4, and 5 decompose, depending on the substitution of the aromatic ring, in water already at room temperature. Therefore, they are useful initiators for solution and emulsion polymerisations in this temperature region. Reactions competing with thermolysis, as the formation of a hydrazone (pH>8) and ionic reactions with suitable reagents (phenols) are described.
Anthracene sensitized photooxidation of polystyrene, 1. Photochemical reactivity of anthracene in hexane solution
Authors: Nowakowska Maria
Published: April 2003

The photochemical reactivity of anthracene in hexane solution was investigated. A kinetic scheme of photochemical and photophysical processes occurring in the system irradiated with light at λ = 365 nm was proposed. The quantum yield of singlet oxygen generation in the system was estimated.
Absorption and luminescence spectra of halogen derivatives of poly(N‐vinylcarbazole)
Authors: Janowski Andrzej , Rzeszotarska Jadwiga , Pielichowski Jan , Ranachowski Jerzy
Published: April 2003

Absorption and luminescence spectra of halogen derivatives of poly(N‐vinylcarbazole) have been investigated in solution and solid films. The emission spectra in solution exhibit excimer phosphorescence only, whereas solid film spectra show excimer fluorescence only. Changes in the character of emission spectra on passing from solution to solid film are discussed.
Polymérisation et copolymérisation d'acétoxy‐2 alcadiènes‐1,3 – l'acétate de (cyclopentène‐1 yle)‐1 vinyle et l'acétate de (méthyl‐3 butadiène‐1,3) yle‐ 2 – formation des polycétones correspondantes
Authors: Bonnans‐Plaisance Chantal , Casals Pierre‐François , Levesque Guy
Published: April 2003

The polymerization of 1‐(1‐cyclopentenyl)vinyl acetate (1) and (3‐methyl‐1,3‐butadien‐2‐yl) acetate (7) under radical conditions, leading to 1,4‐polymers, and the copolymerization with vinyl monomers were studied. The reactivity ratios are compared with those previously described for some acetoxydienes. Polyketones and copolyketones were obtained by alkaline hydrolysis of the polymers of 1 and 7 and copolymers of 1 and 7 with styrene.
Synthèse et caractérisation de copolymères coordinés par des sels métalliques
Authors: Rietsch François , Bottiglione Vincent , Morcellet Joëlle
Published: April 2003

The anionic block copolymerisation of isoprene and 2‐vinylpyridine (2VP) followed by a coordination with iron (III) chloride, leads to thermoreversibly crosslinked copolymers. These copolymers are character+ed by a low polydispersity (M̄w/M̄w≈1,1) between the coordination nodules of poly(2‐vinylpyridine). The study of the swelling ratio at the equilibrium in benzene shows that such a polymeric network does not reach the equilibrium state expected from the thermodynamic analysis of the system. The presence of 2VP in the copolymer induces a screening effect which prevents the solvent diffusion through the polyisoprene network.
Influence of the nature of the blocks on the ordered structures of block copolymers
Authors: Douy André , Gallot Bernard
Published: April 2003

The structure of AB block copolymers with a polydiene block (polybutadiene or polyisoprene) and another block (polystyrene, poly(α‐methylstyrene)), poly(2‐vinylnaphthalene), poly(2‐vinylpyridine) or poly(4‐vinylpyridine) was studied by low angle X‐ray diffraction and electron microscopy. The influence of the nature of the non‐diene block (styrene, α‐methylstyrene, 2‐vinylnaphthalene), the nature and the microstructure of the diene block and the isomery of the vinylpyridine block on the parameters of the lamellar structure and the conformation of the macromolecular chains was established.
Polybutadiènes hydroxytéléchéliques, 2 Microstructure et fonctionnalité des polyméres obtenus par voie anionique. Etude par résonance magnétique nucléaire du proton et du carbon 13
Authors: Camberlin Yves , Pascault Jean Pierre , Pham Quang Tho
Published: April 2003

The examination, by 1H NMR, of anionic hydroxytelechelic polybutadienes in conjunction with accurately measured Mn values allows the simultaneous determination of the number average functionality and the identification of the nature of the chain ends bearing the functional groups. The microstructure of the polymer chains has been studied by 13C NMR. A high proportion of isolated vinyl units has been found only if the percentage of vinyl is less than 70%, whereas the vinyl sequences are atactic. During the functionalization, if lithium is utilized as catalyst, only one molecule of ethylene oxide is added at each end of the polymer chain. With potassium, ethylene oxide polymerizes. Owing to the chain ends, reaction mechanisms of the addition of ethylene oxide onto the living polymer have been proposed.
Formaldehyde polymers, 25. Copolymerization of 6,8‐dimethyl‐4‐oxo‐5‐chromanylmethyl acrylate with styrene, methyl methacrylate, and vinyl chloride
Authors: Ninagawa Akira , Tokunaga Yukio , Matsuda Haruo
Published: April 2003

The free radical copolymerizations of 6,8‐dimethyl‐4‐oxo‐5‐chromanylmethyl acrylate (DCA) with styrene (St), methyl methacrylate (MMA), and vinyl chloride (VC) by the solution polymerization method were studied. For copolymerization of DCA(M1) with St(M2), the reactivity ratios were r1=0,32, r2=0,70; with MMA(M2) they were r1=0,43, r2=2,00; and with VC(M2) they were r1=4,00, r2=0,08. The Q and e values for DCA were 0,54 and 0,42, respectively. It was also shown that the chromanone skeleton acts as UV‐absorber, and inhibits photodegradation of the copolymers.
Radical copolymerisation of vinylidene chloride and methacrylonitrile, 2. Sequence microstructure measured by 13C NMR
Authors: Suggate John R.
Published: April 2003

The radical copolymerisation of vinylidene chloride and methacrylonitrile (M) was studied in bulk, in cyclohexanone, in DMF, and in hexane. From 13C NMR spectra of the copolymers, the dyad and triad monomer sequences and some tetrad and pentad sequences were obtained. Copolymerisation in homogeneous solution showed no dependence on the solvent used (DMF and cyclohexanone). The heterogeneous bulk copolymerisation kinetics were very similar to those of copolymerisation in homogeneous solution, but significantly different from heterogeneous copolymerisation in hexane. The triad sequence distributions could be shown to fit a kinetic scheme incorporating penultimate effects on radical reactivities for copolymerisation from vinylidene chloride rich feeds. However, for copolymerisations from methacrylonitrile rich feeds this model fails because of a dependence upon monomer feed of the reactivity ratio for the ∼︁MM· radical; this might possibly be explained by the involvement of a monomer‐monomer charge‐transfer complex in the copolymerisation.
Kinetische und morphologische untersuchungen zur polymerisation von oxacyclischen monomeren im festen zustand, 5. Zur morphologie der während der sublimation von trioxan‐ und tetroxankristallen wachsenden polyoxymethylene
Authors: Muñoz‐Escalona Antonio
Published: April 2003

The polymerization and crystallization of polyoxymethylene obtained by sublimation of trioxane (1,3,5‐trioxane) and tetroxane (1,3,5,7‐tetroxocane) crystals was investigated. Electron microscopy techniques and thermal analysis were used to characterize the polymer crystals as produced and after annealing. The polyoxymethylene crystals resulting from tetroxane show a regular lamellar folded chain macroconformation similar to those previously reported by polymerization of tetroxane crystals chemically initiated. The polymerization follows a crystallization succeeding polymerization mechanism. Trioxane gives mainly fibrous crystals, showing well oriented electron diffraction diagrams and higher melting points, consisting mostly of extended chains. A “pseudolamellar” morphology was also observed, being established by annealing, that the chain directions are parallel to the edges of the crystals. The strange growing habit seems to be produced by disruption of the electrical field of the trioxane crystals by a water effect. The polymerization seems to follow mainly a simultaneous polymerization and crystallization mechanism. The initiation of the polymerization is in both cases due to the gaseous formaldehyde formed during sublimation.
On the copolymerization of acrylonitrile with styrene in the presence of Lewis acid, 2. Regulation of molecular weight
Authors: Bartoň Jaroslav , Werner Peter
Published: April 2003

The results of the study of the acrylonitrile (AN)‐sytrene (St) copolymerization in the presence of zinc chloride and various hydrogen donors (cyclohexane, octane, isooctane, and decahydronaphthalene) are reported. It was found that the rate of copolymerization (Rp) increases with concentration of the hydrogen donor at constant concentrations of comonomers in acetone in the presence as well as in the absence of a free‐radical source (AIBN). The dependence of the reciprocal value of limiting viscosity number (1/[η]) of the equimolar copolymers on Rp in the system StANZnCl2AIBN is not linear. The position of the minimum on this curve at a given ratio of comonomers depends on the concentration of both zinc chloride and AIBN. The reduction of [η] of the equimolar copolymer attained by the effect of hydrocarbon is relatively small provided the reaction system is homogeneous. On the basis of the results obtained, it may be stated that a change in molecular weight of the copolymer is to be achieved more easily by a change in the rate of copolymerization (effected by AIBN) than by the effect of hydrogen donor (chain transfer).
The terpolymerisation of styrene, methyl methacrylate and maleic anhydride
Authors: Dodgson Keith , Ebdon John R.
Published: April 2003

Application of the Alfrey‐Goldfinger equations to data from terpolymerisations of styrene, methyl methacrylate and maleic anhydride leads to values of the relative reactivity (R) of styrene and methyl methacrylate towards the maleic anhydride radical that are dependent upon the concentrations of the monomers in the feeds. It is shown that it is unlikely that this effect arises from the influence of maleic anhydride‐comonomer complexes but may indicate the importance of a penultimate group effect involving styryl radicals.
Differentialkalorimetrie (DSC) einiger monomerer und polymerer Azoverbindungen
Authors: Nuyken Oskar , Gerum Johannes , Steinhausen Rainer
Published: April 2003

Differential scanning calorimetry (DSC) was used for the determination of decomposition rate constants, activation energies, and reaction enthalpies of different monomeric azo compounds. In all cases, except for 2‐arylazo‐2‐nitropropanes the decomposition was found to follow first order kinetics. The amount of azo‐groups in polymeric azo compounds and their decomposition kinetics were determined by this method.
31P and 19F NMR spectroscopic studies on ring‐opening polymerization of 1,6‐anhydro‐2,3,4‐tri‐O‐benzyl‐β‐D‐glucopyranose by PF5 catalyst
Authors: Uryu Toshiyuki , Ito Katsuhiro , Kobayashi Ken‐Ichi , Matsuzaki Kei
Published: April 2003

In order to elucidate the catalytic behavior of phosphorus pentafluoride in the polymerization of anhydro sugars, 13P and 19F NMR spectra were measured on a reaction mixture of 1,6‐anhydro‐2,3,4‐tri‐O‐benzyl‐β‐D‐glucopyranose (LGTBE) and PF5 with different mole ratios in a temperature range of −40 to −80°C. In the 31P NMR spectrum measured at low temperatures, there was a total of 16 peaks, which consisted of a broad quintet, a septet, and a sharp quartet, being assigned to the PF4O‐group, to PF, and to POF3, respectively. These fluoro compounds were also determined by the 19F NMR spectrum of the reaction mixture. The concentration of PF ions was found to correspond to that of oxonium ions, which are assumed to be actual propagating species, by determining both the concentration of PF from 19F NMR spectrum and the degree of polymerization of 2,3,4‐tri‐O‐benzyl‐α‐D‐glucopyranan obtained. Formation of the PF5: LGTBE complex was observed from the 31P NMR spectrum of the polymerization system at −80°C, which exhibits a broad sextet as well as absorptions due to POF3, PF4O–, and PF. To confirm the PF5:LGTBE complex, the NMR measurement of the PF5: tetrahydropyran complex was carried out. A polymerization mechanism of LGTBE by PF5 catalyst is discussed on the basis of the NMR measurement of the polymerization system.
Darstellung von phenolischen verbindungen und phenol/formaldehyd‐polykondensaten mit ketoxim‐, aldoxim‐ oder 1‐methyl‐4‐hydroxyiminomethylpyridinium‐gruppen und deren wirkung auf parathion‐methyl® und verwandte verbindungen
Authors: Kämmerer Hermann , Hegemann Günter , Lotz Werner , Ritz Jürgen , Pachta Katharina , Müller Oskar
Published: April 2003

Thirteen low molecular weight oximes were prepared: one derivative of acetophenone (1), two derivatives of benzophenone (2 and 3), two derivatives of salicylaldehyde containing two phenolic nuclei (4c and 5c), and eight compounds in which a phenol unit is substituted by a 4‐hydroxyiminomethylpyridiniummethyl group (8a–f, 10c, and 11c). Besides these compounds polymeric phenol formaldehyde condensates were synthesized which contain units deriving from benzophenoneoxime (15b) or from salicylaldehyde (22b) and condensates containing 4‐hydroxyiminomethylpyridiniummethyl groups (23c). A series of low molecular weight and water soluble compounds (8a–f) were proved as antidotes on mice which were poisoned by paraoxon, sarin, soman, or tabun. These compounds showed a distinct but only a little antidote activity in the case of soman and tabun. Adsorption studies of parathion‐methyl in a solution of water and methanol (volume ratio 10:1) by the water insoluble polycondensates showed that the oximes adsorb better than the parent carbonyl products.
Calculation of macrocyclization equilibria for poly(ethylene terephthalate)
Authors: Suter Ulrich W. , Mutter Manfred
Published: April 2003

The cyclization equilibria constant Kx is evaluated for the formation of cyclic poly(ethylene terephthalate)s (PET) in the range of degree of polymerization 2 ≤ x ≤ 10 on the basis of an elaborated form of the Jacobson‐Stockmayer theory. According to this theory, Kx = W(0)·2Γ0(1)/(σcx NA), where W(r) is the probability density function for the chain vector r; Γ0(γ) is the probability distribution, when r = 0 of γ = cos Δθ; Δθ being the deviation of the bond angle formed by cyclization from its unconstrained value; σcx corresponds to the symmetry number of the ring; NA is Avogadro's number. The evaluation of W(r) is performed in different approximations. The required configurational averages for computing the density distribution W(r) and the angular correlation factor Γ0(1) are obtained by Monte Carlo techniques. The density W(0) of chain vectors at r = 0 is overestimated by the Gaussian approximation. Values of W(0) calculated in higher approximation lower Kx for x < 10.

By taking into account the oriental correlation between terminal bonds of the x‐meric acyclic sequence, Kx is lowered additionally by factors of ca. 2,2, 1,3 and 1,1 for x = 4, 5 and 6, respectively. Similar to other polymer chains treated so far, Kx is lowered for medium sized chain lengths by taking into account the deviation from Gaussian distribution and angular correlations of chain ends. This result is in contradiction to experimental data, which yield even higher Kx‐values than expected by the classical Jacobson‐Stockmayer theory for medium sized chain lengths. The inclusion of cis‐ester residues into the all trans‐ester PET chain only slightly reduces this discrepancy. Structural modifications of the PET chain during cyclization experiments are discussed as a rationale for the deviations from the present theory.
Cis‐trans double bond distribution in poly(1,3‐cyclopentylenevinylene); dependence on metathesis catalyst, cocatalyst, and additives
Authors: Ivin Kenneth J. , Laverty D. Theodore , O'Donnell James H. , Rooney John J. , Stewart Cecil D.
Published: April 2003

About one hundred samples of poly(1,3‐cyclopentylenevinylene) (2) were prepared by ring‐opening polymerization of norbornene using a variety of metathesis catalysts based mainly on WCl6 or MoCl5, with EtAlCl2, BuLi, Ph4Sn, and (CH2CHCH2)4Sn as cocatalysts, and with methyl acrylate, diethyl maleate or diethyl fumarate as additives. Ir, Re, V, and Os compounds were also used as catalysts. The double bond pair sequences, trans‐trans (tt), trans‐cis (tc) etc. were determined from the 13C NMR spectra of these samples and the ratios rt(=tt/tc) and rc(=cc/ct) examined as a function of the fraction of double bonds σc having cis structure. For σc up to 0,35 all polymers showed random distribution of cis and trans structures (rtrc = 1), corresponding to a single type of propagating species. Polymers having σc = 0,35–0,85 invariably gave rtrc ≥ 1, with values greater than 5 in some cases. It is proposed that steric crowding of the active site leads both to high values of σc and to restriction of rotation about the metal‐carbene bond of the propagating metalcarbene species, such as to give rise to kinetically distinct conformations which tend to regenerate their own kind on addition of monomer.
Analysis of isotactic polystyrenes obtained with butyllithium and alfin catalysts by carbon‐13 nuclear magnetic resonance spectroscopy
Authors: Kawamura Tokiji , Uryu Toshiyuki , Matsuzaki Kei
Published: April 2003

The 13C NMR spectra of polystyrenes, prepared by butyllithium (BuLi) sec‐butyllithium (sec‐BuLi), propyllithium (PrLi), or Alfin catalyst, were measured at 25,03 MHz and the tacticity of the polymers was determined. The formation of mixtures of predominantly isotactic and syndiotactic polymers with BuLi as catalyst in styrene‐water system was ascertained. With sec‐BuLi and PrLi, only atactic polymers were obtained in the same system. The mechanism of the formation of isotactic polymers is discussed. The polymer obtained by Alfin catalyst had stereoblock structure containing rather long isotactic sequences alternating with atactic ones.
Asymmetric sorbents based on mono‐ and diamines and resolution of racemates by ligand‐exchange chromatography
Authors: Kurganov Alexander A. , Zhuchkova Ludmila Ya. , Davankov Vadim A.
Published: April 2003

The asymmetric sorbents A, B, C, and D were prepared by interaction of a chloromethylated styrene copolymer of the isoporous macronet type (5,5% of crosslinks) with the chiral amines (S)‐1‐phenylethylamine, (R)‐1,2‐propanediamine, and their derivatives. Resins A and B, based on 1‐phenylethylamine, do not sorb Cu(II) ions, whereas resins C and D, based on 1,2‐propanediamine saturated with Cu(II) ions, were successfully used for ligand‐exchange chromatography of amino acids, showing higher affinity to aminodicarboxylic acids than to diaminocarboxylic acids. Sorbent D displays an enantioselectivity of α ≥ 1,5 towards amino acids like Ala, Abu, Ser, or Lys and provides quantitative resolution of enantiomers of some other amino acids. L‐amino acids are retained longer by resins C and D than D‐isomers.
Diffusion of p‐nitroaniline in poly(tetramethylene oxide)‐poly(tetramethylene terephthalate) block copolymers
Authors: Masuko Toru
Published: April 2003

Diffusion coefficients of p‐nitroaniline in poly(tetramethylene ether)glycol terephthalate‐poly(tetramethylene terephthalate) (4GT) block copolymers, containing 4GT wt fraction of 0,345, 0,514, and 0,712, have been determined from sublimative desorption kinetics in the range from 60 to 120°C. The temperature dependence of diffusion coefficients in each diffusion system has been found to be a Williams‐Landel‐Ferry (WLF) type. When the glass transition temperatures (Tg) of the soft segments are selected as reference temperatures, the WLF parameters of C and C in the case of diffusion at temperatures above Tg+100 K can be obtained from a new method, proposed in the present paper, on the basis of Fujita's expression of diffusion coefficient in terms of free volume. Parallel studies of dynamic mechanical properties of these copolymers and the assumption of iso‐free volume state at Tg provide the values of free volume parameters of Bd and expansion coefficients of free volume. Both the quantities so obtained decrease to a small extent with increasing 4GT wt fraction. Alternatively, the temperature dependence of diffusion coefficients in the present study can be expressed exactly by Arrhenius plots. The activation energies of diffusion based on Eyring's rate processes are almost independent of, but the activation entropies decrease significantly with, increasing 4GT wt fraction. An expression of the latter in terms of the free volume parameters is presented.
Crosslinking statistics, 2. Relative reactivities of amylose hydroxyl groups
Authors: Luby P. , Kuniak Ľ.
Published: April 2003

Reproducibility of crosslink distribution in polysaccharides crosslinking depends on the homogeneity of the reaction mixture. If the condition of reaction homogeneity is met, the distribution of substituents (or crosslinks) should directly determine the relative reactivities of the functional groups. The resulting molecular size distribution of fragments of monosaccharide units connected by crosslinks in such a case should be given by the statistical laws of network formation. This principle is exemplified on amylose crosslinked by epichlorohydrin in a homogeneous water‐alkali medium. The relative reactivities of functional groups are investigated in two ways: (1) by specific reactions; (2) calculated theoretically from the molecular size distribution of fragments of crosslinked glucose units. Good agreement of both results supported the above mentioned assumptions. The reactivity of amylose hydroxyls increases strongly in the order OH‐3<OH‐6<OH‐2.
Synthesis and polymerization of methacryl esters having two kinds of nucleic acid bases
Authors: Hattori Masahira , Shimoda Mitsuo , Kinoshita Masayoshi
Published: April 2003

Methacrylic acid esters having two different and same kinds of nucleic acid bases such as theophylline‐theophylline, theophylline‐thymine, theophylline‐uracil, and uracil‐uracil, were synthesized, and polymerized in DMF or DMSO at 70°C using 2,2′‐azoisobutyronitrile as an initiator. The polymers obtained were found to have molecular weights in the range of about 1800‐4000, according to vapor pressure osmometr y and gel filtration measurement. The white powdery polymers were soluble in DMSO, DMF, and trifluoroacetic acid, but insoluble in water, alcohols, and common organic solvents.
Polybutadiènes hydroxytéléchéliques, 3. Silylation des fonctions alcool des polybutadiènes hydroxytéléchéliques radicalaires et détermination de la fonctionnalité moyenne en nombre par 1H NMR
Authors: Fages Geneviève , Pham Quang‐Tho
Published: April 2003

A number of hydroxytelechelic polybutadiene samples were silylated. The completeness of the silylation reaction allows the determination of the number average functionality by continuous wave 1H NMR. The protonated groups of the silylated alcohol functions were identified at 100 and 250 MHz. It is observed that these three primary alcohol functions do not have the same reactivity towards hexamethyldisilazane as silylating agent.
Synthesis and studies of some organic poly(ammonium phosphate)s, 1
Authors: Vyas Prakash C. , Oza Chandra K. , Sharma Ravi S. , Jain Kailash C.
Published: April 2003

Long chain organic poly(ammonium phosphate)s (1a–g and 2) were prepared by a precipitation technique by reaction of poly(lithium phosphate) with organic ammonium salts. Their compositions were established by nitrogen and phosphorus analyses and their polymeric nature was confirmed by molecular weight determinations via end group titrations and by the viscosity method. Studies of conductance at different concentrations indicated their polyelectrolytic behaviour. Paper chromatographic studies supplied additional evidence of a long chain polymeric structure, like Graham's salt and poly(lithium phosphate).