bluuebunny/crossref_metadata_2025 huggingface dataset:
Functional polymers and sequential copolymers by phase transfer catalysis, 27. Synthesis of aromatic‐aliphatic polyformals by polyetherification of 1,4‐bis(chloromethoxy)butane with 4,4′‐isopropylidenediphenol
Authors: Shaffer Timothy D. , Antolin Katherine , Percec Virgil
Published: April 2003

The first examples of aromatic‐aliphatic polyformals were synthesized from 4,4′‐isopropylidenediphenol (2) and 1,4‐bis(chloromethoxy)butane (1) by a two‐phase (aqueous NaOH/toluene), phase transfer catalyzed (PTC) polyetherification. The influence of the reaction conditions upon the polymerization was studied by varying the phase transfer catalyst concentration, NaOH concentration and nucleophile to electrophile ratio. Changes in these parameters and their effects upon the microstructure of these polymers were also examined by 1H NMR (200 MHz) spectroscopy. The reactivity of 1 has permitted, according to our knowledge, the first examples of interfacial polyetherification. Further, this reactivity has also permitted the homopolymerization of 1 through its hydrolysis byproducts under PTC conditions.
Synthèse de composées photoréticulables, 7. Télomères des acides acrylique et méthacrylique gréffés par méthacrylate d'époxy‐2,3 propyle
Authors: Bauduin Gérard , Boutevin Bernard , Mistral Jean‐Pierre , Parisi Jean‐Pierre , Piétrasanta Yves
Published: April 2003

Telomers were prepared from acrylic or methacrylic acid and CCl3Br, C12H25SH, C18H37SH or C8F17C2H4SH by initiation with 2,2'‐azoisobutyronitrile. The transfer constant of CCl3Br and the thiols, which are about 0,03 and 0,5, respectively, were determined. These telomers were used as supports of photopolymerizable functions, which were introduced by grafting of 2,3‐epoxypropyl methacrylate, catalysed with dodecyldimethylamine. The reactions were followed by 1H NMR, elemental analyses, tonometrie, and especially by GPC and titration of the acid functions. The grafting telomers, holding many acrylic functions which react upon UV and electron irradiation, give photoreticulated varnish coatings with very interesting properties.
Effect of a grafted chain as spacer of an insoluble polymeric ligand on the adsorption behaviour and the influence on the catalytic activity of the Cu(II) complex
Authors: Arai Kenichiro , Ogiwara Yoshitaka
Published: April 2003

In order to investigate the effect of a grafted chain as spacer of an insoluble polymeric ligand on the adsorption behavior of metal ions, acrylonitrile was copolymerized with cross‐linked polystyrene beads, and the nitrile groups in the grafted polyacrylonitrile chain were reduced to amino groups which were substituted by reaction with chloroacetic acid. It was found that the conversion of the nitrile groups into amino groups decreases with increasing percentage of grafting. The adsorption behavior of Cu(II) by the polymeric ligand was examined and found to be improved by the introduction of the grafted chain as spacer. The catalytic activity of the complex of the polymeric ligand with Cu(II) in the decomposition of hydrogen peroxide was also examined and found to increase with increasing percentage of grafting.
Flow properties of concentrated solutions of polyarylate in m‐cresol
Authors: Zabala M Jesus , Santamaria Anton , Peña Juan J. , Muñoz M Eugenia
Published: April 2003

The flow properties of concentrated solutions of polyarylate from bisphenol A/50:50 isophthalic acid: terephthalic acid in m‐cresol are studied. The results are discussed in terms of critical concentration Cc and critical molecular weight Mc for the onset of entanglements. Values of Cc = 8,2 wt.‐% and Mc ≈ 3500 are obtained. The dependence of the Newtonian viscosities with temperature allows to obtain different energies of activation of flow for each polyarylate/m‐cresol system, ranging from 9 to 13 kcal/mol (= 37,7 to 54,4 kJ/mol). The following free‐volume‐additivity equation is proposed to fit these data:

where Ea, Eap, and Ead are the activation energies of the solution, the polymer and the solvent, respectively. Vp and Vd are the polymer volume fraction and the diluent volume fraction, respectively, and αp and αd represent the differences between the volume coefficients of expansion above and below the corresponding glass transition temperatures for the polymer and the solvent.
Zum einfluß von zwischenmolekularen Wechselwirkungen auf Die Polymerisation, 12. Copolymerisation von 2‐Naphthylmethacrylat mit Styrol in verschiedenen Lösungsmitteln
Authors: Boudevska Hrissanta , Bratschkov Christo , Todorova Olga , Braun Dietrich , Czerwinski Wojciech K.
Published: April 2003

A study of the copolymerization behaviour of 2‐naphthyl methacrylate (M1), with styrene (M2) was carried out at 60°C in solution with 2,2′‐azoisobutyronitrile as initiator and in different solvents. The following values for the monomer reactivity ratios were obtained by means of the Joshi‐Joshi method:

Chloroform: r1 = 0,16 ± 0,14, r2 = 0,81 ± 0,46

1,4‐Dioxane: r1 = 0,34 ± 0,09, r2 = 0,49 ± 0,39

Acetone: r1 = 0,54 ± 0,11, r2 = 0,63 ± 0,30

Acetonitrile: r1 = 0,24 ± 0,09, r2 = 0,39 ± 0,33

These results are in good agreement with those obtained by means of the Fineman‐Ross and Kelen‐Tüdős methods. The solvent effect is discussed in terms of charge‐transfer complexation between monomer and solvent molecules.
Copolymérisation radicalaire du méthyl‐4 styrène avec le méthacrylate de méthyle ou l'acrylonitrile. Détermination des rapports de réactivité
Authors: Lin Dar Jong , Petit Alain , Néel Jean
Published: April 2003

4‐Methylstyrene (S) was copolymerized with methyl methacrylate (M) or acrylonitrile (A) in benzene or N,N‐dimethylformamide solution, respectively. The reactions were carried out at 50°C, using 2,2′‐azoisobutyronitrile as free‐radical initiator. The copolymer compositions were determined from oxygen (SM) or nitrogen (SA) analysis, 100 MHz 1H NMR, and 25 MHz 13C NMR spectra. These methods lead to the same results. Data plotted according to the Kelen‐Tüdős (K‐T) procedure indicate that the copolymerization of S with M can be adequately described by the terminal‐unit model. The corresponding reactivity ratios (rS = 0,46 ± 0,02 and rM = 0,35 ± 0,02) were in good agreement with literature values and conform with the Q, e‐scheme. On the other hand, the K‐T plot for copolymerization of the SA system indicates deviations from the terminal model (rS = 0,27 ± 0,02 and rA = 0,10 ± 0,01) in the S‐ and A‐rich regions. This departure was interpreted in terms of penultimate effects on the reactivity of the S‐ and A‐ended radicals. The values of the corresponding reactivity ratios were as follows: rSS = 0,18 ± 0,03, rAS = 0,34 ± 0,04, rAA = 0,06 ± 0,01, and rSA = 0,13 ± 0,01. The theoretical curve of copolymer composition versus monomer feed, calculated with these parameters, is in excellent agreement with the experimental data. This finding shows that, on the basis of the composition data alone, the penultimate model provides an appropriate description of the copolymerization of S and A.
Poly(vinylsaccharide)s, 2 Synthesis of some poly(vinylsaccharide)s of the amide type and investigation of their solution properties
Authors: Klein Joachim , Herzog Dieter
Published: April 2003

The structure and synthesis of some poly(vinylsaccharide)s is described. Five different monomers, N‐saccharide‐substituted acryl‐and methacrylamides, were prepared and polymerized to high molecular weight products using different initiator systems. The influence of the chemical structure of the saccharide moiety on the solution properties was studied by viscosity and light scattering measurements, and a comparative discussion of the solution behaviour of poly(2‐deoxy‐2‐methacrylamido‐D‐glucose), poly(1‐deoxy‐1‐methacrylamido‐D‐glucitol), poly(1‐acrylamido‐1‐deoxy‐D‐glucitol) and polyacrylamide is made. The effects of hydrogenation on the intrinsic viscosity of poly(2‐deoxy‐2‐methacrylamido‐D‐glucose) is shown. The crosslinking of poly(1‐acrylamido‐1‐deoxy‐D‐glucitol) as a side reaction was examined by 13C NMR spectroscopy.
Preparative synthesis of guanylate‐rich fragments of the terminal sequence of macronuclear DNA from hypotrichous ciliates using the phosphotriester method in solution
Authors: Schott Herbert , Semmler Rolf , Cloß Knut , Eckstein Heiner
Published: April 2003

Guanylate‐rich oligodeoxyribonucleotides d(G4T4), d(T4G4), d(T4G4T4), d(G4T4G4), and d(T4G4T4G4) were synthesized in amounts up to 350 mg using the triester method in solution. These oligonucleotides correspond to fragments of the terminal of macronuclear DNA from hypotrichous ciliates. The protected oligonucleotides were obtained by block‐condensation of protected 5′‐hydroxyl and 3′‐phosphate derivatives. Mixtures of 2,4,6‐triisopropylbenzenesulfonyl chloride/N‐methylimidazole or 2,4,6‐trimethylbenzenesulfonyl chloride/N‐methylimidazole were used as condensating agents. Different concepts of protecting the nucleotides were investigated and it was found that yields and purities of the resulting oligonucleotides do not depend essentially on the employed concept. The 36mer d(G4T4G4T4G4T4G4T4G4) was obtained by enzymatic phosphorylation of aliquots of the dodecamers d(G4T4G4) and d(T4G4T4), followed by ligation with T4 DNA ligase.
Synthesis and characterization of liquid‐crystalline copolymers with dichroic dyes and mesogens as side groups
Authors: Ringsdorf Helmut , Schmidt Hans‐Werner , Eilingsfeld Heinz , Etzbach Karl‐Heinz
Published: April 2003

Liquid‐crystalline copolymers with covalently attached dichroic dyes were synthesized and characterized. Copolymers with high anthraquinone and trisazo‐dye content were obtained by copolymerization of dye monomers with 4‐cyanophenyl 4‐(6‐acryloyloxyhexyloxy)benzoate (1) and 6‐acryloyloxyhexyl 4‐(trans‐4‐propylcyclohexyl)benzoate (2). Particular attention is given to the influence of the dye content and the dye structure on the liquid‐crystalline behavior of the copolymers.
Synthesis and characterization of vinyl monomers with blocked isocyanato groups
Authors: Sadoun Tahar , Clouet Gilbert , Brossas Jean
Published: April 2003

Vinyl monomers containing blocked isocyanato groups were prepared in one step, by blocking the isocyanato group of 2‐isocyanatoethyl methacrylate with phenol, propanone oxime, butanone oxime, benzophenone oxime or ε‐caprolactam, or in two steps, by blocking one of the two isocyanato groups of 4‐methyl‐1,3‐phenylene diisocyanate with phenol or ε‐caprolactam and the second group with 2‐hydroxyethyl methacrylate. The 1H NMR and the IR spectra of these monomers are discussed.
Electrochemical and chemical syntheses and doping of [poly(2,2′‐dithienyl)‐5,5′‐diylvinylene]
Authors: Bragadin Marcantonio , Cescon Paolo , Berlin Anna , Sannicolò Franco
Published: April 2003

The electroconductive polymer poly[(2,2′‐dithienyl)‐5,5′‐diylvinylene] (1) was prepared by both electrochemical and chemical methods starting from trans‐di(2‐thienyl)ethylene (2). The electrochemically prepared material showed electrical conductivities of up to 40 Ω−1 · cm−1; the neutral, chemically prepared polymer was droped with iodine or arsenic pentafluoride but the conductivities were low. The experimental procedures are described and an interpretation of the results is given.
Synthesis, structure, and phase behaviour of liquid‐crystalline rigid‐rod polyesters and polyamides with disc‐like mesogens in the main chain
Authors: Ringsdorf Helmut , Tschirner Peter , Hermann‐Schönherr Otto , Wendroff Joachim H.
Published: April 2003

Aromatic polyesters and polyamides with disc‐like mesogens in the main chain were prepared from tetra‐substituted hydroquinones and derivatives of 1,4‐phenylenediamine. Depending on the atomatic acids (terephthalic acid, 2,5‐dialkoxyterephthalic acid) used in the condensation reaction, the repeating units of these polymers carried 4 or 6 lateral substitutents. All polymers are highly soluble in several organic solvents, e.g. CHCl3, toluene, acetone. The phase behaviour of the polymers was studied by means of differential scanning calorimetry and optical polarizing microscopy. Depending on the number of lateral substitutents the polyesters and polyamides show crystalline and thermotropic liquid‐crystalline phases. X‐ray investigations showed a board‐like Packing of the rigid‐rod polymers which we have termed as a “sanidic” (meaning board‐like) phase.
Thermoelastic and photoelastic properties of crosslinked liquid‐crystalline side chain polymers
Authors: Gleim Wolfgang , Finkelmann Heino
Published: April 2003

Measurements of stress and birefringence of crosslinked liquid‐crystalline side chain polymers are reported. The results are compared with those obtained for conventional elastomers. It is found that the thermoelastic behaviour in the nematic state completely differs from that observed for common polymer networks due to the anistropic ordering of the mesogenic side chains. The retractive force in the nematic state is found to be independent of path, indicating that the nematic phase is a homogeneous phase. Photoelastic investigations prove the propotionality of stress and birefringence above the clearing temperature Tc which is similar to common elastomers. The stress‐optical coefficient, however, strongly depends on temperature in the pretransformation region. X‐ray measurements show a uniform orientation of the mesogenic side groups in the nematic state. The diffraction patterns observed contain many more reflexes than observed for common nematics.
Structural study of compounds modelling elementary polymer units, 4. Molecular and crystal structures of three isomers of 4,4′‐bis(x‐hydroxyphenoxy)octafluorobiphenyl
Authors: Lindeman Sergey V. , Struchkov Yury T. , Malichenko Boris F. , Shklover Valerii E. , Vasnev Valerii A. , Kameneva Tatiana M. , Sheludko Evgenii V.
Published: April 2003

The paper presents an X‐ray study of the isomers 4,4′‐bis(2‐hydroxyphenoxy)‐, 4,4′‐bis(3‐hydroxyphenoxy)‐, and 4,4′‐bis(4‐hydroxyphenoxy)octafluorobiphenyl, which are used as monomers in the synthesis of polyarylates. The molecular packing in crystals is characterized by intermolecular H‐bonds, donor‐acceptor and stacking interactions between the benzene rings of adjacent molecules, which results in considerable distortion of the molecular geometry. Notably, bending of biphenyl fragments accompanied by distortion of benzene ring planarity was observed, along with unusual conformations of oxydiphenylene fragments and distortions of bond angles at ipso‐carbon atoms bonded to ether oxygen atoms.
Anionic block polymerization of β‐lactones initiated by potassium solutions, 1. Synthesis of poly(4‐methyl‐2‐oxetanone‐block‐2‐oxetanone)
Authors: Jedliński Zbigniew , Kowalczuk Marek , Kurcok Piotr , Brzoskowska Lilianna , Franek Jan
Published: April 2003

The block polymerization of 4‐methyl‐2‐oxetanone (β‐butyrolactone) with 2‐oxetanone (β‐propiolactone) proceeds fast with a yield of more than 90%, in the presence of potassium solutions in THF containing 18‐crown‐6. Poly(4‐methyl‐2‐oxetanone‐block‐2‐oxetanone) polymers having the expected molecular weight and composition are formed by this way. Their glass transition and melting temperatures as well as their melting enthalpies, determined by DSC, show a strict correlation with block polymer composition.
Synthèse de composéas photoréticulables, 8. Réaction des téalomères du méthacrylate d'époxy‐2,3 propyle avec l'acide acrylique et cinnamique
Authors: Boutevin Bernard , Piétrasanta Yves , Parisi Jean Pierre
Published: April 2003

The addition reaction of methacrylic acid (6) to the telomer 3, resulting from 2,3‐epoxypropyl methacrylate (1) and dodecanethiol (2), (DPn = 6) was studied. The percentage of addition at 60°C was found to be 32 after 24 h. When using an epoxide/methacrylic acid mole ratio of 2:1 Products were obtained which can easily be crosslinked by UV irradiation and which stick to aluminium to give water‐resistant products.
Investigation of the polymerization mechanism of 4′‐methylenespiro[2‐benzofuran‐2,2′‐(1,3‐dioxolane)]
Authors: Pan Cai‐Yuan , Lu Shao‐Xiang , Bailey Wiliam J.
Published: April 2003

The propagation reaction of 4′‐methylenespiro[2‐benzofuran‐2,2′‐(1,3‐dioxolane)] (2), initiated by a free radical initiator, was studied by analysis of the polymer structure and by kinetic investigation. The results indicate that the polymer has the structure of poly [methylene‐spiro[2‐benzofuran‐2,2′‐(1,3‐dioxolane)]‐4′‐ylidene‐co‐(2‐oxotrimethylene)] (10). A reasonable propagation mechanism is proposed.
Studies on formaldehyde resins, 25. Kinetic study on the hydroxymethylation of melamine by means of HPLC
Authors: Yoshii Toshio , Konakahara Takeo , Sato Kenji
Published: April 2003

The kinetics of hydroxymethylation of melamine (2,4,6‐triamino‐1,3,5‐triazine) with formaldehyde to form N‐(hydroxymethyl)melamine (2,4‐diamino‐6‐hydroxymethylamino‐1,3,5‐triazine) was investigated in aqueous hydrogen phosphate/phosphate buffer solutions in the range of pH 10,51 to 12,20 at 20°C, determining unreacted melamine by means of HPLC. As a result, this reaction is subject to a general base catalysis, and the second order rate constant k is expressed by k = k′ + kA − [A−] + k[A−]2/[HA] (or k [A−][OH−]), where HA and A− denote acid and basic constituents of the buffer, and k′ is the rate constant in unbuffered media. This rate equation is compared with those reported previously.
The laser‐flash‐initiated polymerization as a tool of evaluating (individual) kinetic constants of free‐radical polymerization, 2. The direct determination of the rate of constant of chain propagation
Authors: Olaj Oskar Friedrich , Bitai Irene , Hinkelmann Franz
Published: April 2003

When a polymerizable system is subjected to periodic light flashes, which induce the formation of primary radicals, a pseudostationary state is established which is characterized by a periodic profile of the (polymer) radical concentration. Within such a period of length t0 the radical concentration will decay according to a second‐order rate law. At the end of this period the radicals, which have escaped termination up to this moment, have propagated up to a chain length L0 = t0·kp·cM, kp representing the propagation rate constant and cM the monomer amount concentration. When the next flash arrives these radicals are opposed to a strongly increased overall concentration of radicals which leads to an enhanced probability for their termination. As a consequence the formation of dead polymer molecules with a chain length close to L0 is favoured. The chain‐length distribution of polystyrene prepared under such pseudostationary conditions, which was evaluated by gel permeation chromatography, in fact exhibits such a peak. The analysis of the theoretical distribution curves, derived in this communication, reveals that it is easily possible to correlate this peak to L0, independently of the mode of termination (disproportionation or combination). Thus, a method of evaluating kp is derived without any reference to the termination rate constant kt and largely independent of all features which usually cause problems in the evaluation of kp and kt (such as primary radical termination etc.). The experimental results agree fairly well with the data reported in literature, especially with those obtained from the number of particles and the rate of polymerization in emulsion systems.
Emulsion copolymerization of methyl methacrylate and ethyl acrylate, 2. Effect of emulsifier concentration and emulsifier blend composition on the polymerization behaviour
Authors: Capek Ignác , Bartoň Jaroslav , Tuan Le Quang , Svoboda Václav , Novotnýa Vlastimil
Published: April 2003

The free radical emulsion copolymerization of methyl methacrylate and ethyl acrylate initiated by ammonium persulfate at 60°C in the presence of a blend of anionic and non‐ionic emulsifiers was investigated. In the interval 2 the rate of copolymerization is approximately proportional to the 0,6th power of the total emulsifier concentration. The number of final polymer particles is proportional to the 0,5th power of the total emulsifier concentration. The dependence of the rate of copolymerization on the composition of the emulsifier system is described by a curve with a maximum at a mole fraction of non‐ionic emulsifier of about 0,5. The mean particle size keeps a constant value until the maximum of the polymerization rate is reached. Beyond this maximum the particle size abruptly increases (mole fraction of non‐ionic emulsifier ≈0,5). The rate of copolymerization, the conductivity and stability of the polymer latex increase, whereas the particle size and interfacial tension of latex and the number‐average molecular weight of copolymer decrease with increasing total concentration of the emulsifier blend.
Spectrophotometric and dichroic studies of poly(vinyl alcohol)‐iodine blue induced by boric acid and tartaric acid
Authors: Pal Medini Kanta , Pal Prasun Kumar
Published: April 2003

Boric acid induces blue colour with λmax at 670 nm in the poly(vinyl alcohol) (PVA)‐iodineiodide system. Tartaric acid (other hydroxy acids, H3PO4, NaH2PO4, NH4Cl, etc.) also induces blue colour with λmax at 590 nm. Unlike starch‐iodine blue, PVA‐iodine blue does not exhibit dichroism in the visible range; the latter system does neither induce chiral aggregation of dyes as done by starch‐iodine. The observed CD in the short UV range, the shape, sign, and [θ]‐values of which depend on the nature of the colour inducing agent as well as on the presence of dye, is interpreted to be induced from the asymmetric carbon atoms of PVA to which I is associated at random, as well as from the asymmetric carbon atoms binding an unhydrolysed acetoxy group present in commercial PVA.
Equilibrium polymerization initiated by polymer chains with active sites
Authors: Cai Gang‐feng , Yan De‐yue
Published: April 2003

According to the theory of multifunctional equilibrium polymerization, the two‐dimensional molecular weight distribution function for the equilibrated copolymers generated from polymer chains with active sites is derived. On this basis the average molecular weights, grafting ratio, grafting efficiency, grafting success, branching distribution, and frequency of grafts, etc. can be predicted from polymerization conditions.
Sequence and branching distribution of ethylene/1‐butene copolymers prepared with a heterogeneous Ziegler catalyst
Authors: Kuroda Nobuyuki , Nishikitani Yoshinori , Matsuura Kazuo , Miyoshi Mitsuji
Published: April 2003

Ethylene/1‐butene copolymers prepared with a heterogeneous titanium‐based catalyst were separated into five fractions by successive solvent extraction, and the triad distributions of each fraction were determined by 13C NMR measurements. Conditional probabilities (PEE, PEB, PBE, PBB), reactivity ratios (r1, r2), and persistence ratio (p) of each fraction were calculated from the triad distributions observed. The analysis of these values suggests that the heterogeneous Ziegler catalyst has multiple active sites, and the copolymer has nearly a Bernoullian sequence distribution.
Hydroxytelechelic polybutadiene, 11. Kinetics of dibutyltin dilaurate‐catalyzed addition reaction between a hydroxytelechelic polybutadiene and propyl isocyanate
Authors: Deschères Isabelle , Pham Quang‐Tho
Published: April 2003

Complexations of 1‐octanol (O) and propyl isocyanate (PI) by dibutyltin dilaurate (DBSnDL) were examined by 350 MHz 1H NMR. Whereas the 1:1 O/DBSnDL complex was easily evidenced, the behaviour of the mixture (1 PI + 1 DBSnDL) suggested slow formation of (a) relatively stable coordination compounds(s). The three alcohol functions of the hydroxytelechelic polybutadiene Arco‐R45M® were found to be equally catalyzed by DBSnDL in the addition with PI in toluene and in the bulk. Linear relationships between initial reaction rates and catalyst concentrations were found only for mole ratios [DBSnDL]/[Arco‐R45M]® < 0,06 and 0,1 in dilute solution and in bulk, respectively. (Acro‐R45M® + PI) additions catalyzed by DBSnDL follow 3rd‐order kinetics. The activation enthalpies and entropies calculated from kinetic data show that, compared to spontaneous addition, catalyzed reaction rates are less sensitive to temperature. Negative activation entropies suggest the existence of relatively stable transition states.
Synthesis of membranes for the dehydration of water‐acetic acid mixtures by pervaporation, 1. Polymer material selection
Authors: Nguyen Trong Q. , Essamri Azzouz , Clément Robert , Néel Jean
Published: April 2003

Poly(vinyl alcohol) (PVA) was studied for use as a basic material for membrane preparation with the aim of dehydrating water‐acetic acid mixtures. Membranes of different nature were made by blending a PVA sample of 96% hydroxyl content with a polyacid or a polybase counterpolymer in water, followed by complete evaporation. The PVA‐polybase blends gave membranes of low selectivity, unsuitable for dehydration. The membrane M5, made of a 1 : 1 (by wt.) blend of PVA with a special grade of polyhydroxycarboxylic acid (PHC1), presents a good combination of selectivity and permeability. It was studied in a water‐acetic acid mixture containing up to 10 wt.‐% of water. The Arrhenius‐type activation energy for the permeation was found to be 9,0 kcal/mol (38 kJ/mol).
Quenching of the excited state of membranes having polymerpendant tris(2,2′‐bypyridine)ruthenium(II) groups by methylviologen and dioxygen
Authors: Kaneko Masao , Nakamura Hideki
Published: April 2003

Quenching of the excited state of copolymer‐pendant Ru(bpy) membranes by methylviologen (MV2+) and dioxygen was studied and its application proposed. The copolymers used were the copolymer of styrene (St) and 4‐methyl‐4′‐vinyl‐2,2′‐bipyridine (Vbpy) and that of methyl methacrylate (MMA) and Vbpy. The copolymer‐pendant complexes were prepared by reaction of the St‐ and MMA‐copolymers with cis‐Ru(bpy)2Cl2. The excited state of the St‐copolymer complex membrane was not quenched by MV2+ solution in aqueous medium, but quenched in methanol. The excited state of the MMA‐copolymer complex membrane was not quenched by MV2+ neither in water nor in water/methanol mixture. The excited state of St‐copolymer complex membrane was not quenched by dioxygen in water, but in methanol. The excited state of MMA‐copolymer complex membrane was quenched by dioxygen both in water and water/methanol mixture. The quenching by dioxygen can be used to measure the oxygen concentration in solutions.
Chloro‐ionenes from dichlorides and tertiary diamines
Authors: Bortel Edgar , Kochanowski Andrzej
Published: April 2003

Five new ionenes were synthesized from tertiary diamines and dihalides. For comparison, four bromo‐ionenes were also prepared. Due to a lower C‐Br bond energy the bromo‐ionenes can be prepared from alkylene dibromides and tertiary diamines, whereas in case of chloroionenes the presence of electronegative atoms or groups of atoms in the dichlorides proved to be the condition to ensure reaction under moderate conditions. The highest initial reaction rates and lowest energies of activation (27,2–35,5 kJ/mol) were observed in runs with 1,3‐dichloro‐2‐propanon (1). Similarly, bis(2‐chloroethyl) ether (2a) proved to be a convenient dihalide for the formation of chloro‐ionenes, displaying reactivities comparable with those of 1,6‐dibromohexane. All reaction orders referring to the preparation of bromo‐ionenes investigated, were found to be about 2, whereas the formation of chloro‐ionenes is first order. In case of bromoionenes the energies of activation were higher (66,7–79,8 kJ/mol) than in the case of chloroiones (27,2–51,8 kJ/mol). The structure of tertiary diamines plays an important role as far as their basicity is concerned, influenced by resonance conjugation, which is the case with Michler's ketone (5) as well as with tetramethylurea (6). The ionenes resulting from the dihalides and tertiary amines proved to be oligomers.
Structure of active centers and mechanism of anionic and cationic polymerization of δ‐valerolactone
Authors: Hofman Andrzej , Slomkowski Stanislaw , Penczek Stanislaw
Published: April 2003

The determination of the structure of the end groups in poly(δ‐valerolactone) (poly(δVL)) by using 1H, 31P NMR, and IR spectroscopy showed that in the cationic polymerization of δVL, propagation proceeds via cyclic dialkoxycarbenium ions as active species and the monomer molecules are incorporated into the polyester chains by an alkyl‐oxygen bond scission. In the anionic polymerization of δVL, propagation proceeds via alcoholate anions and monomer molecules are added with breaking the acyl‐oxygen bond. A similar cationic mechanism operates with alkylating ((CH3)2I⊕SbF6⊖) and acylating (CH3CO⊕SbF6⊖) initiators. However, with the latter, the cyclic dialkoxycarbenium active centers coexist with the acylium cations during the initial period of polymerization. Finally, however, the cyclic dialkoxycarbenium ions become the only active species. The mechanisms of ionic propagation in the polymerization of β‐propiolactone, δ‐valerolactone, and ε‐caprolactone are compared.
Polymerisationsauslösung mit substituierten Ethanen, 10. Kinetik der Polymerisation von Styrol
Authors: Bledzki Andrzej , Braun Dietrich , Titzschkau Klaus
Published: April 2003

The rate of the free radical polymerization of styrene with substituted ethanes as initiators is characterized by a competition of “normal” and primary radical termination. With decreasing initiator concentration the reaction order with respect to monomer and initiator changes in favour of a normal termination. The kinetics of this polymerization process is derived and compared with experimental results.
Untersuchungen über Poly(arylenvinylene), 30. Synthese, Photoleitfähigkeit und Redox‐Verhalten von Poly(9‐methylcarbazol‐3,6‐diyl‐1,2‐diphenylvinylen)
Authors: Hörhold Hans‐Heinrich , Räthe Harald , Helbig Manfred , Opfermann Johannes
Published: April 2003

Soluble poly(9‐methylcarbazole‐3,6‐diyl‐1,2‐diphenylvinylene) (1) Mn = 10000, was prepared by dehalogenating polycondensation of 3,6‐bis(α,α‐dichlorobenzyl)‐9‐methylcarbazole with chromium(II) acetate. The monomer was obtained from 3,6‐dibenzoyl‐9‐methylcarbazole by reaction with PCl5. The chemical structure of 1 was verified by elemental analysis, UV, IR, and NMR spectroscopy, GPC, and VPO. 1 was found to be highly photoconducting, exhibiting a dark conductivity of 10−14 S/cm, which increases on doping with AsF5 to 10−4 S/cm. Its thermal stability under nitrogen is as high as with other phenylsubstituted poly(arylenevinylene)s (dec. temp.: 540°C; residue: 72 weight‐%). The spectral distribution of sensitized (TNF, dyes) photoconductivity was studied and the redox behaviour was investigated by cyclovoltammetry. The redox potentials were found to be E = 0,90 V and E = −2,07 V (vs. Ag/AgCl). The electrochemical oxidation is reversible, associated with the formation of polydications derived from chain segments which consist of two carbazolediylvinylene units. Thus, 1,2‐dicarbazole‐3‐yl‐1,2‐diphenylethylene as model compound well reflects the redox properties of the polymer. The electrochemical band gap energy was found to be 2,97 eV, which agrees closely with the energy of the optical absorption edge of 3,04 eV.
Macromonomer synthesis. New functionalization methods
Authors: Gnanou Yves , Rempp Paul
Published: April 2003

So far, the syntheses of macromonomers by end‐capping of “living” anionic polymers with unsaturated electrophiles, were not always quantitative. Now, we found that macromonomers with unsaturated end groups can be smoothly prepared with quantitative yields from ω‐hydroxy‐poly(ethyleneoxide)s (PEO) applying methods of peptide synthesis. The intermediate PEO with carboxylic, p‐toluenesulfonate or chlorocarbonyl end groups were prepared with quantitative yields. They were transformed into the 4‐vinylphenyl substituted PEO macromonomers by reaction with 2‐(4‐vinylphenyl)ethanol or 4‐vinyl‐aniline, in quantitative yields, in the presence of dicyclohexylcarbodiimide and 1‐hydroxybenzotriazole or triethylamine, respectively. PEO with methacryloyl end groups were prepared from ω‐hydroxy‐PEO and 2‐isocyanato ethyl methacrylate. The resulting macromonomers were characterized by determination of the double bond content and by 1H NMR spectroscopy.
Ein Modell zur Beschreibung reversibler Copolymerisationen
Authors: Krüger Hartmut , Bauer Jörg , Rübner Joachim
Published: April 2003

The reversible copolymerization is described by a model derived from simple kinetic assumptions. The copolymerization behaviour of a system can be calculated from 3 experimental parameters: composition of the monomer mixture, composition and diade distribution of the copolymer. Four additional model constants represent the connection with the thermodynamics of reversible copolymerization. The model leads to the same results as the Monte‐Carlo method described in the literature. The temperature dependence of reversible copolymerizations can be simulated by the model with the thermodynamic values of the four elementary reactions.
Application of the penultimate model in the copolymerization of styrene with maleic anhydride in ethyl methyl ketone at 50°C
Authors: Brown Anthony Stuart , Fujimori Kiyohisa
Published: April 2003

Composition data for the copolymerization of styrene with maleic anhyride in ethyl methyl ketone at 50°C were obtained using a non‐aqueous potentiometric direct titration method, and were analysed using a non‐linear least squares optimization routine. Three variants of the penultimate model were fitted to the data: the four variable model (completely general), the three variable model (rmm = 0,0) and the more usual two variable model (rmm = rsm = 0,0). Of these, the two variable model was adequate to describe the data. Best estimates of the reactivity ratios for data previously reported in the literature were calculated, and in one case the best values were markedly different to those originally given.
Crystallization, morphology, and thermal behaviour of ethylene/propylene copolymers
Authors: Greco Roberto , Mancarella Carlo , Martuscelli Ezio , Ragosta Giuseppe , Yin Jinghua
Published: April 2003

The morphology and the texture of thin films of ethylene/propylene copolymers with crystallizable polypropylene blocks was investigated by optical and electron microscopy as a function of both molecular composition and crystallization conditions. The thermal and melting behaviour was also studied. It was found that variables such as the observed melting point as well as the enthalpy and the entropy of fusion are composition dependent. Contrary, the equilibrium melting temperature seems to be invariant with composition in agreement with the block type of the investigated copolymers.
Immobilisierung von geschützten nucleosiden und mononucleotiden an funktionalisierte perlcopolymerisationsprodukte aus methylacrylat und 1,4‐bis(vinyloxy)butan
Authors: Schott Herbert , Bretzger Waltraud
Published: April 2003

Protected nucleic acid components were coupled to eight differently functionalized bead copolymers, prepared from methyl acrylate and 1,4‐bis(vinyloxy)butane, via amid‐, urea‐, phosphotriester‐ or carboxylic acid ester linkages. The immobilization was performed by methods used in nucleic acid chemistry. The obtained gels carry 1 to 300 μmol per gram of nucleoside or nucleotide derivatives. The yield of derivatization was found to be first of all determined by steric effects of the gel matrix, the size of the nucleic acid component and the route of synthesis selected. Anchor groups, arranged via long spacers, were not effective for the immobilization of nucleic acid components. A “carboxylate‐gel” which can immobilize 300 μmol per gram of a nucleoside derivative may serve as support in the solid phase synthesis of oligonucleotides in large scale.
Spectroscopic characterization of the chromic transition observed for polydiacetylenes
Authors: Coyne Laurence D. , Chang Chih , Hsu Shaw Ling
Published: April 2003

The chromic transition observed for polydiacetylene CHCl3/CCl4 solutions was found to be concentration dependent suggesting a need to reconsider the hypothesis that this transition is a single chain phenomenon. We also found that for some polydiacetylene solutions this chromic transition exhibits a significant amount of hysteresis for the cooling and heating cycles.
Cinétiques de télomérisation, 8. Détermination de la constante de transfert du phosphonate de diéthyle — effets de solvants
Authors: Bauduin Gérard , Boutevin Bernard , Pucci Bernard , Rigaud Jean‐Pierre
Published: April 2003

The transfer constant of diethyl phosphonate to vinyl acetate for free‐radical polymerization at 60°C in non‐aromatic solvents was found to be CT = 0,035. For aromatic solvents CT varies with the concentration of the solvent.
Translational diffusion of small molecules in polymers. Laser flash experiments with polydimethylsiloxanes
Authors: Tilley Mark , Pappas S. Peter , Schnabel Wolfram
Published: April 2003

The quenching of triplet‐excited acetophenone by naphthalene served as a probe reaction for studying the mobility of small molecules in polymeric matrices. The rate constants of the quenching process in polydimethylsiloxanes having weight‐average molecular weights between 3600 and 86000 were found to depend only slightly on the macroscopic viscosity η at constant temperature: kq ∝η −0,1. In the temperature range from 190 to 298 K (Tg = 152 K), the activation energy of the quenching reaction was determined as Eq = 15,1 kJ/mol, i.e. it is practically equal to the value of the activation energy of viscous flow. The high translational mobility of small molecules in very viscous polymeric matrices is explained on the basis of the concept of microviscosity according to which the trnaslational motion of small molecules in polydimethylsiloxanes at T > Tg is determined by the mobility of free volume elements due to segmental motions rather than by motions of the centers of mass of the macromolecules.
Chemical‐composition distribution of a diblock copolymer
Authors: Stejskal Jaroslav , Kratochvíl Pavel
Published: April 2003

The experimentally determined distribution of the chemical composition of styrene/butadiene block copolymers reported by Kuhn is compared with the results of a model calculation assuming that the constituent blocks have a gamma (Schulz‐Zimm) distribution of molecular weights and the ratios of weight‐ to number‐average molecular weights are M̄w/M̄n = 1,025 or M̄w/M̄n = 1,05. A good agreement is found between experimental and calculated distributions.
The effect of polymolecularity on the radius of gyration of stiff polymer chains
Authors: Petrus Vladimír , Bohdanecký Miloslav , Bareiss Rolf E.
Published: April 2003

The z‐average of the unperturbed mean‐square radius of gyration, 〈S2〉o,z, is calculated for polymolecular Kratky‐Porod worm‐like chains, commonly used to represent stiff polymer chains. Polymolecularity correction factors for the Schulz‐Zimm and logarithmic normal distribution functions are tabulated. By contrast with those for unperturbed random coils, they depend significantly on the chain length.
Monte‐Carlo‐simulation for the structure of copolymer molecules of chemical inhomogeneity of second type
Authors: Wittmer Paul , Schmitt Burghard J.
Published: April 2003

A method is discussed for Monte‐Carlo‐simulation of copolymer molecules with chemical inhomogeneity of the second type. The copolymer molecules are formed by a polyreaction with monomer addition without chain termination, e.g. in case of an anionic “living” polymerization. The reliability of the method was statistically tested with examples. The method allows a clear presentation of the copolymer molecules mentioned in the paper.
Polymerization of sodium 10‐undecenoate under irradiation of UV light
Authors: Arai Kenichiro , Sugita Junichi , Ogiwara Yoshitaka
Published: April 2003

The polymerization of sodium 10‐undecenoate (UA‐Na) under irradiation of UV light was found to proceed effectively in a certain concentration range of UA‐Na. Based on the viscosity behavior of UA‐Na aqueous solutions, the effective polymerization is related to the formation of a specific type of micelle, which enhances the rate of chain propagation by localization of the double bonds of UA‐Na molecules within the micelle core. Weight‐average (M̄w) and number‐average (M̄n) molecular weights of the polymer are in the ranges of 3400–1900 and 2350–1300, respectively, depending on the concentration of UA‐Na in the polymerization system. Distribution of the molecular weight of poly(UA‐Na) is rather narrow for a radical polymerization (M̄w/M̄n ≈ 1,4). It was found that the maximum amount of benzene soluble in the aqueous solution of poly(UA‐Na) is smaller than in the aqueous solution of UA‐Na, and that poly(UA‐Na) can solubilize benzene already at very low concentration.
New synthesis of polysulfide polymers: Kinetic study
Authors: Catala Jean‐Marie , Pujol Jean‐Marc , Brossas Jean
Published: April 2003

New polysulfide polymers were prepared by a new process from vinyl monomers, elemental sulfur, and sodium metal in THF. The kinetic study of the reactions at −40°C has shown that the overall process can be described by the competition between a slow reaction (initiation of the monomer by the alkali metal) and a fast reaction (deactivation of the carbanion formed by elemental sulfur). These reactions lead to the establishment of a carbanion stationary state. From this data, the orders of magnitude of the apparent deactivation rates of the different carbanions were obtained: ca. 105 1·mol−1·s−1 for the styrene carbanion and 103–104 1·mol−1·s−1 for the butadiene carbanion.
Synthesis and characterization of photoconductive polymers, 1. Synthesis of poly[2‐(9‐carbazolyl)ethyl vinyl ether], poly[2‐(9‐carbazolyl)ethyl 1‐propenyl ether], and their various copolymers with ethyl vinyl ether
Authors: Haque Shah A. , Uryu Toshiyuki , Ohkawa Haruki
Published: April 2003

2‐(9‐Carbazolyl)ethyl vinyl ether (1), a known vinyl monomer, was synthesized using a phasetransfer catalyst, and homopolymerized with BF3OEt2 or EtAlCl2.2‐(9‐Carbazolyl)ethyl 1‐propenyl ether (2) was synthesized by transetherification of ethyl 1‐propenyl ether with 9‐(2‐hydroxyethyl)carbazole in a yield of 34% as a mixture of 49% cis and 51% trans isomer. It was homopolymerized in 90% yield with EtAlCl2 in toluene at −25°C. Copolymerization of 1 or 2 with ethyl vinyl ether (3) were initiated with BF3OEt2 or EtAlCl2. The yields of copolymers were 78–93%, depending on the polymerization conditions. The solubility of both homo‐ and copolymers was found to be poor. The glass transition temperatures of poly(1‐co‐3) and poly(2‐co‐3) are much lower, than those of poly(1) and poly(2).
Studies in electroactive polymers, 3. Synthesis of cyclopentene/acetylene copolymers using metathesis catalysts
Authors: Farren Trevor R. , Amass Allan J. , Beevers Martin S. , Stowell Jonathan A.
Published: April 2003

Copolymers containing acetylene and pentenamer units were synthesized by sequential addition of cyclopentene and then acetylene to an active metathesis catalyst system. The formation of block copolymers was indicated by UV‐vis spectroscopy, gel permeation chromatography and infra‐red spectroscopy.
Moisture‐curable rubbers, 4. Moisture‐cure of chloroprene rubber
Authors: Yamashita Shinzo , Nakawaki Yuichi , Kidera Akinori
Published: April 2003

Chloroprene rubber (CR) was allowed to react with 3‐aminopropyltriethoxysilane (APS) and then cured by soaking in hot water. The moisture‐cured rubber showed a network‐chain density of 3,6·10−4 mol·cm−3 and a tensile strength at break of 10 MPa. The reaction of CR with APS was found to be a Menshutkin reaction. The activation energy and the frequency factor were 59 kJ·mol−1 and 4,3·104 l·mol−1·s−1, respectively.
Solution properties of poly(methyl methacrylate) in methyl methacrylate, 1. Viscosities from the dilute to the concentrated solution regime
Authors: Stickler Manfred , Panke Dietrich , Wunderlich Winfried
Published: April 2003

The viscosities of samples of poly(methyl methacrylate), PMMA, with narrow molecular weight distributions and with molecular weights in the range 1,75·104 < M̄w < 1,60.106 were measured in methyl methacrylate, MMA, as solvent at 20, 40, and 60°C in the dilute and in the semi‐dilute concentration regime. By extrapolation to zero polymer concentration the limiting viscosity numbers and therefrom the Mark‐Houwink‐Kuhn‐Sakurada parameters for PMMA in MMA were obtained. In addition, unperturbed dimensions were determined from dilute solution viscosity data. Together with some published results for more concentrated solutions of PMMA in MMA the viscosities of the semi‐dilute systems were analysed in terms of scaling theories. It was found that irrespective of temperature, polymer concentration, and molecular weight all data could be quite well fitted by a single master curve when the relative viscosity η/η0 was plotted as a function of the product of the intrinsic viscosity and mass concentration [η]·c. No sharp transitions between different concentration regimes were observed, however, and the scaling law exponents for the entangled solution are significantly higher than predicted by theory.
Fourier transform infrared spectroscopic study of polyacetylene, 2. Thermal isomerization kinetics and mechanism
Authors: Chen Zhongxin , Shen Zhiquan , Liu Min , Shi Mingxiao , Hummel Dietrich O.
Published: April 2003

Thermal isomerization kinetics of high Z (>90%) rare‐earth polyacetylene

IUPAC name: poly(vinylene).

was studied by Fourier transform infrared spectrophotometry in the temperature range of 354 to 443 K. The isomerization kinetics do not follow any simple kinetic reaction order; the apparent activation energy was determined to be 48,1 kJ·mol−1. The Z to E isomerization in polyacetylene is discussed in terms of a diradical two‐step mechanism.
Infrared spectra and crystallinity of isotactic poly(methyl methacrylate) and of its deuterated analogues
Authors: Schneider Bohdan , Štokr Jan , Spěváček Jiří , Baldrian Josef
Published: April 2003

Infrared spectra of partially crystalline and amorphous samples of isotactic poly(methyl methacrylate) (i‐PMMA), poly[methyl (α,α,α‐2H3)methacrylate] (i‐PMMA‐α‐CD3), poly‐[(2H3)methyl methacrylate] (i‐PMMA‐OCD3), and poly[(2H3)methyl (α,α,α,2,2‐2H5)methacrylate] (i‐PMMA‐D8) were measured. Infrared spectra of the pure crystalline forms of these substances were obtained by digital separation. It was found that in acetonitrile, CDCl3, and toluene solutions, i‐PMMA has the same conformational structure as in the amorphous state; conformational structures of crystalline i‐PMMA are not present in the solutions in measurable amounts.
Purity of liquid‐crystal polysiloxanes, 1. Isolation procedures
Authors: Nestor Gary , White Michael S. , Gray George W. , Lacey David , Toyne Kenneth J.
Published: April 2003

The removal of the alkene side‐chain precursor from liquid‐crystal (1.c.) polysiloxanes during their isolation by precipitation has been monitored by thin‐layer chromatography. The commonly used procedure involving only three precipitations has been shown to be frequently insufficient to remove the alkene completely from the 1.c. polymer. Using 8 to 10 precipitations and monitoring the removal of alkene to <0,1 wt.‐%, the resultant polymers have been found to have both higher glass transition temperatures and higher clearing temperatures; more consistent phase transition temperatures are also obtained from batch to batch.