bluuebunny/crossref_metadata_2025 huggingface dataset:
Ion‐trapping in cationic polymerization, 2. Relative rates of trapping and relative chemical shifts for structurally differing phosphines as trapping agents
Authors: Matyjaszewski Krzysztof , Penczek Stanisław
Published: April 2003

The reaction of ethyl trifluoromethanesulfonate with phosphines to form phosphonium salts was used as a model reaction for the “trapping” of the various propagating species by phosphines in the polymerization of THF and other cyclic ethers. In dichloromethane at 25°C, the values of the bimolecular rate constant ktr were determined for various phosphines. For (C6H5)3P:5.10−3 mol−1.l.s−1, for (C6H5)(CH3)2P:0,22 mol−1.l.s−1, for (C6H5)(n‐C3H7)‐(CH3)P:0,13 mol−1.l.s−1, and for (n‐C4H9)3P: 1,3 mol−1.l.s−1. It was found that the ratio ktr/ka (ka is the rate constant of the ethylation of THF by ethyl trifluoromethanesulfonate) changes from 40 for triphenylphosphine to 104 for tributylphosphine. Differences of chemical shifts, measured for various quaternary phosphonium cations differing in one substituent, were observed for ions with various substituents (e.g. based on parent methylpropylphenylphosphine).
Einfluß des temperns auf die negative thermische ausdehnung von polyethylen
Authors: Karl Veit‐Holger , Wolf Frank‐Peter
Published: April 2003

The linear thermal coefficient of expansion for high density polyethylene, extended to draw ratios λ = 8 to 16 is α = −24·10−6 K−1 at 20°C. This value results from the orientation of crystallites with an expansion coefficient αc = −12·10−6 K−1 and from stresses in the amorphous phase. Using the model of series coupling of crystalline and amorphous parts the value αam ≤ −50·10−6 K−1 is calculated for a crystallinity xv = 70%. From measurements of Young's modulus the fraction of tie‐molecules χtie = 0,4% of the sample is assessed and the expansion coefficient αtie = −90·10−6 K−1. Annealing of the samples leads to shrinkage while the density ρ increases slightly and the expansion coefficient α increases considerably. Samples annealed at temperatures closely below the melting point show a slight decrease of the density at 20°C but a value of α exceeding that of isotropic samples. This effect can be explained by preferred orientation of the crystal a‐axis in fibre direction as soon as orientation starts to break down.
13C NMR spectra of polymers made by ring‐opening polymerization of (±)‐endo‐5‐methylbicyclo[2.2.1]hept‐2‐ene using metathesis catalysts
Authors: Ivin Kenneth J. , Lam Luk‐Mui , Rooney John J.
Published: April 2003

A range of olefin metathesis catalysts has been used to prepare ring‐opened polymers of (±)‐endo‐5‐methylbicyclo[2.2.1]hept‐2‐ene (1), having cis double bond contents of 22–100%. The 13C NMR spectra of these polymers are interpreted in terms of TH, TT, HH, HT and tt, tc, ct, ccstructures (T = tail, H = head, referring to the methyl group orientation; t = trans, c = cis, referring to the double bond configuration). The fine structure of the olefinic region at 75 MHz indicates that the cis/trans double bond distribution is blocky when the cis content is more than 50%. The chemical shifts of the ring carbons indicate puckering of the cyclopentane rings. The cis relationship of the methyl carbon and the adjacent olefinic carbons causes an upfield shift in both cases.
Preparation and characterization of a polyacrylamide resin containing thiol groups. Study of the reversible Zn(II) fixation
Authors: Deratani André , Sebille Bernard
Published: April 2003

New resins (6) containing thiol groups within a hydrophilic matrix are described. They contain up to 3,6 mmol thiol groups per g of dry polymer and were prepared by thiolation, via thiolester group formation, of various crosslinked polymers of N‐acryloylaminomethylchloroacetamide (1c) which was synthetized. Their ability to extract Zn(II) ions was evaluated. The effects of contact time, pH, and complexing agents on the fixation reaction were studied. It was found that the equilibrium is reached in a few minutes, the optimal capacity at pH 6 being about 2 mmol Zn(II) per g. The fixation involves three reactions: two leading to thiol group complexation, the third being the retention by the amide function of the resin saturated with Zn(II).
Competition of addition and condensation polymerization at the thermal treatment of 4‐methacryloyloxybenzoic acid and 4‐acryloyloxybenzoic acid
Authors: Golova Ludmila K. , Amerik Yuri B.
Published: April 2003

The nature of the processes of the formation of macromolecules during the thermal treatment of 4‐methacryloyloxybenzoic acid (1) and 4‐acryloyloxybenzoic acid (6) was studied. It was shown, that during the thermal treatment of 1 at 250°C (above the ceiling temperature of the addition polymerization) only a condensation polymerization (polycondensation) takes place. In the case of 6 both addition and condensation polymerization are possible at these temperatures. The rigid chains of the resulting poly(oxy 1,4 phenylenecarbonyl) (3) are parallelized spontaneously and the corresponding ordered melt exhibits a liquid crystalline state. The rigid chain polymer 3 is formed too as a result of polymeranalogous transformations of the corresponding polymers poly[1‐(4‐carboxyphenoxycarbonyl)‐1‐methylethylene] (2) (from 1) and poly[1‐(4‐carboxyphenoxycarbonyl)ethylene] (7) (from 6).
Darstellung von oligothymidinphosphaten durch chemische partialhydrolyse von desoxyribonucleinsäure
Authors: Schott Herbert
Published: April 2003

The method of preparation of oligo(thymidine phosphate)s by chemical partial hydrolysis of herring sperm DNA is described. The DNA is degraded in three steps to a mixture of oligomeric thymidine phosphates. Homologeous thymidine phosphates of the series p(dT)1–6p; p(dT)1–7, (dT)1–7p; (dT)1–7 are isolated chromatographically from the partial hydrolysate in pure form on a preparative scale. The advantages and disadvantages of this new and simple method in comparison to complicated synthetic procedures are discussed.
Radiation polymerisation of solid trioxane at low doses
Authors: Atreyi M. , Kumar Surendra
Published: April 2003

Results obtained from experiments on the radiation polymerisations of solid trioxane done at dose rates one order higher but at a total dose much less than those used by earlier workers are presented. The irradiation of crystalline trioxane samples in air was done using 60Co γ‐rays at room temperature (20–30°C) followed by ‘post polymerisation’ at 55 ± 0,1°C for 24h. The polymer yield was found to increase with dose linearly initially at all dose rates and then passed through a maximum. The molecular weight versus dose curve also exhibited a maximum. Irradiation and ‘post polymerisation’ in nitrogen atmosphere did not affect the yield and molecular weight of the poly(oxymethylene) (POM) obtained, suggesting complete absence of free radical precursors in the initiation step. A comparison of the variation of the number of monomer molecules consumed per 100eV with dose obtained from the present data on ‘post polymerisation’ with that for Okamura's data on ‘insource polymerisation’ suggests that the mechanism of the two types of polymerisation is not the same.
Gel chromatographic fractionation of styrene oligomers
Authors: Sato Hisaya , Saito Kazuhisa , Miyashita Kiyoshi , Tanaka Yasuyuki
Published: April 2003

A series of styrene oligomers having propyl end groups was prepared by oligomerization of styrene with ethyllithium followed by termination with l‐bromopropane. The fractionation of the oligomers by molecular weight and into diastereomers was investigated by gel chromatography using a high resolution styrene‐divinylbenzene gel. The most suitable eluents for the fractionation were chosen by the study of the elution behavior of the oligomers using various eluents having different polarity. The fractionation by molecular weight was done with chloroform as eluent and the 2‐ to 11‐mers of styrene were collected with purities higher than 95%. The isolated 2‐ to 5‐mers were further separated into diastereomers using diisopropyl ether as an eluent. The dimer and the trimer were fractionated into pure diastereomers. The tetramer was separated into 6 diastereomers and the fractionation of the pentamer was also relatively successful.
Stereochemistry of a model reaction for the propagation reaction in the cationic polymerization of alkyl propenyl ethers
Authors: Matsuzaki Kei , Morii Hisayuki , Inoue Naoki , Kanai Taiichi , Higashimura Toshinobu
Published: April 2003

The stereochemistry of the acetal addition to alkyl propenyl ethers was investigated as a model reaction for the cationic polymerization of propenyl ethers. The diastereomers of the acetal adducts were identified by model compounds with similar structure. The modes of both double bond opening and monomer addition were determined. It was demonstrated that the mode of double bond opening is independent of the geometrical structure of the ethyl propenyl ether and mainly threo‐opening takes place, whereas the mode of monomer addition is dependent on the geometrical structure of the monomer.
Functional metal‐porphyrazine derivatives and their polymers, 6. Free radical polymerization initiated by Fe(III)‐phthalocyanine‐2,9,16,23‐tetracarboxylic acid
Authors: Shirai Hirofusa , Ishimoto Akio , Kamiya Nootaka , Hanabusa Kenji , Ohki Kosuke , Hojo Nobumasa
Published: April 2003

The polymerization of various vinyl compounds initiated by the Mt‐phthalocyanine‐2,9,16,23‐tetracarboxylic acid (Mt‐taPc, Mt = Fe(III), Co(II), Ni(II), and Cu(II)) was studied in aprotic polar solvents in the presence and absence of molecular oxygen. Fe(III)‐taPc only was found to initiate smoothly the polymerization of methyl methacrylate (MMA) in the presence of air in aprotic polar solvents by a free radical mechanism. The kinetics of the polymerization of MMA initiated by Fe(III)‐taPc were studied under air in dimethylformamide at 60°C. The rate of polymerization, Rp, can be expressed as Rp = k[Fe(III)‐taPc]0,5[MMA]1,5. From the data of electronic and ESR spectra of this polymerization system, the polymerization mechanism is discussed.
Polyimides derived from bismethylolimides, 3. Synthesis and properties of poly(imide‐urethane)s
Authors: Kurita Keisuke , Imajo Hidetomo , Nakada Tohru , Iwakura Yoshio
Published: April 2003

Poly(imide‐urethane)s having a methylene group between the imido and the oxycarbamoyl groups were synthesized by addition polymerization of bis(N‐hydroxymethyl)imides and diisocyanates in hexamethylphosphoric triamide. Properties of the resulting poly(imide‐urethane)s were studied in comparison with those of the corresponding poly(imide‐urethane)s having no methylene group. The resulting carbamic ester linkage was found to be much more stable against nucleophiles compared with the carbamic ester linkage without the methylene group. However, there appeared to be not much difference in thermal stability between these two kinds of linkages.
Macromers as intermediates for the synthesis of graft copolymers
Authors: Sierra‐Vargas Julio , Franta Emile , Rempp Paul
Published: April 2003

Free radical copolymerization of a macromer and a vinylic or acrylic monomer is a novel method of synthesis of graft copolymers. Each macromer unit gives yield to a graft. Accurate characterization of the samples obtained, especially by means of proton NMR, is possible. The distribution of the grafts along the chain is random. The overall molecular weights of the copolymers formed are low, however.
Reactive polymers containing pendant azetidine or azetidinium functions, 1. Synthesis of poly(acrylic ester)s and poly(methacrylic ester)s of 1‐alkyl‐3‐hydroxyazetidines and related azetidinium salts
Authors: Bogaert Yvan , Goethals Eric , Schacht Etienne
Published: April 2003

Trans‐esterification of methyl acrylate or methyl methacrylate with 1‐alkyl‐3‐azetidinols leads to the corresponding azetidinyl acrylates or methacrylates. These new monomers are polymerized by a free radical mechanism to polymers containing pendant azetidine functions. When these polymers are treated with a mineral acid or with a strong alkylating agent, such as dimethyl sulfate, water‐soluble polymers are obtained. An alternative route is to transform the monomer into the azetidinium salt form and to polymerize this salt in aqueous solution. Azetidinium ion containing polymers are stable at room temperature but cross‐link to insoluble materials above 120°C.
Initiation of 1,1‐diphenylethylene dimerization and isobutylene polymerization by TiCl4, AlBr3 and their mixtures in hydrocarbon solvents
Authors: Masure Michèle , Nguyen‐Anh‐Hung  , Sauvet Georges , Sigwalt Pierre
Published: April 2003

The initiation of the dimerization of 1,1‐diphenylethylene (DPE) by AlBr3 and TiCl4 in heptane at −30°C was studied spectrophotometrically. The yields of carbocations with respect to the concentration of metal halides were low and their absolute concentrations too small to exclude the possibility of cocatalysis by residual impurities. When TiCl4 was added to DPE/AlBr3/heptane (or AlBr3 to DPE/TiCl4), the second halide did not cause an increase of the carbocation concentration greater than when it was added first. TiCl4 alone was found to be no initiator for the polymerization of isobutylene and AlBr3 is only weakly active (lower rates than those observed by Marek et al. and very low conversions were obtained). HCl is an efficient cocatalyst with AlBr3. Mixtures of TiCl4 and AlBr3 gave rates several times higher than either compound separately, and complete conversions. The enhancement of isobutylene polymerization is probably not due to an activation of the initiation step since the same effect is not observed during the cationation of DPE. An alternative explanation, based on a stabilization of the active species and/or an increase of their reactivity, is proposed.
Gel permeation chromatography of polymer mixtures
Authors: Kok Chong Meng , Rudin Alfred
Published: April 2003

When mixtures of polymers are analyzed in a common gel permeation chromatographic solvent the peak elution volumes of both components are shifted with respect to their values at their nominal concentrations in the same solvent and column set. In this article a theory which has been applied previously to account for concentration effects of a single polymer in a GPC solvent is modified to predict peak elution volumes in polymer mixtures. The model invokes solvent‐solute interactions only and provides quantitative predictions of the behavior of mixtures of anionic polystyrene samples with other polystyrenes and with polybutadienes. There is no indication of polymer‐polymer repulsive effects except for polystyrene‐poly(methylmethacrylate) mixtures at relatively high concentrations.
Polymerization of propene to syndiotactic polymer: Effect of incomplete regiospecificity on propagation rate
Authors: Sacchi Maria Carmela , Rigamonti Ennio , Locatelli Paolo
Published: April 2003

The analysis of ethylene/propene copolymers prepared in the presence of a vanadium based syndiospecific catalyst, gives direct evidence that the syndiospecific propagation rate of secondary inserted propene is lower than the non‐stereospecific propagation rate of primary inserted propene.

The analysis of propene/1‐butene copolymers obtained with the same catalyst, confirms that regiospecificity and stereospecificity are nearly unaffected by 1‐butene units in the syndiotactic polymerization of propene.
Trifluoracetylierung von aminosäureestern und dipeptidestern mit N‐trifluoracetyl‐polyamid 66.
Authors: Tesch Helmut W. , Schulz Rolf C.
Published: April 2003

N‐Trifluoroacetyl‐Polyamid 66 (1) is used for the trifluoroacetylation of amino acid‐ and dipeptide esters. Advantages and limitations of the polymeric reagent compared with low molecular trifluoroacetylating reagents are discussed. A mixture of amino acid methyl esters can be converted by 1 to the N‐trifluoroacetyl derivatives, which are separated and identified by gas chromatography.
Über polymere koronanden auf der basis von 18‐krone‐6 enthaltenden vinylmonomeren
Authors: Manecke Georg , Krämer Andreas
Published: April 2003

Vinyl group containing derivatives of 18‐crown‐6 were synthesized and copolymerized with styrene and p‐divinylbenzene of p‐divinylbiphenyl. The selectivity of the alkali metal cation complexation of one of the polymers was investigated. The prepared polymers were applied as catalysts in several nucleophilic substitution reactions. The influence of the crosslinking agent as well as the degree of crosslinking on the catalytic activity of the polymers was studied.
13C NMR sequence analysis, 20. Stereospecificity of the polymerization of D,L‐Leu‐NCA and D,L‐Val‐NCA
Authors: Kricheldorf Hans R. , Mang Thomas
Published: April 2003

The copolymerization of D‐ and L‐Leu‐NCA as well as that of D‐ and L‐Val‐NCA was studied under various conditions. Even nonpolar solvents, such as diethyl ether or ligroin, used for the precipitation of the poly(D,L‐amino acid)s, were found to have an influence on yield and tacticity of the isolated polypeptides indicating that atactic polypeptides of low molecular weight may be soluble in these solvents. 13C NMR spectra of the isolated poly(D,L‐amino acid)s were measured in trifluoroacetic acid and the carbonyl signals were used for the evaluation of the teacticity. Under all reaction conditions only a moderate degree of stereospecificity was found. D,L‐Leu‐NCA initiation with protic nucleophiles, such as benzylamine or diethylamine, favors the formation of isotactic blocks. In the case of D,L‐Val‐NCA again isotactic blocks are slightly favored if benzylamine is used as initiator, while diethylamine, like other strong bases, causes preferred formation of syndiotactic sequences. With strong aprotic bases and electrophilic cocatalysts, i.e. under conditions favoring the “activated monomer mechanism”, the highest degrees of stereospecificity were observed. However, in the case of D,L‐Leu‐NCA isotactic blocks are predominantly formed, while in the case of D,L‐Val‐NCA syndiotactic blocks are favoured. Changing the solvent may result in a reversal sense of the stereospecificity. The absence of long isotactic blocks in all samples of this work was also demonstrated by the good solubility of all samples in various organic solvents.
Polymerisationsauslösung mit substituierten ethanen, 4. Kinetik der polymerisation von methylmethacrylat mit 1,1,2,2‐tetraphenyl‐1,2‐diphenoxyethan
Authors: Błedzki Andrzej , Balard Henri , Braun Dietrich
Published: April 2003

The polymerisation of methyl methacrylate (MMA) by 1,1,2,2‐tetraphenyl‐1,2‐diphenoxyethane is characterised by three steps: during the initial period oligomers from MMA and initiator radicals are formed by primary radical termination. These oligomers produce free macroradicals and initiator radicals by cleavage at the bonds between the last monomer unit and the end group from the initiator. After consumption of the initiator radicals with increasing conversion the normal propagation and termination processes occur. The kinetics derived from this reaction scheme is in good agreement with the experimental results.
Differentialthermoanalytische untersuchungen bei verschiedenen drücken an einer molekulargewichtsreihe von polyethylenoxiden
Authors: Altmeyer Andreas , Karl Veit‐Holger , Ueberreiter Kurt
Published: April 2003

Melt‐ and crystallization‐temperatures were measured of poly(ethylene oxide)s with increasing molecular weight and at various pressures up to 5 000 bar by differential thermal analysis (DTA). Both these temperatures increase with pressure and display a different molecular weight dependence below and above M ≈ 3 000. A similar behaviour is shown by the melt enthalpies, constants a and c of the Simon‐equation and by the undercooling ΔT.

The transition from a zig‐zag‐ to a helix‐structure found by various authors changes to higher molecular weights with pressure, whereas chain folding does not depend upon pressure. The pressure coefficient of the melting temperature and the undercooling as well as the chemical potential are investigated as functions of the molecular weight for poly(ethylene oxide).
Thermomechanical analysis of linear aromatic polyesters
Authors: Ng Tie Hwee , Leverne Williams H.
Published: April 2003

The thermomechanical properties of linear aromatic polyesters, studied using thermomechanical analysis techniques, have been related to the chemical structure and methylene chain length. An increase in the number of methylene groups, the use of an asymmetric diacid, or random copolymerization of the repeating units of these polyesters, resulted in a lower linear thermal expansion coefficient α, a lower Vicat softening temperature Ts, a lower heat deflection temperature Td, and a lower glass transition temperature Tg. With longer methylene sequence lengths, the influence of the methylene groups on the thermomechanical properties is predominant, the data are closer together. The values are generally highest for the terephthalate series and lowest for the copolymer series. Glass transition temperatures calculated from group contributions and measured experimentally agreed. The deflection temperatures approximated the glass transition temperatures and the Vicat softening points the melting temperatures.
Glass transition of styrene/n‐alkyl methacrylate copolymers
Authors: Podešva Jiří , Biroš Jan
Published: April 2003

Dependences of the glass transition temperatures (Tg) of copolymers of styrene (ST) with the n‐alkyl methacrylates [methyl, ethyl, butyl and octyl methacrylate (MMA, EMA, BMA, and OMA)] on their overall chemical composition were measured. All the dependences investigated in this study satisfy the dyad approximation suggested earlier for the description of the sequential distribution effect on Tg of the copolymer either (1) using reciprocal Tg's and weight fractions of the dyads (according to Johnston), or (2) by means of Tg's and mole fractions of rotatable bonds corresponding to the respective dyads (according to Barton). It was shown that for copolymers the monomeric units of which did not differ too much in their number of rotatable bonds in the molecule (e.g., ST/MMA), both these approaches are satisfactory; if the comonomeric units differ markedly in the number of rotatable bonds (e.g., ST/OMA), approach (1) yields more realistic results than (2). Extrapolation to zero content of the styrene component in the copolymer ST/OMA gave Tg of poly(OMA) (245 K), which is experimentally inaccessible by the method employed (differential scanning calorimetry).
Copolymerization of oxetanes, 2. Co‐oligomers in the copolymerization of oxetane with 3,3‐dimethyloxetane
Authors: Bucquoye Marc R. , Goethals Eric J.
Published: April 2003

The cyclic oligomers which are formed during the cationic copolymerization of oxetane (1) with 3,3‐dimethyloxetane (2) were analyzed qualitatively and quantitatively by means of gas chromatography and mass spectroscopy. Cyclic oligomers from trimer up to octamer were detected but, as with the homopolymerizations, the cyclic tetramers were the most abundant. The relative abundances of the different tetramer co‐oligomers were compared with the theoretical abundances, calculated from the reactivity parameters of the copolymerization and the monomer feed ratio, using the method of Ito and Yamashita. There was no agreement between the calculated and experimental values. This was attributed to a lower tendency to cyclize for polymer chains having a 2‐oxonium chain end compared with polymer chains having a 1‐oxonium chain end.
Photoinitiation, 8. Polymerization of methyl methacrylate and copolymerization of methyl methacrylate with maleic anhydride in the presence of zinc dichloride
Authors: Bartoň Jaroslav , Capek Ignác
Published: April 2003

The rate of photoinitiated (at wavelength λ = 365 nm) polymerization of methyl methacrylate (MMA) in acetone in the presence and/or absence of N,N‐dimethylaniline is retarded by zinc dichloride and by maleic anhydride (MAn). The rate of photoinitiated copolymerization of MMA with MAn in acetone is greatly enhanced in the presence of ZnCl2. The maximum copolymerization rate for a given ZnCl2 concentration is obtained for 1:1 mole ratio of MMA and MAn in the feed. It was established that ZnCl2 has no effect on the chemical composition of the MMA/MAn copolymer.
Modifizierte ionenaustauscherharze — synthese und eigenschaften, 1. Sulfomethylierte styrol‐divinylbenzol‐harze
Authors: Döscher Frank , Klein Joachim , Pohl Fritz , Widdecke Hartmut
Published: April 2003

Sulfomethylated resins are prepared by polymer analogous reactions, starting from macroporous poly(styrene‐co‐divinylbenzene) matrices. Different reaction paths are discussed and used in the synthesis. Sulfomethylation can be achieved by reaction of a chloromethylated resin with dimethyl sulfide and sodium sulfonate or alternatively by oxidation of polymer‐bound thiol groups. Both methods give high conversions as shown by IR spectra and titration of the sulfonic acid groups. Poly[1‐(4‐hydroxysulfomethylphenyl)ethylene] (3) is obtained by reaction of poly[1‐(4‐hydroxyphenyl)ethylene] (2) resin with formaldehyde/sodium sulfonate. The thermal stability, catalytic activity, and ion exchange equilibria of the sulfomethylated resin are investigated.
Stereoregularity of polystyrene derivatives, 2. Poly(methoxystyrene)s Obtained by Anionic Catalysts.
Authors: Kawamura Tokiji , Uryu Toshiyuki , Matsuzaki Kei
Published: April 2003

The stereoregularity of poly(methoxystyrene)s was determined from the absorption of the aromatic C1 carbon assuming a first‐order Markov statistics holds for the polymerization as well as polystyrenes. The stereoregularity of poly(p‐methoxystyrene)s prepared by sodium, potassium, or rubidium cations as catalysts in THF hardly varied and syndiotactic‐rich polymers were obtained, whereas a random polymer was formed with cesium‐naphthalene. In the polymerization of p‐methoxystyrene in toluene, syndiotactic‐rich polymers were obtained with butyllithium and random polymers were prepared by sodium or potassium cations as catalysts. The stereoregularity of poly(o‐methoxystyrene)s prepared by sodium or potassium cations in tetrahydrofuran changed with the polymerization temperatures, and highly syndiotactic polymers were formed at−78°C. The structure of poly(o‐methoxystyrene)s obtained in toluene, markedly depended on the initiators; that is, with increasing the size of the ionic radius of the counterions, the isotacticity of the polymers decreased. The mechanism of the polymerization and the substituent effect of the stereoregularity are discussed.
Polymerizations of 1‐(4‐pyridyl)‐1,3‐butadiene
Authors: Kohjiya Shinzo , Fujiwara Shigehiro , Fujii Kentaro , Yamashita Shinzo
Published: April 2003

Polymerization of 1‐(4‐pyridyl)‐1,3‐butadiene (PyBu) initiated by 2,2′‐azoisobutyronitrile (AIBN) or butyllithium (BuLi) was studied. Radical polymerization gave poly(PyBu) of low molecular weight, soluble in chloroform, tetrahydrofuran, or methanol. PyBu was polymerized by BuLi more rapidly than by AIBN, but the produced polyanion was not living. IR and 1H NMR spectra of poly(PyBu) indicate the presence of trans‐1,4‐and trans‐3,4‐units. The content of trans‐1,4‐units was found to be 75 mole‐% (for radical polymerization) or 90 mole‐% (for anionic polymerization). From radical copolymerization with styrene the following reactivity ratios resulted: r1 (PyBu) = 7,21, r2 (styrene) = 0,12; Q = 6, 1 and e = −0,42 (for PyBu). Reaction of PyBu with ethyl bromide in benzene at 30°C produced a polyelectrolyte, as observed in the case of 4‐vinylpyridine.
Study on models of double bond saturation during the synthesis of unsaturated polyesters
Authors: Fradet Alain , Marechal Ernest
Published: April 2003

The addition of hydroxyl groups on double bonds during the synthesis of unsaturated polyesters is studied with the help of model molecules. These are diesters of unsaturated diacids (maleic and fumaric acids) or monoesters of unsaturated monoacids (crotonic, cinnamic and p‐cyanocinnamic acids) with 1,2‐propanediol. The addition reaction take place to appreciable extents only with bis(hydroxypropyl) maleate and fumarate. The reaction is catalyzed by strong acids such as p‐toluenesulfonic acid; it is reversible and favoured by high temperatures. A mechanism is discussed.
Interpolymer complex between poly(ethylene oxide) and poly(acrylic acid): Viscometric studies in THF‐water mixtures
Authors: Chatterjee Saroj Kumar , Chatterjee Nandita , Riess Gérard
Published: April 2003

Systematic studies were performed on interpolymer complex formation between Poly(acrylic acid) (PAA) and poly(ethylene oxide) (PEO) in THF‐water mixtures of different compositions. Viscosity behaviour during complex formation in mixed solvents was found to be entirely different from that observed by other workers in aqueous and in pure organic solvents. The result are interpreted in terms of, (a) preferential solvation of the polymer, (b) Probable change in conformation of the polyelectrolyte moleculer. (c) association of complex molecules in a medium of low dielectric constant, and (d) expected disordering of bound water molecules around PEO by THF. Irrespective of solvent composition, interpolymer complex of PAA and PEO was always found to have 1:1 unit mole ratio.
Über die bestimmung der zahl polymerisationsaktiver zentren von ziegler‐natta‐katalysatoren. Eine modifizierte methode mit 14C‐markierten kohlenstoffoxiden
Authors: Warzelhan Volker , Burger Tycho F. , Stein Dieter J.
Published: April 2003

A modified method for the determination of the number of isotactic sites C* and the overall propagation rate constant k̄p of propene polymerization catalysts with 14C‐labelled carbon oxides is proposed: an excess of 14CO2 or 14CO is added in the abscence of propene and alkylaluminium to a non‐deactivated polymer sample drawn from the polymerization slurry.

The specific radioactivity of the polymer as a function of the time of contact with the radio‐actively labelled inhibitor sharply increases within short times of contact (14CO2 ≤ 20 min, 14CO ≤ 5 min). This is followed by a slower further increase reaching a finite value after 5 to 7h. The initial and end values differ by a factor of 2 to 3. The results are explained in terms of sites with different reactivity assuming that the total number of isotactic sites is determined only after long times of contact with the inhibitor.

So far c* was determined with 14CO2 or 14CO by adding the inhibitor during the polymerization in the presence of propene and alkylaluminium; c* was calculated after short times of contact with the inhibitor, whereas the further steady increase in specific radioactivity was exclusively attributed to side reactions caused by reaction with propene and alkylaluminium.

By this modified method we obtained for TiCl3·(1/3)AlCl3 at 60°C k̄p = 13 dm3/(mol·s) and c* = 0,012 mol Ti*/mol Titotal. Addition of a free Lewis base to the polymerization mixture increases c* leaving k̄p unchanged. In contrast to this, if TiCl3·(1/3) AlCl3 is milled with a Lewis base k̄p can be increased by a factor of ≈ 2,5 with lower or equal c* ‐values. The higher activity of extracted TiCl3‐catalyst is due to higher k̄p and c* ‐values as compared to those using TiCl3·(1/3) AlCl3.
Kinetics of free radical oligomerization: Styrene in carbon tetrachloride
Authors: Chen Show‐An , Chang Min‐Ju
Published: April 2003

For the free radical oligomerization of styrene monomer in the presence of carbon tetrachloride, a simplified reaction mechanism is proposed from which a simple scheme for predicting monomer conversion and molecular weight distribution is obtained. The kinetic constants other than those of the initiator decomposition step are determined by use of conversion data. In the scheme development, the kinetic constants for chain transfer and propagation steps are considered to be chain length independent, except that for the propagation step, an extra rate constant is considered for the reaction of monomer with radical produced in the transfer reaction with solvent. The mechanism proposed is found to be in reasonable agreement with out experimental data.
Determination of the parameters of equation of state for melts of linear polymers according to the model of thermal expansion of polymers
Authors: Roszkowski Zbigniew
Published: April 2003

The previously deduced four‐parameter equation of state for melts of linear polymers was reduced to a three‐parameter form, consistent with the theorem of corresponding states. The methods of determining the characteristic parameters of the new and the previous equation are given. The characteristic parameters for polystyrene, poly(o‐methylstyrene), poly(vinyl acetate), linear polyethylene, isotactic polypropylene and poly(butyl methacrylate) are calculated, using the experimental pVT data from literature. The dependence of the characteristic pressure on the temperature, observed in the case of poly(butyl methacrylate) is explained in terms of bending of the valency angle at the —CH2‐group in the backbone, due to strong steric hindrances in vinylidene chains.
Polymer‐solvent interactions in mixed solvents, 3. Poly(methacrylic acid) and poly(sodium methacrylate) in water‐dioxane mixtures
Authors: Vorreux Gérard , Morcellet Michel , Loucheux Claude
Published: April 2003

The preferential solvation of poly(methacrylic acid) and poly(sodium methacrylate) in waterdioxane mixtures was investigated by means of specific refractive index increment measurements on dialysed and undialysed solutions. The correlation with the solvent‐induced conformational transition of poly(methacrylic acid) was also studied. Potentiometric titrations indicate that this transition occurs at around 25–30 vol.‐% of dioxane. Comparison with previous results on poly(acrylic acid) and poly(sodium acrylate) in the same solvent system and on poly(methacrylic acid) in water‐2‐chloroethanol mixtures, shows differences in the mode of solvation of the compact conformation. It is suggested that this may be dependent on the existence of water‐organic solvent specific interactions such as the formation of a water‐dioxane hydrogen‐bonded complex.
The flexibility of biphenyl and related species utilizable as molecular swivels in rodlike polymers. A CNDO/2 analysis
Authors: Welsh W. J. , Jaffé H. H. , Kondo N. , Mark J. E.
Published: April 2003

Aromatic heterocyclic polymers are exceedingly attractive high performance materials because of their unusually high mechanical strength, chemical resistance and thermal stability, but are very difficult to process unless “swivel” atoms or groups are inserted along the chains to increase conformational flexibility. The present theoretical investigation employs the CNDO/2 method with direct geometry optimization to calculate such flexibility for the wholly aromatic swivels biphenyl, 2,2′‐bipyridyl, 2‐phenylpyridine, 2,2′‐bipyrimidyl, and 2‐phenylpyrimidine. The most important result is the prediction that both flexibility and accessibility of coplanar conformations should increase significantly with the number of ortho‐CH groups replaced by N‐atoms. The calculations also provide information on other conformation‐dependent properties such as optimized geometries, charge distributions, and dipole moments, and these results are found to be in satisfactory agreement with the results of previous theoretical and experimental studies. Finally, since these chains are soluble only in strongly acidic media, the species mono‐ and diprotonated 2,2′‐bipyridyl, 2,2′‐bipyridyl · H3O+, and 2,2′‐bipyrimidyl · 2H2O were also investigated with regard to some of these conformational characteristics.
Effect of the catalyst‐monomer ratio on the molar mass and glass transition temperature of poly(oxy‐2,6‐dimethoxy‐1,4‐phenylene)
Authors: Jauhiainen Tuure‐Pekka
Published: April 2003

2,6‐Dimethoxyphenol was polymerized using Ag2O‐triethylamine complex as catalyst and a study made of the effect of the catalyst‐monomer ratio on the yield, molar mass and polydispersity of poly(oxy‐2,6‐dimethoxy‐1,4‐phenylene). The glass transition temperatures Tg were measured with a computerized differential scanning calorimeter. The effect of the molar mass on Tg of poly(oxy‐2,6‐dimethoxy‐1,4‐phenylene) is discussed. The equation, Tg = Tg, ∞ − K/M, describes well the dependence of Tg on the viscosity‐average molar mass Mv from 1900 to 176000 g/mol. Some poly(oxy‐2,6‐dimethyl‐1,4‐phenylene) samples were studied as reference material.
Polymerization of ethylene oxide. A novel binary catalyst system consisting of triphenylantimony dibromide and triphenylphosphine
Authors: Nomura Ryoki , Hisada Hitoshi , Ninagawa Akira , Matsuda Haruo
Published: April 2003

Polymerization of ethylene oxide (EO)‐catalyzed by a binary system consisting of triphenyl‐antimony dibromide (TPAB) and triphenylphosphine (TPP) was carried out. TPAB itself could induce the polymerization, but the addition of TPP to TPAB greatly enhances the catalytic activity. A characteristic inflection point, which appeared clearly in the time‐polymerization curves, divided the polymerization into two successive steps. The preceding process is a cationic step in which an intermediate antimony dialkoxide is produced and the following a coordinated polymerization. The mean consumption of EO per catalyst at the inflection point was calculated to be 45 and was independent of the mole ratio of [TPP]/[TPAB]. It is assumed that TPP coordinates to the central antimony atom to produce an active complex salt in the second step. The effect of p‐substitution of TPAB in the polymerization was also investigated; the Hammett parameters p for the first and the second polymerization step were found to be +1,7 and +1,0, respectively.
Le poly(α‐acétoxystyrène) et les copolymères de l'α‐acétoxystyrène avec le styrène et styrènes substitués obtenus par polymérisation thermique. Etude de la microstructure et de la stabilité thermique des polymères
Authors: Montheard Jean‐Pierre , Camps Marcel , Kawaye Saadallah , Pham Quang Tho , Seytre Gérard
Published: April 2003

The microstructure of poly(α‐acetoxystyrene), prepared from α‐acetoxystyrene by bulk thermal polymerization, was studied by 1H and 13C NMR spectroscopy. Anomalies observed in the NMR spectra could be ascribed to fragmentations with formation of benzoxy and acetoxy radicals followed by re‐initiation. The thermal degradation of the polymer, resulting in the formation of polyphenylacetylene, rules out certain types of transfer. α‐Acetoxystyrene was copolymerized with styrene or substituted styrenes and the NMR study (1H and 13C) was limited to α‐acetoxystyrene. The composition of the copolymer could be ascertained by means of the resonances of the quaternary carbons of the aromatic cycle. The copolymers were characterized by viscometry, GPC, and thermal degradation. Their compositions, except that of poly(α‐acetoxystyrene‐co‐styrene) were determined by elemental analysis.
Electric dipole moment of cellulose‐ and amylose derivatives
Authors: Araki Kazuo , Imamura Yoshio
Published: April 2003

The electric dipole moments (per repeating unit) of cellulose acetate and tricarbanilate, and amylose acetate and tricarbanilate were determined in 1,4‐dioxane solution at 30°C. The parallel component of the moment to the chain contour was also estimated for samples of various molecular weights, and they were almost independent on molecular weight, indicating no excluded volume effect on the dipole moment. The persistence dipole moment, and monomer dipole component along the chain contour for cellulose derivatives were about 50% smaller than those for amylose derivatives. The relation between the dipole moment and the chain dimension is discussed for cellulose‐ and amylose derivatives.
Polymere charge‐transfer‐komplexe auf der basis von polyvinylalkoholacetalen, 5
Authors: GeißLer Ulrich , Schulz Rolf C.
Published: April 2003

By reaction of poly[2‐(1‐naphthyl)‐1,3‐dioxan‐4,6‐diylmethylene] (3), poly[2‐(2‐naphthyl)‐1,3‐dioxan‐4,6‐diylmethylene] (5), poly[2‐(9‐isobutyl‐3‐carbazolyl)‐1,3‐dioxan‐4,6‐diylmethylene] (7) and poly[2‐((S)‐9‐(2‐methylbutyl)‐3‐carbazolyl)‐1,3‐dioxan‐4,6‐diylmethylene] (9) with 3,5‐dinitrobenzoylchloride (12) or 4,5,7‐trinitro‐9‐fluorenone‐2‐carboxylic acid chloride (2) polymeric intramolecular charge‐transfer‐complexes (4a, 4b, 6, 8a, 8b, and 10) were synthesized. The polymers were investigated by means of UV or remission spectroscopy as well as by differential thermal analysis.
Determination of the orientation distribution function of amorphous polymers by wide angle X‐ray scattering measurements
Authors: Biangardi Harald J.
Published: April 2003

A new method based on the inversion of a relation derived by Krathy, and thereby allowing the determination of the orientation distribution function of amorphous polymers by Wide Angle X‐Ray Scattering (WAXS), is described. With a simple approximation, in many cases disturbing intramolecular scattering can be separated from the measured azimuthal intensity distribution along the first maximum of the amorphous halo. For oriented amorphous poly(ethylene terephthalate), the 2nd and 4th moments of the determined orientation distribution functions agree very well with those from birefringence and spectroscopic measurements. The method is not applicable to partially crystalling polymers, because the approximation for intramolecular scattering does no longer hold. Finally, the intrinsic birefringence of bisphenol‐A‐polycarbonate was determined by this method to be 0,236 ± 0,004.
Cyclization dynamics of polymers, 5. The effects of solvent on end‐to‐end cyclization of poly(ethylene oxide) probed by intramolecular pyrene excimer formation
Authors: Cheung Seung‐Tong , Winnik Mitchell A. , Redpath Anthony E. C.
Published: April 2003

Intramolecular excimer formation between pyrenes attached to the ends of a poly(ethyleneoxide) sample of nominal molecular weight 9600 has been examined in twelve solvents. In ten non‐protic solvents the excimer to pyrene locally excited fluorescene intensity ratio IE/IM is inversely proportional to solvent viscosity, as expected for a diffusion‐controlled process. Similar results were obtained for 〈k1〉 values obtained from flash‐photolysis studies, where 〈k1〉 is the average rate constant for end‐to‐end cyclization in the polymer. In water and methanol, the extent of excimer emission and the rate of intramolecular excimer emission and the rate of intramolecular excimer formation were substantially greater than one would infer on the basis of solvent viscosity alone.
Thermal behavior of salicylic acid/formaldehyde resin
Authors: Patel Ramesh , Patel Rajni , Patel Kanti
Published: April 2003

An attempt is made to study the thermal properties of salicylic acid/formaldehyde resin using thermogravimetry and differential thermal analysis. The kinetic parameters and the stability of the resin are reported.
New organic polymers, 4. Synthesis and characterization of polymers containing 3,3′‐dioxo‐5,5′‐biindol‐2,2′‐diyl units
Authors: Suthar Bhikhu P.
Published: April 2003

Polymers containing 3,3′‐dioxo‐5,5′‐biindol‐2,2′‐diyl units were synthesized by high temperature polycondensation of 4,4′‐diaminobiphenyl‐3,3′‐dicarboxylic acid (1) with ethylene dichloride and dibromide, 4‐chloromethylbenzyl chloride and bromide, 4‐chloromethyl‐2,5‐dimethylbenzyl chloride and bis(4‐chloromethylphenyl) ether under different experimental conditions. These resulting polymers 5a–d were characterized by viscometric and IR Spectral studies and by TG in air. Kinetic parameters of their thermal degradation were evaluated.
Copolymerization of C‐vinyltriazoles and C‐vinyltetrazole with vinyl monomers
Authors: Wouters G. , Smets G.
Published: April 2003

The copolymerizations of 4(5)‐vinyl‐1,2,3‐triazole, 1‐p‐bromophenyl‐4‐vinyl‐1,2,3‐triazole and 2‐methyl‐5‐vinyltetrazole with styrene, methyl methacrylate and vinyl acetate have been examined and the corresponding copolymerization parameters r1, r2 were evaluated. The reactivities Q of these monomers are lower than that of styrene contrarily to other C‐vinylheterocyclic monomers; it is assumed that it results from a limited stabilization of the corresponding radicals. In the case of 4(5)‐vinyl‐1,2,3‐triazole, copolymerizations carried out at different temperatures and varied monomer concentrations show that intermolecular monomer association (as evidenced by NMR and IR measurements) does neither affect the copolymer composition nor the internal monomer triad structure of the copolymer.
Induced optical activity in copolymers of (—)‐p‐(3‐menthyl) acrylate with 4‐vinylpyridine
Authors: Majumdar Ramendra Nath , Carlini Carlo , Bertucci Carlo
Published: April 2003

The present paper reports on the synthesis of copolymers of (—)‐p‐(3‐menthyl) acrylate (1) with 4‐vinylpyridine (2) by radical polymerization in a large range of composition. Reactivity ratio values of the two comonomers, evaluated by the Kelen‐Tüdös method, have allowed to show that 2 exhibits a rather high reactivity as compared with 1. The average sequence length of the co‐units and their distribution in the macromolecules were evaluated. The chiroptical properties of side chain pyridine chromophores were investigated by circular dichroism measurements and related to composition and distribution of the monomeric units.
Adiabatic polymerization of ϵ‐caprolactam in presence of lithium chloride, 3. Oligomer formation
Authors: Biagini Emilio , Pedemonte Bruno , Pedemonte Enrico , Russo Saverio , Turturro Antonio
Published: April 2003

The activated anionic polymerization of ϵ‐caprolactam is strongly affected by LiCl addition to the polymerizing medium. Large variations in the yield of the polymerization products are induced by increasing salt content: both high polymer and cyclic dimer yields sharply decrease as functions of the salt concentration, whereas monomer and (in part) higher oligomers show a relevant increase. Also the production of low molecular weight side products is influenced by LiCl: higher salt concentrations induce the formation of larger amounts of side compounds. Monomer equilibrium data reveal that the salt negatively affects the thermodynamics of polymerization. ΔG variation as a function of LiCl content shows an increasingly relevant influence of the entropic contribution to the standard free energy change. The effects of LiCl on ring‐ring equilibria are qualitatively interpreted on the basis of both the strong ion‐ion interactions between Li+ ions and carbonyl groups and the interchain densification process.
Electrolytic conductivity of polyeiectrolyte solutions
Authors: Vink Hans
Published: April 2003

The electrolytic conductivity of the polyelectrolytes poly(methacrylic acid), carboxymethyl‐cellulose, poly(vinylsulfonates), and poly(styrenesulfonates) was investigated. The concentration dependence of the equivalent conductivity was studied in detail and the limiting equivalent conductivity Λ0 was determined. The rapid increase of the equivalent conductivity in dilute polyelectrolyte solutions, which is characteristic for most polyelectrolyte systems, was found to be due to decreased counterion binding in very dilute solutions. In this respect the behaviour of the poly(styrenesulfonate)s was exceptional, as their equivalent conductivities were practically constant down to limiting concentrations. Also, the poly(styrenesulfonic acid) clearly displayed specific hydrogen ion‐polyion interactions.
Synthèse et transformations chimiques des télomères de l'undécène‐10 oate de méthyle, 2. Synthèse de diols polyhalogénés
Authors: Battais Alain , Boutevin Bernard , Piétrasanta Yves , Sarraf Tarek El
Published: April 2003

Several telomers of methyl 10‐undecenoate were prepared with different telogens and identified by IR and NMR spectroscopy or by GPC. Chemical transformations of these telomers led to new polyhalogenated acids of alcohols having high molecular weights.