bluuebunny/crossref_metadata_2025 huggingface dataset:
New poly(amide‐imide) syntheses, 4 Poly(amide‐imide)s derived from 2,5‐bis(4‐aminophenyl)‐3,4‐diphenylthiophene and various bis(trimellitimide)s
Authors: Yang Chin‐Ping , Hsiao Sheng‐Huei , Lin Jiun‐Hung
Published: April 2003

Fifteen bis(trimellitimide)s 2a–o were prepared by condensation of the corresponding aliphatic or aromatic diamines with trimellitic anhydride. A series of structurally new poly(amideimide)s were synthesized by the direct polycondensation of these bis(strimellitimide)s with 2,5‐bis(4‐aminophenyl)‐3,4‐diphenylthiophene using triphenyl phosphite and pyridine as condensing agents in N‐methyl‐2‐pyrrolidone (NMP). The resultant poly(amide‐imide)s have inherent viscosities in the range between 0,72 and 2,73 dL/g at 30°C in N,N‐dimethylacetamide (cf. Tab. 2). The polymers are amorphous and readily soluble in polar aprotic solvents such as N,N‐dimethylacetamide (DMAc) and NMP. Transparent and tough films can be cast from their solutions. Most aliphatic‐aromatic poly(amide‐imide)s show a glass transition in the range between 203 and 242°C in their differential scanning calorimetry (DSC) traces, whereas the wholly aromatic poly(amide‐imide)s show no discernible transition before decomposition. The thermal stability of the polymers was evaluated by thermogravimetry which showed the 10% weight‐loss temperatures in the range between 414 and 459°C in air and between 451 and 578°C in a nitrogen atmosphere for the aliphatic‐aromatic poly(amide‐imide)s and above 500°C in both air and nitrogen atmosphere for the wholly aromatic poly(amide‐imide)s.
Elementarprozesse der Ziegler‐Katalyse, 6 Ethylen‐ und propenhomopolymerisation mit den stereorigiden katalysatorsystemen iPr[FluCp]ZrCl2/MAO und Me2Si[Ind]2ZrCl2/MAO
Authors: Herfert Norbert , Fink Gerhard
Published: April 2003

The ethylene and propene homopolymerization was investigated by means of the Cs‐symmetric [2,4‐cyclopentadien‐1‐ylidene(isopropylidene)fluoren‐9‐ylidene]zirconium dichloride/methylaluminoxane (iPr[FluCp]ZrCl2/MAO) and the C2‐symmetric [(dimethylsilylene)bis(η5‐inden‐1‐ylidene)]zirconium dichloride/methylaluminoxane (Me2Si[Ind]2ZrCl2/MAO) catalyst systems in toluene. Surprisingly, the Cs‐symmetric catalyst polymerizes propene faster than ethylene. The main results of the kinetic analysis are a first‐order dependence on the concentration of Zr but a bell‐shape in the plot of the polymerization rate versus log([Al]: [Zr]). This is true for both catalyst systems. Furthermore with increasing [Al]:[Zr] ratio the fraction of rmrr pentads is decreased continuously with the Cs‐symmetric catalyst; in the same direction the molecular weights are decreased. On the contrary with the C2‐symmetric catalyst the stereospecificity and the molecular weights remain constant. The kinetic results reflect the complex role of the MAO, i.e. the existence of sterically more and more tight contact species between metallocene and MAO components with increasing [Al]: [Zr] ratio. The different behaviour of the two catalyst systems concerning stereospecificity and molecular weights of the polymers are due to different symmetry and different size of the angle between the planes of the π‐ligand systems.
Solvent effect on the propagation rate constant in the radical polymerization of bis(2‐ethylhexyl) itaconate
Authors: Sato Tsuneyuki , Shimizu Takehiro , Seno Makiko , Tanaka Hitoshi , Ota Tadatoshi
Published: April 2003

Polymerization of bis(2‐ethylhexyl) itaconate (1) with dimethyl azobis(isobutyrate) (2) was carried out at 50°C in various solvents. Polar solvents caused a significant decrease in the polymerization rate (Rp) and the molecular weight of resulting poly(1). The propagating poly(1) radical could be observed as a five‐line ESR spectrum in the actual polymerization systems used. The stationary concentration of poly(1) radical was determined by ESR to be 4,2–6,4 · 10−6 mol · L−1 at 50°C when the concentrations of 1 and 2 were 1,03 and 3,00 · 10−2 mol · L−1. Using Rp the monomer concentration and the polymer radical concentration, the propagation rate constant (Kp) was estimated to be 1,4–6,8 L · mol−1 · s−1, depending on the solvents used. The kp value was smaller in more polar solvents. The solvent effect is explained in terms of the solvent affinity for the propagating polymer chain.
Studies on silicone‐grafted copolyimides, 3. Synthesis of soluble polyimide/polydimethylsiloxane graft copolymer and application to separation membrane
Authors: Akiyama Ei‐ichi , Takamura Yuriko , Nagase Yu
Published: April 2003

Polyimide/polydimethylsiloxane (PI/PDMS) graft copolymer was prepared following the macromonomer method. First, 3‐(3,5‐diaminobenzyloxy)propyl‐terminated polydimethylsiloxane (DAB‐PDMS) was prepared by hydrosilylation of allyl 3,5‐dinitrobenzyl ether with hydrosilyl‐terminated PDMS, followed by catalytic reduction of the two nitro groups. PI/PDMS graft copolymer was synthesized by polycondensation of DAB‐PDMS with 4,4′‐oxydianiline (ODA) and 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride (6FDA), followed by chemical imidation. The average degree of polymerization of the PDMS chain was in the range between 7 and 25. The resulting graft copolymers were soluble in several organic solvents. Membranes were prepared by solvent casting, followed by heating at 220°C in vacuo, upon which the membranes became hardly soluble in organic solvents. The gas permeability coefficients of the graft copolymer membranes were much greater than those of the polyimide homopolymer and of the same order as that of a PDMS membrane. Furthermore, a selective permeation of organic liquids, e.g., tetrahydrofuran, acetone and acetonitrile, was observed in the pervaporation of aqueous organic liquids through the copolymer membrane.
Polyimides, 1. Studies on the thermal curing of imide model compound with tricyclic structure by nuclear magnetic resonance and mass spectra
Authors: Su Ching‐Yie , Lee Yu‐Der
Published: April 2003

A model imide with a tricyclic structure was synthesized by reacting 3‐phenyltricyclo[6.2.2.02,7]‐2,11‐dodecadiene‐5,6 : 9,10‐tetracarboxylic dianhydride with aniline. The thermogravimetry curve showed that it degraded at about 300°C, and its differential scanning calorimetry curve was found to be similar to that of its corresponding polyimides. The thermal curing of this model imide was studied in detail. A curing mechanism was proposed based on the analysis of the cured product using NMR and mass spectroscopy. The results show that the curing mechanism started with a reverse Diels‐Alder reaction, forming an intermediate which either dehydrogenated or further decomposed into 1,1‐diphenylethylene, andN‐phenylsuccinimide. The 1,1‐diphenylethylene andN‐phenylsuccinimide would either polymerize or become hydrogenated to form 1,1‐diphenylethane andN‐phenylsuccinimide, respectively.
Catalytic hydrolysis of activated aromatic esters by branched polyamines
Authors: Van Beylen Marcel , Samyn Celeste
Published: April 2003

Two polymeric amines, poly[(2‐aminopropyl)propyleneimine] (PI) and poly[(2‐aminoethyl)‐ethyleneimine] (PII), as well as the dodecyl‐ and imidazolylmethyl‐substituted derivative of PI, were used for the hydrolysis of p‐nitrophenyl acetate (PNPA), 4‐acetoxy‐3‐nitrobenzoic acid (ANBA) and some of their homologues, in order to elucidate the relations between their overall structure and their catalytic activities. All reactions were carried out at 28,7°C in aqueous solution, and followed spectrometrically using a catalyst concentration in large excess with respect to the substrate concentration (10−4 mol · L−1). The reactions were found to obey pseudo‐first order kinetics. By plotting log[substrate] against time, k2(cat) and consequently the second‐order rate constants k2 were evaluated. The above mentioned polymers show hydrolysis constants which exceed the values obtained for tailor‐made partially substituted polyethyleneimines. Even when linear polythyleneimine was substituted for 42% with 2‐(2‐aminopropylamino)propyl groups, PI and PII give k2 values which are 8 times higher towards PNPA, and 10 times higher towards ANBA, under the same reaction conditions.
Structure and crystallization kinetics of poly(L‐lactic acid)
Authors: Marega Carla , Marigo Antonio , Di Noto Vito , Zannetti Roberto , Martorana Antonino , Paganetto Guglielmo
Published: April 2003

A structural investigation is described of poly(L‐lactic acid) by best fitting of powder X‐ray diffraction patterns. The examined sample shows the already known pseudo‐orthorhombic α‐form, and it was possible to determine the location of the two 103 polymeric helices in the unit cell and the size distribution of the crystallites. Furthermore, a study is reported of the crystallization kinetics of the above cited polymer by light depolarization measurements in an optical microscope. The crystallization kinetic constants in bulk were evaluated in a temperature range (70–165°C) wider than that previously resulting from measurements of radial growth of spherulites.
Particle formation in emulsion polymerization, 2. Aggregation of primary particles
Authors: Hergeth Wolf‐Dieter , Lebek Werner , Stettin Enrico , Witkowski Konrad , Schmutzler Klaus
Published: April 2003

The formation and aggregation of primary particles in the beginning of emulsion polymerization was monitored by surface tension measurements, viscometry, electron microscopy, and static and dynamic light scattering. The dimensions of the primary particles in the emulsion polymerizations of vinyl acetate and methyl methacrylate are of the order of 3 – 5 nm. Immediately after the formation of primary particles these begin to aggregate. The stability of these particles is discussed and conclusions are drawn concerning the formation of new particles in the course of polymerization or in seeded polymerization experiments.
Reactive blending of poly(ethylene terephthalate) and polycarbonate, 1. A reappraisal of the reactions occuring during melt‐mixing
Authors: Berti Corrado , Bonora Virna , Pilati Francesco , Fiorini Maurizio
Published: April 2003

The reactions occurring during melt‐mixing of poly(ethylene terephthalate) and bisphenol‐A polycarbonate have been reconsidered. Certain evidence leads us to conclude that two reactions, usually disregarded in the literature, occur, which have to be considered in the general scheme along with the already described exchange reactions. These reactions lead to the formation of cyclic ethylene carbonate and of aromatic‐aliphatic ether moieties, and therefore introduce significant modifications in the chemical structure of the polymeric material resulting from melt‐mixing. An increase in the amount of aromatic‐aromatic ester groups and the formation of a significant amount of aromatic‐aliphatic ether moieties can be obtained depending on reaction conditions.
Reactive blending of poly(ethylene terephthalate) and polycarbonate, 2. A novel route to copoly(ester‐ether)s
Authors: Berti Corrado , Bonora Virna , Pilati Francesco , Fiorini Maurizio
Published: April 2003

Copoly(ester‐ether)s have been prepared by reacting poly(ethylene terephtalate) (PET) and bisphenol A polycarbonate (PC) at high temperature, under vacuum, in the presence cf titanium tetrabutoxide as catalyst. The polymeric materials obtained in this way, which contain terephthalate, bisphenol A and ethylene glycol moieties, are the result of exchange reactions followed by the elimination of cyclic ethylene carbonate and by a decarboxylation reaction. These copolymers have a higher glass transition temperature and thermal resistance than PET, and a better solvent resistance than PC; their dynamic mechanical spectra are similar to that of PC in the −150 to +50°C temperature range.
Chain dimensions, entanglement molecular weights and molecular weight distributions of poly(aryl ethers). A combined rheological and MNDO analysis
Authors: Herrmann‐Schönherr Otto , Schneller Arnold , Seifert Andreas M. , Soliman Maria , Wendorff Joachim H.
Published: April 2003

The viscoelastic melt properties of a series of different poly(aryl ethers) were analyzed to obtain information on the corresponding chain statistics, i. e. entanglement molecular weights and characteristic ratios C∞. The consistent result is that all chain molecules behave as freely rotating chains with values of C∞ of the order of two to three. MNDO‐calculations were used to obtain a detailed insight into the origin of such a behaviour. The relationship between chemical structure and the corresponding rotational potentials was analyzed. Finally, using a combination of rheological and MNDO (Modified Neglect of Diatomic Overlap) studies, information was derived on the molecular weight distribution of the poly(aryl ethers).
Studies on silicone‐grafted copolyimides, 4. Synthesis and properties of branching copolyimides with fluoroalkyl and poly(dimethylsiloxane) side chains
Authors: Akiyama Ei‐ichi , Takamura Yuriko , Nagase Yu
Published: April 2003

Soluble copolyimides containing fluorinated alkoxy (FA) groups and poly(dimethylsiloxane) (PDMS) side chains were prepared by means of polycondensation of 2,2,2‐trifluoro‐1‐(trifluoromethyl)ethylidene diphthalic anhydride (6FDA) with 4,4′‐oxydianiline (ODA), 3‐(3,5‐diamino‐benzyloxy)propyl‐terminated poly(dimethylsiloxane) (DAB‐PDMS) and 3,5‐diaminobenzyl fluoroalkyl ether (DAB‐FA) followed by imidation. Tough menbranes were prepared from the copolymides by a solvent casting method. The introduction of FA groups and PDMS side chains remarkably increases the hydrophobicity of the copolyimide film, the contact angle of water being raised to 124°C. Introduction of FA groups in the copolyimide resulted also in an increase of the permselectivity of oxygen toward nitrogen of the membrane. Furthermore, the selective permeation of organic liquids was observed in the pervaporation of aqueous organic solutions through the membrane.
Partial swelling of latex particles with monomers
Authors: Maxwell Ian A. , Kurja Jenci , Van Doremaele Gerard H. J. , German Anton L. , Morrison Bradley R.
Published: April 2003

Two methods are described for experimentally determining the concentrations of monomer in both the aqueous phase and the latex particle phase during partial swelling of latex particles, and therefore also during intervall III of an emulsion polymerization. The ratio of the monomer concentrations in the aqueous phase, both below and at saturation, can be related to the volume fraction of polymer in the latex particles via the Vanzo equation. Comparison of theory and experiments for the methyl acrylate and poly(methyl acrylate‐co‐styrene) system shows that the monomer partitioning is insensitive to temperature, latex particle radius, polymer composition, polymer molecular weight and polymer cross‐linking. Thermodynamic treatment of these and previously published partitioning results shows, at higher volume fractions of polymer, that the conformational entropy of mixing of monomer and polymer is the significant term determining the degree of partial latex particle swelling by monomer. Theoretical predictions of experimental results are quite insensitive to values of the Flory‐Huggins interaction parameter and to the latex particle‐water interfacial tension. A simple model is developed for the estimation of monomer partitioning which requires only the saturation monomer concentrations in the particle and aqueous phases.
Thermodynamics of swelling of latex particles with two monomers
Authors: Maxwell Ian A. , Kurja Jenci , Van Doremaele Gerard H. J. , German Anton L.
Published: April 2003

The partitioning of two monomers between the latex particle, monomer droplet and aqueous phases of an emulsion polymer latex are measured at saturation swelling of the latex particle phase (corresponding to intervals I and II of an emulsion polymerization). The monomer and polymer types are varied systematically and the experiments are performed at two temperatures. The results of these experiments correspond well to a simplified thermodynamic theory of the saturation swelling of an emulsion polymer with two monomers, in which it is realized that the fraction of one monomer is equivalent in the latex particle and monomer droplet phases. Further, it is shown that Henry's law holds for monomers, both in the absence and in the presence of swollen latex particles. A simple empirical relationship is developed whereby the concentration of two monomers at any ratio can be calculated from the individual saturation concentration of the two monomers in the latex of interest.
Synthesis of polyradicals by the oxidative coupling copolymerization of 2‐(3,5‐diethynylphenyl)‐4,4,5,5‐tetramethyl‐3‐oxo‐2‐imidazolin‐1‐yloxyl and 1,3,5‐triethynylbenzene catalyzed by CuCl/O2, and their magnetic properties
Authors: Miura Yozo , Inui Kunihiko
Published: April 2003

The present paper describes the synthesis of polyradicals by the oxidative coupling polymerization of 2‐(3,5‐diethynylphenyl)‐4,4,5,5‐tetramethyl‐3‐oxo‐2‐imidazolin‐1‐yloxyl (1) and 1,3,5‐triethynylbenzene (2) catalyzed by CuCl/O2, and their magnetic properties. The polyradicals obtained are dark blue and insoluble in all solvents examined. The ESR measurements of the polyradicals give a broad single‐line spectrum indicating that spin‐exchange narrowing takes place. The spin concentrations determined by the ESR spectroscopic method are 1,17 · 1021 to 1,28 · 1021 spins/g. The vibrating sample magnetometer (VSM) measurements of the polyradicals afford a linear magnetic moment vs. magnetic field dependence with a positive slope, suggesting that the copolymer has predominant paramagnetic properties within the limits of experimental error.
Side reactions during the initiation step in oligomerization of methacrylic esters by electron transfer reaction
Authors: Catala Jean‐Marie , Clauss Margot
Published: April 2003

Anionic oligomerization of methacrylic esters (methyl (MMA), ethyl (EMA), butyl (n‐BMA), tert‐butyl (t‐BMA) methacrylates) was conducted in a one‐step process by mixing, in tetrahydrofuran, the monomer, an alkali metal (sodium) and a deactivating agent (sulfur or tert‐butyl alcohol). The formation of alcohol due to a nucleophilic attack of the ester group by the methacrylic carbanion was quantified and related to the monomer structure, temperature and nature of the living ends. It was shown that this side reaction is not limited to the propagation step but can occur during the initiation step. From mass spectra and nuclear magnetic resonance (NMR) spectroscopy of the protonated oligomers (tert‐butyl alcohol as deactivating agent), it was concluded that this side reaction led to five‐membered cyclic β‐keto esters during the initiation step of MMA, EMA and n‐BMA monomers only. This implies an intramolecular reaction between one carbanion of the dianionic dimer and the penultimate ester group. It was found that this reaction involves primarily dianionic tail‐to‐tail dimer, even though head‐to‐tail dimer was also formed.
Asymmetrically branched alkyl spacers in liquid‐crystalline poly(alkylene 4,4′‐terephthaloyldioxydibenzoate)s
Authors: del Pino Javier , Rocha Carlos Marco , Gómez Marián A. , Fatou Jose G.
Published: April 2003

Poly[oxy‐(1,4‐dimethyltetramethylene)oxycarbonyl‐1,4‐phenyleneoxyterephthaloyloxy‐1,4‐phenylenecarbonyl] (1) was synthesized for the first time, and its thermal behaviour was studied by differential scanning calorimetry, thermooptical microscopy, and X‐ray diffraction. The crystal to liquid‐crystal and the mesophase to isotropic transition temperatures are lower by ca. 100°C than the values reported for the unsubstituted polymer. Moreover, the formation of a three‐dimensional order is hindered in the case of the polymer with lateral substituents and can only be achieved by long annealing times.
Copolymérisation du dicyanure de propène‐1 ylidène‐1 avec l'acétate de vinyle et des styrènes substitutés. Calcul des taux de réactivité et étude de l'effet pénultième
Authors: Monthéard Jean‐Pierre , Boinon Bernard , Raihane Mustapha , Pham Quang‐Tho
Published: April 2003

1‐Propen‐1‐ylidene dicyanide was copolymerized in bulk with vinyl acetate and five substituted styrenes. The reactivity ratios of these copolymerizations were calculated by the Fineman‐Ross or the Kelen‐T¨︁udős method. The penultimate model describes satisfactorily the deviation from the terminal model in the copolymerization reactions between 1‐propene‐1‐ylidene dicyanide and the substituted styrenes.
Cationic polymerization of α‐pinene with the binary catalyst AlCl3/SbCl3
Authors: Higashimura Toshinobu , Lu Jiang , Kamigaito Masami , Sawamoto Mitsuo , Deng Yun‐Xiang
Published: April 2003

Oligomers of α‐pinene (1) with relatively high molecular weight (number‐average molecular weight Mn = 1140, weight‐average molecular weight Mw = 2590) were obtained with the binary catalyst AlCl3/SbCl3 in toluene at − 15°C ([AlCl3]0 = 42,5 mmol · L−1, mole ratio SbCl3/AlCl3 = 0,50). The yield was higher than 90%, and the dimer content was as low as 5 wt.‐%. In contrast, AlCl3 alone gave predominantly dimers and lower oligomers in poor yield, whereas SbCl3 had no catalytic activity for 1. 1H NMR analysis reveled that the structure of the higher‐molecular‐weight fraction (Mn = 2920, Mw = 3690) of the oligomers obtained with AlCl3/SbCl3 is 6, which consists of a cyclohexene ring with an endo‐olefin group, most likely derived from the cationic monomer isomerization of α‐pinene via the ring‐opening of the cyclobutane unit. Effects of the reaction conditions on the polymerization rate and molecular weight were also investigated.
Investigations of the crystallization of polyethylene by means of simultaneous small‐angle and wide‐angle X‐ray scattering
Authors: Bark Michael , Zachmann Hans Gerhard , Alamo Rufina , Mandelkern Leo
Published: April 2003

The isothermal crystallization of linear polyethylene fractions was studied by means of simultaneous measurements of wide‐angle X‐ray scattering (WAXS) and small‐angle X‐ray scattering (SAXS) employing synchrotron radiation. From WAXS the overall degree of crystallinity xc was determined. From SAXS, the scattering power Q was evaluated and compared with several different models for the crystallizing system. When the scattering arises solely from the supermolecular structures, such as spherulites, Q is proportional to xs·xcL·(1 − xcL), where xs is the fraction of material transformed into such structures and xcL is the degree of crystallinity within these structures. By comparing xc with Q it was possible to separate the primary and secondary crystallization and to show that secondary crystallization takes place within the lamellar stacks where the crystals become thicker and the amorphous layers become thinner. The process of recrystallization during annealing of crystalline samples was studied in the same way. Other models were treated in a similar manner.
Reexamination of the Michelson reaction leading to poly(glycerol phosphate). Its functionalization
Authors: Merle Liliane , Boukobza Alain , Spach Gérard
Published: April 2003

Fractionation of the products obtained by the Michelson polyaddition of glycerol 2‐phosphate with diphenyl phosphate chloride gives a definite poly(glycerol phosphate) (PGP) of a molecular weight of about 1000. The exact structure was determined by 31P NMR spectra from which the existence of a random copolymer containig 1,3‐ and 1,2‐PGP sequences can be inferred. The free hydroxyl groups of PGP were grafted with a 1‐thymineacetic acid derivative to an extent of about 40% as determined by 1H NMR.
FTIR spectra and chain conformations in the crystalline forms and clathrates of syndiotactic poly(p‐methylstyrene)
Authors: Guerra Gaetano , Poggetto Francesco Dal , Iuliano Mauro , Manfredi Carla
Published: April 2003

Infrared spectra of syndiotactic poly(p‐methylstyrene) (s‐PPMS) samples, exhibiting various crystalline forms and clathrate structures, are reported in this contribution. Bands due to the syndiotactic stereostructure, bands typical of the two different chain conformations observed in the crystalline structures and bands sensitive to intermolecular interactions typical of the different modes of packing of chains are pointed out. The observed similarities with the case of syndiotactic polystyrene are alos indicated. A complete assignment, via FTIR analysis, of the chain conformations, is presented for all the known crystalline forms and clathrates of s‐PPMS.
Vapour‐liquid equilibria and segment‐molar excess gibbs free energies of concentrated poly(butyl methacrylate) solutions
Authors: Wohlfarth Christian , Zech Birgit
Published: April 2003

Solvent activities were measured by an isopiestic sorption technique for solutions of poly(butyl methacrylate) and poly(tert‐butyl methacrylate), respectively, in various solvents between 323 K and 373 K (or 403 K). The experimental data were reduced to segment‐molar excess Gibbs free energies and to χ‐functions. There is a clear difference in the thermodynamic behaviour of both polymers in their corresponding solutions due to the steric effect of the tert‐butyl group. The chain‐of‐rotators equation‐of‐state model was used to calculate the thermodynamic quantities applying a group‐contribution approach. In general, good agreement can be observed between experimental and calculated results.
New polymer syntheses, 57. Thermotropic polyesters based on 2‐(4‐carboxyphenyl)benzoxazole‐5‐carboxylic acid
Authors: Kricheldorf Hans R. , Thomsen Sven A.
Published: April 2003

2‐(4‐Carboxyphenyl)benzoxazole‐5‐carboxylic acid was prepared from silylated 3‐amino‐4‐hydroxybenzoic acid and methyl 4‐chloroformyl‐1‐benzoate in an “one‐pot procedure”. In addition to the free dicarboxylic acid the acid chloride was prepared and used as monomer. Polycondensations were conducted with the acetates or trimethylsilyl derivatives of phenylhydroquinone, phenylthiohydroquinone, 2,5‐bis(phenylthio)hydroquinone and 4,4′‐oxydiphenol. Furthermore, a copolyester containing 4‐hydroxybenzoic acid was prepared. The resulting polyesters were characterized by elemental analyses, inherent viscosities, differential scanning calorimetry (DSC) and wide‐angle X‐ray scattering (WAXS) measurements and optical microscopy. The polyesters derived from monosubstituted hydroquinones and the copolyester were found to form nematic melts, whereas all other polyesters only form isotropic melts. The structure/property relationships are discussed by comparison with those of the corresponding poly(ester‐imide)s.
Compositional microstructure of polymer prepared by partial hydrolysis of isotactic poly(methyl methacrylate)
Authors: Doskočilová Danica , Mikeš František , Pecka Jan , Kříž Jaroslav
Published: April 2003

The compositional microstructure of partial hydrolyzates of isotactic poly(methyl methacrylate) was analyzed by means of 1H and 3C NMR spectroscopy. The placement of hydrolyzed units was found to be essentially random, and no neighbouring group effect was detected. Thus, at low degrees of hydrolysis, most carboxyl groups are expected to be isolated.
Anionic polymerization of 6‐hexanelactam, 62. Fast catalytic systems in the anionic polymerization of 6‐hexanelactam
Authors: Stehlíček Jaroslav , Puffr Rudolf
Published: April 2003

With magnesium 6‐hexanelactamate bromide (LMgBr) as a catalyst and the N‐acyllactam as initiator an exceptionally high rate of polymerization of 6‐hexanelactam is observed. Side reactions decreasing the concentrations of growth centres and activated monomer (lactam anion) are not affected to such an extent as to explain this acceleration. In the presence of poly(propylene oxide), the side reactions are largely suppressed with LMgBr. The results corroborate the assumption that the reactivity of the N‐acyllactam growth centre is increased by coordination of a magnesium bromide ligand.
Photoreactive polyanhydrides with cinnamic acid units in the main chain
Authors: Pinther Peter , Hartmann Manfred , Wermann Kurt , Günther Wolfgang , Ritter Helmut
Published: April 2003

4,4′‐(Octamethylenedioxy)di‐trans‐cinnamic and 4,4′‐(sebacoyldioxy)di‐trans‐cinnamic acid were synthesized and converted into mixed anhydrides by the reaction with acetic anhydride. Subsequent melt polycondensation produced soluble polyanhydrides having weight‐average molecular weights (Mw) of ca. 11000. The DSC measurements of the polymers exhibited endotherms indicating normal melting processes. On UV‐irradiation of solid films of the polyanhydrides, photocrosslinking of the cinnamoyl moieties in the main chain took place.
Solution‐grown crystals of poly(dimethylphosphazene)
Authors: Kojima Mario , Magill Joseph H.
Published: April 2003

Poly(dimethylphosphazene) crystals have been grown by two techniques, namely: (a) dilute‐solution crystallization and (b) from the supercooled melt. An orthorhombic crystal form with a = 1,390 nm, b = 0,598 nm and c = 0,473 nm was deduced from electron and X‐ray diffraction. There are four monomers per unit cell of density 1,267 g/cm3. Streaks connecting the (hk0) reflections in electron diffraction are suggestive of lattice defects along the [b] axis. Whenever crystals are annealed just below Tm where sufficient mobility exists, the “streaks” are absent when the specimen is cooled to room temperature. Differential scanning calorimetry (heating) exhibits two endothermic peaks at 142°C and 146°C, corresponding to T(1) and Tm transitions, respectively. A mesophase exists between these closely spaced peaks. A wider mesophase range is encountered in poly(oxyphosphazenes).
Novel silicones for transdermal therapeutic system, 4. Modified route to prepare oligodimethylsiloxane containing a cationic end‐group, and its property as transdermal penetration enhancer
Authors: Aoyagi Takao , Akimoto Tomoko , Nagase Yu
Published: April 2003

A modified route to prepare oligodimethylsiloxane (ODMS) containing a quaternary salt at the one chain end was investigated, for the development of a silicone‐based transdermal penetration enhancer. p‐(Chloromethyl)phenethyl‐terminated ODMS (CMP‐ODMS) was prepared by hydrosilylation of p‐chloromethylstyrene with hydrosilyl‐terminated ODMS, as an intermediate. Then, CMP‐ODMS was reacted with pyridine or ethyldimethylamine to afford a quaternary ODMS salt quantitatively. The enhancing activity of drug penetration was evaluated by measuring the amount of indomethacin permeating through the skin, using a two‐chamber diffusion cell having an isolated rabbit abdominal skin mounted between half cells. The obtained polymers effectively enhanced the drug penetration through the skin, whereupon the permeation coefficients were 2 to 15 times that measured without enhancer. Also, the enhancing activities were influenced by the chemical structure of polar and non‐polar end‐groups.
Synthesis of an angularly annulated Diels‐Alder ladder polymer
Authors: Packe Rainer , Enkelmann Volker , Schlüter Arnulf‐Dieter
Published: April 2003

The synthesis of a soluble, angularly annulated Diels‐Alder ladder polymer is described. Its molecular structure is proven by an analysis of the high‐resolution 13C and 1H NMR spectra. Model studies including the structures in the crystal of 9a, 9c, and anti‐4 provide some insight into stereochemical features.
Transition‐metal‐catalyzed vinyl addition polymerizations of norbornene derivatives with ester groups
Authors: Breunig Stefan , Risse Wilhelm
Published: April 2003

Norbornene derivatives containing ester substituents were submitted to Pd(II)‐catalyzed vinyl addition polymerization. The transition metal catalyst was found to tolerate the ester functionality. However, the rate of polymerization was reduced in comparison to the polymerization of norbornene. The polymerization of the pure exo‐isomers produced substantially higher yields than reactions of monomers containing a high proportion of the corresponding endo‐isomer. By varying the ester substituent, amorphous polymers with glass transition temperatures over the range of −40 to 268°C were synthesized. An approximately linear relationship of molecular weight to monomer conversion was established, and the non‐uniformity remained narrow (M̄w/M̄n ≈ 1,15 – 1,25) until high conversions for several of the exo‐isomers studied. This indicates that both chain transfer and chain termination are rare.
Gas transport of hydrocarbon gases through smectic‐A liquid‐crystalline elastomers
Authors: Reinecke Helmut , Finkelmann Heino
Published: April 2003

The transport behaviour of hydrocarbon gases through liquid‐crystalline (l.c.) elastomers is investigated. For different l.c. elastomers exhibiting the smectic‐A phase structure, diffusion and permeation coefficients and solubilities are measured as a function of temperature. The behaviour at the smectic‐A to isotropic phase transformation is discussed and the permeabilities of propane through different l.c. membranes are compared with respect to their network type, spacer length and end group of the mesogens. In methacrylate networks with high phase transformation enthalpies a discontinuous behaviour is observed at the smectic to isotropic phase transformation temperature Tc, as expected for a first‐order phase transformation. Depending on the chemical constitution of the membrane, the l.c. state can reduce or improve the gas transport compared to the isotropic state. With increasing flexibility of the membrane system — caused by a more flexible network, longer spacer or longer end group — the permeabilities exhibit significantly higher values. For all elastomers an increase of the ideal selectivities is observed in the smectic‐A phase.
Synthesis of frequency doubling polymeric materials, 2. Second‐order nonlinear optical properties of poled chromophore‐functionalized polystyrenes
Authors: Vanermen Guy , Samyn Celest , S'Heeren Gert , Persoons Andre
Published: April 2003

The synthesis and frequency doubling properties of nonlinear optical chromophore functionalized polystyrene with 4‐nitro‐ or 4‐cyano‐4'‐hydroxyazobenzene, or 2‐[2‐(4‐hydroxyphenyl‐ethenyl)]‐3,5‐dinitrothiophene are reported. The polymers with longer spacer length of the side chain chromophore show higher X(2) values, because of a better alignment under poling conditions. Values as high as 23,8 · 10−9esu at 1064 nm can be achieved. With a stronger acceptor group (3,5‐dinitronthiophene) a value of 22 · 10−9esu was achieved for a chromophore content which was even 4 times smaller.
Synthesis and properties of high‐molecular‐weight polyesters based on 1,4:3,6‐dianhydrohexitols and terephthalic acid
Authors: Storbeck Reinhard , Rehahn Matthias , Ballauff Matthias
Published: April 2003

The synthesis of high‐molecular‐weight polyesters based on 1,4:3,6‐dianhydro‐D‐sorbitol (DAS), 1,4:3,6‐dianhydro‐D‐mannitol (DAM) and 1,4:3,6‐dianhydro‐L‐iditol (DAI) is reported. The polymers were obtained by polycondensation in solution of the dianhydrohexitols with terephthaloyl dichloride and 2,5‐diethoxyterephthaloyl dichloride. The side groups of the latter monomer lead to a marked improvement of the solubility of the resulting polyesters which can be characterized by NMR techniques and osmometry. It is shown that all polyesters exhibit an excellent stability against thermal decomposition. Materials deriving from the polycondensation with terephthalic acid have glass transitions above 200°C if the molecular weight is high enough. The wide‐angle X‐ray analysis shows that polyesters deriving from terephthalic acid and DAM as well as DAI are semicrystalline. All results demonstrate that these polyesters partly deriving from renewable carbon sources present promising high Tg materials with excellent thermal stability.
Structure formation in solutions of atactic polystyrene in trans‐decalin
Authors: Arnauts J. , Berghmans H. , Koningsveld R.
Published: April 2003

The temperature‐concentration diagram for the system atactic polystyrene/trans‐decalin

System. name: trans‐decahydronaphthalene.

was studied by optical observations and calorimetric investigations. A liquid‐liquid demixing interferes with the glass transition of the polymer‐solvent system. It results in the solidification of the solution. The binodal, the spinodal and the position of the critical point were investigated for a sample with narrow molecular weight distribution. The formation of different morphologies, based on different cooling processes, is illustrated.
Synthesis of a hexyl methacrylate‐terminated disaccharide monomer and study of its radically initiated homo‐ and copolymerization with styrene
Authors: Charreyre Marie‐Thérèse , Boullanger Paul , Pichot Christian , Delair Thierry , Mandrand Bernard , Llauro Marie‐France
Published: April 2003

A new disaccharide monomer, 6(‐methacryloxyloxy)hexyl β‐D‐cellobioside (CHMA, 7h), was prepared through a five‐step procedure (starting from cellobiose), in which the glycosylation and esterification reactions have been optimized. Kinetics of radical homopolymerization in dimethyl sulfoxide solution were studied through 1H NMR, allowing the determination of the parameter kp/kt1/2. Copolymerizations with styrene (S) were also investigated, giving the reactivity ratios rS = 0,64 and rM = 0,08. Characterization of the various (co)polymers in terms of composition, microstructure and molecular weight was carried out using 1H and 13C NMR spectroscopy and gel‐permeation chromatography in tetrahydrofuran, respectively. A preferential syndiotactic configuration was clearly evidenced in the homopolymer.
Living cationic polymerization of styrene by 1‐chloroethylbenzene/tin(IV) chloride in chloroform
Authors: Kwon Oh‐Sig , Kim Yang‐Bae , Kwon Soon‐Ki , Choi Byong‐Seok , Choi Sam‐Kwon
Published: April 2003

Living cationic polymerization of styrene in the presence of 1‐chloroethylbenzene (1‐CEB)/SnCl4 as an initiating system has been investigated in chloroform at ‐15 to +20°C. The best results were obtained at ‐15°C. Under these conditions, the number‐average molecular weight (M̄n) of the products increases linearly with increasing monomer conversion. The molecular weight of the polymer produced could be further increased by adding additional monomer. The molecular weights are in good agreement with the calculated values assuming that one living polymer chain is formed per one 1‐CEB molecular. The molecular weight distributions of the polymers obtained are narrow (ratio of weight‐ to number‐average molecular weights 1,07 ≤ M̄w/M̄n ≤ 1,17). The living character of these polymerizations depends on the polarity of the solvent and on temperature.
Surface tension of poly[(1H,1H,2H,2H‐heptadecafluorodecyl)methylsiloxane]
Authors: Kobayashi Hideki , Owen Michael J.
Published: April 2003

Poly[(1H,1H,2H,2H‐heptadecafluorodecyl)methylsiloxane] (PHDFDMS) was synthesized and the solid surface tension of its cross‐linked films was obtained from water, methylene iodide and various alkanes contact angle data. The value obtained from the Owens and Wendt geometric mean approach using water and methylene iodide data is 7,0 mN/m, the lowest value yet reported for a preformed fluorosilicone polymer. Surface tension values obtained from alkane contact angle data are higher, for example, the Zisman critical surface tension of wetting is 14,9 mN/m. These values fit the trends of other similar fluorinated polymers with the exception of a previous report that PHDFDMS has an anomalously high surface tension.
Melting behavior and crystalline order of ß‐crystalline phase poly(propylene)
Authors: Shi Guan‐yi , Zhang Xiao‐dong , Cao You‐hong , Hong Jie
Published: April 2003

Differential scanning calorimetry and X‐ray diffraction experiments on ß‐nucleated poly(propylene) were made on samples crystallized at different temperatures. The crystal perfection was shown to vary with crystallization temperature. The observed multiple peaks could be related to a ß1‐phase with defective inclination of the chains, a recrystallized or original ß2‐phase of more perfect inclination, and the α‐phase.
Xylan derivatives: aromatic carbamates
Authors: Vincendon Marc
Published: April 2003

Xylan, which is a natural polysaccharide extracted from plant cell walls, is a branched polymer. Linear xylan can be easily obtained through preferential cleavage of the branched sugar units. Xylan is a polyhydroxylated polymer, which is difficult to dissolve in classical organic solvents. The complete substitution of the hydroxyl groups regularly distributed along the xylan chain has been achieved via their reaction with aromatic monoisocyanates. Xylan‐2,3‐bis(phenyl carbamate) (5) and xylan‐2,3‐bis(tolyl carbamate) (6) were obtained with good yield. They were fully characterized by using spectroscopic methods (IR, 1H and 13C NMR). These new xylan derivatives are thermoplastic at high temperatures and decompose beyond 300°C.
Polylactones 21. Polymerization of L,L‐lactide and rac‐D,L‐lactide with hematin and related porphyrin complexes
Authors: Kricheldorf Hans R. , Boettcher Caroline
Published: April 2003

The polymerization of L,L‐lactide was conducted in bulk at 120, 150 and 180°C. Hematin (1a), hemin (1b), 5,10,15,20‐tetraphenylporphiniron(III) chloride, 2,3,7,8,12,13,17,18‐octaethyl‐21H, 23H‐porphiniron(III) chloride (3) and chlorophyllin (4a) were used as initiators. Moderate yields and moderate molecular weights up to 15000 were obtained. Gradual racemization was observed with increasing reaction time and temperature. The results obtained with chlorophyllin and benzylated chlorophyllin suggest an anionic polymerization mechanism for the former initiator. When rac‐D,L‐lactide was polymerized with hematin in bulk at 120, 150 and 180°C, yields up to 74% and molecular weights up to 104 were found. The polymerization of meso‐D,L‐lactide gave lower yields and molecular weights. Both 1H‐ and 13C NMR spectroscopy indicate the formation of nearly random stereosequences in all polymerization of rac‐ and meso‐D,L‐lactide.
Synthese von neuen monomeren schwefelhaltigen acryl‐ und methacrylsäureamid‐derivaten aus 3‐thiazolinen
Authors: Martens Jürgen , Kramer Uwe , Gertje Anja , Schütte Martina
Published: April 2003

Acrylamides containing heteroatoms N, S or O are effective compounds to influence the properties of polymers. On the one hand they determine the chemical and physical behaviour of the synthetic materials, on the other hand they offer new possible applications for such compounds. In this paper a synthetic method affording a new class of monomers prepared from simple educts is described. Thus, 3‐thiazolines 3 are allowed to react with alkenoyl chlorides (e. g. acryloyl chloride) to give 3‐alkenoyl‐4‐chlorothiazolidines. Upon hydrolysis the 3‐alkenoyl‐4‐hydroxythiazolidines 6a–d, 7a, b, 8a–d and 9a, b are obtained. Starting from 3‐alkenoyl‐4‐chlorothiazolidines, several 3‐alkenoyl‐4‐methoxythiazolidines 6e, f, 7c and 9c have been synthesized, too.
Spontaneous polymerization of amphiphilic vinyl monomers, 2 spontaneous polymerization of sodium alkyl 2‐hydroxy‐3‐methacryloyloxypropyl phosphates in micellar and inverse micellar systems
Authors: Yasuda Yutaka , Rindo Katsuhiko , Tsushima Rikio , Aoki Shuzo
Published: April 2003

The spontaneous polymerization of sodium alkyl 2‐hydroxy‐3‐methacryloyloxypropyl phosphates (Cn‐AHMP) was investigated in the temperature range from 35°C to 80°C in water and in benzene. The polymerization activity in both solvents changed with the alkyl chain length in the order: C12 > C8 > C14 ≫ C16. Similarly to the C12 monomer, C14‐AHMP only polymerizes above the critical micelle concentration (cmc), proving that micelle‐formation is essential for the spontaneous polymerization. The polymerization of the C8 analogue occurs even a little below the cmc, in contrast to C12 ‐ and C14‐AHMP. This behaviour suggests the existence of smaller aggregates than the micelle below the cmc in water. The polymerization of C16‐AHMP did not take place spontaneously in both solvents, in spite of the formation of micellar aggregates in water. The lack of polymerization ability is related to the inactivity to generate initiating radical species in the micellar system.
Blends of poly(hydroxy ether of bisphenol‐A) with poly(2‐vinylpyridine) and poly(4‐vinylpyridine)
Authors: de Ilarduya Antxon Martínez , Eguiburu José L. , Espi Enrique , Iruin Juan J. , Fernández‐Berridi María J.
Published: April 2003

Poly(hydroxy ether of Bisphenol‐A), so‐called Phenoxy resin (structure‐based IUPAC name: poly[oxy(2‐hydroxytrimethylene)oxy‐1,4‐phenyleneisopropylidene‐1,4‐phenylene]), is shown to be miscible with poly(4‐vinylpyridine) (P4VPy, poly[1‐(4‐pyridyl)ethylene]) and poly(2‐vinylpyridine) (P2VPy, poly[1‐(2‐pyridyl)ethylene]) over the entire composition range. Miscibility of the blends is evidenced by their glass transition temperatures being intermediate between the pure polymers for the blends of P4VPy and Phenoxy but being higher than the average for the case of the P2VPy/Phenoxy blends. Hydrogen bonding between the components was detected through infrared spectroscopy, which was also used in the study of mixtures of low‐molecular‐weight analogues, in order to calculate the free energies of mixing according to the association model of Painter and Coleman.
Poly(phthalidylidenearylene)s. Gelation in the homopolycondensation of 3‐aryl‐3‐chlorophthalides
Authors: Zolotukhin Mikhail G. , Skirda Vladimir D. , Sedova Elvira A. , Sundukov Vladimir I. , Salazkin Sergei N.
Published: April 2003

The Friedel‐Crafts homopolycondensations of 3‐(4‐biphenyly)‐3‐chlorophthalide (1 a), 3‐(2‐fluorenyl)‐3‐chlorophthalide (1 b), 3‐(4‐phenoxyphenyl)‐3‐chlorophthalide (1 c), 3‐(4‐phenylthiophenyl)‐3‐chlorophthalide (1 d) were studied. The homopolycondensation of 1 a was found to give linear, fully soluble polymers. A gelation, depending on reaction parameters, can occur in the reactions of 1 b–1 d. The methylene group of 1 b was shown to be reactive in the course of synthesis, giving cross‐links. Using the NMR pulsed gradient spin echo method, it was found, that degradation of macromolecular chains in the homopolycondensation of 1 c is followed by gelation. A proposed mechanism of gelation is based on the transformation of intermediate acyloxonium complexes. Similar transformations of acyl‐sulfonium complexes are suggested to occur in the course of the homopolycondensation of 1 d.
Microspheres prepared with a temperature‐responsive macromonomer
Authors: Takeuchi Shigeya , Oike Mitsuru , Kowitz Christoph , Shimasaki Choichiro , Hasegawa Kiyoshi , Kitano Hiromi
Published: April 2003

A macromonomer was prepared from succinimido methacrylate and poly(N‐isopropylacrylamide) (PIPA) with an amino end group. The macronomer (MA‐PIPA) obtained shows a temperature‐responsive transition phenomenon from coil to globule in water at about 36°C. For the copolymer of MA‐PIPA with acrylamide (ratio of monomer residues of N‐isopropylacrylamide (IPA) and acrylamide (AAm) 10:3), the transition temperature of the PIPA chain was the same as that of the macromonomer, whereas the transition temperature of a linear copolymer of IPA and AAm (ratio of the monomer residues 10:3) was much higher than that of PIPA (52°C). Microspheres were prepared by emulsion polymerization of the macromonomer and styrene in the presence of sodium dodecylsulfate. The microspheres obtained show a temperature responsiveness in the critical flocculation concentration. The macromonomer prepared here can be used as a component of temperature‐sensitive devices in various forms.
Lyotropic mesophase of imogolite, 3 observation of liquid crystal structure by scanning electron and noval polarized optical microscopy
Authors: Donkai Nobuo , Hoshino Hiroshi , Kajiwara Kanji , Miyamoto Takeaki
Published: April 2003

The mesophase (lyotropic liquid crystal) of the inorganic rod‐like polymer, imogolite, displays a typical fingerprint texture under a polarized optical microscope (POM), although the mesophase reveals no circular dichroism. The scanning electron microscope revealed a honeycomb structure of thin sheets having pleats in the freeze‐dried sample prepared from the mesophase solution, and POM shows also a fingerprint texture from the same sample. A novel polarized optical microscopic observation procedure was introduced to eliminate the contrast variation and extinction due to the zero amplitude effect which depends on the orientational variation of anisotropic bodies with respect to a polarizer direction under the crossed Nicols. Various textures of lyotropic imogolite liquid crystals were observed with the procedure, and the results were accounted for by a honey‐comb structure of curled thin sheats having pleats. The honey‐comb model is consistent with the observation by scanning electron microscopy on the freeze‐dried sample.