bluuebunny/crossref_metadata_2025 huggingface dataset:
Polymerization of 2‐allylnorbornane using Ziegler‐Natta catalysts: Homopolymerization
Authors: Marathe Sujata , Mohandas Thekke Pangil , Sivaram Swaminathan
Published: April 2003

Polymerization of 2‐allylnorbornane using TiCl4 catalyst results in a polymer which is 40% insoluble in o‐xylene at 130°C, whereas with TiCl3 catalyst, a polymer with 88% insolubility in o‐xylene at 130°C is obtained. The o‐xylene‐insoluble fractions gave a very high melting point Tm = 355°C. The main features of these polymerizations are low catalyst activity and, in the case of TiCl4 catalyst, competitive isomerization of the monomer. Based on a comparison with the properties of an acyclic analogue, poly(4‐methyl‐1‐pentene), the partly insoluble nature of poly(2‐allylnorbornane) and its high melting point can be attributed to the presence of the bicyclic pendant.
The glass transition of mixtures of polystyrene with alkyl‐terminated oligostyrene — experimental evidence for microphase separation in a polymer blend
Authors: Abetz Volker , Müller Gunther , Stadler Reimund , Schlick Shulamith
Published: April 2003

Mixtures of high molecular weight polystyrene (Pn = 961.5; Tg = 373 K) and sec‐butyl‐terminated oligostyrene (Pn = 10.6; Tg = 302 K) show a dependence of the glass transition on the composition (i.e. number‐average molecular weight) which cannot be described by the classic equations of Fox & Flory or Kanig & Ueberreiter. Addition of small amounts of the oligostyrene strongly decreases the glass transition, and above an oligomer content of 40 wt.‐% the glass transition remains constant within experimental error. This behavior can be attributed to the unfavorable interactions between the alkyl‐terminated oligomer and the high molecular weight PS. As a result the oligomer is a bad solvent but — according to the requirements defined by Kanig — an efficient plasticizer. This behaviour is even more pronounced in mixtures of the alkyl‐terminated oligostyrene with a poly(styrene‐co‐maleic anhydride) of low maleic anhydride content. In this case, ESR spectra of the spin‐labelled styrene copolymer demonstrate the existence of microheterogeneities on the 2–5 nm scale. The findings are in qualitative agreement with recent theoretical work of Khokhlov & Erukhimovich on entropy‐induced microphase separation in blends.
Télomérisation radicalarie de monomères N‐acryloyl‐N‐alkylamino esters d'intXérêt biologique
Authors: Leydet Alain , Barragan Véronique , Boyer Bernard , Roque Jean‐Pierre , Pucci Bernard , Pavia André A.
Published: April 2003

Three methyl 11‐(N‐acryloyl‐N‐alkylamino)undecanoates were synthesized from acryloyl chloride and amino‐or alkylaminoundecanoic acid esters. These compounds were telomerized in the presence of 1‐dodecanethiol as telogen to yield telomers with molecular weight lower than 5000. These telomers are likely to generate HIV inhibitor polyanions with good biocompatibility. The K/Kt value was assessed from a kinetic study of the telomerization reaction. NMR spectroscopy analysis indicates that the polymerization degree DPn are in good agreement with expectation for methyl 11‐(N‐acryloylamino)undecanoate. However, they were lower than expected for methyl 11‐(N‐acryloyl‐N‐alkylamino)undecanoate.
Liquid crystalline networks composed of rigid spacerless monomers: kinetics of network formation, anisotropic structure and mechanical properties
Authors: Braun Dietrich , Frick Gerhard , Grell Martin , Klimes Michael , Wendorff Joachim H.
Published: April 2003

Rigid isotropic and anisotropic networks were formed by photopolymerization of spacerless liquid crystalline diacrylates and of mixtures of these diacrylates with spacerless monoacrylates in the isotropic and liquid crystalline state. The total conversion of double bonds and the orientational order is strongly restricted for the case of network formation based solely on the diacrylates due to steric constraints. These constraints are considerably relaxed in networks formed from mixtures of di‐and monoacrylates. Such networks display a well defined orientational order. The dynamical mechanical properties were found to correspond to those found for networks based on diacrylates with flexible spacers, the anisotropy of the mechanical properties of oriented networks is weak.
A spin‐probing study of non‐magnetic ionomers: Cu2+ ‐containing polyethylene/methacrylic acid copolymer neutralized with Zn2+
Authors: Yamauchi Jun , Narita Hidehiro , Kutsumizu Shoichi , Yano Shinichi
Published: April 2003

A spin‐probing technique was first applied to a study of a non‐magnetic ionomer, polyethylene/methacrylic acid copolymer neutralized with Zn2+ (E‐MAA‐Zn); 2 mol‐% Cu2+ ions were incorporated in replacement of Zn2+, and its ESR spectra were observed in detail at various temperatures in order to obtain physico‐chemical properties of E‐MAA‐Zn, especially its structural changes. We found no significant influence of the 2 mol‐% Cu2+ ‐incorporation upon the properties of the Zn2+ ionomer by differential scanning calorimetry (DSC), which showed two endothermic peaks, (1) an irreversible one at lower temperature which is associated with the ionic aggregate phase in the ionomer, (2) a reversible one at higher temperature with considerable thermal hysteresis which is due to melting of the polymer main chains. ESR hyperfine coupling constants (A∥ and A⊥) of Cu2+ showed no sign of structural changes of the polymer around the phase‐transition temperatures, whereas ESR g‐values (g∥ and g⊥) of Cu2+ proved the onset of the softening of the polymers to be attributable to polymer melting. The latter slope‐changes in the temperature dependences were reversible, although with considerable thermal hysteresis. These findings are compatible with the DSC data. As for the irreversibility regarding the endotherm at lower temperature, broad ESR hyperfine components recovered gradually, indicating an order‐disorder nature of the ionic aggregate phase transition.
New poly(amide‐imide)s synthesis, 16. Preparation and properties of poly(amide‐imide)s derived from 3,3‐bis[4‐(4‐aminophenoxy) phenyl]phthalide and various bis(trimellitimide)s
Authors: Yang Cnin‐Ping , Lin Jiun‐Hung
Published: April 2003

A series of novel bis(phenoxy)phthalide‐containing poly(amide‐imide)s 3 were synthesized via direct polycondensation of 3,3‐bis[4‐(4‐aminophenoxy)phenyl]phthalide (BAPP) with various aromatic bis(trimellitimide)s 2 in N‐methyl‐2‐pyrrolidone (NMP) using triphenyl phosphite and pyridine as condensing agents. Poly(amide‐imide)s 3 having inherent viscosities up to 1,68 dL/g were obtained in quantitative yields. Most of the resulting polymers showed an amorphous nature and were readily soluble in polar solvents such as NMP and N,N‐dimethylacetamide. All the soluble poly(amide‐imide)s afforded transparent, flexible, and tough films. The glass transition temperatures of these polymers were in the range of 237–292°C and the 10% weight loss temperatures were above 500°C in nitrogen. The properties of poly(amide‐imide)s 3 were compared with those of the corresponding isomeric poly(amide‐imide)s 3′ prepared from 3,3‐[4‐(4‐trimellitimido‐phenoxy)phenyl]‐phthalide and various aromatic diamines.
Divalent cation interactions with a carboxylated derivative of scleroglucan
Authors: Bosco Marco , Sussich Fabiana , Gamini Amelia , Reisenhofer Edoardo , Adami Giampiero , Rizzo Roberto
Published: April 2003

Divalent cation binding was investigated on a semisynthetic carboxylate derivative obtained from the fungal polysaccharide scleroglucan. Polarography, circular dichroism and isothermal microcalorimetry were used to study both the binding ability of Cu(II), Pb(II), and Zn(II) ions and the macromolecular properties of the systems under investigation. A theoretical model, proposed by Schwarz for the cooperative binding, was used to evaluate binding constants and the parameter σ related to the degree of cooperativity. All findings are discussed in terms of the differences in the binding ability of the different cations investigated. Pb(II) ions exhibit the higher affinity for oxidised scleroglucan and, in addition to this, its binding process is characterised by a cooperative behavior due to the onset of a disorder‐to‐order conformational transition of the polysaccharidic backbone. On the other hand, Cu(II) ions are less effective in the binding and unable to induce the conformational transition.
Association behavior of linear ω‐functionalized polystyrenes in dilute solutions
Authors: Borlenghi Attilio , Pitsikalis Marinos , Pispas Stergios , Hadjichristidis Nikos
Published: April 2003

Linear polystyrenes with dimethylamino end groups were prepared by anionic polymerization, using 3‐(dimethylamino)propyllithium as initiator and high vacuum techniques. The amino group was transformed to a sulfozwitterionic moiety by reaction with 1,3‐propanesultone. The dilute solution properties were studied by means of membrane osmometry (MO), low‐angle laser light scattering (LALLS) and viscometry in solvents with different polarity. The amine‐capped polymers, studied by LALLS in tetrahydrofuran (THF), toluene and CCI4 show no evidence of association. In contrast, the zwitterionic samples exhibited a relatively strong association in CCI4 (relative permittivity ε = 2.24), weak in THF (ε = 7.4), and intermediate in toluene (ε = 2.4). The association numbers were lower than those found for linear polyisoprenes and polybutadienes with the same end groups. Viscosity measurements supported the results drawn from LALLS. The results provide strong evidence that the micelles behave hydrodynamically as star polymers. The association behavior is best described by the linear head packing model.
Temperature dependence of the χ‐parameter between polystyrene and polyisoprene
Authors: Rudolf Bernd
Published: April 2003

The temperature dependence of the interaction parameter χ between polystyrene and polyisoprene was investigated. Cloud point, PVT and small angle X‐ray scattering measurements were performed. From various cloud point curves, χ was determined via the Flory‐Huggins theory. Using the PVT‐‐data, χ could be calculated using an equation‐of‐state approach due to Patterson, and the solubility parameter approach. For both methods, the well‐known Berthelot relationship proved to work well, i. e. no adaption of parameters to the experiments was required. Moreover, χ was determined from X‐ray scattering data, using the random phase approximation. Finally these parameters are compared, and in addition parameters determined from X‐ray scattering on diblock copolymers are included. It turns out that the temperature dependence of the χ‐parameters does not depend too much on the method of determination, its absolute value, however, does.
Synthèse d'homopolymères et de copolymères de la N‐acryloyglycine et de l'acide N‐acryloyliminodiacétique, 3. Evaluation de leurs propriétés complexantes vis‐à‐vis de l'ion métallique Cu2+
Authors: Montembault Véronique , Soutif Jean‐Claude , Brosse Jean‐Claude
Published: April 2003

Homopolymers and copolymers of N‐acryloylglycine with acrylic acid and acrylamide were synthetized by radical mechanism using azoisobutyronitrile as initiator in dioxane at 80°C. Moreover, hydrolysis conditions of the ester groups of the diethyl N‐acryloyliminodiacetate homopolymers and copolymers with acrylic acid and acrylamide, previously synthetized, have been determined to avoid hydrolysis of the amide functions of the diethyl N‐acryloyliminodiacetate and acrylamide units. The obtained macromolecular structures have a density of complexing groups which varies either in the same unit (one or two aminoacetic groups) or along the polymer chain. The influence of this density on the complexing ability of the synthetized polymers for Cu2+ was investigated by potentiometry and by visible and ultra‐violet absorption spectroscopy.
Preparation and structure‐property relationships of polymeric materials containing arylenevinylene segments — perspectives for new light‐emitting materials
Authors: Greiner Andreas , Bolle Babett , Hesemann Peter , Oberski Josef M. , Sander Roland
Published: April 2003

Well defined oligo(arylenevinylene)s were prepared by Pd‐catalyzed coupling of dibromoarenes and styrenes. The mixing behavior of these oligo(arylenevinylene)s with polymers is significantly influenced by the structure of the oligo(arylenevinylene)s. Potential consequences for optical properties are discussed. Segmented polymers with arylenevinylene segments in the main chain are presented and discussed in detail. Light‐emitting thermotropic polymers were obtained with modified distyrylbenzene segments in the main chain. These thermotropic light‐emitting polymers show polarized photoluminescence on orientation on rubbed polyimide substrates. Light‐emitting amorphous polymers with high fluorophore concentrations and high glass transition temperatures were obtained by polymers with arylenevinylene segments in the side chain.
Fabrication of ultrathin film containing bienzyme of glucose oxidase and glucoamylase based on electrostatic interaction and its potential application as a maltose sensor
Authors: Sun Yipeng , Zhang Xi , Sun Changqing , Wang Bo , Shen Jiacong
Published: April 2003

An enzyme multilayer film composed of glucose oxidase and glucoamylase alternating with a bipolar quaternary ammonium salt was achieved on the surface of a quartz slide or a gold electrode and its application as a bienzyme maltose sensor was studied.
Electrochemical dehalogenation polycondensation of 2,5‐dibromopyridine mediated by nickel and palladium complexes
Authors: Yamamoto Takakazu , Saito Nobuo
Published: April 2003

Dehalogenation polycondensation of 2,5‐dibromopyridine, 2,5‐Br2‐Py, to poly(pyridine‐2,5‐diyl), PPy, has been achieved under electrochemical reductive conditions mediated by various nickel(II) and palladium(II) complexes (nickel‐2,2′‐bipyridine (bpy) and ‐phosphine complexes and palladium‐bpy complexes). PPy is obtained as a thin smooth film on a platinum electrode in high yield, and among the nickel and palladium complexes [Ni(bpy)3]2Br2 serves as the best mediator for the electrochemical reductive polycondensation. Carrying out the electrochemical polycondensation in a two‐compartment cell and in a one‐compartment cell gives almost the same results. The PPy film prepared by using the nickel(II) complex gives the same IR and cyclic voltammogram as chemically prepared authentic PPy shows. When PdCl2(bpy) is used as the mediator, the formation of PPy is accompanied by metalation reaction of palladium to PPy.
High‐pressure free‐radical copolymerization of ethene and butyl acrylate
Authors: Buback Michael , Busch Markus , Lovis Kai , Mähling Frank‐Olaf
Published: April 2003

The free‐radical copolymerization of ethene and butyl acrylate was studied between 130 and 225°C at pressures from 1 500 to 2 500 bar. The reactions which were induced either thermally or laser‐photochemically were run in two types of continuously operated devices. Reactivity ratio data referring to ethene‐rich monomer mixtures are presented. These data allow to estimate the copolymer composition in ethene/butyl acrylate copolymerizations carried out in a wide range of temperatures and pressures.
Competing processes for poly(aryl ether‐ketone) synthesis, 3. Polymerization reactions of 1,3‐bis(4‐chlorobenzoyl)benzene and 1,3‐bis(4‐fluorobenzoyl)benzene in N‐methyl‐2‐pyrrolidinone
Authors: Bhatnagar Atul , Mani Rajrathnam S. , King Brandon , Mohanty Dillip K.
Published: April 2003

The effects of N‐methyl‐2‐pyrrolidinone (NMP) as solvent on the polymerization reactions of 1,3‐bis(4‐chlorobenzoyl)benzene (1,3‐CBB) and 1,3‐bis(4‐fluorobenzoyl)benzene (1,3‐FBB) with 4,4′‐isopropylidenediphenol (bisphenol‐A) were examined. The failure of these reactions to produce high molecular weight polymers in the presence of anhydrous potassium carbonate is due to dehalogenation of 1,3‐CBB via substitution radical‐nucleophilic unimolecular (SRN1) processes. On the other hand, 1,3‐FBB undergoes nucleophilic aromatic substitution reactions (SNAR) with the carbonate anion at elevated temperatures. However, it is possible to synthesize high molecular weight polymers from 1,3‐FBB and bisphenol‐A in NMP either by first forming the bisphenoxide with stoichiometric amounts of aqueous sodium hydroxide or in the presence of anhydrous potassium carbonate at a lower reaction temperature.
Redox polymerization of 2‐hydroxyethyl methacrylate, 2. Kinetics, mechanism and solvent effect using manganese triacetate/cyanoacetic acid as the redox system
Authors: Mathew Jainamma , Mahadevan Venkatanarayana
Published: April 2003

Polymerization of 2‐hydroxyethyl methacrylate (HEMA) initiated by the redox system manganese triacetate (Mn)(III)/cyanoacetic acid (CAA) was investigated kinetically in DMF and in HOAc/water (80 : 20 v/v). Monomer (M) conversion was followed gravimetrically. Polymerization was carried out at 31°C and at 41°C. The rate of polymerization Rp in DMF is expressed by the equation, RP, ∝ [M]1,4 [Mn(III)]0,4 [CAA]0,4. In HOAc/water, the polymerization exhibited a strong dependence on the concentration of Mn(III). That is, at low concentrations of Mn(III), the rate variations are [M]1,0, [CAA]0,5 and [Mn(III)]0,5, while at high Mn(III) concentration the polymerization rates are independent of [Mn(III)] and vary as a function of [M]1,5 and [CAA]0,5. Enhanced oxidation of the primary radicals by Mn(III) at higher concentrations has been elicited to explain the observed orders. The degree of polymerization was found to increase with increase in concentrations of monomer and decrease in concentrations of CAA and Mn(III). The polymerization rates as well as the molecular weights of the polymers are higher in HOAc/water than in DMF. The enhanced polymerization rates have been attributed to the increased propagation and the reduced termination rates.
Conformational effects on electrical and spectroscopic properties of 1,2‐di(2‐thienyl)ethylenes and corresponding poly[(2,2′‐dithienyl)‐5,5′‐diylvinylenes]
Authors: Benincori Tiziana , Brenna Elisabetta , Sannicolò Franco , Trimarco Licia , Schiavon Gilberto , Zecchin Sandro , Zotti Gianni
Published: April 2003

1,2‐Dialkyl‐substituted 1,2‐di(2‐thienyl)ethylenes have been synthesized and investigated by cyclic voltammetry. The bulk of the alkyl substituents was modulated in order to progressively increase the torsional angle between the thiophene rings and the plane of the olefinic bond, from a fully planar structure to highly twisted systems. Distortion markedly affects the UV spectra and the oxidation peak potentials of the monomers. The electro‐chemical polymerization experiments gave the following results: (i) (E)‐ and (Z)‐dithienyl‐ethylene systems produced polymers with identical properties; (ii) progressive deviation from planarity increased the oxidation peak potential of the monomer, as far as the polymerization was inhibited; (iii) long and rigid monomeric units reduced chain flexibility, leading to materials with low conductivity and unsatisfactory mechanical properties.
New poly(amide‐imide) syntheses, 19. Preparation and properties of poly(amide‐imide)s derived from N‐phenyl‐3,3‐bis[4‐(4‐aminophenoxy)phenyl]‐1‐oxoisoindoline and various bis(trimellitimide)s
Authors: Lin Jiun‐Hung , Yang Chin‐Ping
Published: April 2003

A series of novel bis(phenoxy)‐1‐oxoisoindoline‐containing poly(amide‐imide)s 3 were synthesized by the direct polycondensations of N‐phenyl‐3,3‐bis[4‐(4‐aminophenoxy)‐phenyl]‐1‐oxoisoindoline (1m, NPBA) with various aromatic bis(trimellitimide)s 2 in N‐methyl‐2‐pyrrolidone (NMP) using triphenyl phosphite and pyridine as condensing agents. Poly(amide‐imide)s 3 having inherent viscosities up to 1,06 dL/g were obtained in quantitative yields. Most of the resulting polymers showed an amorphous nature and were readily soluble in polar solvent such as NMP and N,N‐dimethylacetamide. All of the soluble poly(amide‐imide)s afforded transparent, flexible, and tough films. The glass transition temperatures of these polymers were in the range of 277–327°C, and the 10% weight loss temperatures were above 500°C in nitrogen. The properties of poly(amideimide)s 3 were compared with those of the corresponding isomeric poly(amide‐imide)s 3′ prepared from NPBA and various aromatic diamines.
Miscibility and crystallization behavior of thermosetting polyimide/thermoplastic polyimide blends
Authors: Tang Hao , Dong Lisong , Zhang Jin , Ding Mengxian , Feng Zhiliu
Published: April 2003

Compatibility, morphology, crystalline structure and mechanical properties of the blends of a thermosetting polyimide with thermoplastic polyimides consisting of dianhydrides of different lengths have been studied by the use of dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and small angle X‐ray scattering (SAXS) techniques. The results of our research show that the blends change from compatible to semi‐compatible when the difference between the length of the dianhydrides of the two components increases. Addition of a thermoplastic polyimide inhibits the crystallization of the thermosetting component. However, this effect decreases with increasing length of the dianhydrides and the distribution of the molecules of the thermoplastic polyimide component changes from interlamellar to interfibrillar. Impact strength and morphology of the fractured surfaces indicate that among the semi‐interpenetrating polymer networks (semi‐IPN) obtained the toughening effect of the partially compatible one is the best. The results are discussed in terms of charge transfer interaction between imide group and p‐phenylene group.
Miscibility and specific interactions in blends of poly(2‐ethyl‐2‐oxazoline) with hydroxylated polymethacrylates
Authors: Isasi José R. , Meaurio Emilio , Cesteros Carlos , Katime Issa
Published: April 2003

The compatibility of blends of poly(2‐ethyl‐2‐oxazoline) (PEOX) with poly(2‐hydroxyethyl methacrylate) (PHEMA) and poly(2‐hydroxypropyl methacrylate) (PHPMA) was investigated by means of differential thermal analysis and infrared spectroscopy. Calorimetric results show single glass transition temperatures in the entire range of compositions for both systems. S‐shaped curves are obtained when plotting the glass transition temperatures vs. blend compositions. IR analysis of blends reveals the existence of specific interactions via hydrogen bonding between the carbonyl and hydroxyl groups of PHEMA and PHPMA. The association phenomena were quantitatively studied from room temperature up to 180°C with the aid of spectral subtraction techniques.
One‐pot synthesis of a new hyperbranched polyester containing 3,6‐di‐acceptor‐substituted carbazole chromophores for nonlinear optics
Authors: Zhang Yadong , Wang Liming , Wada Tatsuo , Sasabe Hiroyuki
Published: April 2003

The preparation of a new AB2 monomer and a precursor of AB2 monomer bearing carbazole chromophores is described. A new hyperbranched polymer containing carbazole substituted with two acceptor groups for nonlinear optical materials has been synthesized starting from the precursor of AB2 monomer 3,6‐diformyl‐9‐(11‐hydroxyundecyl)carbazole via Knoevenagel condensation and ester exchange condensation in a one‐pot reaction. This hyperbranched polymer with a mass‐average molar mass of about 20000 g/mol is soluble in common organic solvents. The thin polymer films could be obtained from chloroform solution by spin coating. Differential scanning calorimetry analysis showed no crystalline transitions for this hyperbranched polymer and the glass transition temperature of the polymer is about 97,6°C. The resulting thin and glassy polymer films were shown to exhibit reasonably second harmonic generation efficiencies (d33 = 7 pm/V) after electric corona poling at about 100°C.
Side chain pendant non‐linear optically active polymers synthesised by grafting reactions on maleic anhydride copolymers
Authors: McCulloch Iain , Demartino Ronald , Keosian Richard , Leslie Thomas , Man Hong‐Tai
Published: April 2003

The synthesis of well defined, high molecular weight polymers for non‐linear optical (NLO) applications has been carried out in an effort to improve the film properties of waveguides fabricated from these materials, Free radical methods of polymerisation result in molecular weight limitations due to the chain transfer nature of the NLO active chromophores, and therefore, in order to prepare a high molecular weight polymer, a post polymerisation grafting method was chosen to incorporate side chain pendant chromophores onto a preformed polymer. Alcoholysis of anhydride copolymers resulted in chromophore incorporation levels of up to 90% of available reactive sites. Additional branching of the linear anhydride prepolymers was also carried out using polytetrahydrofuran but this was not shown to improve the mechanical properties of the fabricated films. Since the anhydride opens to an ester and an acid, in order to reduce the ionic content of the final polymer, further reaction of the generated carboxylic acid group was attempted, resulting in partial diester formation, and an improvement in film quality. Electrical field poling at temperatures close to the glass transition was only successful at low electrical field strengths, allowing electrooptic coefficients of values of up to 2.4 pm/V at a poling field of 80 V/μm to be obtained.
Synthesis and properties of highly gas permeable poly(amide‐imide)s
Authors: Fritsch Detlev , Avella Nicola
Published: April 2003

Seven dicarboxylic acids containing one or two preformed imide rings were prepared by condensation of trimellitic anhydride with 3‐amino‐4‐methylbenzoic acid or with the diamines 2,4,6‐trimethyl‐1,3‐phenylenediamine, 3,3′‐dimethoxybenzidine, 3,3′,5,5′‐tetramethyl‐benzidine, 3,3′‐dimethyl‐1,1′‐binaphthalene or by condensation of 2,2‐hexafluoroisopropylidenebis(phthalic acid anhydride) (6FDA) with 2 mol of 3‐aminobenzoic acid or 3‐amino‐4‐methylbenzoic acid. Polycondensation was performed directly in N‐methyl‐2‐pyrrolidone (NMP)/triphenyl phosphite/lithium chloride with oxydianiline, 2,2‐bis(4‐aminophenyl)‐perfluoropropane or 3,3′,5,5′‐tetramethylbenzidine. All the resulting polymers are soluble in NMP, some in tetrahydrofuran (THF) and could be cast to transparent, flexible and tough films. The helium permeability as a probe for diffusivity improves with increasing fluorine content and non‐linearity in the repeating unit.
Transport of water vapour and gases in modified cellulose acetate matrices. Influence of the nature of the penetrant on diffusion and relaxation kinetics
Authors: Nguyen Xuan Quang , Šípek Milan , Nguyen Quang Trong , Hynek Vladimir
Published: April 2003

Membranes developed by modification of a cellulose acetate (CA) matrix were studied by means of the flow method CA matrix is modified by poly(4‐vinylpyridine) (PVP), or an interpenetrating network (IPN) agent. The obtained diffusion coefficients, permeability coefficients and relaxation kinetic parameters for oxygen, carbon dioxide and water vapour enabled us to consider not only the transport properties of the membranes but also the influence of the relaxation processes on the membrane permeability and stability. The results show that the interactions between water molecules and polar groups on the polymer chains cause the membrane material to swell. This swelling process provokes an increase in the permeation flux of ca. 20–30%. Oxygen causes a consolidation of unstable membranes of the cellulose acetate matrix modified by IPN but not of blends with PVP. The consolidation process reduces the membrane permeability by ca. 38%, while carbon dioxide has no effects on the membrane properties. Membranes based on a modified cellulose acetate matrix have higher permeability than pure CA membranes.
Polymerization of 1,4‐butadiene over MgCl2‐supported cobalt catalysts combined with trimethylaluminium
Authors: Takeuchi Masaki , Shiono Takeshi , Soga Kazuo
Published: April 2003

MgCl2‐supported Co catalysts with different loading amounts were prepared from the reaction of CoBr2[P(C6H5)3]2 or CoBr2(C5H5N)2 and MgCl2 in toluene solution. Polymerization of 1,3‐butadiene was conducted with them using Al(CH3)3 as cocatalyst, which gave polybutadiene composed of 1,2 and cis‐1,4 units. The content of 1,2 units could easily be regulated from approximately 0% up to 90% by controlling the loading amount of Co as well as by changing the amount of suitable Lewis base added. The sequence distribution of each unit was determined by means of 13C NMR using hydrogenated polybutadiene. Addition of ethylene to the polymerization system caused a marked decrease in the molecular weight of polybutadiene, but ethylene was incorporated neither in the main chain nor at the chain ends. The chain end analysis of very low‐molecular‐weight polybutadiene by 13C NMR suggested that 1,2 and 2,1 insertion reactions predominantly proceed at the initiation and propagation steps, respectively.
Polyimides with cyclohexyl‐substituted indan groups in the main chain
Authors: Maier Gerhard , Wolf Martin
Published: April 2003

A diamine monomer containing the 1,3‐biscyclohexyl‐1‐methylindan group was prepared, starting from cyclohexyl phenyl ketone in four steps. This monomer was reacted with six different dianhydrides (pyromellitic dianhydride, 3,4:3′,4′‐biphenyltetracarboxylic dianhydride, 3,4:3′,4′‐benzophenonetetracarboxylic dianhydride, 4,4′‐oxydiphthalic anhydride, 4,4′‐sulfonyldiphthalic anhydride, 4,4′‐perfluoroisopropylidenediphthalic anhydride) to give the corresponding polyimides via the poly(amic acid) precursors and thermal imidization. All of these polyimides were soluble at least in N‐methyl‐2‐pyrrolidone (NMP) at elevated temperatures, some were soluble in NMP and chlorinated hydrocarbons even at room temperature. The polymers were characterized by nuclear magnetic resonance spectroscopy, differential scanning calorimetry, and dynamic thermogravimetry. All polyimides proved to be amorphous with glass transition temperatures in the range between 261°C and 295°C depending on the nature of the dianhydride moiety. Their decomposition proceeds in two steps, starting at 400°C probably with loss of the cyclohexyl substituents.
Photocrosslinkable comb‐like polymers for membranes: polyamides from modified 5‐aminoisophthalic acid and aromatic diamines
Authors: Ommer Harald J. , Ritter Helmut
Published: April 2003

A series of new comb‐like aromatic polyamides containing cinnamoyl groups in the side chains were synthesized by acylation of 5‐aminoisophthalic acid with 4‐alkoxycinnamoyl chlorides or N‐cinnamoyl‐6‐aminocaproyl chloride in DMAc solution and then polycondensated directly with various aromatic diamines. The preparation of homogeneous photocrosslinkable membranes from NMR solution was performed. The products were characterized by IR and NMR spectroscopy and thermal analysis. An amorphous structure was proved in all cases. A strong influence of the side‐chain structure on the photoreactivity has been observed.
Phenolic copolymer/polyelectrolyte/non‐ionic homopolymer interactions: thermodynamic and electrochemical studies in dimethylformamide/water mixtures
Authors: Chatterjee Saroj K. , Nigam Shalini , Chhabra Mamta , Kapoor Vandana
Published: April 2003

p‐Aminobenzoic acid/p‐hydroxybenzoic acid/formaldehyde copolymer (I) was prepared and characterized. An interpolymer complex of copolymer (I) was prepared by adding stoichiometric amounts of a polyelectrolyte [poly(methacrylic acid)] and non‐ionic homopolymers [poly(N‐vinyl‐2‐pyrrolidone) and poly(ethylene oxide)]. The stability constant and related thermodynamic parameters (ΔH0 and ΔS0) were determined in DMF‐H2O mixtures of different compositions using Osada's method. The stepwise degradation of the complex is explained on the basis of the relative stability of various interacting forces, particularly in media of varying dielectric constant. Electrochemical studies in the media substantiate the observations from thermodynamic studies.
Free‐radical polymerization of acrylates and vinyl acetates initiated by transition metal/hydrosilane two‐component initiation systems
Authors: Imann Ralf , Bandermann Friedhelm , Korth Hans‐Gert
Published: April 2003

The polymerization of vinyl acetate (VA), methyl methacrylate (MMA), and methyl acrylate (MA) in ethyl acetate and tetrahydrofuran solution was initiated by the two‐component initiating systems Fe(III) 2‐ethylhexanoate or Co(II) acetylacetonate and pentamethyldisiloxane as co‐initiator. Whereas Fe(III) 2‐ethylhexanoate initiated the polymerization of all three monomers also in the absence of the siloxane, with an activity increasing from VA to MA, Co(II) acetylacetonate was completely inactive under these conditions. Addition of the siloxane co‐initiator raised the monomer conversions with both transition metal initiators, particularly pronounced for MMA and MA. Number‐average degrees of polymerization for poly(vinyl acetate) and poly(methyl acrylate) amounted to some hundred or less, but increased to several thousand for poly(methyl methacrylate). Electron spin resonance (ESR) spin trap experiments with N‐tert‐butyl‐α‐phenylnitrone (PBN) revealed that the transition metal compounds and the siloxane undergo a reaction in which free radicals are produced by oxidative cleavage of the co‐initiator to generate hydrogen atoms which initiate the polymerization. With Fe(III) 2‐ethylhexanoate PBN adducts of carbon‐centered radicals are observed in the absence and in the presence of the monomers. By way of contrast, with Co(II) acetylacetonate only the hydrogen atom adduct to PBN is observed in the absence of the monomers. Co(acac)2 is likely to form a new complex with the co‐initiator and the spin‐trap molecules. The co‐ordinated PBN competes with the two parent ligands of the complex for the liberated hydrogen atoms, however, due to favorable reaction rate the PBN‐H adduct is formed preferably. The PBN adducts of carbon‐centered radicals replace the PBN‐H adduct when the monomers are added to the initiator solution, i.e. the H atoms are now preferably trapped by the monomer molecules.
Grafting of maleic anhydride onto poly(tetrahydrofuran)
Authors: Rische Thomas , Zschoche Stefan , Komber Hartmut
Published: April 2003

A well‐defined modification of poly(tetrahydrofuran)s was realized by grafting with maleic anhydride. The grafted products were investigated by Fourier‐transform infrared (FTIR) spectroscopy and 13C nuclear magnetic resonance (NMR) spectroscopy. FTIR spectroscopy evidenced a characteristic shift of the carbonyl valence vibrations of cyclic anhydrides to higher wave numbers due to grafting. The grafting of maleic anhydride, which occurred mainly onto poly(tetrahydrofuran) carbons in α‐position, was proved by means of 13C NMR spectroscopy. Furthermore, it was found that approximately 10% of all graftings took place onto poly(tetrahydrofuran) carbons in β‐position. All the grafted units were monosubstituted succinic anhydride units. Indications for the formation of poly(maleic anhydride) graft units were not found. The quantitative determination of grafted anhydride units was carried out by titration after hydrolysis to the acid form. Remarkably high values of percentage grafting up to 20 wt.‐% of maleic anhydride were obtained using an initiator concentration of only 2.5 mol‐% related to maleic anhydride. The high values of percentage grafting at an initail maleic anhydride concentration of 20 wt.‐% were due to a nearly complete conversion of the maleic anhydride. If the initial amount of maleic anhydride was higher than 20 wt.‐% phase separation took place during the reaction. This phase separation prevented complete conversion of the maleic anhydride.
Polymers of carbonic acid, 12. Spontaneous and hematin‐initiated polymerizations of trimethylene carbonate and neopentylene carbonate
Authors: Kricheldorf Hans R. , Lee Soo‐Ran , Weegen‐Schulz Bettina
Published: April 2003

The purity and reactivity of trimethylene carbonate (TMC, 1,3‐dioxan‐2‐one) depends largely on the purification procedure. Vacuum distillation and recrystallization from CCl4 are less efficient than recrystallization from tetrahydrofuran (THF) or ethyl acetate (EtAc). TMC recrystallized from CCl4 contains between 5 and 8 mol‐% of CCl4 which inhibits the spontaneous polymerization at temperatures ≥ 100°C as do other alkylating agents. The spontaneous polymerization of pure TMC may give high yields (up to 90%) and high molecular weights (weight‐average molecular weights up to 200 000). The polymerization mechanism is discussed. It seems to be anionic in nature. Neopentylene carbonate (NPC, 5,5‐dimethyl‐1,3‐dioxan‐2‐one) is rather insensitive to the purification procedure and does not undergo spontaneous polymerization at temperatures ⩽ 125°C. Hematin initiates the polymerizations of TMC and NPC in bulk, but high yields and high molecular weights were only obtained in the case of TMC.
Influence of polymerization conditions on the copolymerization of styrene with ethylene using Me2Si(Me4Cp)(N‐tert‐butyl)TiCl2/methylaluminoxane Ziegler‐Natta catalysts
Authors: Sernetz Friedrich G. , Mülhaupt Rolf , Waymouth Robert M.
Published: April 2003

Styrene was copolymerized with ethylene using Me2Si(Me4Cp)(N‐tert‐butyl)TiCl2/methylaluminoxane (Me = methyl, Cp = cyclopentadienyl) varying monomer concentration, styrene/ethylene molar ratio and polymerization temperature. Increasing styrene or decreasing ethylene concentration, respectively, in the monomer feed lowered both activity of the catalyst system and molecular weight of the copolymer. Only at low styrene content, a linear correlation of styrene concentration in the monomer feed and styrene incorporation in the copolymer was found. From copolymerizations at various temperatures the activation energy of the insertion step was calculated to be 56 kJ/mol. According to Fineman‐Ross plot, the copolymerization parameters are rE = 23,4 for ethylene and rS = 0,015 for styrene. Investigation of the thermal properties by means of differential scanning calorimetry and dynamic mechanical analysis revealed pronounced decrease of melting temperature and increase of glass transition temperature with increasing styrene content.
Inverse microemulsion polymerization of acrylamide in the presence of hexamethylenetetramine
Authors: Bartoň Jaroslav , Stillhammerová Martina
Published: April 2003

The inverse microemulsion polymerization of acrylamide is retarded in the presence of hexamethylenetetramine. The retardation effect of a given hexamethylenetetramine concentration on the kinetics of the polymerization of acrylamide depends on the pH of compartmentalized water droplets. For non‐crosslinked polymer particles the polymer particle diameter for a given composition of the inverse microemulsion increases in the presence of hexamethylenetetramine, while the relative molecular mass (molecular weight) of the polymer decreases. Depending on the pH value of the compartmentalized water droplets polymer particles with different crosslinking degree (of different swelling index) were obtained. The kinetics of polymerization and the polymer particle characteristics are discussed with respect to the hexamethylenetetramine effect on the stability of dispersed particles in an inverse microemulsion prior to and during the polymerization and in terms of the effect of “in situ” formed hexamethylenetetramine decomposition products and of their reactions with acrylamide and/or acrylamide structural units in the polymer.
Synthesis of polyesters with pendant chloromethyl group by polyaddition of bis(oxetane)s with diacyl chlorides catalyzed by quaternary onium salts
Authors: Kameyama Atsushi , Yamanoto Yuko , Nishikubo Tadatomi
Published: April 2003

A new polyaddition of bis(oxetare)s with diacyl chlorides catalyzed by quaternary onium salts is described. The reactions of the new bifunctional monomer, bis(3‐methyl‐3‐oxetanylmethyl) terephthalate, with terephthaloyl chloride using quaternary ammonium halides proceed smoothly under mild conditions to give the corresponding polyester with chloromethyl group in the side chain. It was proved that quaternary onium halides such as tetraethylammonium bromide and tetrabutylammonium chloride and bromide (TBAB) had high catalytic activity in the polymerization in low polar solvents such as anisole and toluene to produce the polyester with high molecular weight. The polyaddition of various bis(oxetane)s with diacyl chlorides using TBAB as the catalyst also proceeded to give the targeted polyesters with pendant chloromethyl group, which is introduced simultaneously with the formation of the polymer backbone during the reaction.
Synthesis of SBC, SC and BC block copolymers based on polystyrene (S), polybutadiene (B) and a crystallizable poly(ε‐caprolactone) (C) block
Authors: Balsamo Vittoria , von Gyldenfeldt Friederike , Stadler Reimund
Published: April 2003

The sequential anionic polymerization of polystyrene‐block‐polybutadiene‐block‐poly(ε‐caprolactone) (SBC) triblock copolymers as well as polystyrene‐block‐poly(ε‐caprolactone) (SC) and polybutadiene‐block‐poly(ε‐caprolactone) (BC) diblock copolymers was achieved in benzene. To initiate the polymerization of the highly reactive ε‐caprolactone, the nucleophilicity of the carbanion has to be reduced. For this purpose 1,1‐diphenylethylene (DPE) was used. To avoid inter‐ and intramolecular transesterification reactions of the growing caprolactone block, the reaction time of this monomer in the block copolymers was strictly controlled. The reaction between polybutadienyl anions and DPE is too slow, and an incomplete reaction results in side reactions when ε‐caprolactone is added. An alternative method was developed, which consisted in the addition of a small quantity of styrene, after the polymerization of butadiene, to diminish the total reaction time and reduce the probability of chain transfer.
Low‐molecular‐weight poly(imide‐amide)s obtained by copolycondensation of 4,4′‐methylenedi(phenyl isocyanate), trimellitic anhydride and benzoic acid in N‐methyl‐2‐pyrrolidone, 2. Structural defects observed by 1H and 13C NMR
Authors: Sintès‐Zydowicz Nathalie , Pham Quang Tho , Michaud Philippe
Published: April 2003

The in depth examination (by 1H and 13C NMR, DSC, SEC and TGA) of the low‐molecular‐weight poly(imide‐amide)s synthesized with the mixture [4,4′‐methylenedi(phenyl isocyanate) (M) + trimellitic acid anhydride (T) + benzoic acid (B)] in N‐methyl‐2‐pyrrolidone (NMP) at temperatures lower than 180°C allowed the identification and quantitative determinations of all the unexpected and relatively stable structures. While amide functions are readily synthesized, the formation of imide from anhydride and isocyanate functions passes through 4‐amido‐1,2‐benzenedicarboxylic acid (Ti), 1,4‐di‐amido‐2‐benzenecarboxylic acid (T″) and disubstituted urea (u). At 180°C Ti completely disappears but traces of T″ and u remain; thus, the formation of imide can never reach its theoretical quantity. Traces of moisture in NMP may play the role of catalyst in the formation of imide, and reaction mechanisms are proposed.
Influence of the tacticity dependent microstructure on the space charge distribution of poly(vinyl chloride)
Authors: Vella Nathalie , Toureille Alain , Guarrotxena Nekane , Millan José‐Luis
Published: April 2003

The space charge distribution of three samples of poly(vinyl chloride) of different isotactic content has been studied by the thermal step technique, with a view to investigating the influence of some defined microstructural features on that important behaviour. It has been observed that the space charge increases substantially as the content of the local tetrad configuration, mmr, at the end of isotactic sequences increases. A first tentative interpretation is given.
Functionalized poly(ε‐caprolactone) and copolymers with ethylene oxide through heterogeneous anionic coordinated polymerization. NMR characterization and crystallinity
Authors: Jacquier Véronique , Miola Christelle , Llauro Marie‐France , Monnet Christiane , Hamaide Thierry
Published: April 2003

Functionalized poly(ε‐caprolactone)s have been easily prepared by using a new heterogeneous catalytic system consisting of aluminium alcoholate supported on porous silica and the corresponding alcohol in excess. The polymers have been fully characterized by 1H and 13C NMR spectroscopy. Oligo(caprolactone‐co‐ethylene oxide)s have been synthesized by the same catalytic system. The diad comonomer distribution as obtained by 1H NMR suggests a blocky structure. In addition, low degrees of crystallization have been determined by means of DSC.
Influence of chirality on the phase behaviour of copolymers containing cholesterol as mesogenic moiety
Authors: Weidner Steffen , Wolff Dietmar , Springer Jürgen
Published: April 2003

Liquid‐crystalline side‐group copolymers containing cholesterol and chiral nonmesogenic chloropropionate acid groups were synthesized and investigated by means of size‐exclusion chromatography, proton nuclear magnetic resonance (1H NMR), polarization microscopy, X‐ray diffraction and differential scanning calorimetry. In addition the spacers of the cholesterol‐containing side groups were modified by substitution of two of the methylene groups by oxygen ether groups. The cholesterol‐containing homopolymer displays only an SA‐mesophase. Amounts of more than 50 mol‐% of the non‐mesogenic chiral co‐compounds led to the total disappearance of liquid‐crystalline phases. For less than 50 mol‐% a different phase behaviour was observed for the copolymers with unsubstituted and ether‐substituted spacers. Phase transition temperatures depend also on the chirality of the non‐mesogenic groups. Similar results were obtained by investigating a copolymer system, which contains chiral camphor‐10‐sulfonic acid moieties and which was synthesized to check this observation.
Low‐temperature 1H and 13C NMR investigation of trimethylaluminium contained in methylaluminoxane cocatalyst for metallocene‐based catalysts in olefin polymerization
Authors: Tritto Incoronata , Sacchi Maria Carmela , Locatelli Paolo , Li San Xi
Published: April 2003

Toluene‐d8 solutions of methylaluminoxane (MAO) after the addition of different amounts of trimethylaluminium (TMA) have been studied by means of 1H and 13C NMR at a temperature as low as −78°C to freeze out some of the fluxional equilibria of the molecule. A comparison of the half height width of the NMR signal W1/2 and of the mole ratio of the methyl signals before and after addition of known amounts of TMA allowed us to reach the following conclusions about the TMA contained in MAO solutions: (a) TMA is mainly bound to MAO; (b) TMA participates in disproportionation reactions.
Morphological studies on a novel poly(aryl ether ketone)
Authors: Wang Shanger , Wang Junzuo , Zhang Hongfang , Wu Zhongwen , Mo Zhishen
Published: April 2003

The morphology of a novel poly(aryl ether ketone) [PEDEKmK] was investigated via polarizing optical microscopy (POM), TEM, DSC, SAXS and electron diffraction (ED). A distinct change in lamellar thickness, orientation, and spherulitic morphology was observed due to crystal melting and recrystallization. However, the crystal packing mode is found to be identical before and after the recrystallization process.
Mécanisme de photoréticulation de polymères contenant le motif dicyclopentadiène en présence et en absence de benzophénone
Authors: Eisele Gilles , Fouassier Jean‐Pierre , Reeb Roland
Published: April 2003

The study of the mechanism of the processes taking place in photocrosslinking of the homopolymer of dicyclopentenyl acrylate (DCPA), was realized using ultraviolet and Fourier transform infrared (FTIR) measurements. Different kinetics of crosslinking in the presence and absence of benzophenone prove the efficiency of this photosensitive system. The particular structure of the acrylic matrix of poly(DCPA), i.e., the presence of a residual unsaturated bond and a cyclic structure, reveals its high photooxidation potential (hydroperoxyde formation as detected by FTIR between 3 300 and 3 600 cm−1).