bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recent developments in the synthesis and functionalization of conducting poly(thiophenes)
Authors: Roncali Jean , Garnier Francis , Garreau Robert , Delabouglise Didier , Lemaire Marc 
Published: March 2011

AbstractThe mechanism of the electropolymerization of thiophene derivatives has been investigated by varying the electrosynthesis conditions and the monomer structure. The results of these analyses led to the definition of optimized electrosynthesis conditions allowing the control of the electrical and electrochemical properties of poly(thiophenes). On the basis of these results, the properties of these polymers have been modified by means of a new one‐step electrosynthesis of conducting composite materials and by the direct electropolymerization of tailor‐made functionalized monomers. For this purpose, the steric conditions associated to the various possibilities of covalent derivatization have been analyzed, leading to the definition of a “functionalization space”, compatible with the preservation of high conductivity and electrochemical reversibility in the resulting polymers. This concept has been applied to the synthesis of highly conducting chiral poly(thiophenes) on which an effect of enantioselective molecular recognition has been demonstrated for the first time.
Homogeneous N doping of thick polyacetylene films by chemical way
Authors: Mathis C. , Nuffer R. , Rudatsikira A. , FrançLois B. 
Published: March 2011

AbstractThe kinetics of reduction (n doping) of fibrillar films of polyacetylene (PA) by a large excess of organoalkaline electron donors in solution was studied. The doping rate is proportional to dopant concentration and inversely proportional to the square of film thickness (in a range 100–1000 microns). This means that the kinetics of reduction is entirely controlled, in these experiments, by the interfibrillar diffusion of dopants, leading to macroscopic doping inhomogeneity if the reaction is stopped before completion. The maximum doping level achieved at the end of the reaction is mainly controlled by the redox potential of the dopant.Homogeneously doped thick films, at various doping levels, were prepared using a suitable set of dopants in various solvents.
Characterization of the amorphous phase of polyacetylene by thermally stimulated currents
Authors: El Hout Jamal , Chatain Daniel , Lacabanne Colette , Montanerb Antoine , Galtierb Michel 
Published: March 2011

AbstractThe Thermally Stimulated Current (TSC) Spectroscopy has shown that cis‐polyacetylene can be considered as a semi‐crystalline polymer. Indeed a relaxation mode obeying a compensation law has been observed: it is the dielectric manifestation of the glass transition. Upon oxidation, two TSC peaks have been observed. They have been associated with two diffusion processes revealing the existence of two amorphous phases:‐ the intrafibrillar amorphous phase located between crystallites inside the fibrils,‐ the interfibrillar amorphous phase situated between the fibrils and so much more exposed to oxygen.
Ion implantation in poly(para‐phenylene): Stability of the resulting electrical conductivity and influence of the implantation parameters
Authors: Duroux Jean‐Luc , Moliton André , Froyer G. 
Published: March 2011

Abstract: In an attempt to obtain a semiconducting poly(paraphenylene) PPP we have looked at the effect of ion implantion on this conjugated polymer (Ref. 1). The properties of the material may be varied according to the implantation parameters (Ref. 2) and the electrical conductivity after ion implantation of PPP remains almost constant for a long period of time.
Photosensitive systems for microlithography based on organometallic photoinitiators
Authors: Finter J. , Riediker M. , Rotzinger B. , Rohde O. 
Published: March 2011

AbstractThe photodecomposition of the Ar‐laser sensitive photo‐initiator bis(pentafluorophenyl)titanocene 1 was investigated. Two intermediate species were postulated: a pentafluorophenylcyclopentenyl radical 16 which acts as quencher and a ketene acetal radical of the structure CH2‐CH=C(OCH3)OTiRx 17 which could initiate the polymerization.
Conductive properties induced by ion beams in polyimide films
Authors: Davenas J. , Xu X. L. , Boiteux G. 
Published: March 2011

AbstractIon beams have become of widespread use for the modification of surface layers, in particular in electronics where they constitute the main technique for doping semiconductors. Ionizing radiations have also been widely used for the exposure of polymeric resists in lithography. From these reasons resulted an increasing interest for the study of the modifications induced by the ion beam irradiation of polymers (1). Polyimide was considered since heat resistant polymers are required for applications in electronics. The purpose of this work was to combine the processibility of a common polymer which exhibits excellent insulating properties, with ion beams which may induce locally conductive properties by the use of microbeams.
Resist technology for deep‐etch synchrotron radiation lithography
Authors: Mohr J. , Ehrfeld W. , Münchmeyer D. , Stutz A. 
Published: March 2011

AbstractMicrostructures with characteristic dimensions down to one micrometer and structural heights of several hundred micrometers are produced by deep‐etch synchrotron radiation lithography using poly‐(methyl methacrylate)(PMMA) as resist. In the present paper the details of the process are described. Microstructures without defects caused by stress corrosion are produced by polymerization of a methyl methacrylate base casting resin containing 1% of a cross‐linking dimethacrylate onto a metallic base plate and developing the irradiated parts in solvents with solubility parameters at the periphery of the solubility range of PMMA. In this case the structural tolerances of the microstructures are less than 0.05 μm per 100 μm structural height. Measurements of the dissolution rate and the molecular weight and calculations of the absorbed dose show that the irradiated cross‐linked PMMA is only developable if the absorbed dose is greater than 1.6 kJ which yields a molecular weight MW of 14 000 g/mol.
Liquid crystal polymers with terminally 1‐ phenyl −2‐(4‐cyanophenyl)‐ethane substituted side chains
Authors: Spassky N. , Lacoudre N. , Le Borgne A. , Vairon J.‐P. , Jun C. L. , Friedrich C. , Noël C. 
Published: March 2011

AbstractThe synthesis of a series of liquid crystalline side‐chain polyacrylates with oligoether spacers and 1‐(4‐benzoyloxyphenyl)‐2‐(4 ‐cyanophenyl)ethane mesogenic moiety is reported. Polymers were prepared by radical polymerization of the corresponding acrylate monomers. The liquid crystalline nature of these polymers was established by calorimetric measurements, optical texture observations and X‐ray investigations. For the polymer with the diethylene oxide spacer (EO dimer), the unusual I‐N‐SAd‐Nre sequence was observed. For the polymer with the trimer spacer, only “fluid” smectic phases were evidenced.
Synthesis and characterization of side‐chain liquid crystalline copolymers for non‐linear optics
Authors: Noël C. , Friedrich C. , Leonard V. , Le Barny P. , Ravaux G. , Dubois J. C. 
Published: March 2011

AbstractA number of acrylate copolymers having nematogenic groups with ring‐X (X = CN, CF3) terminal substituent and highly polarizable groups with ring‐NO2 terminal substituent linked to the backbone have been synthesized. The liquid crystalline nature of these copolymers has been established by calorimetric measurements, optical texture observations and X‐ray investigations. Ring‐CN substituents enhance nematic thermal stability and tend to repress smectic properties while terminal CF3 groups favor smectic A mesophase formation. These copolymers should possess interesting non‐linear optical properties.
Rigid rod polymers from liquid crystalline phthalocyanines
Authors: Sauer Thomas , Wegner Gerhard 
Published: March 2011

AbstractA number of alkoxy‐substituted silicon‐dihydroxy‐phthalocyanines have been synthesized which form discotic mesophases depending on the side chain length. Metal salt catalyzed polycondensation only gives oligomers while polymer synthesis from activated monomers leads to reasonable high molecular weigths. Indications for the existence of mesophases in this polymer are given.
Dielectric properties under corona charging of thermoplastics for holographic optical switching
Authors: Moisan Jean‐Yves 
Published: March 2011

AbstractPhotothermoplastics are materials which have been proposed for optical switching devices: a grating is recorded by surface deformation of the thermoplastic layer, coated on an organic photoconductive layer used, like in xerography, for an electrostatic image recording material. But first of all an electrical field is applied through a corona charging sequence and obviously dielectric properties of the abietic ester thermoplastic material are of importance. This paper discusses the behaviour of such a layered thermoplastic material in a corona set‐up, by measuring the corona current and the surface voltage following thickness and temperature of the sample and charging or discharging times.
Gelation of an epoxy resin and percolation theory
Authors: Serrano D. , Peyrelasse J. , Boned C. , Harran D. , Monge Ph. 
Published: March 2011

AbstractThe percolation theory has been applied to the isothermal hardening of the TGDDM‐DDS system (tetraglycidyldiaminodiphenyl‐methane‐diaminodiphenylsulfone). At each temperature, the variations of viscosity as a function of the extent of reaction are well described by a percolation law. The variations of the critical threshold and of the percolation parameter with temperature may be explained by a modification of the reaction mechanism. The percolation threshold is in agreement with the gel point defined on the experimental curves of the logarithm of loss modulus as a function of time log G″ = f(t).
Microwave crosslinking of epoxy/aromatic diamine systems: Process and characterization of the networks
Authors: Thuillier Françoise Marie , Jullien Henri 
Published: March 2011

AbstractIn order to determine the influence of the dielectric field intensity on the crosslinking reaction under microwaves, pulsed waves were used to cure epoxy‐amines systems, without catalyst. Cured resins were studied by Fourier transform infrared spectroscopy, 13‐C nuclear magnetic resonance and dynamic mechanical thermal analysis. Structural and mechanical properties were found to be influenced by parameters as pulse repetition period and peak pulse power.
Isocyanate blocking agents use in polyurethane processing
Authors: Camberlin Y. , Michaud P. , Pesando C. , Pascault J. P. 
Published: March 2011

AbstractDifunctional isocyanates blocked with ϵ‐caprolactam and oximes are tested as curing agents in poly‐(urethane‐ureas) prepregs formulations. With ϵ‐caprolactam blocking agent the temperature of dissociation is around 20–40°C higher than with 2‐butanone oxime. Polymerizable blocking agents are proposed for the development of thick pieces. Simultaneous interpenetrating polymer networks are prepared and their morphology and physical properties are investigated using different technics.
Novel high temperature resins based on bis(4‐maleimido‐phenyl)methane
Authors: Zahir S. , Chaudhari M. A. , King J. 
Published: March 2011

AbstractA novel high temperature thermosetting resin system based on the addition polymerization of bis (4‐maleimidophenyl)methane and o, o′‐diallyl‐bisphenol A is presented in this paper. This system offers the combination of easy solventless processing and the high temperature and toughness performance characteristics demanded for the fabrication of C‐fibre laminates. The mechanism of the polyaddition reaction is unusual. In a first step an ENE addition reaction of the maleimide to the allyl group occurs to give a 1:1 adduct with a propenyl phenol type of structure. This is then followed by a Diels‐Alder addition reaction of another maleimide functional group to the ENE adduct (by the so‐called Wagner‐Jauregg reaction) to give a densely crosslinked polymer with glass transition temperatures well over 280°C.
Retardation and relaxation behaviour of poly (ether‐block‐amide)s (PEBA) copolymers by thermally stimulated creep (TSCr) and current (TSCu)
Authors: Demont Philippe , Chatain Daniel , Lacabanne Colette , Glotin Michel 
Published: March 2011

AbstractThe retardation and relaxation behaviour of poly(ether‐block‐amide)s PEBA copolymers was investigated as a function of hard polyamide sequence length by using thermally stimulated creep (TSCr) and Current (TSCu). Two primary TSCr and TSCu peaks, called ßPE and ßPA were observed in the temperature range 150–300 K. The “low temperature” peak ßPE was characterized by a peak position T ßPE which depends poorly upon hard segment content as the corresponding DSC glass transition temperature TgPE. The peak position TßPA of the “high temperature” relaxation showed a progressive shift towards higher temperatures as the hard segment average length was increased as it is observed in series of pure polyamide oligomers. So, complex spectra suggest that an amorphous phase separation occurs in PEBA copolymers. The TSCr ßPE and ßPA modes were analysed by thermal sampling method (TS). The elementary TSCr processes isolated in the ßPE and ßPA distributed retardation modes were characterized by retardation times following a compensation law. The comparison of activation and compensation parameters confirmed the existence of a biphasic amorphous phase in PEBA.In TSCr spectra, an additional peak, noted α, is observed at a temperature close to the DSC melting point TmPE of the poly(tetramethylene glycol) segments.
Properties of poly(vinyl chloride) crosslinked by new difunctional reagents
Authors: Gonnu Michel , Michel Michel 
Published: March 2011

AbstractAlkaline and alkaline earth salts of either dimercaptans obtained by duplication of o‐mercaptobenzoic acid with α, ω‐diols or of o‐mercaptobenzoic acid have been synthesized. Their efficiency has been studied with respect to induction time before change in melt viscosity and crosslinking rate assessed with Haake plasticorder equipped with a Rheomix 600 internal mixer. Then efficiency with respect to crosslinking was also characterized by the assessment of the insoluble fraction in tetrahydrofuran.Mechanical properties of uncrosslinked and crosslinked PVC were compared at different temperature through either static tests with high strain as creep and tensile tests or dynamic test in the elastic domain.Except for creep resistance, crosslinking does not improve mechanical properties of plasticized PVC at temperature lower than 80°C if insoluble fraction in tetrahydrofuran is lower than 100 % by weight. Because chemical crosslinking leads to the existence of two interpenetrated networks, a physical one and a covalent one, the temporary physical network governs the properties until the melting of ordered domains, whereas the covalent network governs the properties if temperature rises above the melting temperature of the crystalline populations. To improve mechanical properties of crosslinked PVC at room temperature, the crosslinking density of the covalent crosslinks must be higher than the density of physical crosslinks. Such a situation is reached if insoluble fraction in tetrahydrofuran becomes 100 % by weight.
Ionomer‐like materials based on 4‐vinylpyridine copolymers
Authors: Jacovic M. S. , Favier J. C. , Janah H. 
Published: March 2011

AbstractThe purpose of this study is to examine the synthesis and to compare the rheological behaviour of ionomer‐like materials obtained by complexation of 4VP residues in statistical and block copolymers with ZnCl2. For statistical copolymers n‐butyl methacrylate was chosen as comonomer, while triblock copolymers involved butadiene (as central sequence). In spite of a different distribution of the 4VP residues along the chains, the complexed copolymers exhibited generally a rheological behaviour typical of that of ionomers. However, owing to this distribution and the poly‐dispersity, the morphology is quite different. The properties of statistical copolymers resulted from the formation of a mixture of multiplets and clusters. For the block copolymer, the Tg of the rubbery phase is close to that of polybutadiene (−84°C), but no relaxation is observed below 230°C and a two‐phase model is adequate in this case. The very large increase of the rubbery plateau is typical of that of a vulcanized rubber.
Synthesis and characterization of model block‐graft copolymers via anionic polymerization: Introduction of poly(isoprene) and poly(ethylene oxide) as graft chains
Authors: Se Kazunori , Watanabe Osamu , Isono Yoshinobu , Fujimoto Teruo 
Published: March 2011

AbstractNew architectural graft copolymers were prepared, that is, the graft chains were situated in terminal or center position of the backbone chain. These graft copolymers were termed block‐graft copolymers. Two different block‐graft copolymers were prepared from a “grafting onto” process and a “grafting from” process via living anionic polymerization. These backbone chains are poly(styrene), and the graft chains are poly(isoprene) and poly(ethylene oxide). The polymers were characterized by GPC measurements, osmometry, and ultracentrifugation. The block‐graft copolymers formed fine microphase separation structures. It was a morphological feature that an apparent volume fraction of the graft to the backbone might be higher than the real volume fraction.
The effect of photostabilizers on polymeric insulation used at high voltages
Authors: Bamji Soli , Bulinski Aleksander , Densley John 
Published: March 2011

AbstractPolymeric insulation used in high voltage applications and subjected to divergent electric fields emits ultraviolet radiation due to electroluminescence. The chromophores present in the polymer initiate photo‐degradation of the material and, in dry environment, this leads to electrical treeing which causes premature failure of the insulation. The role of photostabilizers which can limit the photodegradation caused by ultraviolet radiation is studied for LDPE containing the usual and decreased concentration of air. Degassing or impregnating the polymer with an inert gas decreases the concentration of oxygen and prolongs the time to tree inception because the probability of forming excited or anionic oxygen is reduced.
Influence of lateral substituents on thermal behavior and solubility of aromatic LC‐polyesters
Authors: Schmidt Hans‐Werner 
Published: March 2011

AbstractStructure ‐ property relations of substituted para‐linked aromatic homopolyesters are reported. Thermotropic liquid‐crystalline substituted poly (1,4‐phenylene terephthalate)s with phase transition temperatures less than 230 °C and good solubility in common organic solvents have been synthesized. If a noncoplanar 2,2′‐disubstituted biphenylene moietyis combined with a monosubstituted phenylene moiety with sufficient bulky substituent, polyester with similar properties were obtained. Although these polyesters are soluble up to high concentrations, no lyotropic liquid‐crystalline behavior was observable.
Mesophase structure of flexible‐chain polymers
Authors: Antipov Evgenij , Kuptsov Sergei , Kulichikhin Valerij , Tur Dzidra , Plate Nikolaj 
Published: March 2011

AbstractA structure of polyethylene (PE) and poly[bis(2, 2,2‐trifluoroethoxy)phosphazene] (PPh) has been studied by means of the X‐ray diffraction technique, scanning electron microscopy and differential scanning calorimetry. The polymers under investigation are examples of the organic and inorganic mesophase flexible‐chain polymers not containing the mesogenic groups. When heated above the melting point both polymers form the condis crystal mesophase state which is stable in a wide temperature range. The PE mesophase reveals the pseudohexagonal structure, while the structure of mesophase PPh has some peculiarities arising from the sharp increase in the chain stiffness within a certain temperature range. The PPh mesophase structure is characterized by the perfect one‐dimensional long‐range order of the monomolecular layers and by the short‐range order only along the two other directions within the layer. This structure may be due to the difference between the interactions of the inorganic backbones and regularly alternating side trifluoro‐ethoxy groups.
The cyclolinear polyorganosiloxanes ‐ a new class of mesomorphic polymers
Authors: Godovsky Yu. K. , Makarova N. N. , Kuzmin N. N. 
Published: March 2011

AbstractThe paper summarizes the recent achievements concerning the influence of the chemical structure and rigidity of cyclolinear polyorganosiloxane chains on the glassy, crystalline and mesophase behaviour with a special emphasis on the temperature range of mesophase stability and some thermal, X‐ray and optical characteristics of their mesophase state. The packing of macromolecules in the mesophase state is suggested.
Solid‐state polymerization of diacetylenes under the action of outside forces on crystalline monomer lattice
Authors: Gerasimov G. N. , Pankratov A. N. , Orlenko A. P. , Kozlova N. V. , Sinevitch E. A. , Teleshov E. N. 
Published: March 2011

AbstractThe polymerization of crystalline diacetylenes TS and DCH with different lattice structure was studied under high hydrostatic pressures (up to 4 kbar). It was shown that pressure increases the deformation of chain growing in monomer crystal. The features of such deformation depend on lattice structure that governs the influence of pressure on polymerization rate. We studied also polymerization of diacetylene HD crystals obtained in the pores of stretched polymer (PP). The field of polymer matrix influences the crystal state and the rate of polymerization. It was shown that the interaction of monomer crystals with the matrix leads to growth of more strained chains in these crystals.
Dielectric and pyroelectric properties of disubstituted diacetylenes
Authors: Dormann Elmar , Gruner‐Bauer Petra , Strohriegl Peter 
Published: March 2011

AbstractThe dielectric and pyroelectric properties of monomer and polymer single crystals of substituted diacetylenes carrying polar side groups are presented for four examples: NP/4‐MPU, TS/FBS, DNP and IPUDO. Large and anisotropic permittivities are generally observed. The symmetrically disubstituted diacetylenes IPUDO and DNP show spontaneous electric polarization despite of their symmetric molecular unit in polymer and/or monomer crystals at room or low temperature, respectively. Polar crystals of the unsymmetrically substituted diacetylenes NP/4‐MPU and TS/FBS can be grown from appropriate solvents. However, polymorphism is an obstacle to a systematic tailoring of dielectric properties of diacetylene single crystals.
Synthesis, structure, and properties of aromatic polysulfides
Authors: Sergeev Vladimir A. , Nedelkin Vladimir I. , Nesmeyanov A. N. 
Published: March 2011

AbstractPolycondensation of haloaromatics and sodium sulfide has been studied. An increase in reactivity of functional groups, a change of the composition of the elementary polymeric unit with a change of the relative amounts of the monomers, and a key role of side‐reactions, i.e. intra(molecular) and macrocyclisation, have been revealed. Low‐melting isomeric poly(phenylene sulfides), as well as their derivatives, reactive telechelic oligomers, have been prepared. New methods of preparation of poly(arene sulfides) by transarylation of diphenyl sulfide, polymerisation of cyclic aromatic sulfides, or by direct polycondensation of arenes with sulfur under the action of AlCl3, as well as by polycondensation of aniline with sulfur in the absence of catalysts have been suggested. Structures and properties of newly prepared polymers have been studied.