bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular recognition and signal processing in biosensors
Authors: Scheller Frieder W. , Schubert Plorian , Weigelt Dietmar , Mohr Peter , Wollenberger Ulla
Published: March 2011

The specificity of molecular recognition is reflected to a high degree by the selectivity of the respective biosensor response. Therefore, the application of highly specific enzymes offers advantages for analytical purposes. Using lactate monooxygenase in combination with lactate dehydrogenase and pyruvate kinase, sequentially acting enzyme electrodes for lactate, pyruvate, ADP and enzyme activities, e.g. lactate dehydrogenase, creatine kinase and aminotransferases were developed. A high sensitivity was achieved based on the cycling enzyme pairs hexokinase/pyruvate kinase for ATP and ADP, and lactate monooxygenase/malate dehydrogenase for malate and oxaloacetate, respectively. On the other hand, in a sensor for a large group of substances, the unspecific microsomal cytochrome P‐450 system was applied.
Genetic approaches to protein purification
Authors: Uhlén Mathias , Abrahmsén Lars , Moks Tomas , Nilsson Björn
Published: March 2011

A gene fusion system based on the protein A gene from Staphylococcus aureus has been developed to facilitate purification of recombinant proteins, both in large and small scale. Due to the strong interaction with IgG, it is possible to recover gene products fused to various protein A derivatives, in a one‐step procedure with high yield and in purity. Site‐directed mutagenesis was used to introduce enzymatic and chemical cleavage sites at the fusion point between the protein A derivative and the desired protein. The protein A “tail” can thereby be removed from the affinity purified fusion protein by the appropriate cleavage, releasing biologically active molecules. Recently, the system was improved by designing a synthetic DNA fragment encoding two IgG‐binding domains derived from staphylococcal protein A which are resistant to various chemical cleavages. The gene fusion product is secreted to the culture medium of E.coli and can be recovered simply by passing the clarified culture medium through an IgG Fast Flow Sepharose. The system has been used to immobilize enzymes, to obtain monoclonal and polyclonal antibodies and to produce biologically active human peptide hormones in pilot plant scale.
Characterization of dilute polymer solutions and dispersions by dynamic light scattering ‐exemplified by polystyrene and photographic emulsions‐
Authors: Helmstedt Martin
Published: March 2011

A survey of light scattering methods in the field of polymer characterization and an introduction into fundamental relations of quasielastic light scattering are given. The partially home made RAYLEIGH spectrophotometer and its calibration is described. For monodisperse polystyrene dispersions a maximum deviation of 2 % is obtained. The translational diffusion coefficients of approximately monodisperse linear polystyrene samples dissolved in cyclohexane under theta conditions at 34.5 degrees C agree well with the relation of PETRUS et al., D0 = 1.388 · 10−4 M−0.5. Over a broad range of molecular masses the values measured in 2‐butanone at 25 degrees C give the relation D0 = 6. 16 · 10−4M−0.577 with a small deviation from earlier published data. Results for the growth of silver halide particles during the preparation of photographic seed emulsions are given.
Photon correlation spectroscopy of compatible polymer blends
Authors: Fytas G. , Kanetakis J.
Published: March 2011

The dynamics of concentration fluctuations in compatible polymer mixtures can be investigated by dynamic light scattering. The experiment yields both the dynamic and static structure factors from which the mutual diffusion coefficient and the segment‐segment interaction parameter can be obtained. Examples of applications are the unentangled blends poly(ethylene oxide/poly(propylene oxide) and polystyrene/poly(phenylmethylsiloxane) in the one phase region.
Miscibility and phase separation in polymer blends studied by laser light scattering
Authors: Kammer W. H. , Kressler J.
Published: March 2011

In this paper major emphasis has been placed on the phase behavior of miscible polymer blends, especially on blends containing random copolymers. Blends containing random copolymers generally tend to phase separation at elevated temperatures (LCST behavior). Experimental determination of miscibility areas as a function of temperature and copolymer composition by laser light scattering provides the interaction parameters necessary for theoretical explanations and predictions of various phase separation phenomena.

Just above the LCST polymer blends exhibit regular highly interconnected two‐phase morphologies. The rate of decay of these structures is estimated. The phase separation kinetics can be pursued by laser light scattering and is discussed in terms of CAHN's linearized theory. It can be shown that the linear theory adequately describes the early stage of phase decomposition. The linear theory is also applicable to the reverse phenomenon, the phase dissolution below LCST. unlike the case of phase separation the diffusion‐controlled regime is that in the late stage of phase dissolution.
Raman spectroscopy in high polymer research and production
Authors: Steger Walter Eberhard
Published: March 2011

The mechanism of RAMAN scattering depends on molecular polarizability changes and therefore this method is especially useful for the study of non‐polar bonds. This is shown by reviewing some analytical applications. Knowledge on polymer structure was especially promoted by studies of the lowest‐frequency bending modes, of correlation splittings in case of crystallinity, and by measurements on depolarization of the laser light. RAMAN spectroscopy has possibilities for in‐situ and multi‐method measurements. Newer developments serving the polymer sciences are surface enhanced RAMAN scattering and the RAMAN spectroscopy of electroconducting polymers.
Laser pulse fluorometry as a tool in polymer research
Authors: Boens Noël , De Schryver Frans C. , Ameloot Marcel
Published: March 2011

A time‐resolved fluorescence spectrometer with laser excitation and picosecond time‐correlated single photon counting detection is described. The parameter recovery from experimental data is discussed in detail. Correction methods for errors in the time‐correlated single photon counting technique are indicated. Applications of this photophysical tool to polymer research are given.
Time‐resolved optical absorption spectroscopy of molten polyethylene blends
Authors: Brede Ortwin , Hermann Ralf , Helmstreit Wilfried , Taplick Thomas , Stephen Ludwig
Published: March 2011

By means of pulse radiolysis and laser photolysis experiments with detection by optical absorption spectroscopy short‐living radical transients in pure PE and in PE doped with additives (e.g. di‐>tert‐butyl‐p‐cresol, diphenylamine, benzophenone and carbon tetrachloride) were characterized by their optical absorption spectra and kinetics. It was found that the additive radicals were formed in a very fast process probably via exciton migration and subsequent energy transfer and dissociation reactions.
Time resolved laser spectroscopy of excited state processes in photoinduced polymerization reactions
Authors: Fouassier Jean‐Pierre
Published: March 2011

During the last years, the use of photoinduced radical chain polymerization of unsatured monomers has increased considerably because of the vide applications of these processes in photoactive polymer‐based systems. The present paper is mainly concerned with an investigation of the processes involved. For this purpose, time resolved laser spectroscopy (which appears to be a very convenient method for investigating directly the experimental behaviour of selectively excited chromophores) has been used. The utility of such a technique for the investigation of the primary processes which occur in the excited states of the photoinitiators immediately after the absorption of photons is demonstrated. As examples, main outlines corresponding to the classical processes observed in radical photoinitiated polymerization are considered and discussed: excited state processes in photoinitiators; mechanism of excitation transfer in combination of photosensitive systems; visible laser light induced polymerization; holographic recording.
Laser induced polymerization of acetylene derivatives
Authors: Karpacheva Galina , Khoroshilova Valentina , Davydov Boris
Published: March 2011

He‐Cd laser induced polymerization of aryl‐propargylamines such as phenyl‐ and diphenylpropargylamines were studied. The polymerization of these monomers was shown to be realized only in presence of acceptor of electrons. Polymer formation process is based on the formation of an intermediate compound and its following polymerization by the radical reaction of C≡C bond. Photochemical and photophysical processes leading to the formation of intermediate compound were investigated. The polymers obtained were characterized by IR‐, ESR‐, NMR‐spectroscopy. The conjugated double bond system formation is the main characteristic of these polymers. Some polymer properties were studied.
Advances in ultra‐high load polymer‐supported peptide synthesis with phenolic supports: 2. Use of ‘hydrazinolysis‐hplc’ to check for racemization on c‐terminal amino acid loading and to determine peptide homogeneity during synthesis with selectively labile c‐terminal anchoring linkages
Authors: Baker Philip A. , Coffey Andrew F. , Epton Roger , Johnson Tony , Mole Edward J.
Published: March 2011

2, 4‐Dinitrophenyl‐L‐phenylalanine has been coupled to L‐, D‐, and DL‐amino acid phenyl esters pendant upon a polymer matrix. The esters had been prepared by di‐isopropylcarbodiimide‐mediated condensation, catalyzed by 4‐dimethylaminopyridine. Reverse phase high pressure liquid chromatography (HPLC), using elution solvents consisting of 10 vol.‐% trifluoroacetic acid in water/acetonitrile mixtures, has been used to investigate the 2,4‐dinitrophenyl L‐L and L‐D dipeptide mixtures obtained on hydrazinolysis of each of the dipeptide‐matrix assemblies. ‘Hydrazinolysis‐HPLC’ has been used also to determine intermediate peptide homogeneity in ultra‐high load solid (gel) phase synthesis with Boc amino acids. Cross‐linked poly(N‐[2‐(4‐hydroxyphenyl)ethyl]acrylamide) and two derived polymers incorporating spacer groups have been used as supports. The spacer groups made possible peptide C‐terminal attachment by either HF‐labile benzyl ester or HF‐labile cyclohexyl ester bonds, while still incorporating the phenolic ester linkage susceptible to rapid hydrazinolytic scission.
Crosslinked polyacrylamide‐hydrazide (paah) as matrix for the gel entrapment of cells and enzymes ‐ an overview
Authors: Freeman Amihay
Published: March 2011

The development and use of a gel entrapment technique designed for the immobilization of viable, sensitive cells is described. The method is based on the controlled chemical cross‐linking of prepolymerized, linear polyacrylamide partially substituted with acylhydrazide groups, by glyoxal. The methodology, applications and advantages of this technique for the immobilization of cells and enzymes by gel entrapment are reviewed.
Surface structure of polymers for biomedical applications
Authors: Ratner Buddy D.
Published: March 2011

Biological reactions with synthetic polymers are strongly influenced by the surfaces of those materials. The surfaces are often substantially different in composition and structure from the bulk. By using contemporary surface analysis methods, we can understand polymer surfaces. The surfaces of polymers can also be modified to generate desired biological responses. These points are illustrated with examples involving polyurethanes and RF plasma‐deposited films.
Polyanhydrides: Stability and novel composition
Authors: Domb A. , Langer R.
Published: March 2011

New types of polyanhydrides with advantageous properties with respect to biomedical use were synthesized. The first are aliphatic‐aromatic homopolyanhydrides of the structure: ‐(OOC‐C6H4‐O(CH2)x‐ CO‐)n (=1−10). These polymers display a zero‐order hydrolytic degradation profile for two to ten weeks, the time period of degradation is a function of the length of the aliphatic chain. Stability studies under anhydrous conditions showed that these polymers underwent reversible self‐depolymerization in chloroform but were stable in solid state for over 6 months at 25°C.

The second type of polymer, unsaturated polyanhydride of the structure: [‐(OOC‐CH=CH‐CO)x‐(OOC‐R‐CO)y‐]n, have the advantage of secondary polymerization of double bonds to create a crosslinked matrix. These polymers were prepared from the corresponding diacids polymerized by melt condensation or in solution. Molecular weights of up to 44 000 and 30 000 were achieved for polyanhydrides of p‐carboxyphenoxyalkanoic acid and fumaric acid, respectively.
Ueber die anwendung von in vivo zersetzbaren polymeren in der thoraxchirurgie
Authors: Nakamura Tatsuo , Shimamoto Takeshi , Watanabe Satoshi , Shimizu Yasuhiko , Hyon Suong‐Hyu , Ikada Yoshito
Published: March 2011

Bioabsorbable materials for use in a clinical situation are required to have specific mechanical characteristics and predictable degradation. We have been studying the mechanical properties and the bioabsorbability of polyesters of aliphatic α‐hydroxyacids, such as polylactide, polyglycolide (PGA) and their copolymers, to applying them for surgery, and classifying the effects of the factors governing their biodegradation behavior.

Poly‐L‐lactide (P‐L‐LA) showed slow degradation and maintained initial mechanical properties for a period of more than 3 months after implantation. In contrast, PGA showed rapid degradation and after its absorption at the site of implantation, good replacement of the tissue was observed. On th basis of these results, various clinical applications for thoracic surgery were evaluated as follows: 1) For the fixation of fractured ribs, pins made from either P‐L‐LA or a composite of P‐L‐LA and hydroxyapatite were prepared. 2) For reconstruction of the chest wall, Tricot‐Knit PGA mesh and P‐L‐LA mesh were fabricated.

In vivo tests in dogs were then carried out. P‐L‐LA pins maintained the strength required for connecting the fractured ribs until complete reunion was achieved, while the meshes acted as scaffolding for reconstruction of the connective tissue. In both cases, these materials showed minimal tissue reaction and sufficient biocompatibility.
Surfacial modification of polymer powders as drug carriers
Authors: Matsubara Yoshio , Yagi Tooru , Yamashita Natsuki , Maeshima Toshihisa
Published: March 2011

Preparation of warfarin methacrylate(WaMA) was carried out by esterification of warfarin as thromboembolism drug with methacryloyl chloride. Radical copolymerization of WaMA with 1‐vinyl‐2‐pyrrolidone(VPr) was carried out in 1,4‐dioxane at 60°C using 2,2′‐azoisobutyronitrile as initiator. The surfacial modification of the copolymer powders was achieved using the freeze‐drying by dissolving the copolymer in benzene and micellation by benzene‐in‐water and water‐in‐benzene systems. The hydrolysis of the copolymer including the drug was investigated under mild condition from a view point of released rate of the drug.
Poly(β‐hydroxyalkanoates): Biorefinery polymers in search of applications
Authors: Marchessault R. H. , Bluhm T. L. , Deslandes Y. , Hamer G. K. , Orts W. J. , Sundararajan P. R. , Taylor M. G. , Bloembergen S. , Holden D. A.
Published: March 2011

Poly(β‐hydroxyalkanoates) are nature's high molecular weight thermoplastic polyesters. They occur as storage granules in a variety of bacteria. From a plastics, film, and fibres perspective, the statistically random copolyesters based on β‐hydroxybutyrate (HB) and β‐hydroxyvalerate (HV) repeating units have high potential for commercial exploitation because of their biodegradability. They provide a range of melting points from 180°C down to 80°C and all compositions exhibit high crystallinity due to isodimorphism. The latter is due to the similar crystalline conformations of poly(β‐hydroxybutyrate) (PHB) and poly(β‐hydroxyvalerate) (PHV). The nascent granules of a 21 mole % HV copolyester sample in freeze‐dried bacterial cells were examined by 13C solid‐state NMR. A disorder in the HV ethyl side group was noted but backbone carbons for HB and HV units showed evidence of crystalline order which was confirmed by x‐ray diffraction. In keeping with the isodimorphous properties of this system, electron diffraction of copolyester single crystals for compositions up to 21 mole % HV confirmed a lattice expansion previously observed for bulk crystallized P(HB‐co‐HV). Solution or melt crystallized films showed decreasing rates of crystallization with increasing HV content. Homogeneous blends of PHB with P(HB‐co‐HV) could be formed which showed a single melting peak by differential scanning calorimetry. The potential of P(HB‐co‐HV) as a source of value‐added small molecules is discussed. Depending on the method of degradation (i.e., chemical or pyrolytic) chiral synthons or vinylic small molecules are obtainable in nearly quantitative yields. Because their physical properties resemble those of polyolefins this family of chiral thermoplastics will probably find wide use in biomedical applications where compatibility and absorbability are essential features.
Enzymatic release of drug from polymer matrices: Diffusion and activity of lysozyme within ophtalmic hydrogels
Authors: Cassiani‐Ingoni L. , Subira F. , Bunel C. , Vairon J‐P. , Halary J‐L.
Published: March 2011

Diffusional behaviour of lysozyme into a high‐hydrated hydrogel, used as precursor of contact lenses, is reported. The gel is a swollen statistical copolymer of methyl methacrylate and N‐vinyl‐2‐pyrrolidone (≁ 70% water), and the penetration of the enzyme, labeled with 8‐anilinonaphthalene‐1‐sulfonate, was followed by fluorescence microscopy. Mathematical analysis of the profiles led to the diffusion parameters (D ≁ (2–6) · 10−8 cm2 · s−1). It is shown that the enzymatic activity persists when the lysozyme and the cleavable substrate are trapped in the matrix.
Biodegradation of polymeric drug carriers: Kinetic modeling
Authors: Azhari R. , Lotan N.
Published: March 2011

Analytical models ‐ based on kinetic and mechanistic considerations‐ have been developed, for describing the enzymic degradation of polymers. The models were applied to delineate the degradation patterns expected when endo‐ or exo‐ acting enzymes are used, and when the kinetic constant KM varies with the size (i) of the macromolecular substrate. Utilization of these models, in conjunction with experimentally available data, provides the possibility to define the mechanism of enzymic action, and to determine the kinetic constants of the process. Thus, for example, for the degradation of poly‐N‐(2‐hydroxyethyl)‐L‐glutamine (PHEG) by papain, the correlation between KM and i was established.

The above models can also be used to provide data that cannot be obtained experimentally (e.g. exact chain length distribution of degradation products), and to determine, with minimum effort, the experimental set up required for obtaining a desired array of products. They are, therefore, most useful tools for the design of enzyme–actuated drug delivery devices.
New trends in polymer processing
Authors: Bevis M. J.
Published: March 2011

Recent developments in polymer processing technology for the enhancement of physical properties by more informed control over composition and micromorphology are reviewed. This is followed by a more detailed review of the multi live‐feed moulding process which can impart high levels of anisotropy, by design, in complex shaped articles produced by moulding routes.
Past and future impact of electroactive polymers on the electronics sector
Authors: Matthan Jacob , Uusimäki Antti , Torvela Heikki , Leppävuori Seppo
Published: March 2011

A broad review of the field of applications of electroactive polymers, defined as inherently conductive, charged, piezoelectric and pyroelectric, and systems made electroactive by addition of conductive additives, in the field of electronics and microelectronics. Applications mentioned include the use of polymers for electrodes for rechargeable batteries, electret microphones, hydrophones, vidicons, EMI and ESD protection, and conductor and resistor tracks as thick films on printed circuit boards. Future trends as the development of supermolecular assemblies for parallel processing are also highlighted.
Role of the interface in multicomponent materials
Authors: Ishida Hatsuo , Jang Jyongsik
Published: March 2011

Studies of the relationship between interfacial structure and mechanical properties in multicomponent materials are reviewed in this article. The following categories are considered for role of the interface in multicomponent systems: Interpenetrating polymer network(IPN), catalytic effect of silane coupling agent, morphological differences of filler surface, particle‐particle interaction and particle size of the filler. The interfacial role in terms of the reinforcement mechanism of the composite and the behavior in the melt state is also discussed in the multicomponent system.
New trends in commodity polymers
Authors: Brasz A.J.H.
Published: March 2011

After the recession of the seventies, commodity polymers are today again in a period of stable growth, due to the drastic change in strategy of the polymers producers. Strong cost reduction by debottlenecking, advanced catalyst systems and restructuring improved their position, and diversification in general purpose grades on the one hand and ‘commodity‐plus’ and speciality grades on the other were the key factors for success. Diversification could only be achieved by close cooperation between end‐user, converter, polymer supplier and machine manufacturer and by compounding, blending and grafting. The blends and grafted materials are a new family of materials and are a challenge to all developers in the polymer filed. They create a new future for the commocity polymers.
Compatibility testing in polyamide multicomponent systems by endlinking
Authors: Leumer Gerhard , Rossbach Volker
Published: March 2011

Hitherto, compatibility in polyamide blends has been characterized by physical and mechanical methods exclusively. The work presented here describes the basis and potential of a chemical method for compatibility testing, transferred from protein chemistry (crosslinking technique). This method can also be applied, with appropriate modification, to synthetic polyamides. The degree of heterogeneity follows from the number of different molecule combinations.
Electron spectroscopic imaging studies on semicrystalline and block‐copolymer systems
Authors: Kunz M. , Möller M. , Heinrich U.‐R. , Cantow H.‐J.
Published: March 2011

Discrimination of elastically and inelastically scattered electrons in transmission electron microscopy (TEM) yields electron micrographs with enhanced and specific contrast. Highly resolved micrographs can be obtained in which the contrast reflects the local concentrations of specific elements. In the present work, Electron Spectroscopic Imaging (ESI) by means of a Zeiss EM 902 TEM is reported for polystyrene‐block‐poly(2‐vinylpyridine) diblock copolymers and for a series of differently crystallized polyethylene samples. Excellent contrast can be achieved without staining. The different techniques allow easy verification of the observed morphology.
Free surface on a viscoelastic liquid in a cylinder with spinning bottom
Authors: Siginer D. A.
Published: March 2011

The shape of the free surface and the flow field of a simple fluid driven by the steadily rotating bottom cap of a cylindrical cup is investigated. A regular domain perturbation in terms of the angular velocity of the bottom cap is used. The velocity field is a superposition of a strong primary, azimuthal field and a weaker secondary meridional field. The effect of the aspect ratio and viscoelasticity of the fluid results in multiple cell structures in the meridional plane. The free surface shape determined at the lowest significant order in the perturbation algorithm, is similarly affected by the same factors. Both the flow field and the interface shape are determined for a wide range of aspect ratios and viscoelastic parameters.
Ultrasonic characterization of polymer viscoelasticity. Application to polystyrene
Authors: Massines F. , Piché L. , Lacabanne C.
Published: March 2011

Ultrasonics is presented as a powerful method for the thermomechanical analysis of polymers. An experiment is described where the specific volume of a polymer is measured in simultaneity with the acoustic parameters. The technique allows full control of the thermal history in the temperature range from — 150°C to 300°C, where the material goes from a glasslike to a liquidlike state. Moreover the technique allows measurements to be performed at different pressures, up to 2 kbar. Results obtained on a typical amorphous polymer (polystyrene) are reported and the propagation of sound is discussed in regards to the well defined thermodynamic state for the material. Also, the results discriminate between the thermodynamic and the relaxational aspects of the glass transition.
Viscoelastic study of carbon/epoxy unidirectional composite materials
Authors: Perret Patrice , Chabert Bernard , Gérard Jean‐François
Published: March 2011

Properties of interface in unidirectional composite materials can be studied “in situ” by dynamic mechanical measurements: analysis of relaxations and appearance of damage in shearing. This methodology is applied on composite materials based on an epoxy matrix and carbon fibers with different surface treatments (untreated, oxidized and sized). Mechanical spectroscopy displays modifications of epoxy network with the fiber treatment and evidence for an interphase in the case of sized fibers. Dynamic shearing test clearly shows large differences of behavior with the surface treatments.
Influence of the molecular weight on the elongational behaviour of polypropylene and on the fibre orientation factors
Authors: Prost Catherine , Nemoz Guy , Michel Alain
Published: March 2011

This study shows that the elongational behaviour depends upon molecular weight and upon elongational rate. If the molecular weight is low, elongational viscosity reaches rapidly a steady value but, if the molecular weight is high, the viscosity (or the elongational stress) increases continuously with the time. These behaviours may be explained in comparison of the relaxation rate determined by shear rheology as the reciprocal relaxation time with the elongation rate ϵ. If the elongation rate is lower than the relaxation rate the polypropylene chains may relax and the elongational viscosity reaches a steady value with the time. For high fluidity polypropylene the range of elongation rates within of which the elongational viscosity is constant with time is very large. On the contrary, if the elongational rate is higher than relaxation rate the polypropylene chains undergo a continuous deformation and then the elongational viscosity increases with time. The range of elongational rates within of which the stress is constant is narrow for high‐molecular‐weight polypropylene. Furthermore, the elongational behaviour influences the chain orientation in the crystalline and amorphous phases of the fibres. If the polymer chains are quenched in a relaxed state the orientation is lowered as shown with high fluidity polypropylenes. On the contrary, if the chains are cooled in extended state their orientation may subsist during crystallisation and the orientation factors may reach high values as shown with high‐molecular‐weight polypropylene.
Polyamide 11 as a hard elastic fiber
Authors: Dosià;re M.
Published: March 2011

Fibers of nylon‐11 annealed in contact with formic acid (90%) have the same unit cell as solution grown crystals; the basal planes of the lamellar crystals are parallel to (ool) crystallographic planes. The melting curves and the stress‐strain curves of such annealed fibers are presently reported. The temperature corresponding to the maximum of the melting peak increases with the annealing temperature: an increase of 10°C is observed although the long spacings keep the constant value of 12 nm. Lower elastic modulus but higher strains are obtained with increasing annealing temperatures. Such annealed samples can undergo large extension without occurrence of necking and plastic flow.
Loss of orientation and shrinkability of drawn atactic polystyrene
Authors: D'Amore A. , Nicodemo L. , Nicolais L. , Carfagna C.
Published: March 2011

The loss of orientation is a much more rapid phenomenon than the thermal shrinkage of drawn polystyrene, as shown by birefringence and FTIR measurements. The properties imparted by the orientation can be lost before the complete shrinkage occurs. The implications of this fact are discussed.
Effect of thermal treatment on the micromechanical properties of segmented polyurethanes
Authors: Etienne S. , Perez J. , Darud V. , Pascault J. P.
Published: March 2011

The effects of thermal treatments on segmented polyurethanes were studied by low frequency mechanical spectrometry. Complementary informations on the morphology of microphases and characteristic temperatures were given by other techniques such as DSC and SAXS. We have shown that low temperature treatments affected the morphology of the soft phase. High temperature treatments induced modification of dynamic modulus spectra attributed to the evolution of the microphase separation rate and the degree of crystallinity of some hard domains.
Characterization of the coating layer on glass fibre used as reinforcement in polyepoxyde matrix
Authors: Escoubes Marcelle , Chabert Bernard , Chauchard Jacques , Nemoz Guy
Published: March 2011

R glass fibre for the reinforcement of epoxy matrices has been coated with epoxy prepolymer (as film‐former or sizing agent) or γAPS aminosilane (as coupling agent) or a mixture of these two products. The structure of the coating layer and its interaction capabilities with fibre and matrix have been studied by coupled calorimetry‐gravimetry of sorption of different model reactants and by Fourier Transform infra‐red analysis.
Contact angles of water (polar) and methylene iodide (non polar) on glass surfaces treated with aminosilane / mercaptosilane mixtures. Correlation between silane orientation, surface tensions and wetting hysteresis
Authors: Comte Florence , Sage Daniel
Published: March 2011

Organofunctional silanes are generally used to improve bonding between inorganic substrates and organic resins. They are of particular interest when used as adherence promoters between glass and polymeric adhesives: despite their very different properties, these two materials can be assembled. Glass has a high surface tension‐relatively reduced by water adsorption‐ with a marked polar component. The action of the silane is to substitute itself to the low cohesive layer formed by water and to decrease the polar component of the glass surface in order to make it compatible with the adhesive. Polar alkoxy groups react with the glass and a new surface is then formed, mainly by the organofunctional groups of the silane. This new surface must also have a sufficient surface energy to be wetted by the adhesive. It is, therefore, necessary to determine as well as possible the superficial properties, keeping in mind that a good wettability does not always signify a good adhesion, but is just a necessary condition. We have then measured the advancing θm and receding θd contact angles of water and methylene diiodide on a degreased glass surface, treated or not by A1100 (γ ‐aminopropyltriethoxysilane), A189 (mercaptopropyltrimethoxysilane) or a mixture of both. Rinsing the samples with water treatment has also been considered.
Influence of a filler such as silica on network formation of elastomers
Authors: Bomo F.
Published: March 2011

The mineral nature of silica gives it some particular properties. Its surface chemistry is very reactive. The interactions between silica and vulcanization agents such as accelerators are important and disturb the formation of the elastomer network. Following a description of silica surface chemistry we shall study the interactions of this filler with some accelerators and their impact on the cross‐linking density.
Quantitative determination of low strain amplitude dynamic functions of carbon black filled rubber vulcanizates by statistical analysis of the black secondary agglomeration network
Authors: Susteric Zoran
Published: March 2011

Deformational breakdown of the secondary agglomeration network, a carbon black aggregate chain association readily formed in rubber matrix and held together by van der Waals forces, is treated statistically. Consistent with observation, the resulting expressions for low strain amplitude dependence of the black filled vulcanizates' dynamic functions, i.e. the storage and loss moduli, provide means for determination of characteristic aggregate chain scission energies. The proposed approach additionally accounts for effects of filler content and temperature, the latter permitting evaluation of van der Waals bond dissociation activation energies, if the black chain scission process is assumed to be thermally activated.
Adhesion mechanisms of grafted polyolefins
Authors: Schultz J. , Lavielle L.
Published: March 2011

By comparing surface properties assessed by wettability measurements with polymer‐metal adhesion strength determined by peeling for different grafted polyolefins (acrylic acid grafted polyethylene, acrylic acid and maleic anhydride grafted poly(ethylene‐vinyl acetate), maleic anhydride grafted polypropylene), a general adhesion mechanism can be proposed. The surface polarity is not the main determining parameter for adhesion.

Polyolefin‐aluminium adhesion is obtained through chemical bonding of acid groups grafted in the polymer bulk and basic groups present on the aluminium.
An analysis of the adhesion strength between polyethylene and paper
Authors: Gervason G. , Cheradame H.
Published: March 2011

Composites of polyethylene with paper were studied in order to determine the influence of the surface energy of the paper on their cohesive strength. The papers used in this study had the same roughness, but fifferent surface energy owing to treatment with different sizing agents. The surface energies were determined by the contact angle method with various liquids, and the variations of the cohesive strength were followed by the energy of peeling at 180 °C. It was shown that the peeling energy decreases linearly when the reversible energy of adhesion decreases, and becomes negligible when the paper surface energy is approximately equal the surface energy of polyethylene.
Synthesis and phase behavior of liquid crystalline poly(3‐n‐ALKYL‐4‐hydroxybenzoates)
Authors: Stern R. , Ballauff M. , Wegner G.
Published: March 2011

A series of 3‐n‐alkyl substituted poly(4‐hydroxybenzoates) were prepared by melt‐polycondensation of the corresponding monomers. The length of the alkyl side chains was varied in the range of 3 to 18 carbon atoms. The average degree of polymerisation (DP) was determined by 1H NMR end‐group analysis. The thermal behavior of the polymers was studied by differential scanning calorimetry (DSC) and polarising microscopy (PM). Structural investigations of oriented and not oriented samples were performed by means of wide angle X‐ray scattering (WAXS). The density of the polymers was measured by gradient column technique.
The effect of torsional vibrations superimposed on a creep loaded adhesive joint on its final tensile properties
Authors: Katz Dov , Bron Samuel
Published: March 2011

Aluminum ‐ epoxy single lap joints were subjected at different temperatures to torsional vibrations at constant amplitude superimposed on a creep load. This combination of dynamic and static stresses was chosen in order to simulate to a certain extent the real service conditions of an ordinary bonded joint. The shear strength of these joints was checked in tension at room temperature after their removal from the special device in which the superimposed stresses were applied. It was found that the shear strength of the joint is very dependent on its thermo‐mechanical history. DSC analyses and SEM micrographs of the failure surface were used in an attempt to find some correlation between the mechanical properties and the microstructure of the adhesive.
Advances in inherently conducting polymers
Authors: Aldissi Mahmoud
Published: March 2011

In this review, the various sub‐classes of material and the motivations to study them is given as well as some of their properties and the various proposed applications. First, an introduction to the general area of conducting polymers is given. The various important efforts in materials synthesis and the motivations and goals for these efforts are outlined, particularly, those geared toward making materials with desirable properties such as high conductivities, high molecular and supramolecular order, solution‐ and/or melt‐processability, and some application areas. The morphology plays an important role in determining conductivity and mechanical properties of the materials. Therefore, a brief description to that effect is given. Second, the distinct sub‐classes of material developed here include oriented polyacetylene polymerized in a liquid crystal medium, polyheterocyclic systems synthesized electrochemically, copolymers, and first water‐soluble, liquid crystalline conducting polymers based on polyheterocycles. Third, the various possible applications are mentioned briefly with a focus on electrochemistry, electro‐optical properties, junctions, and shielding against electromagnetic interferences (EMI) in the radio frequency (RF) and microwave (MW) regions.
Electron‐beam and x‐ray resists for microlithography
Authors: Eranian A. , Bernard F. , Dubois J. C.
Published: March 2011

Firstly, general considerations about microlithography and resists were presented, leading to the conclusion that positive resists seemed to be more suitable than negative resists to provide high resolution in electron‐beam lithography and in X‐ray lithography. Therefore, parameters affecting the sensitivity of positive resists to such types of radiation were outlined. Among these positive resists, poly (fluoroalkyl methacrylates) were shown to be interesting candidates, due to their enhanced radiation absorption. Thus, poly(1‐, 1‐ dimethyl 2, 2, 3, 3‐tetrafluoropropyl methacrylate) (called FBP resist) was synthesized and physico‐chemically characterized. The lithographic performances of such a resist were evaluated both upon electron‐beam and X‐ray exposures. Its dry‐etch resistance was also studied. Furthermore, fabrication of Field‐Effect Transistors using this resist was demonstrated.
Electrochemical polymerization of substituted thiophenes
Authors: Havinga E. E. , van Horssen L. W.
Published: March 2011

The electrochemical polymerization of 3‐(n‐butyl)thiophene and of several 3‐ or 3,4‐ substituted α, α'‐terthienyls is described and the properties of the conducting polymers are discussed. A solution in acetonitrile of the terthienyl substituted by a potassium propylsulfonate group is polymerizable as such, and the polymer is the first proven example of a self‐doped conducting polymer. This polymer dissolves readily in water and remains partially self‐doped in solution.
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

The 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

The 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

The 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

: 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

The 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

Ion 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

Microstructures 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

The 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

A 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

A 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

Photothermoplastics 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.