bluuebunny/crossref_metadata_2025 huggingface dataset:
Excimer laser photochemistry of lithographic systems
Authors: Bendig Jürgen , Mitzner Rolf , Dähne Lars
Published: March 2011

Laser photochemical methods are useful in the microchemical field and for microlithographic patterning of integrated circuits. For many reactions a difference in the going on and the result of the reaction is obtained at lamp or at laser initiation, respectively. For the photochemists engaged in lithography the most important properties are: intensity and collimated beam. Several excimer laser exposure systems have been developed in the last years, the importance of which is increasing. At high peak power densities of the excimer laser radiation, new phenomena in photochemical and/or lithographic behaviour are observed. The wavelength‐dependent sensitivity of the positively working naphthoquinone diazide resists is caused by the change of the absorption spectrum within the pulse duration. The intensity‐dependent gradation and resolution of the investigated negatively working azide resists are the result of the further excitation of the intermediately formed nitrenes.
Laserphotochemistry by holographic grating experiments with quantum limited detection sensitivity and holographic optical information storage by photopolymer systems
Authors: Bräuchle Ch. R.
Published: March 2011

Holographic methods are most widely known as techniques for producing three dimensional pictures. However, they can also be used to investigate photochemical and photophysical processes of molecules. Holographic gratings produced by cw and pulsed laser sources have been employed successfully in these investigations during the last decade. In this paper a newly developed holographic grating technique, called phasemodulated holography (PMH), is presented. With this technique for the first time a separated and simultaneous monitoring of the amplitude and phase gratings including the absolute signs of these contributions is possible. Thus, hologram formation mechanisms and the underlying photochemistry can be studied in great detail. This feature and an up to eight orders of magnitude improvement of detection sensitivity (quantum limited detection sensitivity) over conventional techniques makes PMH an ideal tool for the investigation of new materials for holographic optical information storage. This will be demonstrated for several examples i.e. photoactive molecules incorporated in polymer systems.
Laser induced polymerization and crosslinking in imaging materials
Authors: Baumann Reinhard , Roth H.‐Klaus , Fritzsche Klaus
Published: March 2011

Photoactive polymer systems for laser direct imaging processes have become of interest in the last years because of their applicability in the fields of plate making and printed circuit board manufacture. In this paper a method shall be presented to study the sensitivity of photopolymer systems and the deviation from the direct proportionality between the intrinsic laser energy and the monomer conversion, in close connection with the conditions of optical recording taking into account the intensity distribution within the laser beam. That is the reciprocity effect of photopolymer systems under laser irradiation. The method will be demonstrated studying (a) unsaturated polyester and (b) multifunctional acrylate based photopolymer systems.
Recent advances in the study of biopolymers
Authors: Katchalski‐Katzir Ephraim
Published: March 2011

In describing some of the macromolecular characteristics of the nucleic acids, particularly DNA, and of representative proteins, the following aspects are discussed: computer‐assisted modeling as a useful tool for depicting the three‐dimensional structures and macromolecular characteristics of biopolymers; conformational flexibility in biopolymers; parameters determining protein recognition; and the importance of the three‐dimensional structure of antibodies, enzymes, receptors, ion channels, and proteins interacting with nucleic acids, in determining their characteristic biological functions. Many of the problems raised by molecular biologists concerning the mode of action of biopolymers could be tackled by polymer chemists, because of their experience in dealing theoretically as well as experimentally with synthetic and native high molecular weight compounds.
Advances in ultra‐high load polymer‐supported peptide synthesis with phenolic supports: 1. A selectively‐labile c‐terminal spacer group for use with a base‐mediated n‐terminal deprotection strategy and fmoc amino acids
Authors: Butwell Francis G.W. , Haws Edmund J. , Epton Roger
Published: March 2011

Crosslinked poly(N‐[2‐(4‐hydroxphenyl)ethyl]‐acrylamide) has been modified by conversion of each pendant 4‐hydroxyphenyl group to its 2‐(4‐hydroxymethyl‐phenoxy)ethanoyl‐L‐prolyl ester. This provides a spacer group which makes the polymer matrix suitable for solid (gel) phase peptide synthesis with Fmoc amino acids at ultra‐high load (2.2 mmol g−1 of spacer‐modified support). The selectively labile linkages incorporated in the spacer group provide for peptide detachment by either mild acidolysis or hydrazinolysis. The products of hydrazinolysis of intermediate and final peptide‐matrix assemblies are amenable to analysis by high‐pressure liquid chromatography (HPLC).
Polymers as matrices for whole cell immobilization
Authors: Klein Joachim
Published: March 2011

The immobilization of whole microbial cells has become an important tool in the development of biocatalytic processes in the pharmaceutical and food industry. Not only dead, i.e. non growing cells, but recently with higher priority living and growing cells are the biological species, for which simple and efficient polymeric carriers had to be found. In comparison to other methods, like adsorption or encapsulation, entrapment into a polymer network is the most widely used technique. The network can be formed on the basis of a)ionic interactions (ionotropic gelation of polyelectrolytes), b) of polycondensation reactions (epoxides, polyurethanes, silicones) or c) of polymerization reactions (crosslinking polymerization of vinylic monomers, oligomers or polymers). The characteristic features and the efficiency‐controlling parameters of some immobilized cells systems are discussed as illustrative examples.
Investigation of the carrier function of polypeptides. Synthesis, conformation and cytotoxicity of oxazolone conjugates of poly(Lys) and poly[Lys‐(DL‐ALAm)]
Authors: Hudecz Ferenc , Kajtȧr Judit , Kurucz IstvȧN , Kovȧcs Attila L. , Szekerke MȧRia
Published: March 2011

A new group of synthetic macromolecular conjugates was synthesised in which poly(Lys) or a branched polypeptide poly[Lys‐(DL‐Alam)] (m≅3) were used as carrier and 4‐(ethoxymethylene)‐2–phenyl–5 (4H)‐oxazolone as hapten. These conjugates were characterized by amino acid analysis, identification of terminal residues of the side chain, sedimentation analysis. The conformation of conjugates and of carrier polypeptides were analyzed by circular dichroism spectroscopy in water solutions at various pH and ionic strengths. These data indicated a marked dependence of the conformation of the conjugate on the structure of carrier and on the number of the side chain terminal haptens (phOx). In vitro cytotoxicity of these polymers was also investigated using two different assays, by measuring the viability of isolated rat liver cells and the effect on growth of HeLa cells. Toxicity of polypeptides could be diminished by conjugates containing a higher amount of oxazolone. These conjugates with defined conformation and toxicological properties are considered suitable to analyse the carrier function of branched polypeptides, particularly the interaction with the immunological network.
Polymeric supports for affinity chromatography and high‐performance affinity chromatography
Authors: Ernst‐Cabrera Karin , Wilchek Meir
Published: March 2011

Affinity chromatography is the most selective chromatographic method for the purification of biologically active materials. It is based on the biospecific interaction of the substrates with a ligand, which is chemically immobilized onto a suitable matrix (support). Different matrices provided by natural and synthetic polymers are used for the preparation of affinity supports. In this communication we describe and compare the properties of various supports based on polysaccharides, polyacrylamides and inorganic materials. In particular, we discuss the utility of different silica derivatives (especially primary hydroxyl silica) for the immobilization of ligands and high‐performance affinity chromatography.
Affinity of human thrombin for insoluble polystyrene substituted with sulfonate, n‐hydroxyethylsulfamoyl and n‐substituted amidine functions
Authors: Khamlichi S. , Yu X. J. , Muller D. , Jozefonvicz J. , Roeland S. , Fuks R.
Published: March 2011

A new polymeric material was prepared from polystyrene beads with N‐substituted amidines and rendered hydrophilic with sulfonate and N‐hydroxyethylsulfamoyl groups. It was synthesized by reacting the p‐chlorosulfonyl polystyrene with ethanolamine followed by the Michael‐like addition of the terminal OH of the polymer (PSEa) to N‐t‐butyl‐N'‐phenylpropenamidine 1 thus leading to the final polymer PSEaAm. Its affinity constant for human α‐thrombin calculated from the Langmuir adsorption isotherms was about 106 M−1, a value comparable to the one estimated for polystyrene modified with L‐arginine methyl ester. This new material was used as stationary phase in affinity chromatography of thrombin confirming a strong and specific interaction between the positively charged amidinium groups and the enzyme at pH = 7.4 and desorption at pH = 10 and high ionic strength.
Modification of polyetherurethane for endothelial cell seeding
Authors: Klee D. , Breuers W. , Höcker H. , Mittermayer C.
Published: March 2011

Until now no synthetic polymer surface was available suitable for cardiovascular implantation which effectively prevents microthrombosis for a long time. The presented concept of our work is to develop a polymer surface to promote the growth of a durable endothelial cell monolayer which would be formed on the prothesis prior to implantation. A microporous polyetherurethane foil is being used as carrier polymer for the cell monolayer. Suitable functional groups are grafted on the polymer surface by plasma polymerization. The success of the first modification steps is followed by ESCA‐analysis and scanning electron microscopy. The modified carrier polymer is the starting material for covalent binding of biopolymers which react as adhesion supporter between the synthetic polymer surface and the endothelial cells.
Artificial ovum pick‐up chamber
Authors: Hinterhofer O. , Seycek O. , Soboll R. , Zech H. , Urmann S.
Published: March 2011

An artificial implantable ovum pick‐up and transfer chamber was developed for a treatment of patients suffering from infertility caused by tubal defects. The first chamber prototypes were made of Cardiomat 610 polyetherurethane using a dipping technique. Two‐part hollow positive wax models were dipped into the PU‐solution in a tetrahydrofuran /dioxane mixture and dried under a complex rotation simultaneously on two axes in a laminar air flow. Special examinations were made in regard to the form of the chamber and to the reliable function of the chamber perforation. The chamber prototypes have been implanted into sheep, clinical tests are scheduled.
Polydepsipeptides: Ring‐opening polymerization of 3‐Methyl‐2, 5‐Morpholinedione, 3,6‐Dimethyl‐2,5‐morpholinedione and copolymerization thereof with D, L‐Lactide
Authors: Samyn Celest , van Beylen Marcel
Published: March 2011

Poly (ester‐amide)s were synthesized by ring‐opening polymerization of 2,5‐morpholinedione derivatives. The monomers: 3‐methyl‐ and 3,6‐dimethyl‐2,5‐morpholinedione were prepared first, and subsequently polymerized with tin(II) bis(2‐ethylhexanoate) as an initiator at 145°C in bulk. Copolymerizations with D, L‐lactide were also investigated; in this way copolymers with higher molecular weight were obtained, which provide materials with a wider range of properties.
Morphology of poly(ethylene oxide)‐based hydrogels in relation to controlled drug delivery
Authors: Graham N. B. , Mcneill M. E.
Published: March 2011

The crystallinity, morphology and water swelling of a series of hydrogels based on poly(ethylene glycol)s (PEG), ¯n = 1610–8490 crosslinked by 1,2,6‐hexanetriol and the stoichiometric equivalence of dicyclohexylmethane‐4,4′‐diisocyanate as coreactant to form an infinite urethane‐linked network are examined. The equilibrium water uptake was found to be directly related to the ethylene oxide content irrespective of either ¯n(PEG) or the degree of crosslinking. Crystallinity affects the rate of swelling in water. Caffeine was incorporated into slices of hydrogels over a wide range of compositions and water contents by swelling with a solution of the drug. After drying then reswelling to desorb the caffeine the release profiles were drawn, and morphological factors contributing to the bolus and period of zero ‐ order release are propounded.
Evaluation op some cellulosic derivatives as carriers for different drugs
Authors: Dumitriu Severian , Popa Marcel , Beldie Cameluta
Published: March 2011

Three cellulosic derivatives, namely xanthan, (chlorocarbonyl methyl) cellulose and N‐(4‐carboxyphenyl)carbamoyl methyl cellulose were used as support in coupling different drugs. Pilocarpine and neomycine were ionically coupled on xanthan; nalidixic acid, metronidazole and cephalosporine C were covalently coupled on (chlorocarbonyl methyl) cellulose, xanthan and N‐(4‐carboxyphenyl)carbamoyl methyl cellulose, in the latter case dicyclohexylcarbodiimide being used as activator. The influence of some factors on coupling efficiency was followed: drug/support ratio, volume of the solvent, reaction duration, activator/support ratio. The in vitro and in vivo tests proved the biological activity of the newly obtained macromolecular drugs.
Noncovalent complexes of water‐soluble polymers and organoplatinum compounds as potential time‐release antitumor agents
Authors: Howell B. A. , Walles E. W. , Rashidianfar R.
Published: March 2011

The complexation of appropriate organoplatinum compounds by water‐soluble polymers has the potential to provide a time‐release formulation which might afford a substantial reduction in the severity of side effects associated with use of organoplatinum antitumor agents. Both poly‐(N‐vinylpyrrolidone)(PVP) and poly(N‐vinyl‐5‐methyl‐2‐oxazolidone)(PVOM) form stable, biologically active, molecular complexes with organoplatinum compounds containing polar aromatic ligands. Platinum compounds suitable for complexation by these polymers include cis‐dichloro(4‐substituted o‐phenylenediamine)platinum(II), 4‐substitutedcatecholato(1,2‐diaminocyclohexane)platinum(II), and 4‐substitutedphthallato(1,2‐diaminocyclohexane)‐platinum(II) compounds.
The European technical and economic challenge of polymer materials
Authors: Newman F. C.
Published: March 2011

The major challenges facing the polymers industry are the proper use of materials, environmental pressures, the management of diversity and growth, the availability of human resources and the management of competition. Awareness of the broad nature of these barriers and of their complex interactions will help the European polymer industry to play an increasing role in promoting the future of polymeric materials.
Processing, structure and properties of oriented polymers
Authors: Ward Ian M
Published: March 2011

The fabrication techniques now available for the production of highly oriented polymers are reviewed. These techniques include tensile drawing from both melt‐spun and gel‐spun polymers, extrusion under pressure from the melt, and hydrostatic extrusion, ram extrusion and die drawing in the solid phase. In addition, lyotropic and thermotropic liquid crystalline polymers offer new routes to very stiff and strong polymers.

Following the review of processing methods, an account is given of low strain mechanical behaviour and its relationship to structure, thermal properties (including thermal conductivity and thermal expansion behaviour) and barrier properties (permeability to liquids and gases and solubility).
Polymer blends: From molecular structure through morphology to controlled bulk properties
Authors: Teyssié Ph.
Published: March 2011

It is shown how the morphology and the bulk physico‐mechanical properties of polymer blends and alloys may be tailored, by using proper physical and processing conditions for homogeneous systems, and molecular engineering of the interfaces for heterophase ones.

That approach, which has been substantiated by a physical study of the miscibility situations at molecular level, has been applied successfully to commodity and engineering polymer‐polymer blends, but also to polymer‐filler and polymer‐liquid heterophase systems.
Progress and challenge in polymer crazing and fatigue
Authors: Kausch Henning H. , Oudet Christian
Published: March 2011

In this review on polymer crazing and fatigue three aspects have been treated more explicitely: the molecular rearrangements preceding and provoking craze initiation, the competition between disentanglement and chain scission during lateral craze growth, and the distinct fatigue failure mechanism occurring in cyclically loaded PET and PA fibers. An overview on other aspects is given including references to work in progress.
Structural aspects of porous gels
Authors: Flodin Per
Published: March 2011

The mode of formation and the structure of both chemically and physically crosslinked polymer gels are discussed. For both types elastic and porous ones are compared. The chemically crosslinked gels from trimethylolpropane trimethacrylate (TRIM) are interesting because of their narrow distributions of small pores (radii 20 Å) when polymerized in toluene. The large pores (200 Å) on the other hand varied with concentration as could be expected.

One of the ways to obtain porosity for physically cross‐linked gels is to cool solutions of polymers in certain solvents mixtures. Thus, polyacrylonitrile (PAN) yields porous gels when cooling solutions thereof in dimethyl‐formamide/water mixtures. By NMR, DSC, and X‐ray diffraction evidence has been obtained of ordered structures which at least partially exist even above the gel melting temperature.
Polymer conformation at the polymer melt surface
Authors: Silberberg A.
Published: March 2011

Due to the symmetry which characterizes the surroundings of each chain segment in the amorphous melt all (but end) segments are equivalent in their embedment in space. Energetic interactions between segments are confined to segments in contact. Hence, in the presence of a surface only the segments actually in the surface layer will be affected and will have a statistical weight and Boltzmann factor different from segments in the bulk. The number of segments so involved is fixed, since the extent of the surface is controlled. The partition function is comprised of factors which depend neither upon the order of the segments in the chain nor upon the conformation of any particular chain. Only segments finding themselves in the surface contribute to the surface tension, with the largest contribution deriving from the density transition in the interface. This, at most temperatures, is confined to a lamella one segment layer, or less, thick. For polymer of high enough molecular weight end‐effects can be neglected and no allowance for the presence of ends is made here. It is then possible to reach a representation of surface tension in reduced coordinates, as shown already by Posner and Sanchez. Changes in chain conformation near the surface are calculated.
On the superposition of oscillatory and shear flows of viscoelastic liquids
Authors: Siginer D. A.
Published: March 2011

Important flow enhancement effects take place when the motion of a non‐Newtonian fluid is driven either by pressure gradients pulsating around a non‐zero mean or by longitudinal and transversal boundary waves superposed on Poiseuille flow. Flow enhancement in the latter case is an order of magnitude larger than in the former. A regular perturbation in terms of the amplitude of the oscillation is used and closed form formulas given for mass transport rates at the lowest significant order. In particular it is shown that a mean flow may be generated even when the pressure gradients oscillate around a zero mean or the boundary waves are superposed on a fluid at rest if the frequencies of two superposed waves are in certain ratios.
Effect of molecular weight distribution on the rheological behaviour of poly(vinylidene fluoride) (PVDF)
Authors: Carrot Christian , Guillet Jacques , May Jean‐François
Published: March 2011

In this study, six samples of commercial poly(vinylidene fluoride) are investigated. Dynamic and steady‐state shear flow experiments are carried out in the melt state in order to relate their rheological behaviour to their molecular weight distributions. This rheological investigation is performed through the use of some simple parameters related to the viscosity, elasticity and relaxation times. Plots of flow curves in reduced coordinates are used to confirm the above results.
Effect of shear on subsequent rheological transients in polymeric liquid crystals
Authors: Moldenaers P. , Mewis J.
Published: March 2011

The transient rheological behaviour of a lyotropic polymeric liquid crystal is investigated. The system consists of a 12% by weight solution of poly(γ‐benzyl‐L‐glutamate) in m‐cresol. The structural changes caused by steady state shearing and by large amplitude oscillatory flow are measured. This is done by following the linear moduli upon cessation of flow. The stress transients during a stepwise increase in shear rate are used for the same purpose. Flow always increases the subsequent moduli in the system used, but the mode and the intensity of the flow have a complex effect. The variable domain structure seems to be responsible for most of the measured behaviour. The data put specific constraints on the detailed mechanisms that can contribute to the global transient stress.
Study of heat treatment on the behaviour towards shrinkage, orientation and molecular order of stretched poly(vinyl chloride) fibres
Authors: Cousin Patrice , Michel Alain
Published: March 2011

The behaviour of stretched PVC fibres during thermomechanical treatments between 110–160°C has been studied. As far as shrinkage is concerned, three ranges of temperature have been characterized. Within the range 100–140°C the poly(vinyl chloride) undergoes a plastic deformation and has an elastoplastic behaviour. From 140 up to 170°C a creep phenomenon superimposes the elastic behaviour and then the polymer has a viscoplastic behaviour. As the temperature increases above 170°C there is flowing of polymer chains and the fibres break rapidly. Annealings carried out between 100 and 150°C cause the formation of ordered domains which are responsible for the formation of a temporary physical crosslinking network which hinders the shrinkage to such a temperature lower than their melting temperature.

The loss of orientation of the amorphous phase is a rapid process which takes place as the temperature rises above 100°C even if the applied stress counterbalances the overall strain resulting from the potential shrinkage.
Shrinkage of blends of amorphous polymers with polymeric liquid crystals
Authors: Amendola E. , Carfagna C. , Nicodemo L. , Nobile M. R.
Published: March 2011

In this paper the shrinkage behaviour of bisphenol‐A‐polycarbonate (PC), polystyrene (PS), poly((ethylene terephthalate)‐co‐(p‐hydroxybenzoate)) liquid crystal polymer (LCP) is illustrated. Moreover, recoil's curves for PC/LCP and PS/LCP blends are shown. The different behaviour found for the two blends investigated is interpreted by taking into account that compatibility can occur between the two phases of the alloys. Moreover, the different physical state (liquid or solid) of the LCP phase at the recoil's temperature analyzed affects considerably its effectiveness in improving the shrinkage hosting matrix behaviour.
Influence of structure and of tensile modulus of adhesive joint on mechanical strength of metal plates bonded by various epoxy resins
Authors: Gilibert Yvon , Klein L. L. , Micel
Published: March 2011

A double‐lap, adhesive bonded joint, has been optimized with a fixed thickness of the core, in order to maximize the breaking force, and to obtain reproducible results. The shear profile, longitudinal, corresponds in the central region of the overlapping to classical theory, but is represented empirically, near the extremities, by the transversal shear in outer adherends. This furnishes an abscissa of the shear maximum in the joint, that compares with the location expected in a previous study and indicates also the critical level of shear, at the threshold of microcrack initiation, that compares with the breaking strength of the solid adhesive, in a similar manner for three different adhesives for which we observed a certain length of sheared joint with a cohesive fracture.
Use of ionic membranes in the fractionation of water‐alcohol mixtures by the pervaporation process
Authors: François R. , Nguyen Q. T. , Néel J.
Published: March 2011

Five membranes, constituted of ionic chains grafted onto inert matrix, were studied in pervaporation of water ‐ ethanol mixtures of different compositions. The permeability and selectivity of all five membranes showed a marked dependence on the nature of the counter‐ions. Water permeates preferentially through all the types of membrane and counter‐ions, except the protonated carboxylate membrane. For cation exchange membranes with alcaline counter‐ions, the selectivity decreases in the following sequence: K+<Na+<Li+<H+. The permeability of the sulfonate membrane follows the reversed sequence, while that of the carboxylate membrane follows the same sequence, i.e. there is no trade‐off between permeability and selectivity for the latter membrane. The anion‐exchange (quaternized amine) membrane behaved similarly to the sulfonate membrane, i.e. the permeability and the selectivity vary in opposite directions. An attempt to interpret the influence of the nature of counter‐ions on the basis of physico‐chemical properties of the ion pairs was made.
Photosensitive resists used in microlithography
Authors: Schue F. , Giral L.
Published: March 2011

For the electronics industry, resists are resins that can be applied to a substrate in a pattern of exposed and covered areas to leave some areas open for later etching or plating while protecting others for many types of printed circuit boards, whose lines and spaces are 40 nm or more wide, screening is sufficient to give needed resolution. But integrated circuit chips need the finer resolution afforded by photolithography, which uses light sensitive resists for imaging. The new lithographic processes that integrated‐circuit makers are looking at include those based on deep‐ultra violet (less than 300 nm), electron beam, and x‐ray irradiation. Until now, the near‐UV region has been satisfactory, such as at the 436/404, and 366 nm lines of mercury sources. Photoresists may be either positive or negative. Negative photoresists include resins, such as cyclised polybutadiene or polyisoprene, mixed with a bis(azide), which become crosslinked and in‐solubilized by exposure to ultraviolet light. UV irradiation photolyses bis‐(azides) to bis(nitrenes), which form aziridine groups with double bonds of neighboring chains. Developing exposed negative photoresists in a solvent dissolves away resin from unexposed areas. Positive resists are formulations like phenolic resins mixed with relatively large amounts of light sensitive solubility inhibitors, such as diazonaphtoquinones. On exposure to light, the solubility inhibitors rearrange to acidic compounds that can be leached out by bases. Thus, exposed areas of positive resists are the ones dissolved away on development. Alternatively, positive resists can be resins that are depolymerized by irradiation.
ESR and optical measurement on poly(3‐methylthiophene)
Authors: Kiess Helmut , Schärli Matthias , Harbeke Günther
Published: March 2011

The elementary excitations of poly(3‐methyl‐thiophene) in a doping range up to 7.5% have been found to be polarons as evidenced by ESR‐measurements. Above 7.5% doping Pauli susceptibility indicates metallic behaviour. In contrast, at 5% doping the optical absorption spectra show a transition from the three peak structure due to polarons to one with two peaks and commonly assigned to the formation of bipolarons. It is argued that a widening of the polaron levels gives rise to this phenomenon and not the induction of bipolarons. Above 20% doping the formation of a new phase of the material is observed, which is characterized by the disappearance of the peak at 1.6 eV and a well defined isosbestic point at 1.4 eV.
Charge carriers in P ‐ doped polyacetylene, optical study
Authors: Galtier M. , Montaner A. , Lakhliai Z. , Es Sbai A.
Published: March 2011

The dielectric properties of p‐doped polyacetylene are investigated in the infrared and far infrared region. The behaviour of the dielectric function is discussed on the basis of two kinds of carriers: free and pinned carriers. A metallic state is characterized for doping level higher than 0.03 charge per C‐H unit. The effective mass of carriers is shown to be close to the free electron mass.
Organosilicon polymers for lithographic applications
Authors: Hatzakis Michael
Published: March 2011

Organosilicon polymers have found many uses in the electronics industry in the last twenty‐five years due to their low dielectric constant and water‐repelling properties. These uses include insulators and encapsulating materials for electronic parts. More recently, siloxanes are being incorporated into polyimides for the purpose of increasing the water resistance, improving mechanical properties and preventing atomic oxygen attack of polyimides. Only in the last few years, some uses of organosilicon polymers in lithography have been reported. In this paper, a review of these uses will be presented and the requirements for organosilicon materials in lithography applications will be outlined.
An original method for producing polymer micro‐circuits by laser irradiation
Authors: Decker Christian
Published: March 2011

A new method has been developed to transform PVC into carbon by means of an intense laser irradiation and thus produce high resolution conducting images. It consists of a 3‐step process: PVC was first chlorinated by UV irradiation in the presence of chlorine; the resulting polymer was then photodegraded in nitrogen to generate chlorinated polyene sequences; it was finally exposed to an argon ion laser beam (488 nm) in order to achieve the complete removal of chlorine and hydrogen atoms from the polymer backbone. The insoluble carbon material obtained contains no chlorine anymore and proved able to carry electrons. By focusing the laser beam down into the micronic range, complex conductive patterns were directly written onto the photosensitive plate at high speed.
Degradation, under corona charging, of thermoplastics used in holographic optical commutation and stabilization
Authors: Servens C. , Filliatre C. , Daviaud R. , Moisan J. Y.
Published: March 2011

The study of the ageing Kinetics under corona discharge of rosin esters used in holographic optical communication devices has shown that free radical inhibitors improve the stability of these matérials. Therefore, new autostabilized thermoplastic products have been synthesized by grafting antioxydant on rosin acids. The stability of materials prepared from these new thermoplastics has proved greatly enhanced.
Synthesis and mesomorphic structures of comb liquid‐crystalline polymers with lipopeptidic side chains
Authors: Gallot Bernard , Douy André
Published: March 2011

Lipopeptidic macromonomers were synthesized from bi‐functional lipids by two methods and transformed into comb copolymers with lipopeptidic side chains by radical polymerization of their acrylate, methacrylate, acrylamide or methacrylamide terminal group. X‐ray diffraction and differential scanning calorimetry studies showed that comb copolymers exhibit both a thermotropic and a lyotropic behaviour and present smectic and nematic mesophases. The influence of the solvent concentration, the degree of polymerization of the peptidic chains and the nature of the main chains on the structural parameters of the smectic mesophases were established in the case of copolymers with liposarcosine side chains.
A heat resistant PIQ, polymer‐based interconnection using a multilevel lift‐off pillar fabrication
Authors: Sanséau P. , Schiltz A. , Nechtschein J.
Published: March 2011

To achieve a planar multilevel interconnection, we have developed a process using an improved lift‐off pillar fabrication technique in conjunction with a new kind of heat resistant polymer, a copolyimide‐isoindoloquinazolinedione polymer (PIQ). As spin‐on dielectric layer, the PIQ polyimide is shown to satisfy both the processing criteria and interconnection criteria (high thermal resistance, good planarization properties and excellent dielectric properties).
Findings pertaining to polyethylene photooxidation
Authors: Gugumus F.
Published: March 2011

The kinetics and mechanisms of photolysis of the hydroperoxides formed on thermal oxidation of polyethylene have been investigated. The difficulties to explain the results by the generally accepted decomposition mechanism based on homolytic splitting of the hydroperoxy bond are discussed. New mechanisms of hydroperoxide photolysis are proposed. The intermolecular reactions considered account for the main products found experimentally, ketones and trans‐vinylene groups. They are also in agreement with the kinetics of product formation. The intramolecular photolysis reactions envisaged seem to involve a small amount only of the hydroperoxides present in polyethylene after thermal oxidation. However, they affect directly the mechanical properties of the polymer because they involve main‐chain scission.
New approaches to reversible crosslinking in epoxy resins
Authors: Tesoro Giuliana C. , Sastri Vinod R.
Published: March 2011

The objective of the research is to investigate epoxy resins where crosslinks formed in curing reactions can be cleaved and reformed without significant sacrifice in resin properties. Experimental disulfide‐containing crosslinking agents have been selected for the study, including dihydrazides of dithiodicarboxylic acids (aliphatic and aromatic) and dithioaromatic diamines. Conditions for curing reactions and for subsequent cleavage of crosslinks by reduction have been determined in model systems and confirmed for a prototype epoxy resin. A comparative evaluation of cure kinetics, crosslink density, and thermal and mechanical properties has been carried out for resin cured with aromatic curing agents (dithiodianiline and methylenedianiline) and with aliphatic compounds (3, 3′‐dithiopropionic acid dihydrazide and hexamethylenediamine). It has been shown that in resin fully cured with disulfide‐containing crosslinking agents, crosslinks are ruptured by reduction, and re‐established by oxidation under mild conditions, or by reaction of thiol groups with bifunctional alkylating agents.
Thermal degradation of poly(p‐methylstyrene)
Authors: Luda Maria Paola , Guaita Marino , Chiantore Oscar
Published: March 2011

The thermal degradation behaviour, in the absence of oxygen, of poly(p‐methylstyrene) has been investigated. Monomer is the main product formed in the degradation process, together with different oligomers which have been identified and whose amounts have been determined. A reaction mechanism accounting for the formation of the degradation products, and similar to the mechanism established for polystyrene, is proposed. The main differences of the process comparing with polystyrene are the higher amount of monomer which is produced and the crosslinking structures which are formed at T < 400° C.
Polyfunctional esterisocyanates. Useful monomers for the synthesis of ordered polymers
Authors: Mormann Werner
Published: March 2011

A number of mono‐ and difunctional esterisocyanates has been synthesised by the regioselective reaction of isocyanatocarboxylic acid chlorides with trimethylsilyl‐protected alcohols and phenols. The diesterdiisocyanates were reacted with short chain diols to sequential poly(diesterdiurethane)s and with piperazine to poly(diesterdiurea)s. The monoesterisocyanates were anionically polymerized to 1‐polyamides which show lyotropic liquid crystalline behaviour. The new products are characterized by spectroscopy, viscosimetry and thermal behaviour.
Rheological characterization and analysis of a bismaleimide matrix
Authors: Meissonnier Julien , Seferis James C.
Published: March 2011

Bismaleimide resins are becoming increasingly attractive as matrix materials for high‐temperature applications in continuous fiber reinforced composites. Their relative low viscosity as well as the low processing temperature makes them attractive candidates as matrices in high‐temperature applications while retaining the processing ease associated with epoxies. Traditional prepregging as well as autoclaving processes, especially for solvent free (hot melt) systems, are a viable way to proceed. However, the recent interest in toughened matrices makes these processing techniques difficult to specify and control. Specifically, during prepregging and autoclaving, the viscosity of the system must be specified from the initial stages of resin mixing through B‐staging and gelation all the way to the viscoelastic “solid” region. In this work, based on a series of well‐characterized bismaleimide resins, a generalized model for viscosity capable of describing matrix changes as it goes through the processing steps was developed. Measurements of viscosity by the different techniques were related through the model to provide a characterization scheme that may be applicable to both prepregging and lamination steps.
Thermal decomposition kinetics of polypropylene peroxides in the polymer matrix followed by ESR
Authors: Catoire B. , Verney V. , Michel A.
Published: March 2011

Ozonization creates peroxidic species, peroxides and hydroperoxides, in the bulk of polypropylene powder. Their characterization and chemical determination is delicate (135 °C in decalin). Moreover, the thermal decomposition kinetics of the reactive groups at various temperatures cannot be easily followed by usual methods. In order to follow the thermally induced radicals in the polymer matrix, we used the “spin trapping technique” in E S R. Concurrently we looked at the peroxidic decomposition exothermicity using a differential mode technique in D S C. The E S R data show that the spin trap technique can be used successfully to follow the thermal decomposition kinetics. The activation energy (100 kJ/mol) and rate constant values obtained with this technique are in good agreement with those found in the literature by other techniques. The relative thermogram technique in D S C allows to get information about peroxidic decomposition exothermicity.
Some features of the solid‐state polymerization of diacetylenes
Authors: Vinogradov G. A. , Guy M. I. , Gromov L. A. , El'Yashevitch M. M.
Published: March 2011

Simple models of the initial polymerization stage and the polymerization kinetics are considered on the example of the solid state topochemical polymerization of diacetylenes. These models take into account the reaction specifity of the solid state process and the nonlinear character of the monomer units interactions.
Neutron and light scattering studies of polymer blends and block copolymers
Authors: Fischer E. W. , Jung W. G.
Published: March 2011

The structure of compatible polymer mixtures and its temperature dependence can be well described in many cases by the mean‐field approximation. Deviations with regard to the temperature dependence of the correlation length of concentration fluctuations can be explained by taking into account the spatial structure of the interaction potential. Concentration fluctuations and the microphase separation in diblock copolymers are in good agreement with theories based on the random phase approximation. In the two‐phase region the temperature dependence of the scattered X‐ray or neutron intensity is governed by the difference in the thermal expansion coefficients of the two components of the diblock copolymer. Photon correlation spectroscopy (PCS) yields valuable information on the concentration dependence of the mutual diffusion coefficient DAB.
The net distribution of elements in multiphase polymer materials via element‐specific electron microscopy
Authors: Cantow Hans‐Joachim , Kunz Martin , Klotz Stefan , Möller Martin
Published: March 2011

Applications of the Electron Spectroscopic Imaging technique (ESI) within the field of multiphase polymer materials are discussed. Imaging with elastically scattered electrons as well as imaging with electrons with defined energy loss are presented. From the latter the net distribution of elements can be derived.

Several examples are given: Glassy diblock copolymers polystyrene‐block‐poly(2‐vinyl pyridine), polyethylenes, interpenetrating networks, interdiffusion couples, blends of polystyrene and polystyrene‐graft‐poly(oxyethylene), carbon black reinforced natural rubber, and epitactic growth of poly(1‐pentenylene) on isotactic poly (propylene) surface.

Visualization of the rigid amorphous phase in polyethylene is presented, as well as electron spectroscopic diffraction (ESD) of oriented PE. One of the features of ESI is due to the fact that discrimination between true morphology and artefacts is possible in an unbiased manner, even for minor details: Heavy metal staining is abandonable, and structural analysis by one element may be proved by analysis with other elements, which may be present in the sample or which may be added by chemical reaction or interaction with groups within the molecules.
Synthesis of new chelate ionites and some details of their metal ion interaction
Authors: Ergozhin E. E. , Utkelov B. A.
Published: March 2011

The synthetic methods for chelate ionite groups with 8‐quinolinol, 8‐quinolinethiol and some other thiols, thioethers or thioamides were developed, their sorbing and acid‐base properties being studied as well. The stability constants of complexes of metal ions with polymeric chelate groups were determined. A method to calculate the formation function of the complexes on the basis of potentiometric data was proposed. The experiments showed the synthesized sorbents to be applicable in the selective extraction of heavy metal ions from their solutions.
Interpolyelectrolyte complexes as a new family of enzyme carriers
Authors: Zezin A. B. , Izumrudov V. A. , Kabanov V. A.
Published: March 2011

The ability of nonstoichiometric interpolyelectrolyte complexes of dissolving in water and reversible precipitation, induced by the changes of conditions (pH, ionic strength of the solution) was used to create the reversibly soluble immobilized enzymes. The techniques of the enzyme inclusion (penicillin amidase, α‐chymotrypsin, urease etc.) in the interpolyelectrolyte complexes were worked out. It was shown that the application of the reversibly soluble immobilized enzymes allows: (1) to combine all advantages of the homogeneous catalysis with easy separation of enzyme molecules from the reaction mixture in the end of the process; (2) to increase significantly the thermostability of immobilized enzyme via its precipitation by pH decrease; (3) to protect the enzyme from high‐molecular‐weight inhibitors either in the precipitate or in a homogeneous solution; (4) to create self‐regulating enzyme systems in which an attainment of the certain conversion degree results in process termination; (5) to design reversibly soluble polyenzymatic systems.
Structure and superstructure in eutectoid copolymers
Authors: Kilian Hanns Georg
Published: March 2011

Segregation of eutectic co‐units in eutectoid copolymers is behind of forming lamella‐shaped extended chain‐sequence crystals. These are as cooperative units inhomogeneous microphases (IMP). The mean thickness and the thickness distribution of the IMPs are uniquely related to the lengthdistribution of crystallizable sequences (c‐sequences): The primary elements of the colloid structure in eutectoid copolymers are therefore strictly determined by the chain structure. Clusters are formed comprising a finite number of nearly parallel IMPs alternated with amorphous layers. These clusters are the constitutive elements on the secondary level of the colloid‐structure. Hosemann's linear paracrystal is used for modelling the cluster structure and for describing X‐ray small‐angle pattern.
Kinetics of relaxation and unmixing in polymer blends as studied by x‐ray scattering
Authors: Strobl Gert
Published: March 2011

Concentration fluctuations in polystyrene/poly(styrene‐co‐bromostyrene) blends and changes induced by temperature jumps were studied by small‐angle X‐ray scattering. Structure factors in thermal equilibrium show the form given by the random phase approximation. Kinetics of structure changes after T‐jumps within the homogeneous phase or jumps from the mixed state into the two‐phase region are in accordance with the predictions of latest theories, being described by a simple equation of motion. Application of the theory enables a determination of relaxation times dependent upon the wave vectors. At temperatures near to the glass transition, relaxation and growth become nonexponential.
New concepts in the physics and chemistry op solid polymers fracture
Authors: Zarkhin Lev S. , Manevitch Leonid I. , Enikolopian Nikolai S.
Published: March 2011

Elementary events in polymer fracture at the molecular level are the breakdowns of single polymeric chains. Breakdown of a stretched macromolecule is accompanied by its mechanical degradation. Comparison of experimental data on the molecular products of thermal and mechanical degradation points to significant distinctions between these two processes. Generation of highly excited (“hot”) molecular products of mechanical degradation by the growing crack cannot be explained in terms of the kinetic concept of polymer fracture. Elaborate theoretical analysis of polymeric chain breakdown and generation of “hot” molecular products in subpicosecond time range is made by numerical molecular dynamic simulation with a computer. The mechanisms of primary and secondary chain breakdowns are established. The principal initiators of breakdowns are localized nonlinear modes of the lattice soliton type. Generation of highly excited (“hot”) molecular products occurs at the initial stage of mechanical degradation (during≈1 picosecond after the first breakdown).
New aspects of the photo‐oxidation and photo‐stabilization of polymers
Authors: Geuskens Georges
Published: March 2011

The mechanism of the photo‐oxidation of an ethylene‐propylene random copolymer (EPM) has been compared with that of a styrene‐butadiene‐styrene block copolymer (SBS). The former is considered as a model for polyolefins that undergo chain scission on irradiation and the latter as a model for unsaturated rubbers that become cross‐linked. A hindered amine light stabilizer (HALS) that is a better inhibitor of the absorption of oxygen in SBS than in EPM is, however, less efficient to prevent formation of carbonyl groups and change of the mechanical properties. These results are discussed and an explanation is proposed.
Nature and relative contribution of luminescent species in the photodegradation of polyolefins
Authors: Kuroda Hideyuki , Osawa Zenjiro
Published: March 2011

Luminescent species observed in the polyolefins were mainly foreign impurities, i.e., polynuclear aromatics (PNA) adsorbed from an ambient atmosphere. The luminescent species adsorbed under normal atmospheric conditions and an equivalent amount of PNA did not affect the photodegradation of high‐density polyethylene (HDPE). On the other hand, the extracted precipitates from HDPE accelerated the photodegradation of the polymer and, also, 3‐octanone slightly accelerated it, but little effect was observed in 1‐icosene. Therefore, the activity of impurities on the photodegradation of HDPE can be expressed in the following order:

Extracted precipitates >> C=sO > PNA ∞ ‐CH=CH2