bluuebunny/crossref_metadata_2025 huggingface dataset:
Monte carlo calculations of second virial coefficients of chain molecules
Authors: Freire Juan J. , Rubio Ana M. , Poncela Antonio
Published: March 2011

Monte Carlo calculations have been performed for different types of chain molecules whose units interact through Lennard‐Jones potentials. From the averaged Mayer function, we have evaluated the intermolecular two‐body cluster integral, obtaining results for second virial coefficients. We have investigated the following points: a) the site modelization of alkanes by comparison of our results with gas phase data of different linear and branched alkanes and their mixtures. b) the prediction of interpenetration factors for flexible linear and star polymer chains in a good solvent (or excluded volume conditions). c) the determination of the theta point for a model of flexible polymer chains and the comparison of data for finite chains with theoretical predictions.
Phase behavior of diblock copolymers; pressure and temperature dependence studied by small‐angle neutron scattering
Authors: Mortensen Kell , Almdal Kristoffer , Schwann Dietmar , Frielinghaus Henrich
Published: March 2011

The structure factor of a poly(ethylene‐propylene)poly(dimethylsiloxane) diblock copolymer has been measured by SANS as a function of temperature and pressure. In contradiction to the random phase approximation the conformational compressibility exhibits a pronounced maximum at the order‐disorder phase transition. The phase boundary shows an unusual shape: with increasing pressure it first decreases and then increases. Its origin is an increase in, respectively, the entropic and the enthalpic part of the Flory‐Huggins interaction parameter. The Ginzburg parameter describing the limit of the mean‐field approximation is not influenced by pressure.
Surface anchored polymer: Role in adhesion and friction
Authors: Léger Liliane
Published: March 2011

We present an investigation of thin polymer layers formed by either strong adsorption or end grafting on a surface or an interface. Depending on the kind of surface attachment, different internal organisations of the chains are observed: either polydisperse loops for adsorbed layers, or almost monodisperse tails in the case of grafting. The molecular parameters of the layer (length and surface density of anchored chains) and the molecular organisation inside the layer govern the ability of the surface anchored chains to be swollen by a good solvent or to penetrate into a bulk polymer, either a melt or a cross‐linked elastomer, three properties which have been characterised through neutrons reflectivity techniques. We then analyse how the ability of the surface anchored chains to penetrate into a bulk polymer, entangle with it, and then be deformed when this bulk polymer is mechanically solicitated, are key parameters which govern adhesion and friction properties.
Interactions between surfaces coated with solvophobic and solvophilic homopolymers
Authors: Pickett Galen T. , Balazs Anna C.
Published: March 2011

Using scaling theory, we investigate the interaction between two planar surfaces that are coated with both A and B homopolymers. The polymers are tethered by one end and grafted at relatively low densities. The B chains are chosen to be solvophobic, while the A polymers are solvophilic. Calculating the energy of interaction versus distance profile, we find that the curve shows a wide attractive region as the surfaces are compressed. The features of this profile can be tailored by varying the length and grafting densities of the different chains. Our results provide guidelines for controlling the interaction between polymer‐coated colloidal particles.
Polycondensation design of tailored high performance polymers
Authors: Vygodskii Yakov S. , Nesmeyanov A. N.
Published: March 2011

The ways of the preparing of high performance polymers (HPP) having tailored properties are considered. Common two and one step methods of such polymers synthesis are compared. Some peculiarities of one step polycyclization including the catalytic processes are discussed. Matrix polycondensation leading to the formation of HPP and their blends is analysed. The synthesis of some functional polymers (polyamides and polyamides) having quinuclidine moieties is described.
High pressure synthesis of polyimides and related polymers
Authors: Imai Yoshio
Published: March 2011

This paper reviews our current studies on the high pressure synthesis of polyimides and related condensation polymers. After a brief introduction of the solid‐state thermal synthesis of polyimides starting from nylon‐salt‐type monomers, the paper deals with the high pressure synthesis of polyimides, the preparation of polyimide‐silica hybrid materials by the combination of the above synthetic method for polyimides and the sol‐gel reaction for silica synthesis, and the high pressure synthesis of polybenzoxazoles and addition‐type polyaminoimide.
Synthesis of poly(cyclodiborazane)s by allylboration polymerization of dicyano compounds with trimethallylborane
Authors: Chujo Yoshiki , Tomita Ikuyoshi
Published: March 2011

Allylboration polymerization of α, ω‐dicyanoalkanes with trimethallylborane produced the corresponding poly(cyclodiborazane)s in high yields. This polymerization includes the allylboration reaction of cyano groups and the following dimerization of iminoborane species. The intermediate iminoborane species were detected by IR measurement. The poly(cyclodiborazane)s obtained were found to be more stable toward air than those prepared by allylboration polymerization using triallylborane.
Synthesis and molecular properties of new poly(naphthalene‐1, 3, 4‐oxadiazole)s
Authors: Lavrenko Peter , Schulz Burkhard , Strelina Irina , Okatova Olga
Published: March 2011

Poly[(1, 4‐naphthalene)‐2, 5‐diyl‐1, 3, 4‐oxadiazole] and poly[(2, 6‐naphthalene)‐2, 5‐diyl‐1, 3, 4‐oxadiazole] have been synthesized and investigated in conc. H2SO4, by the flow birefringence method, in comparison with poly[(1, 4‐phenylene)‐2, 5‐diyl‐1, 3, 4‐oxadiazole]. Changes in conformation parameters and optical anisotropy of a chain unit induced by incorporation of the naphthalene groups into the macromolecule backbone have been evaluated.
Enzyme‐catalyzed polyester synthesis in organic medium: Ring‐chain equilibrium
Authors: Berkane Christophe , Mezoul Gilles , Lalot Thierry , Brigodiot Maryvonne , Maréchal Ernest
Published: March 2011

Enzyme‐catalyzed synthesis of aliphatic, unsaturated and semi‐aromatic polyesters from methyl diesters and diols was carried out in toluene at 60°C in the presence of supported lipases. Whatever the monomer structure, rings were formed concurrently to linear chains excepted when dimethyl fumarate was used. The yield of rings depends on several parameters such as the monomer structure and the initial concentration of the reactive functions and strongly influences the average molar masses of the unfractionated samples. For aliphatic, unsaturated and semi‐aromatic polyesters, the molar cyclization equilibrium constants (K) were determined and it would appear that the molar distribution of the ringed species obeys Jacobson‐Stockmayer equation: LnK = LnB − 5/2 Lnn, where B and n represent a constant and the number of monomer units of each type in the ring, respectively.
Liquid crystal thermosets from mesogenic isocyanates and epoxides
Authors: Mormann Werner , Irle Christoph
Published: March 2011

Liquid crystal thermosets from mesogenic diisocyanates are described. Aromatic diisocyanates having the functional groups directly attached to the aromatic rings form isotropic thermosets with incomplete conversion due to crystallisation. Diisocyanates with flexible spacers and copolymers with mesogenic diepoxides have been synthesised and polymerised to overcome the geometrical restrictions which prevent the formation of a mesophase. The oxazolidinone moiety stabilizes a mesophase which was demonstrated with model compounds. Both approaches yield liquid crystal thermosets. The influence of the structure of the comonomers on the mesophase stability of isocyanurate/oxazolidinone networks was investigated.
Morphological and phase behavior studies of uniquely derived epoxy/polyimide semi‐IPNS
Authors: Gaw Kevin , Suzuki Hironori , Jikei Mitsutoshi , Kakimoto Masa‐Aki , Imai Yoshio
Published: March 2011

Interpenetrating networks (IPNs) of polyimide (PI) and epoxy were made by reaction of epoxy (EGEBA) with a polyamic acid (PAA). In addition, epoxy was cured with both a monomeric hardener, pyromellitic dianhydride (PMDA) and PAA to see changes in the morphology and glass transitions caused by the monomeric hardener. Due to “molecular interlock” of the individual polyimide molecules that was brought about by the PAA‐epoxy reaction, systems cured with only PAA did not phase separate and showed a significant increase in Tg when compared to PMDA cured epoxy. All PMDA cured systems phase separated By dynamic mechanical analysis (DMA), it was confirmed that all systems containing over 20% PAA had two glass transitions. The extent of miscibility of the polyimide into the epoxy was relatively constant. PAA cured epoxy systems showed phase miscibility over all compositions and cure regimes
Principles of theoretical description of microstructure of linear condensation polymers
Authors: Kuchanov Semion I.
Published: March 2011

Key ideas of general original approach to the theoretical consideration of monomer sequence distribution problem are formulated for linear condensation heteropolymers showing either isomerism due to different fashions of monomer unit alternation in macromolecules of a copolymer or constitutional isomerism resulting from different orientation of asymmetric monomer units in polymers.
Polycarbosilanes containing siloxy and/or silanamine units by polycondensation using hydrosilylation
Authors: Jallouli Aref , Lestel Laurence , Tronc Frédéric , Boileau Sylvie
Published: March 2011

Poly(1,1‐dimethyl‐1‐silylethylene): ‐(SiMe2‐CH2‐CH2)‐n was prepared by polycondensation of HSiMe2‐CH2‐CH2‐SiHMe2 (A) with CH2=CH‐SiMe2‐CH2‐CH2‐SiMe2‐CH=CH2 (B) under suitable hydrosilylation conditions. Functional oligomers with either two SiH or two Si‐CH=CH2 end groups were obtained by using an excess of A or B respectively. These bifunctional oligomers were used as precursors for the preparation of well‐defined networks by reaction with different tetrafunctional crosslinking agents such as D4H, D4Vib) and tetravinylsilane (TVS). They were also used for the preparation of multiblock copolymers by reaction with dimethylsiloxane oligomers. Alternating copolymers were obtained from monomers containing siloxy or silanamine units. Thermal properties of these polymeric materials are presented.
Polycondensation of cyclodextrins with epichlorohydrin. Influence of reaction conditions on the polymer structure
Authors: Renard E. , Sebille B. , Barnathan G. , Deratani A.
Published: March 2011

A series of water‐soluble polymers was synthesized by polycondensation of cyclodextrin with epichlorohydrin under basic conditions. We studied their molecular distribution as a function of molar ratios of reactants. NaOH concentration showed that very high molecular averages (Mw > 106) can be obtained. The substitution patterns were determined by 13C NMR analysis and standard methylation analysis of polysaccharides. The formation of side chains and bridges consisting of sequences of poly(2‐hydroxypropyl)ether units were demonstrated by electrospray ionization mass spectrometry and gas liquid chromatography‐mass spectrometry. The predominant position of substitution depends on the NaOH concentration.
Kinetics of polycondensation in an industrial environment
Authors: Blondel Philippe , Briffaud Thierry , Werth Michael R. G.
Published: March 2011

The influence of industrial reaction conditions on the kinetics of the polycondensation of polyamides is discussed. For analysis reasons the overall process was subdivided into individual kinetic phases. It will be shown that the basic features of the reaction rate in the final reaction stage can be explained assuming second order kinetics combined with a superposed reaction equilibrium. The influence of non‐stoechiometry on the reaction rate is also demonstrated.
1H, 13C, 14N and 15N NMR Study of copolycondensates obtained by 1, 3 dipolar cycloaddition of α, ω‐diazidoalkanes with 1, 1'‐(methylene di‐4, 1‐phenylene) bismaleimide, with N, N'‐1, 4‐phenylene dimaleimide and with isopropylidene‐1, 4‐phenylene dimethacrylate
Authors: Nguyen Hung Anh , Cheradame Hervé , Belleney Joël , Maréchal Ernest
Published: March 2011

Copolycondensates of α, ω‐diazidoalkanes with 1, 1'‐(methylenedi‐4, 1‐phenylene) bismaleimide, with N, N'‐1, 4‐phenylene dimaleimide and with isopropylidene‐1, 4‐phenylene dimethacrylate were synthetized using 1, 3 dipolar cycloaddition reaction (DCA). Their structures were determined by 1H, 13C, 14N, 15N NMR. The results show that at high temperature (150°C), the copolycondensates present a mixture of triazoline/succinimide, of aziridine/succinimide, of enamine/maleimide and of anil/succinimide junctions. At low temperature (20°C), only the triazoline structure is formed. A reaction scheme is proposed via two reactions, DCA and nitrene formation, occuring simultaneously and independently.
Nouveaux Élastomères de polyuréthanes dérivés d'aminoacides
Authors: Fontaine Laurent , Ménard Laurent , Cayuela Olivier , Brosse Jean‐Claude , Sennyey Gérard , Senet Jean‐Pierre
Published: March 2011

Synthesis and characterization of new polyurethane elastomers with rigid blocks derived from aminoacids have been achieved by polycondensation using poly(tetramethylene oxide) (PTMO) as a soft segment. Aminotelechelic oligopeptides or pseudopeptides were used in the hard block, eventually in association with lysine diisocyanate (ethyl 2, 6‐diisocyanatohexanoate, LDI). Physicochemical characteristics of the so obtained materials, especially good filmmaking properties, allow their use as biomaterials of reduced toxicity.
Thermoplastic elastomers by “criss‐cross”‐cycloaddition polymerization
Authors: Maier Gerhard , Fenchl Andrea
Published: March 2011

Segmented blockcopolymers were prepared via the condensation of telechelic precursors. “Criss‐cross”‐cycloaddition of an aromatic aldazine with a diisocyanate gave telechelics with isocyanate functions at both ends. These prepolymers were reacted with α, ω‐dihydroxytelechelic aliphatic polyethers. The cyclo‐addition‐polymers served as hard segments with softening temperatures between 100°C and 150°C. The resulting segmented blockcopolymers exhibited microphase separation. Depending on the length and fractions of hard and soft segments, the mechanical properties varied from tough thermoplastics to soft elastomers with ultimate elongations above 800%.
Synthesis of photoreactive polymers by a distannoxane catalyzed transesterification. Polycondensation of α, ω‐dicarbomethoxy‐1, 4‐oligobutadiene with a photoreactive diol
Authors: Campistron Irène , Reyx Danièle , Hamza Mohammed , Oulmidi Abdelkader
Published: March 2011

Optimal conditions for distannoxane catalyzed transesterification of methyl esters with benzylic alcohols were established by studying the polycondensation of hex‐3‐ene‐1, 6‐bis(methyl oate) (1) with 1, 4‐bis(hydroxymethyl)benzene (2). α, ω‐Dicarbomethoxy‐1, 4‐oligobutadiene (3) was obtained by cross metathesis between cycloocta‐1, 5‐diene and 1. The synthesis of 1, 4‐bis[4‐(hydroxymethyl)cinnamoyl]‐benzene (4) were conducted starting from 4‐(diethoxymethyl)benzaldehyde (5) and 1, 4‐diacetylbenzene. Finally the organosoluble polyester (PE3/4) were synthesized by reacting 3 with 4 and the occurrence of crosslinkings by UV irradiation was checked.
Synthesis and properties of polyurethane macroazo initiators
Authors: Cheikhalard Talal , Massardier Valérie , Tighzert Lan , Pascault Jean Pierre
Published: March 2011

The synthesis of a typical polyurethane macroazo initiator (PUMAI) based on 2, 2'‐azobis(2‐cyanopropanol) (ACP), α, ω‐hydroxy polycaprolactone (PCL) and 4, 4'‐methylene diphenyl diisocyanate (MDI) occurs in a two stage polycondensation procedure. Kinetics of the reaction between ACP and a monoisocyanate (para‐tolylisocyanate, p‐TI), and the reaction between MDI and PCL were carried out. Reaction rates were determined by a suggested kinetic model. Thermal decomposition of PUMay compared to other azo initiators has been investigated. The kinetic and thermal parameters associated with these initiators were determined by thermogravimetric analysis (TGA).
Biosynthetic and biodegradable polyesters from renewable resources: Current state and prospects
Authors: Steinbüchel Alexander , Gorenflo Volker
Published: March 2011

Bacterial poly(hydroxyalkanoate)s (PHA) are a complex class of polyesters, and almost one hundred different constituents are currently known. Unfortunately, most of these constituents only occur in the polyesters if specific precursor substrates are provided as carbon source. Recently, however, bacteria and mutants were isolated, which synthesize PHA exhibiting an interesting composition from simple unrelated substrates obtainable from renewable resources provided by the agriculture. This contribution will provide an example how PHA based on 4‐hydroxyvaleric acid can be obtained from bulk chemicals. In addition, some aspects of our current knowledge on the physiological and molecular basis of PHA biosynthesis will be provided.
Biodegradable polyphosphazenes for drug delivery
Authors: Lemmouchi Yahia , Schacht Etienne , Dejardin Stéphane , Vandorpe Joke , Seymour Leonard
Published: March 2011

Polyphosphazene derivatives having amino acid ester side groups were prepared by reaction of poly(dichlorophosphazene) with ethyl esters of amino acids. The in vitro degradation studies demonstrated that the rate of degradation depends on the nature of the amino acids. Introducing small amounts of hydrolytically sensitive groups such as depsipeptide ester or hydrolysis‐catalysing moieties, such as histidine ethyl ester co‐substituents, resulted in an increase of the degradation. The rate of hydrolytic degradation of the polyphosphazene material could be controlled by the content of the hydrolytically sensitive side groups or by blending hydrolysis‐sensitive polymers with more stable derivatives. The results obtained from the in vivo implantation of biodegradable polyphosphazenes in mice indicate that the materials are very well tolerated by the animal body. Biodegradable polyphosphazenes have been used as matrix for the design of drug delivery systems. The rate of the in vitro release of mitomycin C from biodegradable polyphosphazenes can be controlled by changing the chemical composition of the polymer or by blending polymers of different chemical compositions.
Polylactides ‐ degradable polymers for fibres and films
Authors: Meinander Kerstin , Niemi Maria , Hakola Jyrki S. , Selin Johan‐Fredrik
Published: March 2011

Modification of a poly(L‐lactide) (PLLA) base resin, by treatment with peroxides and compounding with plasticisers, yield resins which can be processed by conventional techniques and equipment to thin blown films, fibres and nonwoven fabrics having properties comparable to those of corresponding PP and PE samples. Film samples have tensile strength between 30 and 50 MPa, elongation at break around 250%, and puncture resistance, measured as dart drop values, of 12 g/μm. Fibres can be spun to filaments or directly to nonvowen fabrics by spun‐bond techniques. These fabrics have mechanical properties comparable to polypropylene materials. The polymer products are readily degraded in a compost to carbon dioxide, water and biomass.
Design and development of biodegradable polymeric poly(carboxylic acids) as co‐builders for detergents
Authors: Swift Graham , Freeman M. B. , Paik Y. H. , Simon E. , Wolk S. , Yocom K. M.
Published: March 2011

This paper outlines the requirements for truly acceptable biodegradable water‐soluble polymers, in effect establishing the goals of a polymer synthesis program. The deficiencies of the current products are thus clearly identified. A brief review of the redundant approaches that have been made to develop biodegradable polymers will be followed by a description of the chemistry and environmental properties of poly(aspartic acid) which has been identified as meeting all the technical requirements for a biodegradable polymeric co‐builder for detergents.
Polymer‐drug conjugates: Manipulation of drug delivery kinetics
Authors: Pitt Colin G. , Wertheim Jason , Wang C. T. , Shah Subodh S.
Published: March 2011

Three methods of manipulating the kinetics of hydrolysis of polymer conjugates were evaluated. It was demonstrated that either first‐order, zero‐order or S‐shaped kinetic profiles could be achieved by systematic changes in the chemical composition of several series of model side‐chain substituted polyacrylates. The changes in kinetics were shown to arise from an increase in the rate constant during solvolysis, resulting from predictable changes in either the water content, secondary structure, or LCST of the polymer conjugate.
Interactions between flow and superstructure of liquid crystalline polymers
Authors: Marrucci G. , Maffettone P. L. , Crescitelli S.
Published: March 2011

The monodomain equation for rigid rodlike polymers in the nematic phase is here extended, in a simple form, to the polydomain situation. The mathematical problem is further simplified by considering a two‐dimensional restriction. Preliminary results are presented for simple shear flows, showing the formation of a superstructure along the sample thickness.
The state of high global chain orientation but nearly random segmental orientation of amorphous polymers
Authors: Fan Qingrong , Qian Renyuan
Published: March 2011

In the rubbery state of amorphous polymers under uni‐axial drawing the global chain orientation will relax in orders of magnitude slower than the relaxation of local segmental orientation. When this state of hot drawn sample is frozen at temperatures lower than its glass transition, Tg, an amorphous state with high global chain orientation but nearly random segmental orientation (GOLR) could result. Experimentally the GOLR state of amorphous polymers is easily realized by uni‐axial drawing the polymer at temperatures 20–30°C above its Tg. The characteristic features of a GOLR state are i) large recovery of the elastic deformation of global chain on being heated to temperatures above Tg, ii) very small birefringence and IR dichroism, iii) nearly isotropic sonic and ultrasonic velocity of propagation, iv) nearly isotropic WAXD pattern, while it shows v) pronounced anisotropy in stress‐strain behavior for large deformations and vi) appreciable anisotropy of thermal conductivity and of microwave dielectric properties. Concrete examples with detailed experimental results will be reviewed.
Photonic materials for electroluminescent, laser and photovoltaic devices
Authors: Hilberer A. , Moroni M. , Gill R. E. , Brouwer H.‐J. , Krasnikov V. V. , Pham T.‐A. , Malliaras G. G. , Veenstra S. , Werts M. P. L. , van Hutten P. F. , Hadziioannou G.
Published: March 2011

This article presents an overview of the work that has been done recently in our laboratory concerning the development and application of new conjugated materials with tunable properties. We have designed polymers containing oligo(phenylenevinylene)‐type conjugated segments of well defined size and structure isolated either in their main‐chain or in the side‐chains. Model oligomers corresponding to the conjugated parts of the polymers have also been studied. We show how these materials perform in light‐emission applications (light‐emitting diodes, lasers) or photovoltaic cells.
Thermally stable organic electroluminescent device using novel amorphous molecular charge‐transport materials, 4,4′,4“‐tris[bis(4′‐tert‐butyl‐biphenyl‐4‐yl)amino]triphenylamine and 4,4,4“‐tri(n‐carbazolyl)triphenylamine
Authors: Ogawa Hiromitsu , Inada Hiroshi , Shirota Yasuhiko
Published: March 2011

For the purpose of developing an amorphous molecular material with a high glass‐transition temperature (Tg) and a low ionization potential for use as a charge‐transport layer in organic electroluminescent (EL) devices, a novel starburst molecule, 4,4′,4“‐tris[bis(4′‐tert‐butylbiphenyl‐4‐yl)amino]triphenylamine (t‐Bu‐TBATA), was designed and synthesized. t‐Bu‐TBATA was found to form readily a stable glass with a Tg of 203 °C. A multilayer EL device consisting of double hole‐transport layers of t‐Bu‐TBATA and 4,4′,4“‐tri(N‐carbazolyl)triphenylamine and an emitting layer of tris(8‐quinolinolato)aluminum was fabricated and its performances were examined. The device was found to exhibit good performances and to be thermally stable, operating even at 170 °C.
Phenylated poly(P‐phenylene vinylenes) prepared via the chlorine precursor route (CPR)
Authors: Wan Wai Chou , Gao Yongli , Goodwin Thomas E. , Gonzalez Stevan A. , Feld William A. , Hsieh Bing R.
Published: March 2011

The synthesis of several highly phenylated PPV derivatives by a chlorine precursor route (CPR) was investigated in order to understand its scope. Three 1,4‐bis(chloromethyl)benzene monomers were prepared via a robust and versatile synthetic procedure involving the Diels‐Alder reaction. The monomers were then polymerized to the corresponding precursor polymers with about 1.0 equivalent of potassium t‐butoxide in THF. Only one monomer gave a soluble precursor polymer while the other two gave insoluble precursor polymers. The soluble precursor polymer was deposited as thin films and then converted to the corresponding PPV derivative, which showed green photoluminesence and electroluminesence.
Modification and characterization of thin polymer films for electrochemical applications
Authors: Brack Hans‐Peter , Scherer Günther G.
Published: March 2011

Proton‐conducting polymer membranes are utilized as the solid electrolyte in low temperature polymer electrolyte fuel cells (PEFC), which are efficient energy converters. We have selected the process of radiation grafting and subsequent sulfonation to prepare novel membranes because of its feasibility as a low cost production method. Investigations of the two first preparations steps, i.e., irradiation and grafting, lead to insight concerning the optimization of these two steps and the dependence of the final membrane properties on the various preparation parameters.
Power‐law exponent in the central region of a polymer layer adsorbed from dilute solution: Comparison between scaling and SCF results
Authors: Fleer G. J. , Leermakers F.A.M.
Published: March 2011

De Gennes predicted the self‐similar structure φ(z) ∞ z−α for adsorbed polymer layers in the semi‐dilute (central) region of the adsorption profile of homopolymers. This power‐law behaviour is recovered in mean‐field SCF calculations. In this case the exponent is α = 2 in good solvents provided D «z «d, where D is the proximal length and d the distal length. We use a ground‐state approximation (GSA) to derive expressions for the two lengths D and d, and show that in the central region the profile is in good approximation given by φ = 1/3(z + D)−2exp(‐(z + D)2/3d2). Unless the chains are extremely long the condition D«z«d is difficult to obtain and corrections on the exponent are necessary. For most chain lengths in the experimental range, the central region is quite narrow. It is shown that for high adsorption energies (small D) α = 2 + 2d−1 in leading order, where d = R/, with R the radius of gyration and φb the bulk solution concentration. For weak adsorption the proximal length D is larger, which leads to a smaller exponent α. The d−1 correction is in excellent agreement with numerical self‐consistent‐field calculations. In poor solvents we have φ = 1/2(z + D)−1exp(‐2(z + D)2/3d2) and α = 1 + 4d−1 in the strong adsorption limit, which implies a larger correction in this case. Our analysis suggests that in a polymer adsorption profile with excluded‐volume correlations (where α = 4/3) non‐universal aspects would also be present if the chain length is finite.
Interpolyelectrolyte complexes formation in dependence on the nature of polyelectrolytes
Authors: Cristea Mariana , Dragan Stela , Dragan Demetra , Simionescu Bogdan C.
Published: March 2011

Interpolyelectrolyte complexes (PECs) were obtained starting from polycations with (N,N‐dimethyl‐2‐hydroxypropylenammonium chloride) units in the main chain and sodium salts of the poly(acrylic acid), on one hand, and poly (2‐acrylamido‐2‐methylpropane sulfonic acid), on the other hand, as polyanions. The polycations were different as concerns both the content of the quaternary ammonium salt groups and the degree of branching. The polyanions were different both by their structure and molecular weight. The complex formation was followed through the variation of the reduced viscosity and of the conductivity of the reaction medium vs. the unit molar ratio polyanion/polycation in two ranges of concentration.
Salt effect on surface modification of silica by interpolyelectrolyte complexes
Authors: Buchhammer Heide‐Marie , Lunkwitz Klaus , Pergushov Dmitry V.
Published: March 2011

The effect of a low‐molecular‐mass salt on the properties of interpolyelectrolyte complexes formed as a result of interactions between poly(diallyldimethylammonium chloride) and copolymers of maleic acid with propylene or α‐methylstyrene in their salt containing non‐stoichiometric mixtures has been studied. Properties of such interpolyelectrolyte complexes were found to be determined by the chemical nature of the polyelectrolytes and by the salt concentration. The effect of salt on the surface modification of silica particles via their interactions with interpolyelectrolyte complexes has been examined. Two different ways of the surface modification of silica particles were used: (i) silica particles were contacted with previously prepared interpolyelectrolyte complexes and (ii) silica particles were contacted with cationic polyelectrolyte at first and then anionic polyelectrolyte was added. The efficiency of the surface modification was shown to be also dependent on the salt concentration and the chemical nature of polyelectrolytes. Turbidimetry, quasi‐elastic light scattering, laser microelectrophoresis, and polyelectrolyte titration were used to characterize studied systems.
Investigation of polyelectrolyte adsorption by means of a novel concept based upon the use of model surfaces and model polyelectrolytes
Authors: Oertel Ulrich , Nagel Jürgen , Hänel Brigitte , Pilch Bettina
Published: March 2011

A concept to study the influence of molecular parameters in the adsorption of polyelectrolytes is presented. Characteristic for this approach is the use of model surfaces and model polyelectrolytes. The properties of both the surfaces and polyelectrolytes can be varied in a well defined way and over a broad range. First experiments show that the method is able to give structural information about the adsorbed polyelectrolytes. The method is very sensitive, adsorption experiments with polyelectrolyte concentrations in the region of micromoles per litre are possible.
Importance of surface tension for physical paint properties
Authors: Osterhold Michael , Armbruster Kornelia
Published: March 2011

Surface tension is a parameter of decisive importance for characterizing painted and unpainted surfaces related to wetting and adhesion phenomena. This article presents measurements of the surface tension of solids by means of an automatic contact angle measurement device. The evaluation of the surface tension is based on a separation into polar and disperse components. In addition, this paper briefly touches on other, more far‐reaching approaches (acid/base) and discusses a method for the determination of dynamic surface tension of liquids.
Sense and non‐sense about polymers
Authors: Feil Herman
Published: March 2011

This paper describes the present developments and future opportunities for industrial biopolymer applications.
The “green” image of polyolefins
Authors: Galli Paolo , Addeo Antonio
Published: March 2011

Polyolefins, because they are produced by non‐toxic monomers such as ethylene and propylene and due to the minimum pollution impact during production and use and low‐thermal capacity during processing, have achieved a recognized “Green image”.

This environmentally friendly image is founded also on the ability of replacing a number of materials and the possibility of contributing to solve the growing problem of recycling plastic parts at the end of their life.
Modelling of θ‐conditions for bisphenol—A polycarbonate single chains
Authors: Özgün Numan , Knopp Birgitta , Jung Bernd , Wortmann Franz‐Josef , Hǒcker Hartwig
Published: March 2011

Assessing conformational dimensions of macromolecules is a topic of long‐standing interest. Because of its simplicity, it is attractive to investigate the chain properties in θ‐conditions. Under these special conditions, the effects of excluded volume of the segments of the polymer chain vanish. The molecular chain is only subject to local constraints resulting from the bond structure and the hindrance to rotations about bonds. To model θ‐conditions a contour length dependent cutoff is introduced ensuring that only nonbonded interactions of atoms of neighbouring monomeric units are taken into account for energy calculations. Using this energy model we will show that it is possible to model θ‐conditions of a single bisphenol‐A polycarbonate (BPA‐PC) chain in vacuum by two different methods: (i) (Pseudo‐) Langevin dynamics simulations and (ii) regular reassignment of randomly generated atom velocities during a molecular dynamics simulation. Both methods can be used to avoid oscillative dynamic behaviour of the chain. Calculations of the end‐to‐end vector and the radius of gyration of the equilibrium ensembles derived from simulations at different temperatures show good agreement with experimental data. Thus our model techniques are well suited to simulate θ‐conditions with small computational expense.
Amphiphilic copolymers in aqueous medium: Characterization of the structure of the hydrophobic microdomains
Authors: Benjelloun Abdesselam , Dorion Catherine , Brembilla Alain , Viriot Marie‐Laure , Adrian Marc
Published: March 2011

The behaviour of new cationic amphiphilic copolymers derived from 3‐vinylpyridine was studied in aqueous medium. The formation of hydrophobic microdomains was evidenced by fluorescence spectroscopy using a molecular rotor as a fluorescent probe and their structure was visualized by cryo‐transmission electron microcospy (Cryo‐TEM). The parameters (shape and size) obtained from Cryo‐TEM were discussed in relation to the copolymers composition and to the local viscosity defined by the rotor fluorescence quantum yield.
Composite material for medical application
Authors: Zamyslov E. V. , Klochkov V. I. , Ostrovidova G. U.
Published: March 2011

Composite material for medical application on the basis of polydimethylsiloxane rubber (PDMS) and graphite was obtained. The physico‐chemical and mechanical properties of the material depending on the quantity, purity of the modifier and its preliminary treatment were studied. The established physico‐chemical properties of the material surface allow to make the preliminary prediction of its thromboresistance.
Broom fibers as reinforcement for thermoplastic matrices
Authors: Avella Maurizio , Casale Luca , Dell'Erba Ramiro , Martuscelli Ezio
Published: March 2011

Vegetable fibers deriving from the basts of broom plants have been used as reinforcement for two polypropylenic matrices: a conventional isotactic polypropylene (iPP) and a maleate modified one (iPPMA).

Before mixing the fibers were subjected to two different extraction procedures: a conventional alkaline treatment and an innovative steam explosion process.

Afterwards, the composites obtained by compression moulding were thermally, morphologically, and mechanically characterized. Moreover, water absorption tests, to examine the behaviour of these materials in wet conditions, were also performed.
Luminescence properties of PPV derivatives carrying anthracene pendent groups
Authors: Jin Jung‐Il , Chung Sung‐Jae , Yu Seong‐Han
Published: March 2011

Photo‐ (PL) and electroluminescence (EL) properties of three different PPV derivatives carrying the 9,10‐diphenylanthracene units are compared. One (polymer 1) of the polymers contains the 9,10‐diphenylanthracene structure as an integral part of the main chain, but the other two have it as the pendent group attached to the main chain through either oxyethyleneoxy (polymer 2) or oxyhexamethyleneoxy (polymer 3) spacer. Polymers 1 and 2 exhibit very similar PL and EL spectra that are more or less of superimposed feature of the spectra from the backbones and the anthracene pendents. In contrast, polymer 3 shows an EL spectrum that is completely different from its PL spectrum. Whereas the PL spectrum of polymer 3 appears to be a combination of the spectra from the main chain and the pendents, as for polymer 1 and 2, the EL spectrum of polymer 3, however, looks as if the lights were emitted only from the backbone. This difference is explained in terms of excited state electronic interactions between the main chain and the pendents.
New polymer architectures: Recent results with polyrotaxanes
Authors: Gibson Harry W. , Gong Caiguo , Liu Shu , Nagvekar Devdatt
Published: March 2011

Recent results from our laboratory have shown that the formation of polyester and Polyurethane rotaxanes by polymerization in the presence of crown ethers is driven by hydrogen bonding of the OH groups with the oxygen atoms of the macrocycles. Here we summarize these findings. Then we describe the application of this type of self assembly for the production of polyrotaxanes by threading preformed macromolecules and for the controlled synthesis of branched and crosslinked systems. These latter protocols comprise a new and novel way to prepare mechanically linked, elastomeric materials. Rheological properties of main chain polyrotaxanes are compared to simple linear backbones; the rotaxanes display higher intrinsic viscosities and lower melt viscosities, reflecting larger hydrodynamic volumes and less entanglement, respectively; these are potentially useful aspects in terms of processability of this new class of polymeric materials.
Synthons as building blocks in the synthesis of liquid crystalline multiblock copolymers
Authors: Bilibin Alexander Y. , Girbasova Nina V. , Tenkovtsev A.V.
Published: March 2011

Synthetic approaches which allow to insert rather long fragments with exactly definite sequence of several single structural units into polymer chains are considered and summarized. The procedure consists in preliminary formation of such sequences in a form of bifunctional “complex monomer” (synthons) which may undergo a polycondensation with other single or complex monomer to form macromolecule with definite alternation of several single monomers. These synthetic approaches were used for the synthesis of LC multi‐block copolymers with definite structure of rigid block.
Effect of component interaction on the melting and crystallization characteristics of pe/pib blends
Authors: Szabó Péter , Epacher Edina , Belina Károly , Pukánszky Béla
Published: March 2011

Linear low density polyethylene/polyisobutylene blends were prepared in the entire composition range. Non‐isothermal and isothermal crystallization of the samples was carried out and melting behavior was studied as a function of composition and crystallization temperature. The equilibrium melting temperature of the neat PE and the blends was determined by the Hoffman‐Weeks extrapolation technique. Flory‐Huggins interaction parameters were calculated by the approach of Nishi and Wang. The decrease of melting temperature with increasing PIB content indicated the interaction of the polymers in the melt. Both irregular chain structure of the crystalline polymer and interaction lead to a decrease of the equilibrium melting temperature and maximum lamellar thickness. The results prove that even relatively weak dispersive forces can lead to the miscibility of two polymers.
Synthesis and physical properties of polyurethanes from saccharide‐based polycaprolactones
Authors: Hatakeyama Hyoe , Izuta Yoshinobu , Kobashigawa Ken , Hirose Shigeo , Hatakeyama Tatsuko
Published: March 2011

Polyurethane (PU) sheets were prepared from glucose‐, fructose‐and sucrose‐based polycaprolactones (PCL). The obtained saccharide‐based PCL's were characterized by gel permeation chromatography, Fourier‐transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The glass transition temperature, thermal degradation temperature, tensile strength, elongation and Young's modulus of the PU sheets were measured. The obtained results suggest that the molecular motion of PU's is enhanced with increasing fraction of PCL chains in PU molecules, and that at the same time the saccharide components act as hard segments.
Biodegradation of polyorganosiloxanes
Authors: Rościszewski Paweł , Łukasiak Jerzy , Dorosz Agnieszka , Galiński Janusz , Szponar Maria
Published: March 2011

Biodegradation of various polyorganosiloxanes (about 30 substances) under the influence of several biotype bacteria strain (16 types) were studied. A special procedure of biodegradation and analytical methods of evaluation the degree of degradation were applied. It was found that nearly all polysiloxanes tested are biodegradable but the degree of degradation depends on their composition and structure, as well as on the type of bacteria strain chosen.
A novel redox system consisting of π‐conjugated polymers and transition metals
Authors: Hirao Toshikazu , Higuchi Masayoshi , Yamaguchi Satoshi
Published: March 2011

Coordination of π‐conjugated polymers to transition metals constructs a novel redox system due to interchangeable various oxidation states of the polymers, which permits transition metals to interact with each other through a π‐conjugate chain. The redox characteristics were found to depend on the electronic interaction with metals and the doping. A combination of copper(II) or iron(III) chloride and polyanilines afforded the complex catalysts with the higher oxidation capability for dehydrogenative oxidation. A catalytic system was also realized in the transition‐metal‐induced oxidation reaction, in which π‐conjugated polymers serve as redox‐active ligands participating in the reversible redox cycle. The Wacker oxidation of terminal olefins proceeded catalytically in the presence of a catalytic amount of polyaniline or polypyrrole derivative under oxygen.
Photoinduced water oxidation by polymeric iron cyanide complex
Authors: Abe Toshiyuki , Shiroishi Hidenobu , Kinoshita Kosato , Kaneko Masao
Published: March 2011

It was found that photoelectrochemical water oxidation takes place at a polynuclear iron‐cyanide complex‐coated electrode called Berlin Brown (BB; Fe4III[FeIII(CN)6]33 3X). The electrode‐coated BB showed electrocatalytic activity for water oxidation to produce O2 not only in the dark but also under illumination to result in photoinduced water oxidation. The amount of the photoelectrochemically produced O2 increased with the thickness of the BB film, indicating that the BB works as a bulk catalyst.
Efficient epoxidation of terminal and internal alkenes using t‐butylhydroperoxide catalysed by polybenzimidazole‐supported Mo(VI).(PBI.Mo)
Authors: Olason Gunnar , Sherrington David C.
Published: March 2011

A polybenzimidazole‐supported Mo complex (PBI.Mo) has been prepared by a method already reported. Extensive investigation of digestion procedures has shown a dry‐ashing method using NaNO3/HNO3 (conc.) at 560°C to be an optimal method for preparing samples for Mo analysis by atomic absorption spectrophotometric methodology. Mo loadings in the range 1.32–0.62 mmol Mo g−1 polymer were demonstrated. PBI.Mo has been used as a heterogeneous catalyst in the epoxidation of cyclohexene, methylene‐cyclohexane, 4‐vinyl cyclohexene, styrene, 1,3‐pentadiene and allyl chloride, bromide and alcohol using t‐butylhydroperoxide as the oxidant. The catalyst is very effective for the first four substrates, somewhat less active than soluble MoO2acac2, but providing final yields and purity of products generally better than using MoO2acac2. The 1,3‐pentadiene displays an overall conversion of ∼35% with a distribution of the four possible monoepoxide isomers similar to that obtained with MoO2acac2 as catalyst. The allylic substrates showed poor conversion probably as a result of secondary (oligomerisation) reactions involving the epoxide products. Running the epoxidations for extended periods in air allows in situ generation of alkyl hydroperoxides in the case of cyclohexene and 4‐vinylcyclohexene and these are then effective internal oxidants for further Mo catalysed epoxidation of these alkenes. When run under anaerobic conditions the reactions are very clean with no evidence of any free radical processes contributing. In all cases Mo leaching is minimal. Good activity is seen in the recycling of PBI.Mo in the case of styrene and 1,3‐pentadiene, although with cyclohexene and 4‐vinylcyclohexene steady deactivation is seen, probably as a result of catalyst fouling. Thermogravimetric analyses suggest that it might be possible to burn off the foulant without destroying the catalyst.
The propagating species in living cationic polymerization: Living nature and steric structure of polymers
Authors: Kanaoka Shokyoku , Higashimura Toshinobu , Sawamoto Mitsuo
Published: March 2011

This paper discusses the nature of the living growing species in cationic polymerization from the viewpoint of the steric structure of poly(isobutyl vinyl ether) [poly(IBVE)]. At −78 °C, living polymerization was induced with the HCl‐IBVE adduct (1)/ZnCl2 system in a EtNO2/CH2Cl2 mixture, whereas similar systems with EtAlCl2 led to conventional cationic polymerization. In this polar medium, both systems gave polymers with very similar and low isotacticity (meso ≈ 56%), indicating that the propagating reaction is mediated by free ions. Thus, regardless of solvent polarity, or involvement of free ions or ion pairs, living cationic polymerization requires a suitably nucleophilic counteranion. As model reactions of the growing species, 1/ZnCl2 and 1/EtAlCl2 were directly analyzed by 1H NMR spectroscopy.
Some still unsolved problems in carbocationic polymerization
Authors: Sigwalt Pierre
Published: March 2011

Some controversial problems in both “conventional” and “living” carbocationic polymerizations are discussed: direct initiation, apparently negative activation energies, effect of hindered bases and of other electron donors.
Model block copolymers with complex architecture
Authors: Hadjichristidis Nikos , Poulos Yiannis , Avgeropoulos Apostolus
Published: March 2011

The synthesis of non linear block copolymers of the type (BA)2B (3‐miktoarm star copolymer), (BA)3B (4‐miktoarm star copolymer), (BA)3B(AB)3 (super H‐shaped), B2AB2 (H‐shaped) and (B,A)A(B,A) (π‐shaped), where A is polyisoprene 1,4 and B is polystyrene was performed using anionic polymerization techniques and suitable chlorosilane chemistry. Characterization data showed that the samples are molecularly and compositionally homogeneous. TEM, SAXS and SANS were used to study the microphase behavior of the copolymers. For all samples, the results were analyzed in the frame of the theoretical predictions given by Milner and taking into account the results from previous studies on the A2B and A3B miktoarm star copolymers.
Styrolux+ and styroflex+ ‐ from transparent high impact polystyrene to new thermoplastic elastomers: Syntheses, applications and blends with other styrene based polymers
Authors: Knoll Konrad , Nießner Norbert
Published: March 2011

Styrolux and Styroflex are styrene and butadiene based block copolymers prepared by butyllithium initiated anionic polymerization. Styrolux is a transparent, tough and stiff thermoplastic material for high speed processing. Its specially designed molecular structure allows homogeneous mixing with general purpose polystyrene maintaining the transparency. Styroflex is a newly commercialized product with the mechanical behavior of a thermoplastic elastomer, e.g. low modulus and yield strength, high elongation and excellent recovery. High transparency and thermal stability give the competitive edge over conventional styrene‐butadiene elastomers. Styroflex, Styrolux and general purpose polystyrene form a unit construction system e.g. for transparent film materials and injection molded parts with fine‐tunable hardness and toughness.