bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemical composition distribution of graft copolymer prepared by macromonomer technique: Determination by gradient HPLC
Authors: Teramachi Shinya
Published: March 2011

The chemical composition distributions (CCDs) of poly(methyl methacrylate)‐graft‐polystyrene samples prepared from the polystyrene macromonomers having methacryloyl and p‐vinylbenzyl end‐groups were determined by high‐performance liquid chromatography (HPLC) based on reversed‐phase and normal‐phase adsorption modes. The CCDs determined by both modes were in good agreement with one another, indicating that the effect of the molecular weight distribution on the CCD is negligible. The results demonstrated the features of the CCDs in agreement with the theoretical predictions and the strong effect of the intrinsic reactivity of the end‐group on the copolymerization reactivity of the macromonomer.
Investigation of statistical, block and graft copolymerizations using nmr‐sensitive initiators and macroinitiators
Authors: Harwood H. James , Christov Latchezar , Guo Mingming , Holland Troy V. , Huckstep April Y. , Jones Daniel H. , Medsker Robert E. , Rinaldi Peter L. , Saito Takeshi , Tung Deborah S.
Published: March 2011

13C‐ and 31P‐NMR studies on polymers and copolymers derived from 13C‐enriched AIBN, 13C‐enriched dibenzyl ketone and diphenyl‐2,4,6‐trimethylbenzoylphosphine oxide (Lucrin TPO) are reported. They provide information about the influence of solvent on the initiation step in copolymerization reactions, the selectivity of diphenylphosphinyl radicals and the chemical behavior of radicals derived from dibenzyl ketone. In addition, NMR, molecular weight and molecular weight distribution measurements on polymers obtained from polymerizations of methyl methacrylate conducted in the presence of stilbene indicate that stilbene or radicals derived from it may be able to moderate MMA polymerizations.
New aspects of pseudostationary polymerization and their application
Authors: Olaj Oskar Friedrich , Zifferer Gerhard
Published: March 2011

Contrary to the stationary state little thought has been given so far to the general principles of the pseudostationary state. In this discourse an attempt is made to demonstrate that — within wide limits — arbitrary initiation profiles may be used to determine kp/kt (kp = rate constant of chain propagation, kt = rate constant of chain termination) from the frequency dependence of rate of polymerization (in analogy to the rotating‐sector technique) as well as to evaluate kp from the chain‐length distribution (CLD) of samples prepared under pseudostationary conditions. Adverse factors like nonspontaneous transformation of absorbed photons into primary radicals do not invalidate this result. The existence of a universal relationship (independent of the initiation profile) is proved to exist for the second moment of the CLD of samples prepared under pseudostationary initiation conditions for constant (chain‐length independent) kt. Pseudostationarity, however, might be also achieved if not the initiation but the termination is periodically varied. In this case the CLD has a completely different shape but allows determination of kp likewise. Finally, the case of chain‐length dependent kt is shortly discussed in connection with pulsed‐laser initiation. Although the general equation for the second moment of the CLD does not apply any longer for this case some generality appears to exist under these conditions, too.
The Correlation between segment interaction parameter and interface width of polymer blends
Authors: Stamm Manfred
Published: March 2011

The correlation between the segment interaction parameter and the interface width of incompatible polymer blends can be used to obtain information on the segment interaction of incompatible polymers via an accurate measurement of the narrow interface width by neutron reflectometry. Several model systems are discussed including polystyrene/poly(cyclohexyl acrylate‐stat‐n‐butyl methacrylate), polystyrene/ poly (styrene‐ stat‐p‐bromo styrene) and poly styrene/poly(methyl methacrylate).
In‐situ deformation studies of rubber toughened PMMA: A SAXS analysis of the response of core‐shell particles to deformation
Authors: He Chaobin , Donald Athene M. , Butler Michael F. , Diat Olivier
Published: March 2011

The deformation behaviour of core‐shell rubber particles in a polymer matrix under tensile strain was studied using small‐angle X‐ray scattering (SAXS) combined with computer simulation of the scattering. The core‐shell rubber particles first undergo inhomogeneous deformation, followed by a progressive debonding at the rubber/poly(methyl methacrylate) (PMMA) interfaces beyond the yield point. A dilatation band of cavitated rubber particles, with a tilt angle of 46–48°, is also observed in samples with a high rubber particle concentration.
Limitations of short‐term ageing tests in assessing polyethylene blends for wire and cable applications
Authors: Tran Conchita
Published: March 2011

Medium‐density PE (MDPE) and high‐density PE (HDPE) compounds are commonly used in telecom wire insulation. Many of these compounds are blends of low‐density PE (LDPE) with HDPE in a ratio in which the two PE are immiscible. These blends feature very low mechanical properties that are often interpreted erroneously as being thermal degradation of the compound.
Controlled architectures and property synergisms of polypropene/polyamide 6 blends prepared via reactive processing
Authors: Rösch Joachim , Mülhaupt Rolf , Michler G. H.
Published: March 2011

Variation of molecular architectures of blend compatibilizers and reactive processing reaction conditions gave excellent control on morphology development and toughness/stiffness balance of polypropene/polyamide 6 blends. Basic structure/property relationships of blends containing discrete PA6 phases, PA6 nanoparticle cores encapsulated in a rubber shell, dispersed PA6 particles with rubber subinclusions, and percolation structures of agglomerated core/shell particles were investigated. Deformation behavior of percolation structures were analyzed by means of high‐voltage transmission electron microscopy.
Chemical modification of polyolefin blends
Authors: Chodak Ivan , Repin Hans , Bruls Willie , Janigova Ivica
Published: March 2011

The effect of crosslinking on the properties of low density polyethylene / polypropylene blends was investigated. It was found that crosslinking results in much higher deformability of the blends compared to uncrosslinked materials. A decrease in crystalline portion determined by DSC leads to lower modulus in crosslinked samples. High drawability of crosslinked samples is mainly attributed to peculiar behaviour of PE part of the crosslinked blend where thicker lamellae are formed during drawing.
Encapsulation: A new concept to control alloys morphology
Authors: Patrice Perret , Alain Bouilloux , Marius Hert , Igor Leclere
Published: March 2011

A new concept for tailoring polyamide or polyester / polyamide alloys containing core shell particles has been developed. This alloy technology is based on the combination of one polyester and one polyamide (or two polyamides) of different melting points and a rubbery ethylene ‐ acrylic ester ‐ glycidyl methacrylate terpolymer. Optimum properties are a function of compounding temperature profile. Resulting alloys offer a good balance of flexibility, toughness and dispersed phase morphology stability.
Microphase separation in correlated random copolymers
Authors: Angerman Henk , Brinke Gerrit Ten , Erukhimovich Igor
Published: March 2011

In this paper we present the results of a calculation of the phase diagram of a highly polydisperse multiblock copolymer in the weak segregation limit. The theory for polydisperse systems developed by Erukhimovich and Dobrynin [Erukhimovich, I.; Dobrynin, A. V. Macromol. Symp. 81, 253 (1994)] has been used. The model of the copolymer has the following characteristics: the blocklengths, as well as the molecule lengths are highly polydisperse (Mw/Mn = 2). The average number of blocks per molecule is very large and the effects of the finiteness of the blocklengths (the fluctuation corrections) are ignored. The resulting phase diagram shows some remarkable differences with the phase diagram of a regular monodisperse multiblock. Known differences are e.g. the order of the transition from the homogeneous state, and the variation of the period of the microstructure with the X‐parameter. In addition, we found a peculiar feature at the critical point: the phase boundaries have discontinuous derivatives.
Artificial muscles based on nematic gels
Authors: De Gennes Pierre‐Gilles , Hébert Matthieu , Kant Rama
Published: March 2011

Mechano‐chemical conversion through the swelling of polymer gels suffers from several limitations, as far as the artificial muscles applications are concerned: mechanical response is too slow and strong local stress damages the sample. We propose a different approach to bypass these difficulties: artificial muscles based on nematic gels. When the temperature is lowered below the nematic clearing point, strong uniaxial deformations occur. The estimated shape relaxation time is well within actual muscle contraction times.
Thermal relaxation in poled non‐linear optical sidechain polymers: Influence of annealing
Authors: van Der Vorst Cornelis P.J.M. , van Gassel Rob A.P.
Published: March 2011

The influence of different annealing treatments has been investigated on the stability of the Electro‐Optic coefficient in a poled DANS (4‐dimethylamino‐4′‐nitrostilbene) sidechain polymer, which was poled near its Tg‐onset of 140°C. The annealing treatments and the EO relaxation experiments were performed at 120°C. The EO stability can be significantly increased both by an annealing treatment after poling and by annealing before poling. This latter effect is concluded from the reduction of the EO relaxation rates in successive relaxation cycles performed in the same polymer sample ‐ completely depoled and repoled in between the cycles. The effect from the different annealing treatments on the time‐dependence of the EO relaxation process is different and is analyzed in terms of a Debye‐like model with a single, time‐dependent Debye relaxation time r(t)=ri+C. t3. The time‐dependence of r and the observed effects from annealing are attributed to the parallel relaxation process of physical ageing.
Neutron scattering studies of syndiotactic polystyrene crystals
Authors: Moyses Stéphane , Sonntag Philippe , Spells Stephen J.
Published: March 2011

Neutron scattering experiments are reported on solution grown crystals of syndiotactic polystyrene (sPS) at small and large q, in order to investigate the chain conformation within the lamellar crystals. From the results in both the Guinier and the intermediate ranges, we come to the following conclusions: The chain folds in one or several sheet depending on the molecular weight, comparison between measured and calculated intensity plots give strong indication that a is the fold direction. The statistical model recently built for the spatial arrangement of stems in a sheet‐like structure is successful again, and demonstrate a strong statistical preference for adjacent re‐entry.
Anisotropic agarose gels
Authors: Rochas C. , Hecht A.M. , Horkay F. , Geissler E.
Published: March 2011

Agarose hydrogels deswell reversibly over a wide range of concentration. Two types of deswelling measurements are considered here, isotropic and uniaxial. We describe some of the properties of the gels observed in the deswollen state. In both the isotropic and uniaxial geometry, the swelling pressure varies approximately as the square of the concentration.
Molecular recognition effects in polyaniline
Authors: Ikkala O. T. , Pietilä L.‐O. , Vikki T. , Österholm H. , Passiniemi P. J. , Ahjopalo L. , Österholm J.‐E.
Published: March 2011

Polyaniline (PANI) is known to dissolve in strong acids, such as sulphonic acids. PANI, in its electrically conductive form, is generally regarded to be poorly soluble in low‐acidic solvents and to be infusible, closely resembling fully aromatic rigid rod polymers. We show that “less” acidic solvents and plasticizers can be found based on phenyl‐phenyl interactions in combination with hydrogen bonding. The requirement is that the interactions are strong enough and, importantly, sterically match the complementary moieties of the sulphonic acid doped PANI. Dihydroxybenzenes and bisphenols are examples of such low‐acidic compounds. This type of molecular recognition allows solution and melt processibility of PANI doped by generic sulphonic acid, such as methanesulphonic acid or alkylbenzenesulphonic acid. Molecular recognition is also offered as an explanation for the previously observed high solubility of camphorsulphonic acid (CSA) doped PANI in phenols.
Structural changes of the molecular complexes and consolute phenomena in binary liquid mixtures
Authors: Brovchenko Ivan V. , Oleinikova Alia V.
Published: March 2011

Consolute phenomena in the aqueous solutions of the polymers are considered In view of the temperature induced structural changes of the hydrogen bonds between water and functional groups of polymer. The lower and upper critical consolute points are attributed to the appearance of the “critical” concentration of the complexes with one hydrogen bond between single water molecule and functional group of polymer. Namely such kind of the hydrogen bonds are responsible for the formation of the strongly associated water clusters, that may be followed by phase separation. Experimentally observed dependences of the critical consolute temperatures for the aqueous solutions of polyethylene glycol on the molecular weight of polymer and adding of salts are well reproduced in the framework of the proposed model.
Polymorphism of the poly(ethylene oxide)/Li triflate complexes
Authors: Moulin Jean‐François , Damman Pascal , Dosière Marcel
Published: March 2011

We hereafter present the study of the high concentration zone of the PEO/Li triflate phase diagram. This system was found to form three different molecular complexes. Their thermal behaviour was elucidated by use of three complementary techniques: Calorimetry, X‐ray diffraction and optical microscopy.
Effect of absorption of low‐molecular‐weight compounds by some polymer flocculants
Authors: Zheltonozhskaya Tatyana B. , Romankevich Olga O. , Syromyatnikov Vladimir G. , Bulavin Leonid A. , Kudrya Vladislav Yu. , Ogul'chansky Tymish Yu. , Yashchuk Valeriy M.
Published: March 2011

The sorption properties of the intramolecular complex ‐ poly(acrylamide) to poly(vinyl alcohol) grafted copolymer (PVA‐PAAN) in block state were investigated with respect to a number of compounds. The relatively small molecules of phenol, phenylalanine in water solution as well as nitrobenzene in hexane are strongly absorbed by PVA‐PAAN films. The large humine acid molecules (sizes are larger by more than ≈ 10 times) are absorbed by PVA‐PAAN very weakly. It was determined the absorption influence on the character of polymer film solution. In a number of cases the oscillation of the dilution and sorption were observed when determining the critical concentrations of guest molecules in the upper layer of polymer films were achieved. The possible mechanisms of absorption were discussed.
Polymer‐solvent interaction in physical networks
Authors: Solovyov M.Ye. , Ivashkovskaya T.K. , Irzhak V.I. , Galushko A.G.
Published: March 2011

The theoretical model of thermodynamical properties of swollen polymer network with physical junctions is proposed. Temperature transitions in network depending on solvent volume fraction and strain are investigated. As is shown, phase transition and collapse — decollapse processes are obtained in dependence on thermodynamical parameters and concentration of physical junctions.
Microstructure of poly(ethylene oxide) gels dispersed in various organic solvents
Authors: Kobayashi Masamichi , Kitagawa Kenji
Published: March 2011

Ordered structure formed in gels of poly(ethylene oxide) (PEO) dispersed in various organic solvents has been investigated by means of infrared spectroscopy. In a cooled gel (below −35 °C) of PEO dispersed in a 1:1 mol/mol mixture of chloroform and carbon disulfide, a uniform (7/2) helical conformation is formed, in contrast to the distorted helix present in the monoclinic crystal modification. In a low‐temperature range below −65 °C formation of a rigid polymer‐solvent complex is suggested. The structure of the resultant gels as well as the gelation behavior are strongly dependent on solvent, reflecting the difference in the strength of polymer‐solvent interactions.
Complex formation of boric acids with DI‐ and TRI‐ carboxylic acids and poly(vinyl alcohol) in aqueous solutions
Authors: Kobayashi Mitsue , Kitaoka Yoshinori , Kobayashi Masamichi
Published: March 2011

Complexation of dihydroxyboryl compounds such as dihydroxyboryl phenylalanine and boric acid with polycarboxylic acids as well as polyols was studied by infrared spectroscopy and zone electrophoresis. By consulting the results obtained, gel formation of poly(vinyl alcohol) (PVA) in aqueous solutions of boric acids (BA) and borax was studied. The IR spectra of aqueous PVA‐BA gels indicate that BA mainly assumes a planar triangle form, while the local conformation of PVA in the gel is different from that in aqueous solutions.
A small‐angle neutron scattering study of the helical form involved in the thermoreversible gelation of syndiotactic poly(methyl methacrylate)
Authors: Saiani A. , Guenet J.M.
Published: March 2011

The chain trajectory in syndiotactic poly(methyl methacrylate) thermoreversible gels has been studied by neutron scattering. Theoretical fits of the scattering curves are consistent with a double‐stranded helix in which the inner helix adopts a structure proposed by Kusuyama et al. The solvent is thought to be intercalated between the two strands of the double helix.
Role of the polymer microstructure in the thermoreversible gelation of poly(vinyl chloride)
Authors: López Daniel , Mijangos Carmen , Guenet Jean‐Michel , Santamaría Antxon , Eugenia Muñoz María
Published: March 2011

Gels of polyvinylchloride (PVC) and PVC copolymers of different microstructure and molar composition, were prepared in a series of diester‐like solvents. The viscoelastic properties of these gels were evaluated as a function of temperature and the molecular structure was studied by small‐angle neutron scattering. The degrees of proton association in the polymer solutions were determined by 1H NMR spectroscopy by measuring the intensity of proton bands of CH2 monomeric units. The body of experimental data shows clearly that there is a straight relation between molecular structure, viscoelastic properties of the gel, degree of polymer‐solvent interaction and polymer microstructure.
A spreading model for the oxidation of polypropylene
Authors: George Graeme A. , Celina Mathias , Lerf Claude , Cash Gregory , Weddell David
Published: March 2011

A model for the heterogeneous oxidation of polypropylene (PP) is proposed in which it is considered that there is a small initial fraction, po, of oxidizing centres which have a high local rate of oxidation. Within these zones there is a free radical chain reaction producing secondary oxidation products, volatiles and chemiluminescence (CL) from peroxy radical termination reactions. These zones progressively spread (rate coefficient b/s−1) and the free radical reactions die away within the volume of the original zones, producing a measurable concentration of oxidation products (rate coefficient α/s−1). Analysis of the CL‐time curve as representing the instantaneous infectious, fraction, pi, in the spreading model enables the parameters po, b and α to be determined and profiles of the remaining fraction (pr) and dead or oxidized fraction (pd) constructed. Analysis of CL curves from 120°C to 150°C gives an activation energy for spreading in PP particles of 96kJ/mol. Both single particles and groups of particles of different types of PP have been examined and evidence is presented of rapid surface spreading of oxidation from particle to particle.
LCP polyesters vs thermosetting polyesters: A paradigm for research in the 21st century
Authors: Economy James , Frich Dan , Schneggenburger Lizabeth A.
Published: March 2011

In this paper we attempt to trace the course of development of our work on aromatic copolyesters starting in 1963 with the successful polymerization of p‐hydroxybenzoic acid and its aromatic copolyesters and continuing up to the present. In so doing a number of interesting issues are identified which provide us with important insights into the rapidly changing research environment of the past 30 years. Perhaps more importantly, some of the key requirements for successfully carrying out research into the 21st Century within a University framework begin to emerge. As part of the overview, a brief retrospective of work over the last 40 years in the field of high temperature polymers is given to provide a suitable background to the motivation for our research.
Amalgamation of ziegler‐natta and metallocene catalysts
Authors: Soga K. , Jin J. , Kaji E. , Uozumi T. , Suzuki Y.
Published: March 2011

The MgCl2 supported half titanocenes and Ti(4, 4, 4‐trifluoro‐1‐phenyl‐1, 3‐butanedionato)2Cl2 catalysts were synthesized and applied to propene polymerization. Without supporting on MgCl2, those complexes displayed almost no activity even using methylaluminoxane (MAO) as cocatalyst. When supported on MgCl2, on the other hand, the resulting catalysts could be activated by ordinary alkylaluminums to yield polypropene in fairly high yields. The catalyst isospecificity was markedly improved by the addition of a suitable Lewis base.
A new class of multifunctional poly(1, 6‐heptadiyne)‐based materials by metathesis polymerization
Authors: Choi Sam‐Kwon , Lee Ji‐Hoon , Kim Hwan‐Kyu
Published: March 2011

A new class of multifunctional polymers based on poly(1, 6‐heptadiyne) derivatives with various functional groups such as carbazole unit for photoconductive polymers and nonlinear optical (NLO) chromophores for NLO polymers were synthesized by metathesis polymerization. The polymerizations were carried out with MoCl5‐ and WCl6‐based catalysts. The catalytic activity of MoCl5 was found to be greater than that of WCl6. The resulting polymers exhibited photoconductivity and large optical nonlinearity. These conjugated polymers have good solubility in common organic solvents, long‐term stability toward air oxidation, and high electrical conductivity.
Structure‐property behavior of polyurethanes, polyurethane ionomers, and their acrylates
Authors: Kim Byung Kyu
Published: March 2011

Polyurethanes(PU), PU ionomers, PU ionomer acrylates, PU latex interpenetrating polymer network(LIPN), latex AB crosslinked polymers (ABCP), and uv‐curable PU ionomer acrylates have been prepared and characterized in terms of structure‐property relationship, together with shape memory function of PUs.
Polymers with macrocyclic architectures: Synthesis and properties
Authors: Deffieux Alain , Beinat Sylvie , Schappacher Michel
Published: March 2011

The preparation by living polymerization and the investigation of the properties of polymers with cyclic chain architectures have been recently undertaken. The cyclization involves a unimolecular end‐to‐end reaction of a heterodifunctional linear precursor. The elementary steps of the cyclization mechanism are examined in the light of matrix‐assisted laser desorption/ ionization mass spectrometry (MALDI‐MS) data obtained on linear polystyrene precursors and cyclized products. The synthetic procedures developed to prepare macrocyclic polymers of various structures, as well as macrocyclic random and block copolymers are then reviewed and discussed. The main characteristics of the cyclic (co)polymers are compared to the corresponding linear chains and some of the original properties that are induced by the cyclic chain architecture are presented.
Synthesis of a liquid crystalline semi‐ordered aromatic polyester and high‐resolution solid‐state 13c nmr investigation of local motions
Authors: Jo Byung‐Wook , Jin Jung‐Ii , Laupretre Francoise
Published: March 2011

A liquid crystalline sequence‐ordered polyester was prepared from isophthalic acid and 4‐hydroxyphenyl 4‐hydroxybenzoate in a 1:1 mole ratio. The local motions of this polymer were investigated by high‐resolution solid‐state 13C NMR and the results were compared to data obtained on liquid crystalline or semicrystalline random terpolyesters with very similar compositions. Whereas no motions of the hydroquinone rings could be detected below the glass‐transition temperature of the semi‐ordered polymer, the para‐hydroxybenzoic acid units exhibit a certain degree of freedom in the temperature range between 450 K and 500 K.
Processing of high density polyethylene and poly(ethylene terephthalate) blends
Authors: Basu Sumit , Kale Dwarkanath D.
Published: March 2011

Commercial grades of high density polyethylene, HDPE and waste poly(ethylene terephthalate), PET were melt blended over a wide range of compositions. Effect of ethylene acrylic acid copolymer, EAA, ethylene vinyl acetate copolymer, EVA and maleic anhydride grafted EVA as compatibilizers on rheology and mechanical properties of the blend was studied. EAA was found most suitable compatibilizer.
Free volume studies in miscible polymer blend systems
Authors: Campbell Jonathon A. , Goodwin Y. A. , Ardi Mohsen Safari , Simon George P. , Landry‐Coltrain Christine J. T.
Published: March 2011

This paper summarises the currently available literature concerned with measurement of free volume in miscible, amorphous polymer blends using positron annihilation lifetime spectroscopy (PALS) which probes excluded volume at the angstrom level. Previously reported data is compared with new data from a range of different blend systems. Miscible blends tend to show a negative deviation of free volume size (and to a lesser degree free volume fraction) on mixing due to the intimacy of packing of the blend component macromolecules. A largely immiscible system is also reported and shows a different behaviour (positive deviation of free volume size) and this is ascribed to additional free volume at the interface.
Application of thin films of conjugated polymers in novel light‐emitting devices and liquid crystal “light‐valves”
Authors: Macdiarmid Alan G. , Avlyanov Jamshid K. , Huang Feng , Huang Zheyuan , Wang Hsing‐Lin , Wang Pen‐Cheng , Epstein Arthur J.
Published: March 2011

Light‐emitting electroluminescent diodes and electrochemically‐driven electroluminescent devices involving conjugated polymers are described. The effect on the properties of polypyrrole films (deposited from aqueous polymerizing solutions of pyrrole) caused by the hydrophilicity/hydrophobicity of the substrate surface is utilized by a “microcontact printing” technique to form patterned liquid crystal display devices.
Multifunctional polymers as multi‐role materials for photonics
Authors: Prasad Paras N. , Bhawalkar Jayant D. , Kumar N. Deepak , Lal Manjari , Cheng Ping Chen
Published: March 2011

Multifunctional polymers can play multi‐roles such as laser light source, passive interconnects, optical signal processing and optical data storage in the development of photonics technology. In this paper, two approaches to achieve nanostructure control to introduce multifunctionality at both molecular and bulk levels are presented. A novel concept of multiphasic nanostructured composites is discussed. Various applications of a specific multifunctional property introduced by strong two‐photon absorption and efficient fluorescence are presented. The combined action of these two functions produces upconverted emission. Specific applications discussed are upconversion lasing, optical data storage, confocal microscopy, and photodynamic therapy.
Electronic structures of some novel functional polymers
Authors: Yamabe Tokio , Bakhshi A. K. , Yamaguchi Yoichi , Ago Hiroki
Published: March 2011

The electronic and geometric structures of some novel donor‐acceptor polymers containing alternating electron donating group X (X=CH2, SiH2, S, O or NH) and electron accepting group Y (Y=>C=CH2, >C=O, >C=CF2 or >C=C(CN)2) along the conjugated cis‐polyacetylene backbone, obtained on the basis of the one‐dimensional tight‐binding self‐consistent field‐crystal orbital (SCF‐CO) method at the MNDO‐AMl level of approximation, are presented.
Negative cilia model for biocompatibility: Sulfonated peo‐grafted polymers and tissues
Authors: Kim Young Ha , Han Dong Keun , Park Ki Dong , Kim Soo Hyun
Published: March 2011

To improve the biocompatibility of polyurethane (PU) and bioprosthetic tissue (BT), they were chemically grafted with a hydrophilic poly(ethylene oxide) (PEO) and further negatively charged sulfonate groups (SO3) to produce PU‐PEO‐SO3 and BT‐PEO‐SO3, respectively. PU‐PEO‐SO3 was much more blood compatible than untreated PU and PU‐PEO, and the degree of surface cracking and calcification on implanted PUs was decreased in the following order: PU > PU‐PEO > PU‐PEO‐SO3. Also, less calcium deposition of BT‐PEO‐SO3 than that of BT control was observed in in vivo animal tests. Such superior blood compatibility, biostability, and anticalcification of sulfonated PEO‐grafted PUs and tissues might be attributed to synergistic effects of nonadhesive and mobile PEO and negative sulfonate acid groups via a negative cilia model.
Surface thermomechanical and glass transition temperature measurements of polymeric solids
Authors: Kajiyama Tisato , Tanaka Keiji , Takahara Atsushi
Published: March 2011

The surface molecular motion of polymeric solids was investigated on the basis of scanning force microscopic and temperature‐dependent X‐ray photoelectron spectroscopic measurements. The surface of the monodisperse polystyrene films was in a glass‐rubber transition state even at 293 K in the case of number‐average molecular weight less than ca. 30k. The surface glass transition temperature, Tgs for the symmetric poly(styrene‐block‐methyl methacrylate) diblock copolymer films were much lower than those for the bulk samples. A remarkable depression of Tg at the air‐polymer interface was explained by the surface localization of chain end groups.
Order within order: Studies of semifluorinated block copolymers
Authors: Ober C. K. , Wang J. G. , Mao G. P.
Published: March 2011

Several new semifluorinated compounds and polymers modified with these groups were synthesized and investigated. The polymer supports for these mesomorphic groups were styrene‐diene block copolymers in which the semifluorinated groups were attached to a hydroxy‐modified diene block. The characteristics of the smectic phase formed and its effect on the self‐ordering behavior of the block copolymers were examined.
Structural effects on biodegradation of aliphatic polyesters
Authors: Doi Yoshiharu , Abe Hideki
Published: March 2011

Various types of aliphatic polyesters were prepared by both biosynthetic and chemosynthetic methods, and their biodegradation tests were carried out under aerobic conditions in the river water. Biodegradabilities of polyester films were evaluated by monitoring the time‐dependent changes in the biochemical oxygen demand (BOD), weight loss (erosion) of polyester film, and dissolved organic carbon concentration (DOC) of test solution. The microbial copolyesters were degraded in the river water at a rapid rate, and the weight‐loss‐ and BOD‐biodegradabilities of the majority of biosynthetic polyesters were 100 % and 80±5 % for 28 days, respectively. In contrast, the biodegradabilities of chemosynthetic polyesters were strongly dependent of the chemical structure of monomeric units.
Potential of two‐dimensional near‐infrared correlation spectroscopy in studies of pre‐melting behavior of nylon 12
Authors: Ozaki Yukihiro , Liu Yongliang , Noda Isao
Published: March 2011

This review paper discusses the potential of generalized two‐dimensional (2D) near‐infrared (NIR) correlation spectroscopy in studies of pre‐melting behavior and hydrogen bonds of nylon 12. A 2D NIR study on dissociation and hydrogen bonds of N‐methylacetamide (NMA) is also reviewed here as a model compound study of nylon 12. Fourier transform (FT)‐NIR spectra in the region of 9000–5000 cm−1 of nylon 12 were measured over a temperature range of 30–150°C where gradual weakening of inter‐ or intramolecular associative interactions and decrease of local order leading to the eventual fusion of nylon 12 crystals are observed. The 2D correlation analysis provided the following conclusions for the pre‐melting behavior of nylon 12. (i) There are at least eight bands in the 6800–6100 cm−1 region assignable to free‐ and hydrogen‐bonded NH groups of nylon 12 in various environments. The asynchronous 2D correlation spectrum in the above region indicates that the amide groups with free carbonyl oxygen appear first and then the unassociated free amide and amide groups with free NH follow as the temperature is increased. (ii) The asynchronous spectrum in the 6000–5500 cm−1 region, where the first overtones of the CH2 stretching modes are expected to appear, indicates that substantial amount of disordered or dissociated components start appearing before the disappearance of more ordered components. It seems that they appear as the pre‐melting precursors (or even possibly as the indirect cause) to the precipitous decrease of the ordered components associated with melting of nylon 12 occurring at a much higher temperature.
Creep rate spectroscopy using a laser interferometer as ultra‐high resolution technique for study of relaxations
Authors: Peschanskaya Nina N. , Yakushev Pavel N. , Sinani Alfred B. , Bershtein Vladimir A.
Published: March 2011

An original laser‐interferometric Creep Rate Spectroscopy (CRS) method has been developed and used as the low‐frequency and high‐resolution technique for studying of microplasticity and relaxations in different materials including brittle ones. New possibilities of CRS for polymers are demonstrated.
Dispersion of normal modes in cis 1,4 polybutadiene
Authors: Wadhwani Navina , Tandon Poonam , Gupta Vishwambhar D. , Rastogi Shantanu
Published: March 2011

Among the synthetic polymers of commercial potential, poly‐butadiene is an important rubbery material and it encompasses the bulk elastomers in use. To the best of our knowledge, a complete normal coordinate analysis with full phonon dispersion curves for cis 1,4 polybutadiene (CPBD) have not been reported so far. In the present communication, we report a complete normal coordinate analysis with full dispersion curves, density‐of‐states and calculation of heat capacity. The normal coordinate analysis has been carried out using the Urey‐Bradley force field and the Wilson's GF matrix method as modified by Higgs. A comparison has been made with trans 1,4 polybutadiene (TPBD). The prominent features of the dispersion curves like crossing over and regions of zero‐slope away from the zone centre are discussed. To check the validity of the force field used and the assignments, normal mode calculations are also performed for unsaturated C‐deuterated and fully deuterated CPBD.
The diffusion of water into pet followed in‐situ using FT‐IR ATR
Authors: Sammon Christopher , Everall Neil , Yarwood Jack
Published: March 2011

The diffusion of water into PET containing a comonomer has been followed in‐situ using FT‐IR ATR. Varying degrees of crystallinity were induced into the polymer by annealing at 85°C (above the glass transition temperature). The diffusion coefficients were calculated by a least squares fit of the experimental diffusion data to theoretical sorption curves and are found to decrease with increased crystallinity. Some evidence for a crystalline ‘skin’ is discussed.
Cationic polymerization of 1,3‐pentadiene I. infrared, 1H‐NMR and 13C‐NMR investigations on the microstructure of poly(1,3‐pentadiene) synthesized with cationic catalysts
Authors: Vautrin‐Ul Christine , Pla Fernand , Petit Alain
Published: March 2011

This study deals with cationic polymerization of the cis‐ and trans‐isomers of 1,3‐pentadiene. The microstructure of the polymer chains is studied by 1H‐NMR, 13C‐NMR and IR spectroscopies. It is shown that the trans‐diene gives strictly trans‐1,4 and trans‐1,2 residual linear insaturations, whereas the cis‐isomer yields also cis‐1,4, cis‐1,2 and 3,4‐units whose overall content can reach 10 mol‐%. According to the cyclization degree of the macromolecules, ranging from 30 to 70 mol‐%, the number of trans‐(1,2+1,4) units varies between 33 to 65 mol‐% and that of trans‐1,2 units between 4 and 20 mol‐%. An analytical method is proposed to evaluate the average number of rings present in the polycyclic sequences. It is found that the cyclic fragments of the polymer chains consist of bi‐ or tri‐cyclohexane fused rings containing α tetrasubstituted double bond.
Stability under γ irradiation aging of an EPOXY/AMINE resin embedding simulated nuclear waste: Critical assessment of the techniques investigating chemical structure (IR and SIM spectroscopies) and bulk properties (DMA, DSC)
Authors: Stevenson I. , Colombini D. , Debré O. , Thomas J. P. , Romero M. A.
Published: March 2011

In order to predict the long term behaviour of materials simulating embedded nuclear waste (concentrate of evaporated radioactive effluents, mixture of anionic and cationic exchange resin), several techniques have been used:

— Infrared and HSF‐SIMS spectroscopies to investigate chemical structure: no significant differences have been observed between irradiated epoxy resin matrix samples and non‐irradiated ones. No structural modification in the materials have been evidenced but some ion exchange resin irradiated in water seem to trap chlorine while releasing their borate content.

— Dynamic mechanical analysis (DMA) to follow the irradiation effect on relaxational mechanisms. A small increase of the temperature Tα associated with the glass transition temperature for a weak total dose whereas a decrease of Tα for greater doses have been detected (these variations are however close to measurement errors).

— Differential scanning calorimetry (DSC) to follow the thermal behaviour of the γ irradiated simulated radioactive materials: DSC results agree with those obtained using DMA.
FTIR analysis of cysteic acid and cysteine‐S‐thiosulphate on untreated and bleached human hair
Authors: Signori Vittoria , Lewis David M.
Published: March 2011

Human hair was analysed by FTIR spectroscopy and single fibre analysis was achieved using an IR microscope, an ATR diamond cell was also found very useful in determining the cysteic acid content of hair tress samples. Several different data manipulations were also assessed.
Macromolecules in ordered media. 6. Effect of the phospholipidic bilayer composition on poly (2‐vinyl pyridine) ‐ liposome association
Authors: Porcar Iolanda , García Rosa , Soria Vicente , Abad Concepción , Campos Agustín
Published: March 2011

The intrinsic fluorescence emission of poly (2‐vinyl pyridine) has been exploited in order to gain insight into the nature of the interaction with artificial membranes. In this contribution, the study has been focused on the effect of the phospholipid bilayer composition on the association to the polymer. Fluorescence data have been converted into association isotherms and then analyzed in terms of both binding and partition models. Results show that the association is enhanced by the presence of negative charged phospholipid as a constituent of the liposomal membrane. The strong surface density dependence of the polymer‐liposome association indicates the predominantly electrostatic nature of that interaction.
Ordering and mobility of ferroelectric liquid crystal dimer as studied by FT‐IR spectroscopy with 2D‐IR correlation analysis
Authors: Shilov Sergej V. , Skupin Holger , Kremer Friedrich , Wittig Tobias , Zentel Rudolf
Published: March 2011

Both a conservative rapid‐scan FT‐IR technique and a novel step‐scan FT‐IR technique with 2D correlation analysis were used to study the orientation and the mobility of a ferroelectric liquid crystal dimer during switching under an electric field. The detailed mutual arrangements of different molecular segments (mesogen, poly(methylene) chain, polysiloxane chain) in a smectic C* phase were derived from the static spectra. It was shown that the long mesogen axis, the average poly(methylene) and the average polysiloxane chain axes do not coincide with each other. The hindered rotation of the carbonyl group is confirmed. Time‐resolved FT‐IR technique was used to follow the segmental motion with a time resolution of 5 μs. The temperature and electric field strength dependencies of the mobility of these segments are discussed. 2D correlation analysis of time‐resolved data reveals small differences in the behavior of the carbonyl and the benzoic rings in the mesogen moieties, that can be explained as differences in the orientation distribution functions of these moieties.
Chemical analysis of polymers using transmission electron microscopy/electron energy‐loss spectroscopy: The example of poly(ethylene terephthalate)
Authors: Varlot Karine , Martin Jean‐Michel , Quet Christian , Kihn Yolande
Published: March 2011

We have performed EELS analysis of poly (ethylene terephthalate) (PET) in the analytical TEM in order to evaluate the possibility to obtain chemical analysis of the polymer at sub‐micrometer scale. Due to irradiation damage, it revealed necessary to work at the lowest possible electron dose, typically below 103 C.m−2, and with the specimen cooled to liquid nitrogen temperature. In the acquired spectra, we propose an identification of the different chemical bondings in agreement with XANES experiments.
Small‐angle X‐ray scattering and rheological characterization of alginate gels
Authors: Stokke B. T. , Drager K. I. , Yuguchi Y. , Urakawa H. , Kajiwara K.
Published: March 2011

The wide applicability of alginates is due to the ease of which gelation can be introduced and that the gelation conditions are compatible with requirements imposed by for instance living cells. The “egg‐box” model describes the gel‐inducing ions embodied in cavities formed by sequences of α‐L‐GulA of the alginate copolymers in a pairing reaction yielding junction zones. Small‐angle X‐ray scattering showed that the cross‐sectional radius of gyration for an alginate with fraction of α‐L‐GulA, FG, = 0.39, increased from Rg,c = 3.5Å for alginate in solution to 7.6Å for homogeneous Ca‐gels at [Ca2+] = 10 mM. The homogeneous Ca‐alginate gels were obtained by in situ release of Ca2+ from Ca‐EGTA or CaCO3 using a slowly hydrolyzing lactone. Either increasing the [Ca2+] for a given FG or increasing FG by selection of an alginate from a different seaweed specie and using constant [Ca2+], yielded larger initial slopes and curvature in the cross‐sectional plots of the SAXS data. This indicate the coexistence of junction zones differing in multiplicity characterized by shifting the distribution towards larger multiplicity either for increasing FG or [Ca2+]. The present finding of junction zone formation by lateral condensation of α‐L‐GulA sequences depending on the composition of alginate and Ca‐concentration are significant extensions of the “egg‐box” model that correlate the sequential arrangement of α‐L‐GulA and β‐D‐ManA in alginate to the structure of the junction zones in the Ca‐alginate gels.
Solubilization of oligosaccharides into chloroform by their incorporation into polystyrene as pendant groups
Authors: Kobayashi Kazukiyo , Kamiya Shoko
Published: March 2011

Solubilization of hydrophilic saccharide chains into organic solvents has been attempted by incorporating saccharide‐substituted styrene unit into polystyrene main chain. Lactose‐, maltopentaose, and amylose‐substituted styrene monomers were copolymerized with styrene. Resulting chloroform‐soluble copolymers were characterized, and structural formation was investigated. Copolymers of lactose‐substituted styrene and maltopentaose‐substituted styrene with styrene were dissolved into chloroform. The chloroform‐soluble polymers contained about 12 disaccharide lactose chains or 1.7 maltopentaose chains as the pendant groups in one polystyrene molecule. Chloroform‐insoluble methyl orange was dissolved into chloroform with the help of chloroform‐soluble polystyrene having some saccharide chains. On the other hand, when an amylose‐substituted styrene unit was inserted in a polystyrene chain, the resulting polymer became insoluble into chloroform. Amylose polysaccharide of DPn = ∼24 was not dissolved into chloroform by this method.
Chemistry and biochemistry of hemicelluloses: Relationship between hemicellulose structure and enzymes required for hydrolysis
Authors: Puls Jürgen
Published: March 2011

The lignified plant cell wall is a composite material in which cellulose, hemicelluloses and lignin are in tight association. Xylans constitute the predominant hemicellulose of hardwoods and straw, wherease galactomannans represent the largest hemicellulose fraction in softwoods. Naturally occuring hemicelluloses, commercially available hemicelluloses and xylans and mannans from technical processes have distinct differences with respect to degree of polymerization and extent of branching. In principle, naturally occuring hemicelluloses carry more side chains compared to those which have been extracted with alkali or under pressure and heat. The presence or absence of substituents is also reflected by the enzymes required for complete hydrolysis. The action of the depolymerizing xylanases and mannanases may be partly dependent on debranching enzymes. Special empasis is therefore given on the substrate requirements of the so‐called accessory enzymes (i.e. α‐glucuronidase, α‐arabinosidase, α‐galactosidase, acetyl‐ and phenolic acid esterase) as well as on synergy effects with the depolymerizing enzymes.
Polymer‐solvent interaction of molecular dispersed and supramolecular structures of cellulose urethanes
Authors: Klohr Erik , Zugenmaier Peter
Published: March 2011

Investigations in dilute, semidilute and highly concentrated solutions have been carried out to characterize cellulose triphenylurethane derivatives as solute. In dilute solutions molecular dispersed chains were found with different Kuhn segment lengths depending on the solvent as well as on the placement of the substituents at the phenyl ring. Elongated, reversible clusters are formed in the semidilute concentration range and have to be considered as building blocks of the helicoidal cholesteric structure in highly concentrated solutions. Since all theoretical descriptions for the lyotropic liquid crystalline state consider the Kuhn segment length as basic quantity, it is not surprising that these theories fail to predict the isotropic‐anisotopic phase transition correctly.
Supramolecular architectures of cellulose derivatives
Authors: Schulze M. , Seufert M. , Fakirov C. , Tebbe H. , Buchholz V. , Wegner G.
Published: March 2011

Several cellulose derivatives belong to a special class of polymers called hairy‐rod macromolecules which are used to generate well‐defined supramolecular architectures by the Langmuir‐Blodgett (LB) technique. In particular trimethylsilyl cellulose (TMSC) forms monomolecular films on the Langmuir‐trough and is transferred onto hydrophobic substrates with a constant transfer ratio, as it does not undergo chemical changes in the film‐building process. Silylated celluloses was regenerated which represents a convenient method for the generation of homogeneous ultrathin films with hydrophilic surfaces. The adsorption of polymers and dyes as well as biomolecules onto regenerated and modified cellulose LB films have been studied. In addition, chemical reactions, such as cycloaddition, desilylation and crosslinking reactions within single monolayers have been performed.