bluuebunny/crossref_metadata_2025 huggingface dataset:
Demixing and polymerization in systems of anisotropic globular particles: A molecular dynamics simulation study
Authors: Brugè F. , Martorana V. , Fornili S. L. , Palma‐Vittorelli M. B.
Published: March 2011

We report a first set of results of Molecular Dynamics simulations of phase separation in a two‐dimensional system of identical particles bearing attachment sites at their surface. Morphology of regions of aggregation so obtained appear similar to images of biologically self‐assembled structures. Also, they evidence the relevance of the region of thermodynamic instability and of the presence and range of interaction of specific attachment sites. Particles of our system are apt to represent indifferently, though grossly, globular proteins or rigid cells, bearing specific and fixed adhesion sites at their surface. Results illustrate some basic aspects of the origin of the morphology of extended biomolecular/cellular structures, self‐organized from initially homogeneous solutions.
Crosslinking index, molar mass distribution and rubber equilibrium shear modulus during polyfunctional crosslinking: Part II: Application to real systems
Authors: te Nijenhuis Klaas
Published: March 2011

In a previous paper a theory was presented concerning gels formed by polyfunctional crosslinks in a polydisperse primary polymer. The equilibrium shear modulus as well as the crosslinking index were obtained as functions of the functionality of the crosslinks and of the sol fraction. In this paper the theory is applied to gelatin gels (known functionality of crosslinks) and to poly(vinyl chloride) gels (known number of crosslinks).
Boundary conditions for ionotropic gelation of polyuronides
Authors: Braudo Evgenij E. , Yuryev Vladimir P.
Published: March 2011

The determination of reagent concentrations sufficient for gelation in the course of a crosslinking reaction in solution enables characterization of macromolecular coil dimensions as a function of solvent quality and calculation of the apparent equilibrium constant and the reaction order with respect to polymer. Interactions of polyuronides with polycoordinative metal ions are discussed.
Diffusion through rubbery and glassy polymer membranes
Authors: Blume I. , Smit E. , Wessling M. , Smolders C. A.
Published: March 2011

Mass transport of a number of organic vapors through polydimethylsiloxane films (PDMS) and carbon dioxide through a variety of polyimides based on a hexafluorotetracarboxylic acid unit (6FDA) were investigated. Vapor diffusion through PDMS films strongly depends on the concentration of the penetrant molecules in the network. For chloroform, increasing diffusivity at lower upstream activities occurs due to network plasticization, while a decreasing diffusion coefficient at larger concentration is supposed to stem from penetrant molecule clustering. The diffusion of carbon dioxide in 6FDA‐based polyimides was modelled on a molecular basis. An exponential relation was found between Δcp and the diffusion coefficient and the permeability, respectively. This relation holds also for on‐chain modifications.
Self‐diffusion of azo dyes in poly(vinyl chloride) gels and solutions: Dye‐polymer interactions
Authors: Griffin William G. , Griffin Mary C. A.
Published: March 2011

Measurements of the self‐diffusion coefficients of two azo dyes in poly(vinyl chloride)/bis(2‐ethylhexyl) phthalate gels and solutions by the forced Rayleigh scattering technique are reported. The dependence of dye diffusion coefficients on polymer concentration and temperature has been determined and it is observed that both dyes seem to bind reversibly to the polymer. The energetics of dye binding are analyzed and the apparent dependence of the equilibrium dye‐binding coefficients on the polymer concentration is discussed.
X‐ray scattering studies of fatty acid films on water and on Cdcl2 solutions
Authors: Kjaer K. , Als‐Nielsen J. , Kenn R. M. , Böhm C. , Tippmann‐Krayer P. , Peterson I. R. , Bibo A. M. , Helm C. A. , Möhwald H. , Leveiller F. , Jacquemain D. , Weinbach S. , Leiserowitz L. , Deutsch M.
Published: March 2011

X‐ray diffraction methods for Langmuir films on the surface of water are briefly presented, together with recent results for docosanoic acid monolayers on pure water and for eicosanoic acid monolayers on an ionic subphase.
Fluorescence microscopy studies of layer/substrate interaction during the Langmuir‐Blodgett transfer: Fractional condensation and local layer modification in lipid monolayers at the three‐phase line
Authors: Spratte Karl , Riegler Hans
Published: March 2011

Transfer fluorescence microscopy reveals the substrate‐mediated fractional condensation and phase‐selective deposition of dipalmitoylphosphatidylcholine (DPPC) and dimyristoylphosphatidylethanolamine (DMPE) monolayers during the LB‐transfer. Preferentially the higher ordered liquid‐condensed (LC) state is transferred onto the substrate during the transfer of a monolayer in the LC/LE (liquid/expanded) coexistence state on the water subphase. This is manifested in the directly observable attraction of LC‐domains towards the three‐phase line and observation of a domain‐free gap as consequence of the segregation of the fluorescent probe into the floating monolayer adjacent to the three‐phase line. Fingering domain growth nucleating at the three‐phase line and the substrate‐mediated pressure deposition of probe‐free material corroborate the preference of the solid substrate for the higher condensed phase. These observations are caused by changes in the free energy of the monolayer due to the replacement of the aqueous interface by the solid substrate surface.
Ice nucleation by monolayers of aliphatic alcohols
Authors: Popovitz‐Biro R. , Gavish M. , Lahav M. , Leiserowitz L.
Published: March 2011

Monolayers of aliphatic long chain alcohols (CnH2n+1OH) were found to induce nucleation of ice at temperatures approaching O°C in contrast to water‐soluble alcohols which are efficient antifreeze agents. The corresponding fatty acids and alcohols with bulky hydrophobic groups, induce ice nucleation at temperatures lower by as much as 12°C. The freezing point induced by the amphiphilic alcohols was found to be sensitive not only to area per molecule but also to chain length and parity, reaching higher temperatures for monolayers with n odd. Grazing incidence X‐ray diffraction studies performed on some of these alcohols at the air/water interface (at 5°C and at zero pressure), demonstrated the formation of crystalline two‐dimensional clusters with a distorted hexagonal cell whose dimensions resemble those of hexagonal ice. The catalysis of ice nucleation by these alcohol monolayers may be rationalized in terms of the structural match between the monolayer domains and the ab layer of hexagonal ice.
A study of microgel star amphiphile monolayers
Authors: Shen Jiacong , Zhang Xi , Cha Xiao , Yin Rui
Published: March 2011

This paper reports on the synthesis of a microgel star amphiphile and on the behaviour of its monolayers both on the water surface and on solid substrates. On the water surface, the monolayer surface pressure relaxes at constant area, leading to a “duckweed”‐type structure. The hydrophilic groups play an important role in this process. On solid substrates, Langmuir‐Blodgett films can be fabricated from it with unit transfer ratio and good laminar structure.
A compact Raman microprobe/microscope: Analysis of polydiacetylene Langmuir and Langmuir‐Blodgett films
Authors: Batchelder D. N. , Cheng C. , Müller W. , Smith B. J. E.
Published: March 2011

A compact Raman microprobe/microscope has been developed which contains no wavelength dispersive elements. Multilayer dielectric filters, tuned by rotation, provide sufficient wavelength selectivity for taking Raman spectra and forming Raman images of samples as small as 1 μm in diameter. The application of the instrument is demonstrated by Raman spectra and images of polydiacetylene Langmuir and Langmuir‐Blodgett films.
Amphiphilic dyes for NLO in LB‐films
Authors: Laschewsky A. , Paulus W. , Ringsdorf H. , Lupo D. , Ottenbreit P. , Praß W. , Bubeck C. , Neher D. , Wegner G.
Published: March 2011

The influence of structural variations of phenyl‐hydrazones and stilbazium salts on monolayer behaviour and second‐harmonic generation in LB‐monolayers is discussed. In contrast to the stilbazium salts the variation of the substituents of the phenylhydrazones does not influence the absorption maximum of the dyes in resonance enhancement of the nonlinearity. This allows a direct comparison of the substitution pattern on SHG.
Thermodesorption of LB‐multilayers of metal stearates
Authors: Höhne U. , Möhwald H.
Published: March 2011

Thermodesorption of stearate multilayers containing different metal ions was investigated by Interference‐enhanced Reflection (IeR) and Nomarsky microscopy. Heating of samples in air leads to desorption of stearyl chains and to formation of metal oxide clusters.

A new approach to build controlled structures was made by preparing a surface with neighbouring hydrophobic and hydrophilic areas. It is shown that arranging inorganic particles in a predetermined way is possible.
Composition and lateral distribution of self‐assembling monolayers containing surfactant and dye
Authors: Quint P. , Möhwald H.
Published: March 2011

New methods to prepare monolayers with defined lateral distribution of the components are described. These methods make use of different principles: (1) H‐type dye aggregates in an OTS‐matrix and fatty acid domains in a NBD‐dye matrix are prepared by the self‐assembling technique. This is demonstrated by fluorescence microscopy and UV/Vis‐spectroscopy. (2) If the support is structured by photolithography, adsorption and desorption occur preferentially on one of the two types of surface. It is shown that by this method dyes can be distributed laterally with an accuracy of better than 0.5 μm.
Discotic liquid crystals at the air water interface
Authors: Karthaus Olaf , Ringsdorf Helmut , Urban Claus
Published: March 2011

The monolayer properties of two types of discotic liquid crystals, hexasubstituted triphenylenes 1 and azo derivatives of phloroglucinol 5, were examined. First investigations show that these discotic liquid crystals form stable monolayers. It could be shown that electron acceptors insert into the monolayer of 1. Azo discs display a packing behaviour at the monolayer that is ascribed to a side‐on packing of the molecules.
Mono‐ and multilayers from preformed polymers‐influence of molecular weight
Authors: Matzenbach A. , Ottenbreit P. , Prass W.
Published: March 2011

Amphiphilic homopolymers have been prepared which are able to form ordered monofilms at the gaswater interface and which can be transferred onto solid substrates. The monofilm and LB‐multilayer properties of these compounds were investigated as function of molecular weight. In monofilms a small but distinct dependence of molecular weight on the properties in the fluid phase of the monofilm was observed for molecular weights (weight average) below 70 000 dalton. In LB‐multilayers, however, no such influence could be detected.
Raman‐spectroscopy and ‐imaging with surface‐plasmon polaritons
Authors: Knobloch H. , Knoll W.
Published: March 2011

We report on surface plasmon field—enhanced Raman imaging investigations of Langmuir—Blodgett multilayer assemblies of cadmium arachidate. This new method is a combination of Plasmon surface polariton field—enhanced Raman scattering with an optical multichannel detection scheme. The imaging capabilities of a CCD—camera are used to spatially resolve the Raman—spectral information of a heterogenous sample.
A novel configuration for the optical characterization of waveguiding layers
Authors: Alberti B. , Peterson I. R.
Published: March 2011

When a transparent layer of sufficient thickness is suitably coated on both sides with metal, the structure supports one‐dimensionally bound optical modes which propagate in two dimensions but which can be detected externally in a very simple manner. We show that this configuration can be used to determine the optical constants of the layer.
Synthesis and characterization of topologically interesting vinyl polymers
Authors: Hogen‐Esch T. E. , Sundararajan J. , Toreki W.
Published: March 2011

A series of macrocyclic poly(2‐vinylpyridine)&s were synthesized by high dilution (∼10−5 M) coupling of the two‐ended living precursor dianions with 1, 2‐ and 1, 4‐bis‐(bromomethyl)benzene (1, 2‐ or 1, 4‐DBX). SEC measurements indicate that the macrocycles contain less than 5% linear precursor and that the hydrodynamic size of the macrocycles is substantially (∼30%) less than that of the linear precursor. At very low MW, the sizes of macrocyclic and linear polymers differ less, particularly for the case of the 1, 2‐DBX product. Viscometry measurements in THF of linear and macrocyclic polymers also indicated substantial size differences of linear and macrocyclic P2VP.

The values of the glass transition temperature (Tg) for both the 1, 2‐ and 1, 4‐DBX macrocycles were found to increase with decreasing MW as qualitatively predicted by entropy calculations. Thus, as the degree of polymerization decreases, the macrocyclic chains become conformationally stiffer and this is reflected by higher Tg values. The differences in Tg between linear and macrocyclic P2VP are quite large (∼40K) around a DP of 40 and decrease to values of a few degrees at a DP of around 200. These differences are diagnostically useful in estimating the linear content of the macrocycles below a DP of 100.
New polymers by homogenous zirconocene/aluminoxane catalysts
Authors: Kaminsky W. , Bark A. , Arndt M.
Published: March 2011

With homogenous catalysts on the basis of chiral metallocenes and methylaluminoxane it has become possible to polymerize cyclic olefins like cyclobutene, cyclopentene or norbornene. No ring opening reaction occurs. The crystalline polycycloalkenes show extremly high melting points between 400 and 600°C. Copolymers of cyclopentene with propene are amorphous. They have a low molecular weight and glass transition point. On the other hand the glass transition temperature of norbornene/ethene copolymers exceeds 130°C. These copolymers could be used as materials for optical discs and fibers.
Synthesis of block and graft copolymers of tetrahydrofuran and cyclic acetals
Authors: Franta Emile , Reibel Léonard
Published: March 2011

The polymerization of tetrahydrofuran under a living form allows quantitative functionalisation as well as the formation of copolymers. Cyclic acetal polymerization is more complex but through the “Activated‐Monomer Mechanism” approach, it is possible to prepare telechelic polymers as well as block and graft copolymers with particular emphasis concerning amphiphilic ones.
Living and apparently living carbocationic polymerizations
Authors: Sigwalt Pierre
Published: March 2011

Some years ago, the occurrence of living carbocationic polymerization had not generally been expected to be possible, since it is well known that most carbocationic species are quite unstable and have very short lifetimes, and since transfer to monomer had been shown to be important, particularly near room temperature. However, during the last years, many reports of living carbocationic polymerizations have been made. They were based on the observation of various features usually linked to living polymerizations, such as a linear increase of mol. wts. with conversion, sometimes even after several monomer additions, which was attributed to the absence of termination and transfer. In some cases, narrow mol. wt. distributions were also obtained.

There seems to be now a general agreement that in these polymerizations a reversible termination occurs, making eventually further growth possible on all macromolecules. Another general feature of those apparently living systems is that the ratio of propagation rate and initiation rate is not too high, so that the concentration of macromolecules is approximately equal to that of the initiator.

But the experimental data do not necessarily imply, as this has been generally assumed, that transfer is absent and that the nature of active sites is completely different from those in more classical systems. It is shown that the values of transfer constants already measured in these last ones are compatible with the results obtained in the apparently living systems. A perfectly linear relationship between number‐average degree of polymerization (D̄P̄n) and polymer yield may be observed even up to mol. wts. of about 2.104 with transfer constants ktrM/kp as high as 5.10−4 in apparently living systems. Termination and transfer might be, however, reduced in some cases by various means that are examined, such as the presence of polar additives, a lowering of temperature and the presence of excess monomer. The distinction between systems obeying all the main criteria for living polymerization and those which are only apparently living is discussed.
Exchange reactions in the living cationic polymerization of alkenes
Authors: Matyjaszewski Krzysztof , Lin Chih‐Hwa
Published: March 2011

Living cationic polymerization of alkenes is discussed in terms of rapid dynamic equilibration between carbenium ions and either covalent species or onium ions. Rates of exchange between these species have strong effect on polydispersities of the synthesized polymers. In the discussed living systems, rates of exchange are faster than rates of propagation. Propagation proceeds via classic carbocationic mechanism.
Aluminium complex of a schiffs base as new initiator for oligomerization of heterocycles
Authors: Vincens Valérie , Le Borgne Alain , Spassky Nicolas
Published: March 2011

A chiral aluminium complex of a Schiff&s base is a new initiator for the preparation of defined (number‐average degree of polymerization, functionality) oligomers derived from heterocyclic monomers (oxiranes, β‐lactones).
Emulsion polymerization of vinyl chloride, 2 potassium persulfats decomposition in the presence of PVC latex
Authors: Georgescu Cecilia‐Speranta , Sarbu Adriana , Butucea Victor
Published: March 2011

The decomposition rate of potassium persulfate (KPS) in aqueous solutions, in the presence of sodium dodecyl sulfate (SDS) and poly(vinyl chloride) latex (PVC) was studied. The dissolved SDS increases the decomposition rate constant (kd) while the SDS aggregation as micella and/or its adsorption on the polymer hydrophobic surface results in a decreasing kd. The emulsifier ‐ free surface of the polymer particles increases the decomposition rate. A reaction mechanism based on emulsifier ‐ emulsifier and emulsifier ‐ polymer hydrophobic interactions is put forward.
New functional polyamides derived from citric acid and L‐lysine: Synthesis and characterization
Authors: Boustta Mahfoud , Huguet Jovanka , Vert Michel
Published: March 2011

New functional aliphatic polyamides bearing pendant carboxylic acid and tertiary alcohol groups have been synthesized by step‐growth polymerization of protected citric acid in the diacyl chloride activated form and protected L‐lysine using the interfacial method. It has been found that a secondary reaction occurs during polymerization and leads to the formation of intramolecular imide cycles. Cleavage of protecting groups and partial or total hydrolysis of imide functions were carried out stepwisely. Resulting structural changes are discussed on the basis of IR and 13C NMR data.
Reactivity of aryl chlorides with sodium sulfide in the synthesis of aromatic polyamidethioethers
Authors: Nykolyszak Tania , Fradet Alain , Maréchal Ernest
Published: March 2011

The synthesis of aromatic copolyamidethioethers by reaction of dichlorobenzanilides with Na2S has been studied. The reactivity of chlorine atoms is strongly dependent on the nature of the substituent in para position. It is related to the 13C NMR shifts of the relative carbons‐the more deshielded, the more reactive‐and hence to charge densities, agreing with aromatic nucleophilic substitution mechanisms. The results are discussed in relation to the various mechanisms which have been put forward for the reaction of Na2S with 1, 4‐dichlorobenzene (PPS synthesis).
Polymerizability of linear or cyclic monomers under hydrostatic high pressure
Authors: Cansell F. , Fabre D. , Petitet J. P.
Published: March 2011

The behaviour of various monomers (linear, cyclic and heterocyclic) compressed in a diamond anvil cell up to 30 GPa and heated between 20 and 100°C was investigated by Raman spectroscopy. We have showed that the σ liaisons between C‐C, C‐Si, C‐H and Si‐O were stable up to 30 GPa under hydrostatic pressure conditions. On the contrary, C=C or aromatic rings can induce the formation of macromolecular compounds with original properties.
Structure‐property relations and processing of rod‐like aromatic polyamides
Authors: Hatke Wilfried , Schmidt Hans‐Werner
Published: March 2011

Homopolyamides and copolyamides with structural characteristics such as bulky lateral substituents, non‐coplanar, 2, 2′‐dimethylbiphenylene units and comonomers of different length were prepared and their structure‐property relations investigated. Polyamides with high solubilities and very low or no degree of crystallinity are obtainable by a combination of monomers with bulky lateral substituents and non‐coplanar biphenylene units. These polyamides form tough, transparent films with good mechanical and thermal properties. Lyotropic liquid crystalline behavior was found in some cases for polyamides with non‐coplanar biphenylene units. The incorporation of monomers with bulky substituents on the terephthalic acid unit lowers the chain stiffness and significantly influences the formation of lyotropic solutions.
The biopolymer bacteriorhodopsin in optical data processing
Authors: Bräuchle Ch. , Hampp N.
Published: March 2011

Bacteriorhodopsin (BR) from Halobacterium halobium [1] is embedded as a twodimensional crystalline lattice of BR‐trimers in the lipid bilayer of the cell membrane [2]. BR consists of a single polypeptide chain of 248 amino acids which is arranged in seven transmembrane α‐helices. A retinal molecule bound via a Schiff base to lysine‐216 forms the chromophoric group [3]. Under illumination BR creates a proton gradient across the cell membrane which is used by a membrane‐bound ATP‐ase for ATP synthesis [4].
Interphase compatibilization of composites with immiscible blends as matrix: Glass beads filled nylon 6 / polypropylene blend‐composite
Authors: Ishida Hatsuo , Scherbakoff Natalia
Published: March 2011

The effect of a filler on the compatibility of an immiscible Nylon 6/polypropylene blend is studied. A compatibilized system with maleic anhydride grafted polypropylene is used as a reference. Dynamic mechanical analysis, differential scanning calorimetry and scanning electron microscopy measurements are performed for these two distinct systems containing treated and non‐treated glass spheres. An improvement of the properties towards surface‐induced compatibilization is observed when the filler surface is treated with a suitable silane coupling agent. Changes in the viscosity and main relaxations of the studied system are correlated with the presence of the filler and with its surface treatment. The crystallinity, adhesion and morphology behavior supports the rheological results. In this system, the filler takes not only the usual role of reinforcing material but also a new role as modifier of the interphase structure.
Crystal‐amorphous interphases in binary semicrystalline/amorphous polymer blends
Authors: Yoon D. Y. , Ando Y. , Rojstaczer S. , Kumar S. K. , Alfonso G. C.
Published: March 2011

Crystal‐amorphous interphases in binary polymer blends that are miscible in the melts but phase separate due to crystallization of one polymer have been investigated theoretically by employing lattice models and experimentally by dielectric spectroscopy measurements. Theory predicts the extent of tight adjacent re‐entry to depend strongly on the energy Eq disfavoring the tight‐fold conformations and to increase slightly with favorable interaction energy ‐ χAB in the blends. The interfacial region of varying composition is predicted to depend strongly on χAB, with the interfacial thickness varying with the reciprocal of |χAB|1/2. Therefore, in the limit χAB → 0 the amorphous polymer, which is miscible in the melt, is predicted to be completely excluded from the interlamellar region, in agreement with experimental results. Dielectric relaxation experiments on semicrystalline blends of poly(vinylidene fluoride) (PVDF) with poly(methyl methacrylate) (PMMA) or poly(vinyl pyrrolidone) (PVP) show the existence of nearly pure PVDF interphase which is not penetrated by PMMA or PVP, despite their strongly favorable interactions with PVDF. These experimental results are discussed and compared with theoretical predictions.
“Synthetic metals”: A novel role for organic polymers
Authors: MacDiarmid Alan G. , Epstein Arthur J.
Published: March 2011

The synthesis and p‐ and n‐doping of polyacetylene, (CH)x, the prototype conducting polymer or “synthetic metal” is described together with a qualitative description of its band structure and changes in band structure on doping to yield positive and negative solitons. Other conducting polymers are briefly discussed. The polyanilines, a large class of versatile conducting polymers involving a novel non‐redox doping process, considered as being of significant commercial technological importance are discussed in particular with reference to their ease of processing. Present and future technological uses of conducting polymers are noted.
Poly(phenylene ether ketones) prepared by electrophilic polycondensation methods
Authors: Jansons Viktors , Dahl Klaus
Published: March 2011

Poly(phenylene ether ketones) were prepared by polyacylation reactions in hydrogen fluoride‐boron trifluoride and by aluminum trichloride promoted Friedel‐Crafts reactions modified by Lewis bases. Structural and engineering properties of these polymers are presented.
Development of thermotropic liquid crystalline polymers
Authors: Calundann G. W. , Charbonneau L. F. , Shepherd J. P.
Published: March 2011

Wholly aromatic, thermotropic liquid crystalline (LC) terpolyesters made from 6‐hydroxy‐2‐naphthoic acid (HNA) and 4,4′‐biphenol (BP) as key components have been prepared and evaluated for utility as high performance fiber precursors. The processability and fiber properties of a specific composition (1) made from both HNA and BP were compared with those of a more well‐known LC terpolyester made from p‐hydroxybenzoic acid, tere‐ and isophthalic acids and BP (Ekonol® type). The advantages of polymer 1 and its high‐modulus fiber are described.
Conducting polymers in redox devices and intelligent materials systems
Authors: Baughman R. H.
Published: March 2011

Applications opportunities are described for conducting polymer devices, including (1) batteries and redox capacitors, (2) electromechanical actuators, (3) electrochromic windows and displays, (4) chemical separation and chemical delivery systems, and (5) indicators and sensors. Each of these potential application areas depends upon the dramatic property changes which occur during chemical or electrochemical doping. Since the properties profiles of conducting polymers can be reversibly changed either chemically or electrochemically, these polymers also provide exciting candidates for intelligent materials systems ‐ where sensor, logic element, and actuator functions can be either partially or fully integrated. Results of device and properties investigations are used to evaluate future possibilities for conducting polymers in intelligent material systems.
Novel concepts in electronic polymers: Polyaniline and its derivatives
Authors: Epstein Arthur J. , MacDiarmid Alan G.
Published: March 2011

Polyanilines have been known for over one hundred years. Recent studies of this chemically flexible polymer have demonstrated unusual chemical, electrical, and optical phenomena, both in insulating forms and conducting forms. The polyanilines differ substantially from earlier studied polyacetylene, polythiophene, polypyrrole, polydiacetylene, and other polymers in that their electronic structure is based on the overlap of alternating nitrogen atoms and C6 rings. Two classes of the emeraldine form of polyaniline are distinguished by preparation route and crystal structure. For both classes, the Pauli susceptibility indicative of metallic state is correlated with the formation of a three‐dimensionally crystalline region. Charge conduction studies of oriented films and fibers demonstrate that three‐dimensional order between chains is critical for high conductivities. Within the crystalline regions the conduction electrons are substantially delocalized in three‐dimensions while the dc transport is dominated by quasi‐one‐dimensional variable range hopping in the disordered regions. This delocalized charge leads to high absorbance (loss) at microwave frequencies, important for a broad range of applications. The ability to derivatize polyaniline at ring and nitrogen positions allows one to test concepts for the control of conductivity as well as improved processing. The monomethyl derivative, poly(orthotoluidine), has nearly identical electronic structure and crystal structure, yet its conductivity is three orders of magnitude lower than that of emeraldine hydrochloride. This is attributed to increased interchain separation and decreased interchain correlation causing 1‐D localization. Similar 1‐D localization is observed in the self‐doped sulfonated polyaniline system. Extensive photoinduced optical studies of the insulating base forms of polyaniline show the importance of ring rotation in stabilizing photoexcited positive polarons. Long‐lived photoinduced absorptions are observed which are suggested to be a possible basis for erasable optical information storage technology.
Linear infrared dichroism by a double modulation technique
Authors: Abetz Volker , Fuller Gerald G. , Stadler Reimund
Published: March 2011

In the first part of this paper an experimental setup using Fourier‐transform infrared spectroscopy (FTIR) in combination with a photoelastic modulator (PEM) for linear dichroism measurements is described. The second part shows the influence of PEM‐amplitude and scan‐velocity on the sensitivity of the instrument. The third part deals with the fringe‐problem in the baselines of absorbance spectra and its influence on the determination of the linear dichroic ratio.
Application of infrared and Raman microspectroscopy to the study of polymeric materials
Authors: Pastor José M.
Published: March 2011

Microspectroscopic techniques have been developed to analyze vibrational spectra with high spatial resolution. Technical characteristics of Raman and infrared microspectroscopies are discussed and some of the main spectroscopic investigations on polymeric materials are described.
Infrared spectroscopy on new multiphase thermoplastic elastomers based on hydrogen bond complexes ‐ temperature dependence and orientation behaviour
Authors: Abetz Volker , Hilger Christopher , Stadler Reimund
Published: March 2011

The structure and deformation behaviour of a new class of thermoplastic elastomers is studied by temperature dependent infrared (IR) spectroscopy and by IR ‐ dichroism spectroscopy. The thermoplastic elastomer is based on polybutadiene with statistically distributed side groups which form an anisotropic supramolecular structure via hydrogen bonds. Changes in the IR spectra at elevated temperatures are related to the melting of the ordered structure. The uniaxial deformation behaviour is studied by linear dichroism Fourier‐transform (FT)‐IR spectroscopy. A deformation model is developed which accounts for the major experimental results: while the polybutadiene segments behave as flexible chains with characteristic rubberlike elasticity the polar units within the supramolecular structure show an orientation behaviour characteristic for rodlike molecules.
HPLC‐FTIR identification of reactive diluents in epoxy resins
Authors: Meyer Ulrich , Salzer Reiner , Raddatz Joachim
Published: March 2011

This report compares two types of interfaces for HPLC–FTIR, an on–line and an off–line system. The on–line system consists of a flow cell and an IR beam condenser. In the off–line system, the diffuse reflectance of the solute is measured after evaporation of the solvent. Both systems have been compared with regard to detection and identification limits of the solute.

Normal phase HPLC provided the best conditions to identify less concentrated components by FTIR detection.

Reactive diluents of aromatic or aliphatic structure have been identified in epoxy resins of low and medium molecular weight.

The identification limit for off–line detection is at least one order of magnitude below the limit for on‐line detection.
Ion conduction in polymer electrolytes comprising crown ether and AZA‐crown structures
Authors: Cowie J.M.G.
Published: March 2011

Ion conduction, in solid solutions of salts mixed with comb‐branch polymers with oligo(ethylene oxide) side chains, has been shown to reach levels that can be of practical use in dry battery applications. Further improvements in conductivity levels may require the discovery of polymer electrolytes capable of inducing greater degrees of ionization of the salt. New systems containing crown ether and aza‐crown units have been synthesised and a preliminary assessment of some of these has been carried out. The results are compared with those obtained with the linear side chain analogues, and are sufficiently encouraging to merit further study.
The characterization of polymer deformation by rheo‐optical fourier‐transform infrared spectroscopy
Authors: Siesler H. W.
Published: March 2011

The mechanical properties of polymeric materials are of considerable importance to their engineering applications. Apart from the chemical structure and the thermal history, molecular orientation has a major influence on the mechanical properties of a polymer. The increased need for more detailed data and a better understanding of the mechanisms involved in polymer deformation has led to the search for new experimental techniques to characterize transient structural changes during mechanical processes. With the advent of rapid‐scanning Fourier ‐ transform infrared (FTIR) spectroscopy, simultaneous vibrational spectroscopic and mechanical (so‐called rheo‐optical) measurements during the deformation of polymers have emerged as a very informative probe for the study of deformation and relaxation phenomena in polymer films in the late seventies and have since then been applied to obtain data on strain‐induced crystallization and orientational and conformational changes during mechanical treatment of a wide variety of polymers.
Free radical entry in emulsion polymerizations
Authors: Maxwell Ian A. , Morrison Bradley R , Gilbert Robert G , Sangster David F , Napper Donald H
Published: March 2011

Measurements of the rate coefficients characterising the entry of free radicals into seed particles in styrene emulsion polymerizations has allowed the rate determining step for entry to be identified. This was found to be the rate of production of oligomeric species in the aqueous phase by monomer addition to the primary free radicals. Once formed the subsequent diffusion of these species to the latex particles (and their incorporation within these particles) is relatively fast, contrary to the assumptions of the previous diffusion controlled theories. The experimental results imply that the entering free radicals contain only two or three monomer units. Thermodynamic considerations show that such species should be both water soluble and surface active. Similar conclusions have been reached for other sparingly water soluble monomers, such as butyl acrylate and butyl methacrylate.
Molecular architecture control in acrylic polymers by group transfer polymerization
Authors: Webster Owen W.
Published: March 2011

The living polymerization of methacrylates by a repeated silyl Michael addition reaction (GTP)a operates at room temperature and permits a high degree of molecular architecture control. Chelic, telechelic, block, comb, star, loop, and ladder polymers have been synthesized. For nucleophilic catalysts other than bifluoride, a dissociative mechanism is now proposed.
Photophysics of vinyl aromatic polymers
Authors: Ghiggino Kenneth P.
Published: March 2011

The experimental approaches required to characterize energy migration and excimer formation in vinyl aromatic polymers are considered. As an example the photophysical processes occurring in poly(acenaphthylene) (PACE) and water soluble acenaphthylene copolymers have been investigated using steady state and time resolved fluorescence spectroscopy. Excimer formation in these polymers is determined by both structural and dynamic factors. The difficulties in the application of fluorescence decay analyses to examine energy migration in polymers are discussed. For PACE with a 9‐methylanthryl (9MA) end‐group and the copolymers containing solubilized 9MA, energy migration and transfer can be demonstrated.
Viscoelastic properties of polymers: From molecular models to non‐linear behavior
Authors: Marin G. , Benallal A.
Published: March 2011

The molecular models of polymer physics (reptation, tube renewal) give a reasonable picture of the diffusion and relaxation of long and flexible chains: the concept of “tube renewal” (constraint release) added to the reptation idea explains the polydispersity effects for multimodal blends as well as for commercial linear polymers. The real issue now is to introduce these concepts in the formalism of non‐linear viscoelasticity in order to explain the experimental data, as a first step in the range of moderate rates of deformation, then at very high strains.
Transient rheological behaviour of melts of liquid‐crystalline polymers compared with that of flexible polymer melts
Authors: Booij H. C. , Palmen J.H.M.
Published: March 2011

Transient rheological behaviour of melts of flexible polymers can be described qualitatively by factorable constitutive equations, the functions of which can be obtained by oscillatory and step strain experiments. In start‐up experiments thermotropic LCP melts can exhibit very large overshoots of the stresses, followed by minima, after which steady states are reached through damped oscillations of the signals. It is also possible that the normal stress remains periodic for long times, with large amplitudes, as is shown for a nematic copolyester melt that has been squeezed during the gap setting process. These periodicities scale with the number of revolutions of the rotating plate. After cessation of flow the stresses relax quickly to values that may be unequal to zero and dependent on the position in the period of the stresses where flow is stopped. Dynamic experiments reveal that the melts are very elastic in that state.
Chain conformation in polymer melts during flow as measured by small angle neutron scattering
Authors: Muller R. , Picot C.
Published: March 2011

The anisotropic form factor of polystyrene (PS) chains during tensile and simple shear flows in the melt has been measured by small angle neutron scattering (SANS) on quenched samples containing deuterium labeled chains. For all tensile experiments, carried out in a wide range of strain rates, including linear viscoelastic behaviour, the chain conformation is well predicted by a temporary network model involving the recoverable strain. For binary blends of two PS with different molecular weight, the technique allows to characterize the chain conformation of either species. The scattering patterns of sheared samples show that the principal directions of molecular orientation depend on the magnitude of the scattering vector q: At high q (local level on the chain) the orientation is close to 45° with respect to the shear axis, whereas at low q the chains appear to be almost aligned with the stream lines.
Shear flow characterization of blends containing liquid crystal polymers
Authors: La Mantia Francesco Paolo , Valenza Antonino
Published: March 2011

A simple phenomenological approach is proposed in order to predict the presence of minima in the viscosity‐composition curves of blends of thermoplastic with liquid crystal polymer (LCP). When the viscosity of the liquid crystal polymer is larger than that of the thermoplastic matrix, a minimum is observed. A possible explanation of the presence of yield stress in the flow curves of these blends is also given.
Possibilities and limits of pyrolysis
Authors: Kaminsky W.
Published: March 2011

In the public and administration the acceptance for landfilling or incineration of plastic wastes is decreasing. By pyrolysis it is possible to recover hydrocarbons from polymers. Rotary kilns and fluidized bed processes are investigated as processes. As yet, no process has come to an industrial stage. The fact that more plastic wastes will be collected in the future gives a chance for building plants with higher capacity which will be working more economically. Mechanical problems with feed and output could be solved.
Chemical changes in engineering thermoplastics
Authors: Bolon Donald A. , Irwin Patricia C.
Published: March 2011

Parts molded from reground BPA polycarbonate (PC) resin recovered from used objects do not always give the desired physical properties as parts molded from virgin resin. This loss of properties appears due to a surface hydrolysis of the PC which results in a reduction in molecular weight and formation of bis‐phenol‐A (BPA). The hydrolysis appears to be aided by exposure to uv‐light and humidity. If the surface of the PC is washed with caustic solution, BPA and low MW oligomers are removed and many of the physical properties of the PC are restored.
Recycling of PVC floor coverings; first results after one year of practice
Authors: Bonau Hugo
Published: March 2011

Since the end of 1990, the “Arbeitsqemeinschaft PVC Bodenbelags Recycling (Society for the recycling of PVC floorings, AgPR)” collects and recycles PVC floor coverings in Germany. AgPR is an activity as well of PVC producers as of PVC floor covering manufacturers. 19 European companies participate in this venture. AgPR collects used floorings in several areas of Germany. It also pays 150 DM/t of PVC flooring delivered to its recycling plant in Großefehn. This plant has a capacity for recycling 5000 t/a. The used floor coverings are comminuted, ground to powder size and after that reused to manufacture new floor coverings.
Recycling of poly(ethylene terephthalate) (PET)
Authors: De Winter W. , Mariën A. , Heirbaut W. , Verheijen J.
Published: March 2011

After a survey of the mostly utilized recycling methods for fibres and bottles, the possibilities of recovering films are discussed in more detail. This presentation describes primarily the melt‐recovery method, which is used by us and by other manufacturers. During this process the greatest difficulties arise from the presence of impurities and contaminations. The influence of these determining parameters on the recycling process and on the re‐usability of the recovered PET are elucidated, with special emphasis on the role of the oligomers.
Compatibilization and impact modification of mixed recycled plastics
Authors: Scobbo James J.
Published: March 2011

In order to solve the problems related to the reuse and recycling of polymer materials, approaches must be developed to address the incompatibility of most plastics. In many cases, the complete separation of dissimilar plastics may not be economically feasible or technologically possible, so commingled plastics recycling may be the only option. Our work has concentrated on upgrading the performance of a blend of two incompatible polymers. For this, we have used a model composition of two plastics commonly found in business machine housings. Our approach concentrates on compatibilization of the blend with a tailored copolymer, in addition to impact modification of the different phases. Improvements in mechanical performance of the blends are elucidated through the use of transmission electron microscopy.
Use of compatibilizers in polymer blends
Authors: Boutevin Bernard , Pietrasanta Yves , Robin Jean‐Jacques , Pabiot José , Leseur Benoit
Published: March 2011

Among the different ways of recycling plastic wastes, one of the techniques used consists in processing these products without any preliminary separation of the different plastic families. The bad performances of the obtained materials lead to the use of emulsifiers. The work described in this study concerns the synthesis of emulsifiers prepared by chemical modification of polymers with ozone. This reaction produces the formation of peroxides which are then used to initiate the grafting of comonomers. According to this method, we obtain graft copolymers usable as emulsifiers in the elaboration of polymer blends. Those graft copolymers prepared according to this method improve mechanical performances of polymer blends.
Block copolymer micelles in aqueous media
Authors: Munk P. , Ramireddy C. , Tian M. , Webber S. E. , Procházka K. , Tuzar Z.
Published: March 2011

Polystyrene‐block‐poly(methacrylic acid) and poly(methacrylic acid)‐block‐polystyrene‐block‐poly(methacrylic acid) di‐ and triblock copolymers form micelles with polystyrene cores and poly(methacrylic acid) shells when dissolved in water/1, 4‐dioxane mixtures, rich in dioxane. These micelles can be transferred into water rich mixtures, into water, and into aqueous buffers by stepwise dialysis. Quasielastic light scattering and sedimentation velocity experiments show that in dioxane rich mixtures exists a dynamic micellization equilibrium, while in dioxane poor solutions and in aqueous buffers the equilibrium is frozen. The process of mixed micelles formation was observed in dioxane rich solutions.
New synthesis of polyaromatics through oxidative polymerization by using metal complexes with air
Authors: Tsuchida Eishun , Yamamoto Kimihisa , Nishide Hiroyuki
Published: March 2011

The oxidative polymerization provides a new synthetic route to polyaromatics. Poly(p‐phenylene sulfide) (PPS) is produced by oxidative polymerization of thiophenol with a vanadyl complex catalyst. The metal complexes act as an efficient catalyst of oxygen oxidative polymerization. The polymerization to yield PPS is discussed especially focusing on the catalytic mechanism of the complexes.
Hydroformylation of vinyl acetate to α‐acetoxypropanal catalyzed by a silica‐supported polyalumazane‐rhodium complex
Authors: Guan Shi‐You , Huang Mei‐Yu , Jiang Ying‐Yan
Published: March 2011

Hydroformylation of vinyl acetate was catalyzed by silica‐supported polyalumazane‐rhodium complex to give α‐acetoxypropanal in higher than 90% yield. The product was only α‐acetoxypropanal, isoaldehyde, and no β‐acetoxypropanal, normal aldehyde, or any other by‐product was observed. The catalyst was very stable in the hydroformylation, and it could be reused several times without any remarkable change of catalytic activity.
Activation and copolymerization of CO2 by macromolecule‐metal complexes
Authors: Chen Li‐Ban
Published: March 2011

The activation of CO2 and relevant comonomers can be promoted by using catalysts consisting of appropriate chelating polymers, suitable bimetallic combinations, and prepared by appropriate procedures. In this way, aliphatic polycarbonates, polycarbonate‐polyurethanes, saturated and unsaturated polycarbonate‐polyesters, as well as some other copolymers were synthesized in high yields.
Effects of chemical modification of supports on properties of tertiary amino resin dispersed palladium catalysts for the hydrogenation of methyl acrylate
Authors: Chen Chunfu , Sun Juntan , Li Hong , He Binglin
Published: March 2011

Tertiary amino resins (TAR) were chemically modified by quaternization with methyl iodide. By this route six partly quaternized tertiary amino resins (PQTAR) with different I/N mole ratio were synthesized. Four different reducing agents, i.e., NaH, LiAlH4, CH3OH‐NaOH and NaBH4, were tested for the preparation of palladium catalysts dispersed on TAR or PQTAR. The rate of hydrogenation of methyl acrylate and the amount of Pd leached from the catalysts during the hydrogenation reaction were found to be dependent not only on the type of reducing agent but also on the structure of polymer support. Both the rate of hydrogenation and the amount of Pd eluted closely relate to the I/N mole ratio of the polymer supports.