bluuebunny/crossref_metadata_2025 huggingface dataset:
Theoretical investigations on the cationic propagation of vinyl monomers
Authors: Hallpap P. , Bölke M. , Heublein G. , Weiss C.
Published: March 2011

Experimental investigations for elucidation and description of the complex mechanism of cationic polymerization can be confirmed, completed and deepened by quantum chemical model calculations. This is shown by means of calculations with CNDO/2– and MINDO/3–method considering solvent influence. The problems dealt with here are stability of counterions and cationic chain ends, potential energy surface of a cationic propagation step in the gas phase and in solution, the solvent effect on both reactions in competition with cationic propagation and on cationic copolymerization.
Verification of transfer‐suppressed cationic polymerization of vinyl monomers
Authors: Heublein O. , Spange S.
Published: March 2011

A general approach to a transfer‐suppressed proceeding of cationic vinyl polymerization is put forward. The fundamental principle of the method consists in stabilization of the counter‐ion by interaction with acceptors. This results in an orbital controlled cation‐anion interaction and by this, suppression of side reactions, for example chain transfer due to lowering the ß‐hydrogen acidity of the growing cation and the specific monomer solvation of the propagation transition state.

It is shown that picric acid, initiated polymerization of p‐methoxyatyrene and vinyl ethers, runs free of transfer in contrast to LEWIS‐acid initiated systems. Cationic polymerization, initiated by iodine based systems, are in the same category as demonstrated by molecular weight distributions, monomer addition experiments, thermokinetical data and UV‐spectroscopical measurements. The results are discussed in the framework of a general energetic scheme of propagation via cation‐anion orbital controlled interactions with propagating ion pairs.
Cationic polymerization by cyclic halonium ions I. The 2,5‐dimethylhexane/Bcl3/isobutylene system
Authors: Biswas Mukul , Kennedy Joseph P.
Published: March 2011

Aged 2,5‐dichloro‐2,5‐dimethylhexane (DDH)/BCl3 mixtures readily initiate the polymerization of isobutylene in CH2Cl2 at −35°C and yield asymmetric telechelic polyisobutylenes in the liquid range with narrow molecular weight distributions (Mw/Mn < 2.0). Kinetic studies indicate that chain transfer monomer is absent and DDH is not a chain transfer agent (i.e., inifer). According to results of model experiments, 1H and 13C NMR spectroscopy, chlorine‐content, dehydrochlorination, and IR studies, the structure of the head group of the polyisobutylene product is Cl(CH3) 2CH2CH2C(CH3)2‐and that of the tail group is ‐CH2C(CH3)2Cl. In line with the results of kinetic investigations and structure characterization studies it is postulated that the initiating cation is a cyclic chloronium ion formed from the DDH during aging in the presence of BCl3: magnified image
Activated monomer propagation in cationic polymerizations
Authors: Penczek Stanislaw , Kubisa Przemyslaw , Szymański Ryszard
Published: March 2011

New mechanism of cationic polymerization of cyclic ethers and acetals consisting in the activated (e.g. protonated) monomer addition to the electrically neutral macromolecule e.g.: magnified image

is discussed. It is shown, that when the ‐OH in the tail‐group is more nucleophilic than monomer itself this mechanism has chances to dominate over the traditional mechanism of propagation, involving tertiary oxonium ion.

Kinetics of the polymerization process, elementary reactions, competition with the tertiary oxonium ion growth are discussed. Examples are given, based on the work on ethylene oxide and epichlorohydrin polymerization, showing how to apply the theory of the activated monomer in order to avoid side reactions, namely cyclization and disproportionation of the chains.
Polymerization of N‐substituted lactams
Authors: Puffr Rudolf , Sebenda Jan
Published: March 2011

This study deals with a comparison of the rates and activation parameters of the polymerizations of N‐methyl and N‐benzoyl derivatives of lactams containing 4, 9 or 13 ring atoms initiated by carboxylic acids, amino acids, strong protonic acids or Lewis acids. The respective polymerization mechanisms of substituted and unsubstituted lactams are discussed. The initiators mentioned above lead to the polymerization mechanisms with activated monomer in most cases. The use of stable carbenium cations results in a new type of polymerization of N‐benzoyl lactams with a cationic propagation centre on the chain.
Sterically controlled propagation in the cationic ring‐opening polymerization of bicyclic acetals
Authors: Sumitomo Hiroshi , Okada Masahiko
Published: March 2011

This paper deals with sterically controlled propagation in the cationic ring‐opening polymerization of bicyclic acetals in relation to the chemical synthesis of structurally regulated polysaccharides, particularly focusing on the following two topics:

1) Chemical synthesis of (1→6)‐β‐linked polysaccharides by the ring‐opening polymerization of 1,6‐anhydrosugar derivatives. 2) Asymmetric selective copolymerization of racemic bicyclic acetal with optically active monomer.
Polymerization of ethylene with supported zirconium organic compounds
Authors: Ulbricht Joachim , Giesemann Jürgen
Published: March 2011

The polymerization of ethylene was studied with supported catalysts prepared by the reaction of Zr(benzyl)4 and Al2O3. The influence of the preparation of the catalysts and the reaction conditions on the overall rate of the polymerization was established. The rate exhibits a maximum which depends on the thermal pretreatment of the support and the quantity of the fixed Zr(benzyl)4. The concentration of the active centres of the catalysts was determined by quenching the polymerization with labelled butanol. The catalysts possess active centres which have different rates of propagation for ethylene. The decrease of the polymerization rate is caused by chemical reaction. The higher the concentration of free hydroxyl groups on the catalyst, the higher the rate of deactivation. Hydrogen in the monomer feed produces a decrease or an increase of the polymerization rate depending on the preparation of the catalysts.
Elastomers by atactic linkage of α‐olefins using soluble Ziegler catalysts
Authors: Kaminsky W. , Schlobohm M.
Published: March 2011

With bis (cyclopentadienyl) zirconiumIV‐compounds and methylalumoxane as soluble Ziegler catalyst propylene can be polymerized to pure atactic polypropylene with molecular weights up to 600 000. The copolymerization of ethylene and propylene or butene gives elastomers with different properties. The butene units are distributed at random in the polyethylene chain as carried out by 13C NMR measurements. The regiospecifity of the catalyst leads exclusively to the formation of head‐to‐tail enchainments. Using ethylene together with propylene and diolefins, EPDM rubber is formed. Glass transition temperatures of ‐60 to ‐50 °C could be observed.
Vinyl polymers with pending fluoranthene groups and their charge transfer behavior
Authors: Pfänder Rudolf , Höcker Hartwig
Published: March 2011

In the present paper the preparation of vinyl monomers with pending fluoranthene groups and different spacer length, their radical polymerization and their electron donor acceptor (EDA) complex formation with tetracyanoquinodimethane, tetracyanoethylene and SbCl5are studied. EDA complexes with a spacer length of 3 methylene groups are particularly favored. The electrical conductivity of the complexes as well as of radical cation salts of the polymers generated by anodic oxidation (formation of dark foils) is low (10−5S/cm) and the ESR signal is very broad ‐ indicating trapped electrons ‐ in contrast to highly crystalline low molecular weight fluoranthene radical cation salts.
The influence of matrix structure on the activity and selectivity of polymer supported catalysts
Authors: Widdecke H. , Klein J. , Haupt U.
Published: March 2011

The influence of the pore structure, surface area, crosslinking density and the distribution of catalytic groups on the activity / selectivity of polymer supported catalysts was investigated. As model catalysts a variety of styrene‐divinylbenzene‐copolymers functionalized with sulfonic acid groups were used. The isomerization of 1‐butene and the cleavage of methyl tert ‐ butyl ether (MTBE) were studied as gas phase reactions in the presence of the acid resins. The activity and selectivity was controlled by the acidity and accessibility of the polymer supported catalyst.
States of molecular assembly and physical properties of crystalline long‐chain compounds studied by vibrational spectroscopy
Authors: Kobayashi Masamichi , Kobayashi Tohru , Cho Yonghae , Kaneko Fumitoshi
Published: March 2011

Various types of molecular assembly of long‐chain compounds in solid states were investigated by means of infrared absorption, Raman and Brillouin spectroscopic methods. As for the polymorphism in even‐numbered n‐fatty acids, three monoclinic modifications, B, C, and E, all consisting of the orthorhombic polyethylene sublattice, give rise to their characteristic infrared and Raman spectra. A dynamical equilibrium between cis and trans conformations of the hydrogen‐bonded carboxyl groups in modification C, which is related to the high‐temperature stable character of this phase, is reflected to a dramatic change with temperature in the low‐frequency Raman spectra. A new type of reversible solid state phase transition was found between two A‐type (triclinic) modifications of myristic, palmitic, and stearic acids. The γ→α phase transition of oleic acid was found to be caused by a conformational disordering of polymethylene chains at the lamellar interfacial region.

Two basic polytype structures, Mon and Orth II, of stearic acid B were investigated, and it was found that the low‐frequency phonon frequencies (below 50 cm−1) were strongly influenced by the polytype structure. Based on the spectroscopic considerations, Orth II was predicted as the thermodynamically stable phase around room temperature compared with Mon, and the stability is responsible for the vibrational free energy term. Some experimental findings which support this prediction were obtained. The values of the stiffness tensor elements of Mon and Orth II, measured by Brillouin scattering, indicate that the mechanical behavior of bulk crystals is very dependent on the polytype structure.

The relationship between the mobility of chain molecules and the width of the spectral bands was investigated in a quantitative manner for the case of n‐alkane molecules entrapped in the urea inclusion adducts. The changes in the half‐width for the polarization components of various Raman bands on the transition from the orthorhombic to the hexagonal phase are interpreted in terms of the correlation functions of the Raman tensor related to the rotational motion of the alkane molecules around the chain axes.
Hydrogen bonding in polymers: III further infrared temperature studies of polyamides
Authors: Coleman Michael M. , Skrovanek Daniel J. , Painter Paul C.
Published: March 2011

Fourier transform infrared temperature studies of two semi‐crystalline polyamides, nylon 12 and a terpolymer of nylon 6/66/610 are presented. The results obtained are consistent with those recently published from similar studies of an amorphous polyamide and nylon 11 and further bolster our general interpretation of the infrared spectra of polyamides.
Characterization of Kevlar fiber surfaces using a newly developed infrared photoacoustic technique
Authors: Chatzi E. G. , Urban M. W. , Koenig J. L.
Published: March 2011

A newly developed infrared photoacoustic technique has been used to obtain information about the orientation of the surface functional groups of Kevlar‐49R fibers. This method involves the use of a highly polarizable gas in the photoacoustic cell and comparison of the spectra with a non‐polarizable coupling gas. A highly polarizable inert gas, xenon, enhances the surface modes oriented parallel to the surface and suppresses the intensity of the perpendicular modes. This method shows differences in the structure of the skin and the core of the fibers. The polymer chains in the skin are oriented parallel to the surface, and in the core they are almost radially oriented.
Computer‐supported infrared spectrometry of polyethylene, ethene copolymers, and amorphous poly(alkyl ethylene)s
Authors: Solti Agnes , Hummel Dieter O. , Simak Peter
Published: March 2011

The advent of computer‐supported IR spectrometers, especially Fourier‐transform IR interferometers, made possible considerable progress in the fine‐structure elucidation of the seemingly well‐known polyethylene and ethene copolymers. This paper gives a review on the results obtained in several laboratories in the following fields: identification of side‐groups and olefinic structures, characterization of ethene homo‐ and copolymers made with different catalysts, by spectral enhancement, difference and derivative spectroscopy, and measurements of the dichroism of oriented samples. In one chapter, recent results with amorphous poly(alkyl ethylene)s obtained with a modified Phillips catalyst are reported.
Electronic spectra of dilute solutions of cationic and radicalic poly (n‐vinylcarbazole)
Authors: Klöpffer Walter , Rippen Gerd , Kowal Joanna
Published: March 2011

Fluorescence spectra of liquid solutions of PVCA are dominated by two kinds of excimer emission which are characteristic for the mode of preparation of the polymer. Luminescence spectra of solid solutions are more monomer‐like, indicating shallow exciton traps. Substantial hypochromic effects are reported for the two lowest energy singlet transitions of PVCA. No significant difference could be observed for PVCA samples of cationic and radicalic origin.

Note a ‐ Presented in part at the EUROANALYSIS V European Conference on Analytical Chemistry, Kraków, August 1984
Ordnungszustände im system polyamid‐6 und polyamid‐6, 6
Authors: Keil Wolfgang , Trafara Gundolf
Published: March 2011

Blends of PA‐6 and PA‐6,6 were studied by DSC for different conditions of crystallization. All samples were characterized by x‐ray diffraction. From dilute solution the components crystallize in separate modifications. In the melt both components are compatible. PA‐6‐ and PA‐6,6‐segments are linked together. During rapid quenching of the melt in the samples of about equal composition of PA‐6 and PA‐6,6 a modification is formed possibly built by a three‐dimensional network of hydrogen bonds between PA‐6‐ and PA‐6,6‐segments. If the samples of the same composition are annealed at 25 K below the melting temperatures of PA‐6 and PA‐6,6 for 3 hours in each case a modification appears as in quenched samples in addition to only partially ordered crystallites of PA‐6 and PA‐6,6. Despite optimal annealing there is no complete separation of the components.
Sterically controlled cationic propagation in the ring‐opening polymerization of bicyclic acetals and bicyclic oxalactones
Authors: Sumitomo Hiroshi , Okada Masahiko
Published: March 2011

Sterically controlled cationic propagation in the ring‐opening polymerization of bicyclic acetals, which is important and attractive in relation to the chemical synthesis of structurally defined polysaccharides, involves a selective cleavage of acetal bonds, configurational changes of the asymmetrical acetal carbons, and the enantiomer selection at the chiral growing chain end.

Also in the polymerization of a bicyclic oxalactone having bicyclo[3.2.1]octane skeleton resulting peculiarly in the selective formation of macrolides of specific ring sizes, the exclusive bond scission accompanied by the inversion of the configuration of the acetal carbon takes place, and, as a result, sequences of four or five consecutive monomer units of the same chirality form at a growing chain end. Optically pure cyclic tetramer and cyclic pentamer (20‐ and 25‐membered macrolides, respectively) were prepared by the oligomerization of a monomer mixture of 36 % optical purity under the reaction conditions where racemic monomer gave racemic cyclic dimer highly selectively, whereas optically active monomer afforded cyclic tetramer and cyclic pentamer, respectively.

Ring‐opening polymerization of another two kinds of newly synthesized bicyclic lactones having bicyclo[2.2.2]octane skeleton was conducted by the use of cationic, anionic, and coordinated initiators. From 1H and 13C NMR analysis of the resulting polyesters and comparison of the spectra with those of model compounds, the mechanism of polymerization, together with the polymerization reactivity of the monomers, is discussed.
Ring opening polymerization of cycloolefins by means of metathesis catalyst: Kinetic and thermodynamic effects on the product distribution
Authors: Höcker Hartwig
Published: March 2011

The metathesis reaction of cycloolefins is a ring‐opening polymerization with a metallacyclobutane system as the key intermediate. A kinetically and a thermodynamically controlled regime of the reaction clearly can be distinguished, the latter being characterized by a ring‐chain equilibrium.
Telechelic polymers by cationic ring‐opening polymerization
Authors: Goethals Eric J.
Published: March 2011

By means of cationic ring‐opening polymerization a wide variety of telechelic polymers can be prepared. After a general description of the chemistry of this kind of polymerization, the introduction of functional end groups by initiation, by end capping and by transfer reactions is described. The following monomers, which have successfully been used to produce telechelics by cationic mechanisms, are discussed: tetrahydrofuran, various epoxides, cyclic acetals and cyclic amines, cyclosiloxanes.
Polymerization of phosphorus containing cyclic monomers: Synthesis of polymers related to biopolymers
Authors: Penczek Stanislaw , Biela Tadeusz , Klosinski Pawel , Lapienis Grzegorz
Published: March 2011

The mechanism of polymerization is discussed, in which cyclic esters of phosphoric acid, and related compounds are converted into linear macromolecules, modelling nucleic and teichoic acid backbones. Structures like deoxyribose polyphosphate and glycerol polyphosphate were prepared from the corresponding cyclic compounds.

These polymerizations involve heterolytic breaking of the P‐O bond in the cyclic monomer and proceed by ionic mechanism. Both 5‐ and 6‐membered monomers have been polymerized. The thermodynamic parameters of the ring‐chain interconversion were determined; the 5‐membered rings polymerization is driven by the exothermicity of the ring‐opening, whereas polymerization of several 6‐membered rings is endothermic and allowed because of the positive change of entropy.

Anionic polymerization, and particularly the pseudo(coordinate)anionic polymerization provides, in contrast to the cationic process, high‐molecular‐weight polymers with more uniform structure. Anionic polymerization proceeds mostly (at the applied conditions) on the macroion – ‐pairs. The elementary reactions consist of the nucleophilic attack of the paired macroanions on the phosphorus atom in the cyclic monomer molecule. Rate constants of the elementary reactions for the model monomers will be presented.

Stereochemistry of the propagation steps is shown to be governed by the statistical ring‐opening, leading to the three kinds of polymer units (head‐to‐tail and two symmetrical units).

Apart from the ring‐opening, the polyaddition of diepoxides to phosphorous and phosphoric acids is described.

Finally, a few examples of preparation of models of biopolymers are given, namely poly(deoxyribose phosphate) and poly(glycerol phosphate).
Physical properties of polyesters prepared from β‐lactones
Authors: Prud'Homme Robert E.
Published: March 2011

Polyesters derived from substituted β‐propiolactones exhibit a wide variety of physical properties depending upon the number, nature and position of their substituents. Their properties can be changed even more by preparing atactic and isotactic polyesters, and polyesters with intermediate degrees of isotacticity. Moreover, the isotactic polyesters with opposite configurations form stereocomplexes with unique properties.
Kinetics and mechanism of epoxy oligomers curing
Authors: Rosenberg B. A.
Published: March 2011

A review of new results concerning kinetics, thermodynamics and mechanism of epoxy oligomers curing with various nucleophilic agents (amines, phenols, carboxylic acids) has been made. The concept of the mechanism of such reactions is formulated on the basis of this study. Kinetic data obtained are interpreted within the framework of cyclic transition state. The addition of nucleophilic agent to epoxy ring is rather complicated. It results from preliminary formation of homo‐ and heteroassociates of reaction system components which finally form reactive cyclic heteroassociates. Reaction products are formed as a result of monomolecular rearrangement with synchronous transfer of electrons in the reactive cyclic heteroassociates.
Conformational properties of polyhydroxyethers
Authors: Burchard W. , Bantle S. , Wachenfeld‐Eisele E.
Published: March 2011

The conformation of four types of polyhydroxyethers and one amine‐cured triglycidyl isocyanurate resin were studied. Static and dynamic light scattering as well as small angle neutron scattering revealed a scarcely detectable influence of branching on the overall dimensions. The branching density has, however, a very pronounced effect on the intrinsic viscosity. The behavior of the latter results from the inverse proportionality of the intrinsic viscosity to the segment density. Estimation of this apparent density gave swelling ratios of only 2 to 5. The cured epoxy resins showed no swelling up to molecular weights of 10 000; in the higher molecular weight region the swelling ratios increase continuously up to a factor of 9.
The characterization and structure‐property relations of epoxies
Authors: Morgan Roger J.
Published: March 2011

The structure‐deformation/failure process‐mechanical property relations of epoxies used as matrices in high performance fibrous composites are presented. Such composites are fabricated either from fiber‐epoxy prepregs or by filament winding. The parameters that affect the processing, cure reactions and the resultant chemical and physical structure of the epoxies are discussed. The deformation and failure processes of these glasses are described. The structural parameters that control the deformation and failure processes, the mechanical response and aging of epoxies are addressed and means of improving their processing and performance are described.
Intrinsically conductive organic polymers as electrode material for functional ceramics in electronics
Authors: Schnöller M. , Wersing W. , Naarman H.
Published: March 2011

Layers of intrinsically conductive organic polymers were chemically or electrochemically applied to ferroelectric ceramics. Using chemically deposited polypyrrole layers as an example, the applicability of these layers for electrodes was demonstrated and compared with metal electrodes. Practically the same, almost square hysteresis loops were observed with these polymer electrodes. In addition, equivalently high permittivity and piezoelectric constants were found. Conductive polymer layers can be used to an advantage in all applications where only relatively low operating frequencies are used, i.e. especially for all types of piezoelectric transducers which function quasistatically. Due to their elastic properties they are also interesting for piezoelectric composites. Furthermore, because of their optical absorption they appear to be interesting for pyrodetectors. They can also be considered for electrical screening and protective layers as well as for further applications.
Electrodeposition and cycling of polypyrrole
Authors: Beck Fritz , Oberst Manfred
Published: March 2011

Polypyrrole has been electrodeposited at a constant current density of 4 mA cm−2 onto Pt from 0.1 M pyrrole, 0.1 M NBu4 BF4 in dry CH3CN. The thickness of the polypyrrole has been varied over a wide range of 0.02 to 50 μm. Elemental analysis reveals an excess of hydrogen in the polymer. The electrochemical equivalent corresponds to an insertion of 25–35 mole % BF4‐anions and a current efficiency of 80–100% for the electrodeposition process. SEM technique shows a highly textured material at a thickness larger than 1 μm. Reversible water vapour adsorption of this material has been detected. The potential/time curve during galvanostatic electrodeposition is without special features. The start potential, USSCE = 0.9 V, is relatively negative. A slight decay of potential in the course of the electrodeposition of thick layers is explained in terms of increasing surface roughness. Cyclic voltammetry has been used for a systematic investigation into the role of the positive and negative endpotentials. The importance of a total primary discharge after electrodeposition has been clarified. At a film thickness d exceeding 1 μm, the cyclovoltammetric curve degenerates, and the anodic peak flattens and shifts to more positive potentials. Active mass utilization decreases with increasing d and with increasing voltage scan rate vs. The plot of anodic peak current density vs. vs is linear for layers below 1 μm thickness. For thick layers and at high vs, deviations occur, indicating a transport limitation in the film. As the film is not homogeneous, a quantitative evaluation is not possible.
Formation and electronic conductivity of polyaniline
Authors: Thyssen A. , Borgerding A. , W. Schultze J.
Published: March 2011

Potentiostatic measurements of polyaniline (PANI) formation show the growth of a metallic conducting phase, probably growing after instantaneous nucleation by a semisphere mechanism. The double layer capacity proves the formation of a metallic phase at first, but in a later stage the surface is covered by any dielectric reaction product forming an interface of a few nm thickness. Various measurements of electron transfer reactions show the very good conductivity of the PANI film within a potential range of 0 to 1 V. A large nucleation overvoltage hinders the cathodic metal deposition. Oxidation at higher potentials causes an overoxidation with the formation of an insulating film.
Possibilities of formation or modification of polymers by means of chemical reactions during processing (polymer processing)
Authors: Rätzsch Manfred
Published: March 2011

The trends for polymeric engineering materials are marked by the search for defined thermomechanical, plastic‐elastic stability of dimension, and surface properties. This trend is caused by the demands for higher usage values of the polymers and more efficient processing technologies. The greatest chances are granted to the chemical modification and reactive compounding of known polymers to reach the aims of this development. Thermodynamically, most of the polymers are incompatible with each other and no sufficient disperse distribution is reached by only physical mixing. During the last 10 years a good compatibility at the interfaces has been found as one supposition and the influence of the viscosity of the polymer components and of the shear rate in the mixing machine as a further supposition to reach a fine‐dispersed distribution. Polymer composites with fibres and fillers are a further importent group of materials. The properties of composites are also determined by the interactions in the interfaces, by the dispersity of the fibres and fillers, and by the physical properties of the interfaces. Polymer‐analogous reactions, polymer blends, and polymer composites with and without low molecular reactants in the melt are decisively influenced by the parameters of the compounding machine. The quality of mixing, distribution of the residence time and of the shear rate, and the temperature profile of the reaction mixture are essential criterions for the course of the reaction. Continuous and quasi continuous technologies as, e. g., extruders and internal mixers are preferred. The lecture will deal with the present state and technical possibilities. Polymer syntheses in screw extruders are a new trend for the future. All these possibilities offer prospective chances of development.
Specific features of the field‐induced effects in comb‐like liquid‐crystalline polymers
Authors: Platé N. A. , Talroze R. V. , Shibaev V. P.
Published: March 2011

The main problems concerning the liquid crystalline polymers and their behaviour in outer fields are discussed. The influence of the mesophase structure type of the side‐chain LC polymers on the orientation processes in mechanical, electrical and magnetical fields is shown. The field effects in polymers permit to evaluate the specific peculiarities of the polymeric state of liquid crystals.

During the last 10 years the field of Liquid‐Crystalline (LC) polymers has been developed and is going to expand so intensively that one could not predict this at the time when first lyotropic and thermotropic LC‐systems were discovered.

Not only thousand of new LC polymers were synthesized and our Symposium gives a good example of very interesting papers devoted to this area, but it became clear that LC‐state of polymers should be considered as normal, thermodynamically stable, widespread state of macromolecular substances ‐ the idea which you hardly could find in textbooks a decade ago.

First applications of thermotropic LC‐polymers start to be described (memory devices, optical filters, ferroelectric polymers) while lyotropic systems continue its victorial march in the field of high tenacity fibers and films.

It is absolutely impossible to give in one lecture an overall review of what is going on in this area because this would need at least 5–6 lectures of two hours each. That is why on preparing this talk we decided to concentrate ourself onto only one side of this rich picture ‐ the field induced effects in comb‐like LC thermotropic polymers.
Poly(phenylenevinylene)s ‐ synthesis and redoxchemistry of electroactive polymers
Authors: Hörhold H.‐H. , Helbig M.
Published: March 2011

The development of PPV‐systems has moved from intractable powders to solution processible film‐forming materials by introducing solubilizing phenyl groups. This opens new uses ranging from thin‐film insulators, over photoconductive electrophotographic recording materials, to novel electroactive battery electrodes. In addition, the phenylated PPV may be utilized as a promising thin‐film precursor for microstructured carbon patterns with a stable electrical conductivity (σ = 40 S/cm).

PPV is not a metal‐like conductor, but rather a high‐ohmic photoconductor with a band gap of 2.4 eV. It can be made highly conducting upon appropriate chemical or electrochemical treatment (σ= 10−4 − 103 S/cm).

The formation of coexisting polymeric ion radicals (polarons) and diions (bipolarons) is well understood in terms of the concept of chain segment redox reactions (ECS concept).

A wide variety of PPV derivatives has been synthesized and characterized by their electrochemical oxidation and reduction potentials. Substituents like phenyl, methoxy and cyano groups have a significant influence on the redox potentials of PPV as the standard polymer (EOx = 0.8 V, ERed = −1.7 V).

Thus, for poly(1,4‐phenylene‐1,2‐diphenylvinylene) a broadening of the band gap up to 2.9 eV along with an increase of the oxidation potential up to 1.2 V is estimated.

The knowledge of the redox potentials which reflect fundamental properties of conjugated polymers is essential for theoretical and practical reasons.
Synthetic polymers today and in the future of pharmacy
Authors: Kálal Jaroslav
Published: March 2011

Synthetic polymers have since a long time played a relatively important role in present‐day medicinal practice. Many devices in medicine and even some artificial organs are constructed with success from synthetic polymers. It is possible that synthetic polymers may play an important role in future pharmacy, too. This lecture should but scratch the surface of several directions in this particular field.
Polymers for medical applications
Authors: Frommelt H.
Published: March 2011

The paper starts with some general introductory comments on properties and influence factors such as biocompatibility, surface structure, processibility and purity. Hence it is derived that polyurethanes deserve special attention as biomaterials, which is explained by the variability of the structure. A number of examples with new types of polyurethane elastomers are described, their advantages and disadvantages are pointed out, and conclusions are drawn for further research.
Direct methods in small‐angle scattering
Authors: Svergun D. I.
Published: March 2011

Direct methods of small‐angle scattering data treatment and interpretation are reviewed. The possibilities of Tikhonov's regularization method for solving ill‐posed experimental data processing problems (desmearing, size distribution functions evaluation) are shown; comparison with other data treatment methods is made. Methods for direct reconstruction of the structure of particles in isotropic monodisperse objects are presented. The cases of particles described by one‐ and two‐dimensional density distributions and the possibilities of application of the multipole expansion theory are considered.
Applications and limitations of deuterium labeling methods to neutron scattering studies of polymers
Authors: Wignall G. D. , Bates F. S.
Published: March 2011

Deuterium labeling techniques have been widely used to study polymer chain configuration and motion, based on the assumption that the H‐ and D‐ chains are thermodynamically identical and that the interaction parameter between them, XHD is zero. By an appropriate choice of the degree of polymerization and temperature, both critical scattering and phase separation can be made to occur, due solely to the small but finite thermodynamic differences between protonated and deuterated molecules. These experiments helped delineate the range of validity of the assumptions which had been used hitherto in neutron scattering studies of polymers. The majority of previous experiments, carried out at modest molecular weights, have been shown to be in large part unaffected by such effects.
A review of some recent applications of small‐angle scattering in studies of polydisperse systems and porous materials
Authors: Schmidt Paul W.
Published: March 2011

Recent progress in two fields of small‐angle scattering is reviewed: (a) New procedures have been developed by Kotlarchyk and Chen and by Triolo, Griffith, and Compere for calculating the intensity of the small‐angle scattering from polydisperse systems of interacting particles of different sizes. These techniques have significantly increased the quantitative information that can be obtained from the scattering data. (b) The pore boundaries in many porous solids have been found to be fractal surfaces. In a porous solid in which the pores have an average diameter ϵ and the pore boundary surfaces have a fractal dimension D, the scattered intensity for qϵ, >> 1 is proportional to q−(6‐D), where q = πλ−1sin(θ/2), θ is the scattering angle, and λ is the wavelength. Some small‐angle scattering studies of fractal porosity are outlined.
A new approach in small‐angle neutron scattering: A method of triple isotopic substitutions
Authors: Serdyuk Igor N. , Yu. Pavlov Michail
Published: March 2011

A new method is proposed for studying the structure and mutual arrangement of selected components in multicomponent particles. Here the difference between the scattering curve of a solution containing two types of structurally identical particles (differing only in the degree of deuteration) and the scattering curve of a solution containing particles of a third type (deuterated to an intermediate degree) is considered. This difference scattering curve differs only by a numerical multiplier from the “vacuum” scattering curve of the particle in which the scattering density is equal to the difference between the scattering densities of the particles of the first and second types. This means that any particle component which is deuterated (protonated) to the same degree in the particles of three different types does not contribute to the difference scattering curve and, consequently, is “invisible” for neutrons. The difference scattering curve depends neither on the isotopic content of the solvent nor on the inter‐particle interference and particle association. Possible applications of this method are discussed.
The determination of the lamellar thickness in semi‐crystalline polymers by small‐angle scattering
Authors: Vonk C.G.
Published: March 2011

Three small‐angle scattering methods for determining the thickness of the crystalline lamellae in polymers are described. These are based on 1. observation of the identity period, 2. determination of the specific surface of the phase boundary, and 3. analysis of the shape of the peak at the origin. The conditions for application of these methods and the types of average obtained are discussed, and some results are presented.
Liquid crystal polymers: Studies of labelled parts by Neutron scattering
Authors: Pépy G. , Cotton J.P. , Hardouin F. , Keller P. , Lambert M. , Moussa F. , Noirez L. , Lapp A. , Strazielle C.
Published: March 2011

The studies of the conformation of comb‐like liquid crystal polymers have been made by Small Angle Neutron Scattering (SANS) with samples containing mixtures of totally protonated polymers and homologous polymers with deuterated backbones. For a polymethacrylate the conformation of a chain is determined in the isotropic nematic and smectic phases. Theoretical predictions of Renz and Warner (similar to the hairpin model of de Gennes) are verified from the temperature dependence of the radius, parallel to the director, of one chain in the smectic phase. When the terminal groups of the pendant part of the monomer are deuterated a segregation seems to occur. The problem of the generalization of results is raised.
Emulsifying effects of block copolymers in incompatible polymer blends
Authors: Leibler Ludwik
Published: March 2011

We discuss some theoretical aspects of interfacial and emulsifying activity of block copolymers A‐B in incompatible blends of homopolymers A and B. We predict the reduction in interfacial tension due to equilibrium adsorption of copolymers at the interface. It is shown that for an appropriate choice of block copolymer composition and molecular weight a very low interfacial tension can be achieved. This suggests a possible existence of a thermodynamically controlled stable droplet phase in which minority homopolymer particles protected by an interfacial film are suspended in a majority homopolymer matrix. The size distribution of the droplets depends on the rigidity and spontaneous radius of curvature of the interfacial film which, as we show, can be controlled by molecular parameters of copolymers.
Miscibility mapping in some blends involving poly(styrene‐co‐acrylonitrile)
Authors: Cowie John M. G. , Lath Dieter
Published: March 2011

Binary interaction parameters, Xij have been determined for the monomer pairs, styrene‐acrylonitrile and methyl methacrylate‐acrylonitrile from phase separation measurements in homopolymer‐copolymer blends. These have been used to predict regions of miscibility in different blends of statistical copolymers where the components were (a) poly(styrene‐co‐acrylonitrile), (b) poly(styrene‐co‐methylmethacrylate) and (c) poly(methylmethacrylate‐co‐acrylonitrile). Agreement between prediction and experiment was good in all cases. Extensive miscibility ranges were obtained for blends of (a) with (b), and (a) with (c), but combinations of (b) with (c) are immiscible.
Structured polymer blends
Authors: Meijer H. E. H. , Lemstra P. J. , Elemans P. H. M.
Published: March 2011

Various morphologies can be realized via processing of incompatible polymer blends such as droplets or fibers in a matrix and stratified or cocontinuous structures as is shown for the model system polyethylene/polystyrene The structures induced are usually intrinsically unstable. Modelling of extrusion processes and continuous mixers yields expressions for the shear rate and shear stress but also for the limited residence time and the number of reorientations. These results could be combined with detailed knowledge of respectively distributive and dispersive mixing processes to predict the development of various morphologies as a function of time. Control of morphology is of utmost importance. In the case of droplets in a matrix, usually encountered in toughening of glassy polymers, the use of compatibilizers and/or reactions at the interphases is utilized. However, in designing specific morphologies i.e. structured polymer blends, fixation of intermediate morphologies before final processing is a prerequisite. Some preliminary results will be presented.
Automotive industry and polymer blends
Authors: Moro A. , Chiolle A. , Credali L. , Foschini G.
Published: March 2011

A key to the success of plastics in the automotive industry is the use of alloying technology which, relatively quickly leads to tailor‐made materials at interesting cost‐performance ratios. In this paper an overview of the various criteria used in the laboratory in testing alloys for auto parts is given and an attempt is made to point out the most significant determinations. The results obtained comparing the materials indicate how inadequate the standard methods are in describing the real behaviour of the items under operating conditions. Nonetheless, just making some modifications in test geometry leads to a sufficiently realistic correspondance between laboratory test data and item performance.
Examples of “intrinsically” and “extrinsically” determined phase morphologies in polymer alloys
Authors: Lohmar J. , Meyer K. , Ag Hüls
Published: March 2011

The properties of polymer alloys are strongly dependent on their phase morphologies. Usually, the phase dispersion and domain sizes are affected by the process and can be influenced and stabilized only “extrinsically” by dispersants and emulsifiers. But, there are some examples of alloys with phase morphologies which are “intrinsically” determined and thus independently of the processing conditions. This aspect of phase determining factors is discussed using four principally different examples of polymer alloys.
Investigations of blends containing coil polymers and thermotropic main‐chain polymers
Authors: Friedrich Klaus , Hess Michael , Kosfeld Robert
Published: March 2011

Blends containing main‐chain thermotropic, semiflexible polyesters and flexible‐chain polymers (PC and PET) are investigated by calorimetry and microscopy. First results of studies about the mechanical behaviour by torsional pendulum are presented.
Prediction of phase separation behaviour from thermodynamic measurements in the one phase region
Authors: Higgins J. S. , Fruitwala H. , Tomlins P. E.
Published: March 2011

When a polymer blend is heated to within the unstable region of the temperature ‐ composition diagram spinodal decomposition may be observed using small angle neutron scattering. In the one phase region scattering has been used to obtain the temperature and composition dependence of the second derivative with respect to composition of the Gibbs free energy of mixing. Correlation of these two types of measurement not only tests the current theories of spinodal decomposition, but provides insight into the molecular parameters controlling domain morphology in phase separation blends.
Dynamic mechanical spectrometry for the study of multiphase polymer materials
Authors: Cavaille J. Y. , Jourdan C. , Perez J.
Published: March 2011

The dynamic mechanical behaviour of multiphase polymer materials depends on two factors: (i) properties of each phase and (ii) geometric arrangement of these phases (so‐called morphology). Analysis of experimental results has been performed in order to separate these two factors; it leads to informations about morphology, presence of interphase between main phases, chemical composition of different domains and possible changes in physical properties of one phase, induced by its neighbours. The interest in such an analysis based on mechanical spectrometry appears important because of difficulties in direct investigations (low contrast in Electron Microscopy, poor information provided by X‐ray measurements on amorphous polymers … )
Monosized magnetic particles and their use in selective cell separation
Authors: Ugelstad J. , Berge A. , Ellingsen T. , Aune O. , Kilaas L. , Nilsen T.N. , Schmid R. , Stenstad P. , Funderud S. , Kvalheim G. , Nustad K. , Lea T. , Vartdal F. , Danielsen H.
Published: March 2011

The principle of activated swelling has made available polymer particles in the range of 1–100 μm, highly uniform in size, and with great variations in morphology and chemical composition. A short description of the method is given.

On the basis of monosized porous macroreticular particles, monosized magnetic polymer particles (MMP) are prepared which are uniform in size as well as in content of magnetic oxides. These particles have found applications in a number of selective cell separation procedures. Special types of MMP have been developed for isolation of organelles and viruses. The use of MMP as contrast agent in magnetic resonance imaging is shortly described.
Chemically and physically crosslinked porous gels
Authors: Flodin Per
Published: March 2011

Chemically crosslinked gels made by polymerization and copolymerization of trimethylolpropane trimethacrylate have been characterized. Bimodal pore size distributions were obtained. The radii of the large pores (100 Å to 1 μm) varied with concentration while the small ones (20 to 30 Å) were largely independent of the concentration of TRIM. A mechanism of formation of the pores is outlined.

Physically crosslinked gels of polyacrylonitrile with highly porous structures were made by cooling polymer solutions in DMF containing varying amounts of water. By controlling the thermal treatment the pore sizes could be varied from 0.1 to 1 μm.

Finally the surface modification of cellulose fibers with derivatives of dichlorotriazine is described. It is shown that derivatives containing double bonds in the side chain can form covalent bonds across the interface between cellulose and an unsaturated polyester.
Mechanism of activation of hydroxyl‐containing polymers with N‐hydroxysuccinimide and carbodiimides: Reason for leakage
Authors: Wilchek Meir , Miron Talia
Published: March 2011

The carbodiimide‐mediated reaction of N‐hydroxysuccinimide with carboxyl groups immobilized to hydroxyl‐containing polymers (such as Sepharose or Trisacryl) leads to N‐hydroxysuccinimide ester and N‐hydroxysuccinimide derivatives of β‐alanine which react subsequently with the hydroxyl group of the polymer via ester and carbamate bonds. These derivatives are formed upon interaction of dicyclohexyl carbodiimide with three equivalents of N‐hydroxysuccinimide followed by a Lossen rearrangement. The amount of β‐alanine thus coupled is very high compared to the number of carboxyl groups present on the resin. The β‐alanine bound through the ester bond comprises about 90% of the β‐alanine bound. Alkaline treatment of the ester bonded β‐alanine containing polymers (prior to coupling of amino‐containing ligands) causes a rearrangement yielding β‐alanine with a free carboxyl group coupled through a stable carbamate linkage. After coupling of amino‐containing ligands, the above‐described rearrangement cannot occur, and the β‐alanine‐linked ligand leaks from the polymer via hydrolysis of the ester bond. The newly formed carboxyl groups (derived from the rearrangement) can be used to prepare active esters (e.g. nitrophenyl). Upon coupling with amino‐containing ligands, these esters yield resins bearing chemically stable bonds.