bluuebunny/crossref_metadata_2025 huggingface dataset:
Nuclear reaction analysis: A study on the interface formation in polymer mixtures below the critical point
Authors: Steiner U. , Chaturvedi U. K. , Zak O. , Krausch G. , Schatz G. , Klein J.
Published: March 2011

We describe a method for directly determining the composition profile of deuterated polymer chains in polymer mixtures. Our technique, nuclear reaction analysis, is based on the 2H(3He, 4He)1H nuclear reaction. By detecting 4He in a forward geometry, we achieve a spatial resolution of 14 nm (FWHM). We use this technique to probe the broadening of the interface between two partially miscible polymers. We found that such a system attains a finite interfacial width in equilibrium. For short times, we monitor the dynamics of interface formation. We found that the interfacial width increases significantly slower than in the case of free diffusion.
Functional polymeric monolayers and liposomes
Authors: Zaitsev S. Yu , Zubov V. P.
Published: March 2011

Some lipid‐like monomers were synthesized by acylation of synthetic and naturally occurring amine‐containing lipids with acryloyl chloride. The surfactant properties and peculiarities of polymerization of lipid‐like monomers in oriented systems were investigated. On the basis of such monomers, polymeric monolayers and liposomes were prepared that have the structural similarity to biomembranes and enhanced stability. The applicability of such systems for immobilization of membrane proteins was shown for the example of bacteriorhodopsin.
Spectroscopic studies of the stability of monolayers of 2‐docosylamino‐5‐nitropyridine at the air/water interface
Authors: Decher Gero , Klinkhammer Frank
Published: March 2011

Monolayers of 2‐docosylamino‐5‐nitropyridine (DCANP) at the air/water interface were investigated by UV/Vis spectroscopy. The combination of this method with the classic constant‐area relaxation technique yields insight into the longtime stability and the collapse behavior of monolayers. We have demonstrated that monolayers of DCANP are certainly stable under standard deposition conditions. At surface pressures above 20 mN/m monolayer instabilities lead to the formation of a three‐dimensional head‐to‐head multilayered structure.
Optical waveguiding and nonlinear optical characterization of 2‐docosylamino‐5‐nitropyridine Langmuir‐Blodgett films
Authors: Bosshard C. H. , Küpfer M. , Flörsheimer M. , Günter P. , Pasquier C. , Zahir S. , Seifert M.
Published: March 2011

Well ordered Y‐type Langmuir‐Blodgett (LB) multilayers of 2‐docosylamino‐5‐nitropyridine (DCANP) have been characterized with linear and nonlinear optical techniques. The nonlinear optical susceptibilities have been determined for the wavelengths λ = 1064 nm (d33 = (7.8±1) pm/V, d31 = (2.0 ± 0.5) pm/V) and λ = 1318 nm (d33 = (5.6 ± 1) pm/V). Waveguiding experiments with grating couplers allowed the excitation of TEo and TMo modes propagating over more than 20 mm. Guided wave attenuation coefficients as low as 12 dB/cm (at the wavelength λ = 632.8 nm) are reported. Coupling experiments allowed the determination of the dispersion of the refractive index n3 (n3632.8 nm = 1.598). The refractive index data could be used to calculate phase‐matching conditions for frequency doubling with TE modes in DCANP waveguides.
Synthesis Of 2‐D polymer from semi‐amphiphilic Langmuir‐Blodgett (LB) films
Authors: Porteu Florence , Palacin Serge , Ruaudel‐Teixier Annie , Barraud André
Published: March 2011

Semi‐amphiphilic monolayers formed via adsorption of tetraethynylpyridinium porphyrins to a dihexadecyl phosphate monolayer are allowed to react with ammoniacal silver nitrate or ammoniacal cuprous chloride, in order to form two‐dimensional polymolecular species in which silver diacetylide groups or diacetylenic bonds are expected to link adjacent coplanar macrocycles. Evidences are given for the formation of these ultrathin two‐dimensional networks.
Monolayer phases of the fatty acids and their ethyl esters
Authors: Bibo Anna Maria , Knobler Charles M. , Peterson Ian R.
Published: March 2011

The miscibility correspondence between water‐surface monolayer phases of the fatty acids and their ethyl esters was determined. Ester phases were found corresponding to all the known phases of the acids, and vice versa, in similar relative positions of the π‐T diagram. Evidence is presented for the existence of a ninth distinct miscibility category, represented by a phase in each of the pure materials, and a tenth found only in mixtures. We propose a tentative correspondence to bulk smectic miscibility categories.
Fluorescence as probe for transport and lateral order in vapor grown Langmuir‐Blodgett(LB) multilayer‐type single crystals of anthracene chromophores with fatty acid tails
Authors: Weiß D. , Kietzmann R. , Storck W. , Lehnert J. , Willig F.
Published: March 2011

Fluorescence spectra of anthracene moieties with fatty acid tails attached at the 2‐position are reported for Langmuir‐Blodgett(LB)‐type multilayer configurations obtained as single crystals in the gas phase. These systems are considered the best ordered experimental model systems for chromophores with fatty acid tails arranged in the LB multilayer configuration. Closest agreement of the fluorescence spectrum with that of the unsubstituted anthracene crystal is found for the 4‐(2‐anthryl)‐1‐butanoic acid (2A4) crystal. Packing of the anthracene moieties is very similar in both crystals. Low‐temperature spectra (10 K) reveal strong broadening of the peaks due to spatial disorder in the 2A4 crystal. 7‐(2‐Anthryl)‐1‐heptanoic acid (2A7) crystals and even more so actual 2A7 LB multilayers have less structured fluorescence spectra that extend further to lower energies. Picosecond time resolved fluorescence decay curves show exciton transport and trapping in low energy traps. Compressed ground state pairs with excimer‐type spatial configurations are excited directly in the red (476 nm) to emit structureless excimer‐type fluorescence.
Concentration dependence of the electro‐optical spectra from two‐dimensional aggregated chromophore systems
Authors: Grewer Georg , Lösche Mathias
Published: March 2011

The linear and the quadratic Stark effects have been employed to characterize aggregate formation of an amphiphilic cyanine dye mixed with arachidic acid in various concentrations within Langmuir‐Blodgett multilayers. Two different electrode configurations with the electric field directions parallel and normal to the films have been employed to test the responses of the electronic spectra to external fields. The observations have been used to quantify the induced and static dipole moment changes on excitation of the chromophores. A comparison of the results obtained from different multilayer arrangements is suggestive of inter‐layer couplings for the case of head‐to‐head configurations of the aggregated chromophores. The results from the mixing studies reveal the evolution of two different aggregated species, one shifted hypsochromically and one shifted bathochromically from the monomer absorption and serve to quantify the relative proportions and sizes of these aggregates.
Surface functionalization and surface recognition: Plasmon optical detection of molecular recognition at self assembled monolayers
Authors: Häußling Lukas , Knoll Wolfgang , Ringsdorf Helmut , Schmitt Franz‐Josef , Yang Jianling
Published: March 2011

The synthesis of biotin‐ functionalized organic mercaptans and their chemisorption on gold surfaces is described. Biotin bound covalently to self assembled monolayers is recognized by streptavidin from aqueous buffer solutions. Spacer length and packing density of the biotin labels on the organic surface determine the docking kinetics. With a flexible and hydrophilic spacer very fast ‐diffusion controlled‐docking is observed. As an alternative method of self assembly the spreading of organic mercaptans on water surfaces is established. Pressure‐area diagrams of different functionalized mercaptans and disulfides are shown and their monolayer properties are discussed.
Selection rules for self‐formation in the molecular nanotechnology
Authors: Tamulis A. , Janušonis S. , Bažan L.
Published: March 2011

Self‐formation in molecular nanotechnology is based on interaction between organic and biological molecules. Selection rules of the distinct interactions of the symmetric and topologically similar molecule self‐formation are investigated.
Characterisation of LB multilayers of soluble phthalocyaninatopolysiloxane
Authors: Schwiegk S. , Fischer H. , Xu Y. , Kremer F. , Wegner G.
Published: March 2011

Tetra(methoxy)tetra(octyloxy)phthalocyaninatopolysiloxane (PcPS), a soluble rigid‐rod polymer, forms stable monolayers on water, which can be transferred onto solid substrates. The orientation of the polymer in the transferred layers is induced by the flow on the water subphase. If a convergent flow is induced, the molecules will be aligned parallel to the dipping direction. A DC‐conductivity of 10−7 S · cm−1 was measured for the undoped films. Measurements with an  sandwich structure show rectification and hysteresis characteristics. PcPS modified by terminal double bonds in the side chains can be crosslinked by UV irradiation. Patterns can be developed in these films using a negative photoresist technique.
The influence of structure change on electrical properties of conducting LB films produced from hexadecyl‐TCNQ and heptadecyldimethyl‐TTF mixture
Authors: Berzina T. S. , Shikin S. A. , Troitsky V. I. , Yanusova L. G.
Published: March 2011

Conducting Langmuir‐Blodgett films of hexadecyl‐TCNQ and heptadecyl dimethyl‐TTF mixture in the ratios from 1:1 to 1:2.5 are studied. Temperature dependence of film conductivity possesses some specific features. Strong increase of conductivity and decrease of activation energy take place after annealing at 307–315 K. On the other hand, the film loses conductance after heating above 315 K. To explain this behaviour the investigations of conducting multilayers by means of electron diffraction, electron microscopy, and X‐ray small‐angle scattering were carried out. Some relations between changes of electrical properties and structural transformations are ascertained.
Ultrathin metal films and inorganic clusters via thermodesorption of LB films
Authors: Tippmann‐Krayer P. , Meisel W. , Höhne U. , Möhwald H.
Published: March 2011

Langmuir‐Blodgett multilayers of cadmium arachidate and ferric stearate were investigated during heating in order to derive information on processes involved in thermodesorption and on the inorganic microstructures left on the substrate after thermodesorption. We studied these processes by X‐ray induced photoelectron spectroscopy (XPS), interference enhanced reflection (IeR), Nomarsky microscopy, electron microprobe analysis and in the case of Fe57‐ions by conversion electron Mössbauer spectroscopy (CEMS).

Two different mechanisms of desorption were observed. In the case of cadmium arachidate multilayers it is shown that before desorption the film ruptures laterally and then forms droplets. At temperatures between 250°C and 350°C the aliphatic molecular part is desorbed and the inorganic material (Cd) remains on the surface. These threedimensional Cd‐clusters have a rather uniform lateral distribution and dimension (0.5–2μm) and normal extension larger than 1000Å. The size may be controlled via nucleation and growth kinetics.

In contrast to this thermodesorption of the aliphatic chains of ferric stearate multilayers leads to a rather uniform continuous oxidic layer. By means of CEMS it could be shown that during desorption under H2‐atmosphere the iron was reduced (e.g. 40% metallic iron). The degree of oxidation can be controlled via temperature and time of reduction.
Visco‐elastic properties of thin films probed with a quartz crystal resonator
Authors: Johannsmann D. , Embs F. , Willson C. G. , Wegner G. , Knoll W.
Published: March 2011

We report on the visco‐elastic characterization of thin layers using a quartz crystal resonator. A parallel ellipsometric setup is used to determine optical thicknesses. A theory of thickness shear resonators covered with visco‐elastic films is presented. The glass transition of a 350 nm film of low‐molecular‐weight polystyrene can be followed. Secondary resonances in frequency shift and damping are observed, when the wavelength of transverse sound is in the same order of magnitude as its thickness. The UV‐induced desorption of poly[(bis)‐m‐butoxy‐phenyl‐silane] shows strong visco‐elastic effects, if done under oxygen atmosphere. Desorption via an oily phase consisting of medium‐size oligomers is suggested.
An electron diffraction study of deposited docosanoic acid monolayers
Authors: Steitz R. , Mitchell E. , Peterson I. R.
Published: March 2011

Docosanoic acid monolayers deposited on thin polymer films under different water surface conditions have been investigated using transmission electron diffraction at normal and tilted incidence. Diffraction patterns obtained from the L2 and L2' phase are quite similar, but distinctly different to samples coated from the CS phase. The former were consistent with molecules perpendicular to the substrate, arranged in a texture of grains with unusual orthorhombic packing. There is evidence for a phase transition from a liquid crystalline phase on the water surface.
X‐ray study of LB multilayers of cadmium soaps in the vicinity of the break up point
Authors: Merle H. J. , Lvov Y. M. , Peterson I. R.
Published: March 2011

Temperature dependent SAXS measurements were carried out on multilayers of two different salts, cadmium palmitate (hexadecanoate) and behenate (docosanoate). The pattern characteristic of layer structure disappears at a transition temperature well below the bulk melting point in both cases. Examination by means of optical microscopy shows that the LB films break up at a temperature close to this transition. Measurements in its vicinity demonstrate that over a certain temperature range just below the transition a second set of peaks arises in the diffraction pattern. During this transition region of about 3 °C width two d‐spacings for both salts were found, suggesting the simultaneous existence of two different structures for each component at the same temperature.
New amphiphilic terphenyl liquid crystals for the preparation of highly ordered ultrathin films
Authors: Decher G. , Maclennan J. , Straus M. , Sohling U.
Published: March 2011

Four new amphiphilic liquid crystals have been synthesized, in which terphenyl was used as the mesogenic unit. In order to enable the formation of Langmuir Monolayers at the air/water‐interface, the molecules were equipped with slightly polar headgroups such as esters or a carboxylic acid group. All compounds can be transferred onto solid substrates. In addition, it is possible to prepare freely suspended films of at least one compound in the temperature range of the smectic phases. The phases of the different states, bulk, monolayer, freely suspended film, and Langmuir‐Blodgett multilayers have been investigated by means of monolayer isotherms, optical textures, differential scanning calorimetry (DSC) and small angle X‐ray scattering.
Stereocomplexation of poly(methylmethacrylates) in monolayers at the air water interface
Authors: Brinkhuis R. H. G. , Schouten A. J.
Published: March 2011

When mixtures of isotactic and syndiotactic PMMA are spread on the air water interface from a non‐complexing solvent, a pressure induced transition can be observed, that is identified as a stereocomplexation between the two stereoregular components in the mixture, similar to bulk or solution processes. Analogous to the monolayer crystallization of isotactic PMMA, double helical structures are formed that can be transferred to solid substrates forming oriented thin films.
Formation and x‐ray and electron diffraction study of Cds and Pbs particles inside fatty acid matrix
Authors: Erokhin V. , Feigin L. , Ivakin G. , Klechkovskaya V. , Lvov Yu. , Stiopina N.
Published: March 2011

Langmuir‐Blodgett films of lead and cadmium stearate were treated by exposure to H2S atmosphere. Such treatment lead to formation of CdS and PbS particles and protonation of stearic acid head‐groups. The process was studied by small‐angle X‐ray scattering. The reaction was shown to be completed after 5 hours of treatment.
Langmuir trough with enhanced performance
Authors: Ivanov G. R. , Todorov A. T. , Petrov A. G.
Published: March 2011

Here is presented the general design and performance of a new Langmuir‐Blodgett trough. It is designed as a very precise flexible research instrument. It has a velocity dynamic speed range in excess of 1:10 000, stick‐slip free movement at velocities below 0.5×10−6 m/s, special antivibration construction, Wilhelmy type surface pressure sensor connected to a Lock‐in amplifier, micrometer precision position sensors, analogue feed back loops for the surface pressure and velocity control. It is a fully computerized instrument with a productivity of 18 measurements per second with an IBM PC/AT computer. The software has a lot of new features. For the first time we have measured such perturbational parameters for the film quality as the unevenness of the velocity and the acceleration spectra of vibrations of the barrier and the substrate holder. Unevenness as high as 48% can be measured while the amplitude of the vibrations were in the range of 10−4 m/s2 at medium speeds. These values are several times higher than the background ones.
Studies of monolayer/substrate adhesion as function of the monolayer headgroup charge: DMPE and DMPA
Authors: Engel Maria , Riegler Hans
Published: March 2011

The variation of the work of adhesion between lipid monolayers and a plane silicon oxide surface in a typical LB‐configuration is measured as function of the subphase pH. The adhesion energy is deduced via fluorescence microscopy from the equilibrium meniscus height. With increasing pH the negative headgroup charge of both, dimyristoylphosphatidylethanolamine (DMPE) and dimyristoylphosphatidic acid (DMPA) monolayers increases. The increasing charge of DMPE is reflected in a measured decrease of the work of adhesion at higher pH. The DMPA/SiO2 interaction is not affected by increasing headgroup charges. These results are qualitatively understood in terms of an electrostatic double layer interaction between charged surfaces. It predicts decreasing adhesion for increasing, but low surface charge densities (DMPE). whereas the adhesion is constant for high surface charge densities (DMPA).
Epifluorescence microscopy studies of fatty acid monolayers: Domain formation induced by polymeric gegenions
Authors: Chi L. F. , Johnston R. R. , Ringsdorf H.
Published: March 2011

The monolayer behavior of long‐chain fatty acids at the air/water interface on a poly(ethyleneimine) containing subphase was investigated. The interaction of the polymeric gegenions in the subphase leads to expanded states and permits the visualization of the aggregation behavior of different long‐chain fatty acids via fluorescence microscopy. The monolayer morphologies and their variability were intensively studied by fluorescence microscopy. In addition, the transfer of the complexed fatty acid monolayers to solid substrates has been investigated.
Surface‐plasmon optical characterisation of asymmetric soap films
Authors: Lawall R. , Knobloch H. , Knoll W.
Published: March 2011

Stable water films covered by arachidic acid monolayers were prepared on vertically arranged glass/Ag/SiO2‐substrates, which were partially pulled out of a film balance trough. The thickness profiles were recorded by on‐line‐measurement, using the thickness dependence of the dispersion of surface plasmon polaritons. The surface plasmon imaging technique allows for a thickness resolution of 0.2 nm and a height resolution of ca. 20 μm. Variations of these profiles as a function of the lateral pressure of the horizontal arachidate layer on the film balance were observed.

For the first time Raman studies were made on asymmetric soap films. The intensity ratio of the Δηa = 2800 cm−1 to the Δηs = 2850 cm−1 line in the CH‐stretching vibration range shows a dependence on the lateral pressure in the monolayer.
The role of the hydrophobic force in bilayer adhesion and fusion
Authors: Helm C. A. , Israelachvili J. N.
Published: March 2011

The Surface Forces Apparatus technique was used for measuring the adhesion, deformation, and fusion of bilayers supported on mica. The technique allows the molecular rearrangements to be followed in real time during the fusion process, and the most important forces involved to be identified. The adhesion between two bilayers can be increased by two orders of magnitude if they are thinned so as to expose more hydrophobic groups. For all the bilayer systems studied a single basic fusion mechanism was found in which the bilayers do not “overcome” the short‐range repulsive steric‐hydration forces; instead, local bilayer deformations allow these repulsive forces to be “bypassed”. The results further indicate that the most important force leading to the direct fusion of bilayers is the hydrophobic attraction acting between the hydrophobic interiors of bilayers (1, 2).
Structure analysis of discotic, sanidic and ferroelectric crystals and liquid crystals using electron microscopy
Authors: Voigt‐Martin I. G. , Schumacher M. , Simon P. , Honig M.
Published: March 2011

Three types of liquid‐crystalline materials with specific molecular structures were investigated using electron diffraction and high resolution imaging. Discotic and smectic liquid crystals were compared with the crystalline state. The superstructure of the sanidic liquid crystals showed effects in the line profiles and contour plots of the electron diffraction patterns.
Anionic vinyl polymerization and polycombination reactions induced by electron transfer reactions
Authors: Höcker Hartwig
Published: March 2011

1, 1‐Diphenylethylene is not capable of being homopolymerized, neither by radical nor by anionic mechanism. This is due to both electronical and sterical reasons. 1, 1‐Diphenylethylene, however, is eligible to electron transfer reactions to yield the radical anion which subsequently upon combination reaction forms the dimeric dianion. On the other hand, 1, 1‐diphenylethylene may be subjected to the nucleophilic addition of strong nucleophiles such as carbanions, e.g., butyllithium or polystyryllithium. Upon this reaction, a carbanion is formed the nucleophilicity of which is significantly reduced as compared with that of the starting carbanion. Molecules containing the characteristic group of 1, 1‐diphenylethylene twice, in analogous reactions, may be subjected to polycombination reactions upon electron transfer. The polymers exhibit cyclic or linear structure depending on the molecular structure of the starting divinylidene compound. Upon reaction with carbanionic species, biscarbanions are formed which may be used as initiators for the anionic polymerization of suitable monomers. A variety of divinylidene compounds and their specific features are presented.
Living cationic polymerization of vinyl monomers: New initiators and functional polymer synthesis
Authors: Sawamoto Mitsuo , Higashimura Toshinobu
Published: March 2011

This paper focuses on two recent topics in living cationic polymerization of vinyl monomers, i.e.,

(a) Development of new initiating systems: RCOOH/Lewis acid for vinyl ethers; CH3CH(C6H5)Cl/SnCl4/nBu4NCl for styrene.

(b) Synthesis of shape‐controlled poly(vinyl ethers): Tri‐armed star polymers; Multi‐armed spherical polymers.

For the RCOOH‐based systems, a generalized concept of living cationic polymerization was discussed on the basis of the effects of the counteranions (or R) and Lewis acids (ZnCl2 and EtAlCl2). The CH3CH(C6H5)Cl‐based system permitted a truly living cationic polymerization of styrene. The tri‐ and multi‐armed poly(vinyl ethers) included new amphiphilic polymers of unique topology, solubility, etc., all of which were prepared by living cationic polymerization.
Some special aspects of the copolymer synthesis with Ziegler‐Natta catalysts
Authors: Spitz R. , Pasquet V. , Joly J.‐F.
Published: March 2011

An approach of the special problems observed in copolymerization with Ziegler‐Natta heterogeneous catalysts is given on the basis of linear low‐density polyethylene synthesis in gas phase reaction. The reaction is controlled by chemistry and not by diffusion. The ethylene‐l‐butene copolymerization reactivity computed from the kinetic study varies with the copolymer composition, and this is due to the fact that the comonomer acts as a ligand of the active centers. The reactivities computed from NMR analysis are also not really reliable as the copolymer is a mixture of copolymers with different compositions.
Synthesis of soluble LC‐polyesters
Authors: Heitz W.
Published: March 2011

Soluble LC polymers were synthesized with the aim to approach molecular reinforcement. Chemical modification results in a decrease of the crystallinity and an increase of the solubility. Substitution of the amide hydrogen in poly(4‐aminobenzoic acid) by a methyl group reduces the stiffness of the polymer very much, and as a result no lyotropic solutions are obtained. Poly(p‐phenylene terephthalate) with substituents on the hydroquinone or on both monomer units were synthesized. With one phenylalkyl group in the repeating unit the polyesters are crystalline with melting points > 300°C. With two substituents the polymers form in many cases amorphous anisotropic glasses at room temperature. 2‐Biphenyl is the most effective substituent with regard to increase of solubility. These polyesters form isotropic solutions in chloroform. Isotropic films obtained from these solutions become anisotropic on heating above the glass transition temperature. Films of polyester/polycarbonate blends show additivity of E‐modulus with respect to both compounds.
Kinetics of ε‐caprolactone polymerization on dialkylaluminum alkoxides
Authors: Duda Andrzej , Penczek Stanislaw
Published: March 2011

Polymerization of ε‐caprolactone initiated with dialkylaluminum alkoxides is a living system; formation of macrocyclics is fully depressed. Polymerization initiated with diethylaluminum alkoxide and diisobutylaluminum alkoxide proceeds on monomeric (deaggregated) active species, reversibly aggregating into trimers for the former and into dimers for the latter initiator. Kinetic treatment of this system allowed to determine simultaneously the aggregation‐deaggregation equilibrium constant and the rate constant of propagation. Propagation most probably proceeds with insertion (pseudoanionically). Application of amines, complexing the growing species, allowed to break down the aggregates; polymerization became firstorder in initiator. Only secondary amines complexed strongly enough with growing species, the tertiary ones did not affect polymerization, at least up to the ratio 2:1 ([amine]/[initiator]o). Rate constants of propagation in all of the studiedo systems, whether aggregated or not, have been found to be the same and equal to 0, 04 1·mol−1·s−1 at 25° in THF solvent. This value is approx. 102 times lower than for ion‐pairs at these conditions. Moreover, rate constants are almost the same for the growing species …‐OAl(C2H5)2 and …‐OAl(i‐C4H9)2, although aggregation is very much influenced by the size of the alkyl groups.
Synthesis and reactions of telechelic polyacetals
Authors: Goethals Eric J. , De Clercq Ronny R. , De Clercq Hilde C. , Hartmann Patrick J.
Published: March 2011

Telechelic polyacetals have been synthesized by endcapping of bifunctionally living polyacetals with tertiary amines. Bifunctionally living poly‐(1, 3‐dioxolane) (poly‐DXL) was obtained by polymerization of the cyclic acetal initiated with terephthaloyl‐bis‐triflate. Attempts to prepare well defined bifunctionally growing poly‐DXL with trifluoro‐methane sulfonic acid anhydride failed. Low molecular weight dialkyl formals containing functional groups were used as transfer agents for the polymerization of cyclic acetals to control the molecular weight of the polymer and to introduce functional endgroups. Polytelechelic hydroxy‐terminated poly‐DXL was synthesized by copolymerization of DXL and glycidol. The latter monomer reacts as comonomer through its epoxy ring and as transfer agent by its hydroxyl group.
Polymerization chemistry of the family of cyclic imino ethers
Authors: Saegusa Takeo , Aoi Keigo , Miyamoto Masatoshi , Chujo Yoshiki
Published: March 2011

Characteristics of the polymerization mechanisms of the family of cyclic imino ethers are described. The variety of the mechanism of propagation has been systematized on the basis of the nature of propagating species, i.e., cationic or electrophilic covalent (dipole) species. In the polymerizations of 2‐alkyl cyclic imino ethers (5‐ and 6‐membered), propagation mechanism via one of these two different species has been established, which is dependent upon the relative nucleophilic reactivities of the monomer and the counter anion derived from initiator.

The polymerization of cyclic pseudoureas having a cyclic amine substituent at 2‐position proceeds in two different ways. Ionic propagation leads to the single isomerization/ring‐opening polymerization involving only the cyclic imino ether ring. On the other hand, covalent propagation gives rise to the double isomerization ring‐opening polymerization involving the two rings of cyclic imino ether and cyclic amine.

Polymerization of 5‐membered cyclic iminocarbonate with a sulfonate initiator proceeds through the isomerization/ring‐opening of 2‐oxazoline ring. The same monomer was isomerized to the corresponding cyclic urethane when it was treated with benzyl bromide.
13C‐13C NMR coupling constants in substituted allylic ion‐pairs of the type occurring in anionic diene polymerization
Authors: Bywater Stanley , James Worsfold D. , Black Paul E.
Published: March 2011

13C‐13C NMR coupling constants have been measured on the 1:1 adduct of tert‐butyllithium and butadiene, a model for the active centres in the anionic polymerization of butadiene. Solutions in three solvents in which solvation and aggregation properties differ were studied, tetrahydrofuran, diethyl ether and benzene. The 2‐methyl‐ substituted analogue, more appropriate for isoprene type systems was also converted to the potassium salt and a comparison was made of the effect of counter ion. Ion‐pair structure is discussed in terms of these measurements.
Anionic copolymerization of α‐methylstyrene and styrene: Kinetics and mechanism
Authors: Chen Fei , Ying Shengkang
Published: March 2011

A kinetic study of copolymerization of styrene and α‐methylstyrene accompanied with depropagation, initiated by n‐butyilithium in cyclohexane with tetrahydrofuran as an additive polar solvent, has been performed. The various propagation rate constants of active species and the complexation equilibrium constants between different kinds of active species were determined. Furthermore, the reactivity ratios of two monomers with regard to monomeric, monoetherated and dietherated active species were obtained.
Synthesis of new, functionalized poly(butyl vinyl ether) oligomers and novel copolymers containing these materials
Authors: Verma A. , Nielsen A. , Bronk J. M. , McGrath J. E. , Riffle J. S.
Published: March 2011

This paper reports the synthesis and characterization of new, functionalized poly(alkyl vinyl ether) oligomers, and block copolymers containing poly(alkyl vinyl ether) and poly(methyl methacrylate). Using the HI/ZnI2 initiating system in nonpolar solvents (hexane, toluene) at −20°C, both monofunctional and difunctional poly(alkyl vinyl ether) oligomers of predicted molecular weights precisely terminated with aldehyde, primary hydroxyl and ester endgroups have been prepared. Novel diblock copolymers comprised of poly(methyl methacrylate) and poly(butyl vinyl ether) have also been synthesized using a combination of living cationic and living group transfer polymerization.
Cationic polymerization of isobutyl vinyl ether initiated with the system aluminium trichloride/ethyl acetate, in toluene solution
Authors: Leleu J.‐M. , Tardi M. , Polton A. , Sigwalt P.
Published: March 2011

The cationic polymerization of isobutyl vinyl ether initiated with the title system apparently has some features of a living polymerization (linear increase of number average molecular weight M̄n with conversion). However, evidence is given for the occurrence of a transfer reaction resulting in the increase of the number of macromolecules, and this even for relatively low molecular weights.
Cationic oligomerization of isoprene and structure of its oligomers
Authors: Audisio Guido , Priola Aldo , Rossini Alessio
Published: March 2011

The results obtained in a study of isoprene cationic oligomerization in the presence of some oxyacids (H2SO4, CH3SO3H, Nafion® H) are reported. Oligomers up to pentamers are obtained which were examined through gas chromatography/mass spectrometry analysis either of the reaction products or of the hydrogenated products. The structure of the dimer fraction was investigated and revealed the prevalent presence of α‐pinene and p‐cymene together with different cyclic unsaturated hydrocarbons. Only small quantities of linear dimers were found. Possible reaction mechanisms are presented.
Inverse‐microsuspension polymerization: Mechanism, kinetics and modelling
Authors: Hunkeler David
Published: March 2011

A mechanism has been developed for the inverse‐ microsuspension polymerization of acrylic water soluble monomers. This free‐radical reaction scheme includes elementary reactions for polymerization in the aqueous and organic phases, nucleation in the monomer droplets and heterophase oligoradical precipitation. The latter being the dominant initiation process. A unimolecular termination reaction with interfacial species has also been elucidated and has been found to compete with and often dominate over the conventional biomolecular reaction. A kinetic model is developed which includes the influence of ionogenic monomers and polyelectrolytes and is able to predict the rate, molecular weight and composition data well for polymerizations of acrylamide and copolymerizations with quaternary ammonium cationic monomers. A categorization and systematic nomenclature for heterophase water‐in‐oil and oil‐in‐water polymerizations is also developed based on physical, chemical and colloidal criteria.
Thermal polymerization of arylacetylenes: A stepwise activated monomer mechanism
Authors: Sekiguchi Hikaru , Kang Hee‐Cheol , Tersac Gilles , Sillion Bernard
Published: March 2011

Kinetics of the thermal polymerization of ATR(acetylene‐terminated resin) model compounds, bisphenol A monobenzyl mono(ethynylaryl) ethers, was studied by means of GPC and the resulting oligomers were characterized by FTiR, UV, and H1 NMR techniques. It was found that monomer was consumed rapidly at first, and later slowly, yielding a mixture of dimer, low oligomers (DP ⩽ 6) and higher ones. The concentrations of every lower species remained nearly constant throughout the polymerization (except first ten minutes). In order to account for these results, a new mechanism involving the activation of monomer and its attack on the end unit of the polymer chain was proposed. This is the first example of activated monomer mechanism (a. m. mechanism) for non‐catalyzed polymerization of unsaturated monomers and, at the same time, the first example of stepwise a. m. mechanism. The structure of the resulting polymer will be discussed on the basis of this mechanism.
Copolymerization of methyl vinyl ketone with styrene in the presence of cobalt(II) nitrate
Authors: Masuda Seizo , Minagawa Keiji , Tanaka Masami , Asahi Yutaka
Published: March 2011

Copolymerization of methyl vinyl ketone (MVK) with styrene was carried out at 50°C in the presence of cobalt(II) nitrate. The resulting monomer reactivity ratios decreased with an increasing concentration of the cobalt salt. This finding suggests that the metal salt participates in the propagation step of the copolymerization. Absolute copolymerization parameters were determined by assuming a three‐component system as free MVK (M1), MVK complexed with cobalt(II) nitrate (M2), and styrene (M3): k11/k12 = 0.184, k11/k13 = 0.235, k22/k21 = 7.18 × 10−2, k22/k23 = 6.79 × 10−4, k33/k31 = 0.380, and k33/k32 = 2.77 × 10−3, and Q2 = 19.65 and e2 = 2.83. The complexed MVK monomer is more reactive to the polymer radical with the terminal styrene unit than the free MVK. Very small values for the monomer reactivity ratios, k22/k23 and k33/k32, show the marked alternating tendency for the copolymerization of the complexed monomer with styrene. In practice, however, alternating copolymer could not be obtained because of the poor solubility of cobalt(II) nitrate.
Grafting of amino groups on polybutadiene by hydrosilylation
Authors: Hazziza‐Laskar Judith , Hélary Gérard , Sauvet Georges
Published: March 2011

Hydrosilylation catalyzed by hexachloroplatinic acid was used to introduce tertiary amino groups in an hydroxytelechelic polybutadiene. Kinetics and mechanisms were investigated. At low silane concentration, the reaction is first‐order in Pt, second‐order in silane and zero‐order in vinylic double bonds. The apparent rate constant is inversely proportional to the concentration of amino groups (inhibitory effect). At high silane concentration, very sharp acceleration periods are observed and explained by a transformation of a weakly active Pt(II) catalyst into a more active Pt(O) compound.
New filaments and fibres of polyetherimide
Authors: Böhringer B. , Schilo D. , Birkenfeld W. , Odenthal W.
Published: March 2011

Polyetherimide is a high‐performance polymer which can be extruded to fibres and filaments. The threads are amorphous and have a smooth and closed surface. The material can be drawn and subsequently processed to textiles in the conventional way. Filaments of polyetherimide are flame‐resistant. The chemical resistance of polyetherimide is good; the polymer is particularly resistant to diluted acids, salts and oxidants.
Nonlinear viscoelastic stress relaxation behaviour of aramid fibers
Authors: Wortmann F.‐J. , Schulz K.
Published: March 2011

With the increasing demand for polymers as materials for construction, the exact analysis of their mechanical properties in general and of their viscoelastic performance in specific becomes of increasing importance. An analytical model is introduced which enables to systematically describe the influence of strain on the stress relaxation performance of Kevlar®, Nomex®, and Technora®. The analysis is based on a two‐phase model, comprised of an elastic and a viscoelastic contribution and a shape‐invariate relaxation function. The change of the phase moduli and of the mean relaxation times with strain is documented for the three aramid fibers and discussed with respect to their morphological structures.
Silicate coupling layer for metal to polymer adhesion improvement: Physical‐chemical fundamentals and technological importance
Authors: Tiller H.‐J. , Göbel R. , Gutmann N.
Published: March 2011

Silicated metal surfaces may improve the adhesion of polymers to metal surfaces. Two different methods of silicate formation ‐ a flame pyrolysis of orthosilicates and a sol‐gel coating based on a CrIII‐ doped SiO2‐sol ‐ are proposed. The coupling of the SiO2‐layer on the metal oxide surface, their structure and morphology and, the effect of the silane coupling agent on the adhesion mechanism are discussed. The formation of stable and durable compounds is proved by shear strength measurements and SEM analysis of the interface after boiling tests. Additionally, the adhesion of glued joints between glasses, ceramics and metals is also improved by this method.
Effect of the polymer matrix on the properties of advanced composites
Authors: Altstädt Volker
Published: March 2011

The relationships discussed here clearly show that for the development of composite materials a multidisciplinary approach encompassing polymer chemistry, physics, engineering and material science is necessary. The complex composition of fiber reinforced polymeric composite materials, involving the synergistic interplay of individual components, requires new methods for the development of materials, which are not solely based on the formulation chemistry of the components.

In the future, resistance against the application of advanced composites must be reduced, by gaining more confidence in the performance of this new class of materials with a fundamental understanding of their properties and potential. It will thus be possible to abolish unreasonable test methods and to use design characteristics which take maximum advantage of this material class.
Combination of glass fibres and minerals in polyamides
Authors: Hewel M. , Sun F.
Published: March 2011

Polyamides reinforced with glass fibres are characterised by high values for modulus of elasticity and notched impact strength but also have the negative properties of rough surfaces and anisotropy ‐ particularly anisotropic shrinkage. Mineral‐filled polyamides have good surface properties, are isotropic and have high impact strength, however, the elasticity modulus is only slightly better than for normal polyamides and notched impact strength values are relatively low.

Through a combination of glass fibres and mineral filler, surface properties can be improved and anisotropy reduced. In order to achieve the optimum mechanical properties a range of 0 ‐ 50 wt.‐% glass fibre content and 0 ‐ 40 wt.‐% mineral content was systematically examined using statistically designed experiments. This investigation showed the relationship between the “Responses”, surface appearance, shrinkage, modulus of elasticity, impact strength and tensile properties and the “variables”, glass fibre and mineral content. Optimal products, based on the model functions, can be chosen in this way.
Dynamics and deformation behaviour in non‐hydrogen bonded model urethanes under heat and stress as studied by dielectric and infrared spectroscopy
Authors: Boese D. , Eisenbach C. D. , Fischer E. W. , Hayen H. , Nefzger H. , Planer‐Kühne G. , Reynolds N. , Spiess H. W.
Published: March 2011

A model polyether‐urethane with monodisperse N‐alkyl polyurethane hard segment has been investigated by differential scanning calorimetry, dielectric spectroscopy and infrared spectroscopy. The temperature dependent changes in the enthalpic and dielectric properties have been correlated with specific molecular motions and transition processes in the hard and soft phase. The orientation of the hard and soft segments under uniaxial stress changes with the strain and mechanisms for the orientation and deformation behaviour have been proposed. Effects of the thermal history of the sample on the properties have been discussed as well.
Liquid‐crystalline silsesquioxanes
Authors: Kreuzer Franz‐Heinrich , Maurer Robert , Spes Peter
Published: March 2011

Liquid‐crystalline silsesquioxanes were synthesized by combining mesogens with spherical silsesquioxanes. Most of the synthesized compounds exhibit smectic phases. Lateral connection of a mesogen results in a nematic phase. All phases are optical uniaxial positive, i.e. calamitic structures are favoured. LC‐silsesquioxanes represent a new group of liquid‐crystalline side‐chain polymers with backbones ranging from centrosymmetric cage like structures of siloxanes or heterosiloxanes to linear ladder structures. They can be considered as the link between the linear side‐chain polymers and surface treated silica or quartz.
Thermotropic poly(urethane)s from nematic diisocyanates
Authors: Mormann Werner , Benadda Saria
Published: March 2011

A number of novel triad diesterdiisocyanates with a core of either a (substituted) hydroquinonedibenzoate or diphenyl terephthalate are described. Due to their higher aspect ratio (length of mesogenic core) with regard to diad esterdiisocyanates, thermotropic diurethanes and hard segment type poly(urethane)s are obtained and characterized with regard to their phase behaviour. The influence of the structure of the diisocyanate as well as that of the diol is discussed.
Structure, dynamics and phase separation in liquid crystalline polymers, block copolymers and blends as revealed by solid state NMR spectroscopy
Authors: Spiess H. W.
Published: March 2011

A short survey is given of possibilities solid state NMR techniques offer for the study of functional polymers. Three examples are described explicitly, photoinduced reorientation of liquid crystalline polymers considered for information storage, phase separation and the mobility in the interfacial regions in segmented model polyurethanes composed of hard and soft segments and determination of domain sizes in incompatible polymer blends.
Time‐resolved, static light scattering: New possibilities in polymer characterization
Authors: Becker A. , Schmidt M.
Published: March 2011

We have developed a highly sensitive, multi‐angle, static light scattering (TRSLS = time resolved static light scattering) instrument, which measures the angular dependent Rayleigh scattering intensity of solutions simultaneously at 38 angles within approximately one second. It is thus suitable as a quick and easy to use static light scattering device for routine polymer and colloid characterization. The time resolution allows the kinetics of many systems to be investigated down to a second time scale, such as polymerization kinetics of linear, branched and crosslinked polymer structures, thermoreversible gelation, growth of colloidal particles, structural changes in micellar systems, etc.
Molecular structure and dynamics in monolayers of long chain alkanes and alkyl‐derivatives
Authors: Rabe Jürgen P. , Buchholz Stefan
Published: March 2011

Long chain alkanes (C34H70 and C50H102), a fatty acid (C17H35COOH) and an alkyl‐substituted triiodobenzoate (I3H2C6COOC18H37) have been adsorbed at the interface between organic solutions and the basal plane of graphite. In‐situ scanning tunneling microscopy (STM) has been employed to investigate their structure and dynamics on the scale of 10 pm and 1 ms or longer. All adsorbates form two‐dimensional polycrystals. The molecules tend to organize in lamellae with the extended alkyl chains oriented parallel to a lattice axis within the basal plane of graphite. The n‐alkane chains pack in a lattice commensurate with the graphite lattice and the carbon skeleton planes approximately perpendicular to the substrate. Due to the additional space required by a carboxyl end group the alkyl lattice in the fatty acid is incommensurate with the substrate and the carbon skeleton planes lie approximately parallel to the surface. In the triiodobenzoate the headgroup takes the space of about two alkyl chains resulting in an interdigitated packing.
Main‐chain side‐chain liquid crystal polymer blends for improved physical properties
Authors: Cheng Wei‐Ming , Rasoul Husam A. A. , Stackman Robert W.
Published: March 2011

Previous work has demonstrated that compatible blends of main‐chain liquid crystal polymers (LCP) with side‐chain LCP's can be prepared. The present work was carried out to extend the scope and application of this finding to liquid crystal polyesters, similar to commercially available LCP's and to demonstrate the effect of the blend composition upon the physical and mechanical properties. A series of melt‐processable main‐chain polyesters was prepared as well as a series of acrylic polymers and copolymers which possess a side‐chain mesogenic unit, similar to that of the main‐chain LCP's. While the results of the blending studies of these high molecular weight materials were somewhat ambiguous as to compatibility, there are strong indications that the presence of the side‐chain mesogen containing polymers does result in an improvement in the overall mechanical properties of the main‐chain LCP.