bluuebunny/crossref_metadata_2025 huggingface dataset:
Charge transfer interactions in liquid crystalline polymers probed by fluorescence spectroscopy
Authors: Horie Kazuyuki , Huang Hsuwen , Sone Masato , Watanabe Junji
Published: March 2011

Rigid‐rod aromatic LC polyester with long alkyl side chains and two thermotropic LC polyesters (PET40/OBA60 and PB‐10) were studied by fluorescence spectroscopy to investigate their charge transfer interactions corresponding to LC configuration and changes during phase transition.
Theoretical aspects of systems with competing interactions
Authors: Kramer Edward J.
Published: March 2011

This contribution from a non‐theorist aims to give some introduction to the following theoretical papers as well as some of the points brought out in the oral discussion.
Thermodynamic order and random disorder in liquid crystal elastomers
Authors: Terentjev Eugene M.
Published: March 2011

This article focuses on the continuum aspects of liquid crystal elastomer structure. There are two opposing tendencies, the lack of thermal fluctuations that enhances the order in the system, and the random quenched disorder that leads to a highly frustrated polydomain state in equilibrium. Imposing an external field (mechanical stress) changes the balance between order and disorder, this process being monitored by a polarised light scattering.
Interplay of ionic and nonionic interactions in weakly charged polyelectrolytes
Authors: Khokhlov Alexei R. , Makhaeva Elena E. , Zeldovich Konstantin B.
Published: March 2011

We describe the results of theoretical and experimental studies of the regular heterogeneities on a nanometer scale which are formed in the systems containing weakly charged polyelectrolytes due to the competition of ionic and hydrophobic interactions. In particular, we consider the effect of microphase separation in poor solvent polyelectrolyte solutions and gels and nano‐self‐assemblies emerging in the complexes of polyelectrolyte gels with oppositely charged surfactants. The practically important application connected with metal nanoparticles formation in regular microstructures in polyelectrolyte systems is considered as well.
Influence of crystallinity on the morphology of poly(ethylene oxide) containing diblock copolymers
Authors: Hillmyer Marc A. , Bates Frank S.
Published: March 2011

Low‐molecular‐weight poly(ethylene oxide)‐polyalkane (PEO‐PA) diblock copolymers have been examined between the order‐disorder transition and PEO melting temperature using small‐angle neutron scattering (SANS), differential scanning calorimetry (DSC), and dynamic mechanical spectroscopy (DMS). Crystallization imposes layered ordering with polymer stems oriented perpendicular, or tilted, relative to the microdomain interface, thereby disrupting conventional amorphous microdomain morphologies. This effect can be used to switch the high symmetry bicontinuous ordered G phase to lower symmetry cylinders or lamellae.
Ferroelectric block copolymers
Authors: Brehmer M. , Mao G. , Ober C.K. , Zentel R.
Published: March 2011

A block copolymer consisting of polystyrene and a side chain ferroelectric liquid crystalline polymer was synthesized using polymer analogous chemistry on a monodisperse poly(styrene‐b‐isoprene). Composition was adjusted to give lamellar microstructure after addition of the mesogenic side groups. If placed in an LC cell without orientation of domains, no ferroelectric response was observed. After shearing the thin film, presumably due to alignment of lamellae, a bistable ferroelectric switching could be detected.
Hybrid materials made from polymeric betaines and low molar mass salts
Authors: Bonte Nelly , Laschewsky André , Vermylen Valérie
Published: March 2011

The blending of polyzwitterions with low molar mass salts, in particular with salts containing bulky, organic ions is studied. In many cases, homogeneous blends are obtained using stoechiometric amounts of salt, and in selected cases, the amounts of salt which can be admixed is even substantially higher. In contrast to inorganic salts, bulky organic salts are efficient plasticizers. Although the fundamental interaction in such blends is of electrostatic nature, the miscibility depends in a subtle way on specific interactions between particular ionic groups as well as on the molecular structures of polymer and salt.
Induction and stabilization of liquid crystal order in H‐bond complexes containing non‐mesogenic species
Authors: Talroze Raissa V. , Kuptsov Sergei A. , Lebedeva Tamara L. , Shandryuk George A. , Stepina Nina D.
Published: March 2011

A new approach to create mesomorphic ordered systems is discussed. It is based on the idea to use noncovalent interactions in the designing of thermotropic structures by modelling lyotropic liquid crystal (LC) when the water interlayer is changed by appropriate solid substances that are able to interact with the polar part of an amphiphilic molecule without any strong change in the intermolecular interactions between the non‐polar “tails”.
Length scales in heterogeneous polymers from solid state NMR
Authors: Spiess H. W.
Published: March 2011

New methods for probing structure and dynamics of heterogeneous polymers by multidimensional nuclear magnetic resonance (NMR) are described. On the molecular level high resolution multiple quantum spectroscopy of solids probes connectivities of different functional groups on length scales below 1 nm. On a mesoscopic scale NMR spin diffusion techniques probe phase separation and interfacial effects in polymer blends and block copolymers. On a macroscopic scale NMR imaging techniques allow to spatially resolve differences in order and mobility in the necking region or in shearbands of deformed polymers. The techniques are illustrated with amorphous polymers, elastomers, and core‐shell systems.
The effects of hydrogen bonding on the liquid crystalline behavior of semiflexible poly(urethaneester)s
Authors: Laus Michele , Angeloni Annino Sante , Francescangeli Oriano , Galli Giancarlo , Chiellini Emo
Published: March 2011

The peculiar liquid crystalline behavior of two poly(urethane‐ester)s TDI‐C6C4 and TDI‐C6C8 is reported. Evidence is provided of the formation of two nematic mesophases, a cybotactic nematic and a conventional nematic mesophase, in TDI‐C6C8 and of one cybotactic nematic mesophase in TDI‐C6C4. IR spectroscopy indicates that different hydrogen bonded and non‐bonded structures occur with varying temperature. The transition from the nematic cybotactic mesophase to the nematic mesophase, or to the isotropic phase, is accompanied by a substantial decrease of the strength of the hydrogen bonds. This is also reflected in the dynamic‐mechanical behavior of these poly(urethane‐ester)s which is similar to the one of slightly crosslinked thermoreversible networks.
Hydrogen bonding as the origin of both liquid crystallinity and polymer formation in some supramolecular materials
Authors: Lee Chien‐Ming , Griffin Anselm C.
Published: March 2011

The use of lateral substitution on the aromatic rings of the diacid component of diacid/bispyridyl AABB supramolecular LC polymers is effective at retarding crystallization presumably by introducing a ‘carbuncle’ along the chain which interferes with the requisite efficient close packing of molecular units. We have examined both one and two chloro groups per ring and have observed a glass transition and fiber formation in the least crystalline complex.
Synthesis of block copolymers by oligomer‐coupling reactions in the bulk: Bisimidazoline/cooh and bisoxazolinone/nh2 reactions
Authors: Fischer Thomas , Lefèbvre Hervé , Fradet Alain
Published: March 2011

The polyaddition reaction of bisimidazolines with α, ω‐dicarboxy polyamide‐12 in the bulk at 200–240°C (oligomer coupling reaction) produces high MW polymers, while degradation reactions were observed with aliphatic polyesters. The chain extension of a α, ω‐dicarboxy polyamide‐polyoxytetramethylene‐polyamide oligomer with 2, 2'‐tetramethylene‐bis(imidazoline) yielded a poly(poly‐ether‐block‐polyamide). 4‐substituted and 4, 4‐disubstituted bis(5(4H)oxazolinones) are efficient coupling agents for amino‐terminated oligomers, allowing the rapid synthesis of copolymers containing polyether and polyamide blocks. The chemistry of these chain‐coupling reactions has been studied by NMR. DSC shows the phase separation between the hard (polyamide) and the soft (polyether) blocks.
Structure development and change in properties of polymers during mechanical degradation
Authors: Xu Xi
Published: March 2011

The effects of ultrasonic irradiation, high speed stirring and vibro‐, jet‐ or pan‐milling on structure and change in properties of polymers were studied in hopes of gaining an innovative route to enhance the processability and properties of polymer materials via polymer stress reaction. A brief survey of ongoing research work done by the author and his colleagues is given in this paper.
Influencing polymer properties by regiospecific complexation
Authors: De Witte Inge C. , Bogdanov Bogdan G. , Goethals Eric J.
Published: March 2011

ABA block‐copolymers in which the A segments are capable of forming complexes and B is a non‐complexing segment, have been used to prepare polymer materials with properties that can be changed by adding a complexing agent. The complex forming segments were poly(ethylene oxide) (PEO), linear polyethylenimine (LPEI) and poly(N‐tert‐butylethylenimine) (PTBEI).

Commercially available liquid ABA block‐copolymers, in which A is PEO and B is poly(propylene oxide), were investigated with high molar mass poly(acrylic acid) (PAA) as the complexing agent for PEO. It was found that the mixtures containing 3 to 7 wt.‐% of PAA, showed a marked shear‐thickening behavior leading eventually to gelation. This was attributed to the transformation of intramolecular polymer complexes, at low shear rates, to intermolecular complexes, at high shear rates, due to the chain stretching of PAA. ABA copolymers in which A is LPEI or PTBEI and B polytetra‐hydrofuran (PTHF), were prepared. Complexation of these copolymers with low molecular weight poly‐acids or PAA in polar and non‐polar solvents as well as in bulk have been investigated. ABA copolymers in which A is PEO and B a PTHF segment were prepared. These block‐copolymers show two melting points: one at appr. 55°C, due to the PEO segments, and one at appr. 30°C due to the PTHF. Upon addition of alkali metal salts such as sodium iodide or sodium thiocyanate, complexes with PEO are formed and as a consequence, the melting point of the PEO segments shifts to appr. 160°C. The complexed materials behave as thermoplastic elastomers up to that temperature.
Functionalization of polyolefins in the melt through reaction with molecules and macromolecules
Authors: Ciardelli Francesco , Aglietto Mauro , Ruggeri Giacomo , Passaglia Elisa , Castelvetro Valter
Published: March 2011

Functionalization of polyolefins with diethyl maleate (DEM) is investigated to improve compatibility with other polar polymers through reactive blending. Functionalization experiments were carried out in the melt with peroxide initiator and mechanical mixers as reactors. The effect of feed composition, reactor type and duration on the functionalization degree, degradation and crosslinking reactions were examined starting with different ethylene polymers. In this way conditions were identified allowing modulation of functionalization with 2‐(diethyl succinate) groups from 0.2 to 2.5% mole, and keep to negligible level undesired by‐reactions such as crosslinking and degradation. The chemical reactivity of these functional groups to form interchain covalent bonds was investigated in case of the reaction of the ester groups on the polyolefin backbone with the amino end group of linear polyamides (in particular PA 6). Evidences of the formation of grafted polymer on the basis of fractionation of the resulting mixture, instrumental analysis and morphological characterization are presented.
Melt memory effects in polymer crystallization
Authors: Alfonso Giovanni C. , Scardigli Paolo
Published: March 2011

Polymer melts submitted to local shear flow fields, as well as isotropic solid samples, were treated in the melt at different temperatures and for various duration of time. The effects of thermal history on kinetics and morphological characteristics of subsequent isothermal crystallization was investigated. Results suggest that subcritical pseudocrystalline aggregates, behaving as predetermined athermal nuclei when temperature is brought below melting point, can survive in the melt for long time. Their concentration decays exponentially with a single characteristic relaxation time. For all investigated polymers, temperature dependence of relaxation times can be fitted by an Arrhenius law with high apparent activation energy. Experiments performed with narrow molecular weight fractions of poly(ethylene oxide) suggest that relaxation times relevant to destruction of oriented nucleation precursors are proportional to M1,5.
Modern problems of the theory of macromolecular reactions in polymer blends
Authors: Platé Nicolai , Litmanovich Arkady , Yashin Victor , Kudryavtsev Yaroslav , Govorun Elena
Published: March 2011

The main task of the theory of macromolecular reactions in polymer blends is to describe an evolution of the blend structure under the concerted action of the reaction and interdiffusion. For a polymeranalogous reaction proceeding with autoacceleration in a compatible blend, the task has been solved by methods of linear non‐equilibrium thermodynamics. The set of reaction‐diffusion equations derived permits to describe the blend structure in details, including the parameters characterizing compositional heterogeneity and units' distribution of the reacting chains in any local region of the blend. For incompatible blend of two homopolymers, the competition between a phase separation and the reaction of end‐coupling with a formation of diblock‐copolymer has been considered. The peculiarities of the processes mentioned as well as the actual problems in this field are discussed.
Polymer composites with dual gradient structure
Authors: Choe Chul Rim , Park Min
Published: March 2011

Functionally dual gradient type of carbon fiber reinforced epoxy composites, in which crosslinking density of epoxies and content of carbon fibers are gradually varied through the thickness, were fabricated by using centrifugal force. The spatial variation of fiber content and the crosslinking density change of epoxies were confirmed by checking densities and glass transition temperatures, respectively, along the thickness. The mechanical properties of the polymer composites were also measured.
Polyarylate gas separation membranes
Authors: Paul D. R. , Pixton M. R.
Published: March 2011

The molecular design of polymers for membrane separation of gases is illustrated for the oxygen/nitrogen pair by a series of polyarylates. The use of tetrabromo ring substitutions combined with a fluorene connector group on the bisphenol with or without a t‐butyl group on the isophthalic acid monomer leads to state‐of‐the‐art productivity‐selectivity combinations.
In‐situ complex membrane: Dehydration of pyridine aqueous solution by pervaporation
Authors: Lee Young Moo , Oh Boo‐Keun
Published: March 2011

In this study, we proposed in‐situ complex(ISC) membrane as a new type of PIC. We adapted simple acid/base reaction to invent the ISC membrane and applied to the dehydration of pyridine aqueous solution. ISC forms from the interaction of pyridine in feed and acid moiety in membrane and enhances the water transport through the membrane because of its hydrophilic nature. We compared the separation results by using ISC concept with those of non‐ISC membranes and investigated the effect of the concentration of acid moiety in the membrane on the dehydration of pyridine/water mixture.
Synthesis and thermal modification of n‐substituted functional polymaleimides
Authors: Chung Chan‐Moon , Ahn Kwang‐Duk
Published: March 2011

Syntheses, advantageous thermal modification and properties of variously N‐substituted functional polymaleimides are described. Specific thermal properties of the polymers monitored by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) are summarized. The facile modification of the functional polymaleimides by thermal or acid‐catalyzed deprotection offers versatile means in functional transformation and lithographic application of the polymers.
Development of a multideveloping photoresist and its application to make liquid crystal display color filter
Authors: Tseng C. H. , Liu J. M. , Cheng H. C. , Hsieh P. J.
Published: March 2011

This paper reports the fabrication of a single expose multideveloping positive Diazonaphthoquinone (DNQ) /Novolak photoresist capable of simplifying the fabrication process of color filter plates composed of red, green, blue pixels and black matrix. Film thickness retention was measured on multideveloping photoresist(MDPR) containing novolak resins made from various phenolic compounds including cresols, xylenols, trimethylphenol, resorcinol and their copolymers. It was found that there were suitable combinations of phenolic compounds to exhibit appropriate thermal stability, wide process window as well as compatibility to electrodeposition of color films.
Bioconjugate polymer materials that control cell functions
Authors: Imanishi Yukio , Ito Yoshihiro
Published: March 2011

Several examples of controlling cell functions in serum‐free culture media containing immobilized growth factor are reported. First, the growth and adhesion of cultured STO cells was regulated by insulin conjugated with thermo‐responsive polymers. Second, a photo‐immobilization technique was applied to insulin immobilization, and the photo‐immobilized insulin accelerated the growth of CHO cells. Third, photo‐immobilized EGF affected the differentiation of PC‐12 cells. Finally, a patterned artificial juxtacrine stimulation of CHO cells by insulin covalently immobilized by photo‐lithography is discussed.
Synthesis and characterization of biocompatible and biodegradable polymers
Authors: Sung Yong Kiel , Song Dae Kyung
Published: March 2011

New polyesters were synthesized using Krebs cycle acids. Poly(1, 4‐butanediol dilactate succinate)(PBDS) and poly(1, 4‐butanediol dilactate 2‐acetoxy succinate)(PBDAS) were prepared by the polycondensation of 1, 4‐butanediol dilactate with succinic anhydride and 2‐acetoxy succinic acid, respectively. Poly(1, 4‐butanediol succinate)(PBS) was also synthesized from 1, 4‐butanediol and succinic anhydride. PBS/PBDS and PBS/PBDAS blends were prepared by the method of solvent casting. The effects of crystallization time and temperature onto melting behavior of PBS/PBDS and PBS/PBDAS blends were investigated by differential scanning calorimetry. The compatibility of each blend system was discussed using equilibrium melting point depressions. The biodegradation behavior was studied using PBS, PBDS, and PBDAS as the sole carbon source by Aspergillus niger. The molecular weights of the polymers which were obtained from GPC analysis decreased after degradation in five weeks.
Evaluation of the curing state of epoxy thermoset systems
Authors: Lachenal Gilbert , Poisson Nicolas , Sautereau Henry
Published: March 2011

The characterization of thermoset networks has been carried out using numerous techniques but accurate determination of the extent of reaction is sometimes difficult. Some of these techniques have ben evaluated rapidly. As example, curing of epoxy‐hardener systems have been investigated by DSC, infrared spectroscopy and other techniques and results were compared. Advantages and drawbacks of each technique are discussed and the risks of obtening misleading results for the kinetic studies or for the determination of reaction extent are underlined. Theses conclusions can be applied to numerous reactive thermoset systems.
Study of the spectral properties of inhomogeneous granular materials
Authors: Ventura CÉLine , Papini Marie
Published: March 2011

The variation of the spectral properties of semi‐transparent (polystyrene: PS), transparent (potassium bromide: KBr) and opacified particles (silver coated silica spheres: Ag‐SiO2) is presented from 0.25 to 20 μm. The spectral properties of binary mixtures PS/KBr and PS/Ag‐SiO2 are also studied.

The sensitivity of the spectral properties to the particle diameters causes the near‐normal hemispherical spectral reflectance R to decrease when the particle size increases from 10 to 1800 μm. The addition of KBr transparent particles to PS powders results in an increase in the reflectance values of the mixtures in the near and mid‐infrared wavelength range. Furthermore, the effect of the addition of opacified reflecting particles depends on the wavelength region and on the PS content ([PS]). For < < 1.64 μm, R decreases when [PS] decreases from 1 to 0.56 and then R increases for [PS] values decreasing from 0.56 to 0. For < > 1.64 μm, R decreases when PS content increases from 0 to 1.
Spectroscopic evidence of the polymer tacticity as an important parameter for the configuration of the adsorbed pmma layer
Authors: Grohens Yves , Brogly Maurice , Labbe Clorinthe , Schultz Jacques , Prud'homme Robert E.
Published: March 2011

PMMAs with a racemic fraction (fr) ranging from 0.07 to 0.9 and a molecular weight of about 40000 Dalton are adsorbed on aluminum mirrors and alumina powder. The fraction of bonded carbonyl group (p) linked to the substrate by acid‐base interactions is determined by infrared spectroscopy in reflectance mode (IRAS for aluminum mirrors, DRIFT for alumina powder). Calculated values of p range from 0.5 to 0.2 from isotactic to syndiotactic isomers. Ellipsometric thickness (h) of PMMA films are measured on aluminum surfaces and provide values increasing with the average syndiotactic sequence length (ns). Solid state 13C NMR is performed on PMMA adsorbed on alumina powder to provide experimental evidence of interfacial conformational changes. The changes in methylene carbon chemical shift, due to a lowering in the γ‐gauche effect, are more pronounced for isotactic PMMA than for the syndiotactic form. These experimental results lead to the conclusion that the extent of flattening of polymer chains on the substrate depends on the PMMA stereoregularity.
Inelastic neutron scattering studies of polyethylene and N‐alkanes
Authors: Parker Stewart F.
Published: March 2011

High quality inelastic neutron scattering (INS) spectra of randomly oriented polycrystalline polyethylene, perdeuteropolyethylene and highly oriented polyethylene are presented. The instrumental resolution was significantly better than previous work and has revealed increased detail in the 0 − 600 cm−1 region. For the polycrystalline sample, comparison with the best available dispersion curves shows that these qualitatively reproduce the INS spectrum, apart from the energy of the maximum in the in‐plane C‐C bending mode v5. For the oriented samples, comparison with calculated INS spectra show fair, but not exact, agreement with the experimental spectra.
Application of polymer spectroscopy to the characterization of a sticking gel used in fabrics printing
Authors: Larena Alicia , De Ríol José Manuel
Published: March 2011

The goal of this paper is the making of several physico‐chemical analyses in order to identify the different components which integrate a sticking gel used in fabrics printing. The polymer spectroscopy analyses include infrared spectroscopy and mass spectrometry. Once the main compounds of the sticking gel are found out, we describe the usual components that can be found in a sticking gel formula and each contribution to the final behaviour of the whole, as well as its right adjustment for some given printing conditions, which place this kind of commercial products in an unsurpassable situation, with no rival in this field.
Electron beam curing of methacrylated gelatin studied by EPR and FT‐Raman spectroscopy
Authors: Scherzer Tom , Beckert Annett
Published: March 2011

Gelatin was modified with glycidyl methacrylate. The methacrylated gelatins were cross‐linked by electron irradiation. The cross‐linking process was studied by FT‐Raman and EPR spectroscopy.
Dextran fatty acid esters as polymeric surfactants with low hemolytic activity
Authors: Bauer Kurt H. , Reinhart Thomas , Stenz Robert
Published: March 2011

Practically all low molecular weight surfactants show hemolytic activities. Aside of this serious disadvantage almost all low molecular weight solubilizers cause considerable side effects, particularly during or after parenteral application. Polymeric surfactants, however, usually show no or only very little hemolytic effects. They therefore are supposed not to be able to penetrate neither into cellular or erythrocyte walls nor into phospholipid bilayers, resp., similar bilayer membranes due to their large molecular size. Therefore no decay of biological bilayers should be expected with polymeric surfactants. The only pharmaceutically widely used polymeric surfactants are at the moment polyoxyethylene‐polyoxypropylene block copolymers (poloxamers (INN), Pluronicsr̀ and Pluriolsr̀). Unfortunately they have only poor solubility capacities. In order to find better solubilizing polymeric surfactants, some water soluble dextran fatty acid esters (Ref. 1) were synthesized and tested with respect to their solubilisation capacity and hemolytic activity.

Usually the hemolytic activity is tested by standard methods using purified animal or human erythrocyte suspensions. As erythrocytes also contain a relatively high amount of lactose dehydrogenase (LDH), we studied the suitability of the highly sensitive, and in the medical diagnostic well known LDH test, as a supplemental hemolytic determination method (Ref. 2). The advantage of this test is, that there is no need of the time consuming purification and standardization as it is required with the erythrocytes' suspension. It can be performed with original blood and without costly preparations at all.

The synthesized dextran fatty acid esters proved themselves as very little hemolytic and, compared with the polyoxyethylene‐polyoxypropylene block copolymers, they show improved solubilisation capacities.
Silylation of cellulose regiocontrolled by bulky reagents and dispersity in the reaction media
Authors: Koschella Andreas , Klemm Dieter
Published: March 2011

Reaction of cellulose (1) with the bulky thexyldimethylchlorosilane (TDMSCl) leads to regioselectively functionalized silyl celluloses with degree of substitution (DS) up to 2. Uniform 6‐O‐thexyldimethylsilyl cellulose (2) was obtained in ammonia‐saturated aprotic dipolar media, which was unexpected in a heterogeneous reaction. On the contrary, the 6‐O‐selectivity is low under homogeneous conditions in a N,N‐dimethylacetamide (DMA)/LiCl solution, and with an excess of TDMSCl 2,3‐di‐O‐thexyldimethylsilyl cellulose (3) can be synthesized. The polymer structures were characterized by two dimensional NMR spectroscopy after subsequent methylation (polymers 4 and 5), desilylation (polymers 6 and 7) and acetylation (polymers 8 and 9) as well as by HPLC after chain degradation of 4 and 5 to the complementary methyl glucoses.
NMR studies of chiral discrimination by phenylcarbamate derivatives of cellulose
Authors: Okamoto Yoshio , Yashima Eiji , Yamamoto Chiyo
Published: March 2011

Chiral recognition mechanism of tris(4‐trimethylsilylphenylcarbamate) (1) and tris(5‐fluoro‐2‐methylphenylcarbamate) (2) of cellulose which are effective chiral stationary phases for HPLC were investigated using NMR spectroscopy. The phenylcarbamate derivatives are soluble in chloroform and exhibited chiral discrimination for several enantiomers in NMR as well as in HPLC. Especially, enantiomers of 2,2'‐dihydroxy‐1,1'‐binaphthyl (4) were distinctly discriminated by 2 in 1H and 13C NMR spectroscopies. The binding geometry and dynamics between 2 and the enantiomers of 4 were investigated on the basis of spin‐lattice relaxation time, 1H NMR titrations, and intermolecular NOEs in the presence of 2. These NMR data were fully consistent with the chromatographic elution order. On the basis of these results, combined with molecular modeling, the chiral discrimination mechanism is proposed.
Chemical stability of some model polysaccharides
Authors: Franz Gerhard , Feuerstein Ulrike
Published: March 2011

A series of different Polysaccharides with actual or potential medicinal or industrial utilization such as linear fructans of the inuline type, branched fungal ß‐1.3, 1.6‐glucans, galactomannans of the guar type, acidic polysaccharides such as alginates, pectins were submitted to experimental stress‐ and non stress conditions. The resistance to humidity, thermal degradation, pH influence and microbial decomposition was studied by measuring the relative viscosity, reduction in DP values, degradation of specific conformations and glycosidic linkages.

It could be clearly shown that most polysaccharides are stable at room temerature in a dry environment. At increased temperature even in the absence of water, polymer decomposition was documented. Polysaccharide solutions, when stored under thermal stress (40°, 60°, 80°C), showed structure dependent rapid progress in degradation of primary and secondary structures. The kinetics of these decompositions were measured over prolonged periods in order to give a practical background for the utilization of such polymers in pharmaceuticals, cosmetics and food products.
Segmented polymers — A new class of doped non‐conjugated polymers with enhanced electrical conductivity
Authors: Schopov Ivan , Sinigersky Vesselin
Published: March 2011

A new class of segmented non‐conjugated dopable polymers, built up from short conjugated blocks connected with flexible chains (spacers), has been proposed. After the redox reaction of doping these polymers exhibit properties similar to those of the fully conjugated polymers and increase considerably their electrical conductivity. A solid state polymer effect has been observed. It has been found that the conjugated building units (biphenyl, diphenyl ether and 1,3,4‐oxadiazole) do not interact with the dopant when included in a low molecular weight substance. When these units are incorporated in a polymer chain they change their reactivity and the polymer can be doped. The doping process takes place only when the polymer is in the solid state and the nature of this phase is of considerable importance. The phenomenon observed, i.e. doping of non‐conjugated polymers with segmented structure could be explained with a favourable arrangement of the conjugated blocks in the solid phase, leading to enhanced π‐π ‐ interaction (equivalent to extended conjugation). By the collective interaction of several conjugated blocks with the dopant the polymer is partially oxidized and charge carriers are formed. The result is enhanced electrical conductivity.
Progress in controlled polymerization and design of novel polymer architectures
Authors: Baumert Martin , Frey Holger , Hölderle Matthias , Kressler Jörg , Sernetz Friedrich G. , Mülhaupt Rolf
Published: March 2011

Recent developments of new synthetic methods are stimulating the design of new polymers. Modern generations of highly active and selective transition metal catalysts give excellent control on molecular weight, regio‐ and stereoregularities, long‐ and short‐chain‐branching, polymer crystallization, and morphology of olefin, diene, cyclolefin, and styrene polymers. Ethene is copolymerized with polar comonomers such as carbon monoxide and acrylates in new low pressure processes. Catalytic coupling reactions of aromatic halogen compounds and bisphenols afford rigid polyarylenes. „Living” radical polymerization (“TEMPO” and “ATRP”) produce a wide range of telechelics, block copolymers and cascade macromolecules. In reactive processing oxazoline‐mediated coupling reactions are the key to melt diversification of well‐known polymers. Supramolecular concepts are being applied to tailor hybrid polymers and nanocomposites. Precision in polymer synthesis is the key to new materials with wide application range.
Monte Carlo simulations of the polymer glass transition: From the test of theories to material modeling
Authors: Paul Wolfgang , Binder Kurt , Wolfgardt Mathias , Baschnagel Jörg , Tries Volker
Published: March 2011

We present results on the glass transition in polymer melts using Monte Carlo simulations of the bond fluctuation lattice model. There are two questions we address in this work. What is the temperature dependence of the entropy density in such a model polymer melt and how well is it described by theories like the Gibbs‐DiMarzio theory of the glass transition? And to what degree is one able to map the Hamiltonian of such an abstract lattice model onto a specific polymer material and use it to model the large scale and long time properties of a realistic polymer melt?
Neutron spin echo investigations in the α and β relaxation regime of polybutadiene
Authors: Richter D.
Published: March 2011

This short review presents quasielastic neutron scattering and dielectric experiments on the α and βslow relaxation in polybutadiene. Exploiting the momentum transfer dependent dynamic structure factor, spatial information about the underlying molecular motions is obtained. While the βslow process reveals itself as a local jump with average jump distances of about 1.5 Å, the α relaxation is diffusive and occurs statistically independently from the βslow process. With this result a consistent interpretation of dielectric spectra on the same polymer is achieved.
Significance of different modes in dynamics of chains in a dense medium
Authors: Erman Burak
Published: March 2011

Singular Value Decomposition technique is used to decompose the trajectory of the fluctuations of atom positions into their modes for a chain of fifty bonds embedded in a fluctuating environment. The temperature of the environment is changed according to a Monte Carlo Metropolis scheme. Results show that at low temperatures only a few modes are significant, these being the slowest ones. For high temperatures, on the other hand, higher modes corresponding to fast fluctuations of atom positions are significant as well.
The control of reactions in the synthesis of tailored polycondensates
Authors: Maréchal Ernest
Published: March 2011

This lecture deals with some problems connected to the synthesis and the characterization of tailored polycondensates. They will be illustrated by examples mainly from our laboratory and bearing on block‐copolycondensates, macrocycles and some structures obtained by enzymatic catalysis. We will particularly emphasize the analysis of the structures and of the eventual side reactions.
Organometallic reactions as tools to build new metal‐containing conjugated polymers
Authors: Lavastre O. , Even M. , Troccon C. , Dixneuf P. H. , Pacreau A. , Vairon J‐P.
Published: March 2011

By using organometallic reactions like Pd‐catalyzed C‐C coupling, metal‐carbon bond formation and silicon‐carbon bond cleavage, novel carbon‐rich organometallic monomers HC≡C‐C6H4‐C≡C‐[M]‐C≡C‐C6H4‐C≡CH ( [M] = ‐Ru(dppe)2‐ and (η5‐C5H4)2Fe) and organic monomers H‐(C≡C‐C6H4)X‐C≡CH (x = 1 to 3) have been obtained. They have been used for the design of novel homo and hetero metal‐containing polymers via organometallic polycondensation reactions based on quantitative metal‐carbon bond formation.
Synthesis of hydrolytically stable phosphorus‐containing polymers via polycondensation and their utilization in polymer blends
Authors: Srinivasan Satya , Kagumba Lawino , Riley Daniel J. , McGrath James E.
Published: March 2011

Amorphous polyarylene ether homo‐ and copolymers were synthesized which were based upon bisphenol A and either 4, 4'‐dichlorodiphenylsulfone, 4, 4'‐difluorobenzophenone or 4, 4'‐difluorodiphenyl phenylphosphine oxide. Solution blends were prepared from these homo‐ and copolymers with linear bisphenol A based polyhydroxyether, which was used as a model for the epoxy or vinyl ester thermosetting matrix resins for composite materials. It was observed that transparent, single Tg blends could be prepared from the phosphine oxide containing homopolymer and a 50/50 phosphine oxide/dichlorodiphenylsulfone copolymer. The other homopolymers produced materials with two Tg's, implying that they were definitely phase separated systems. Thermogravimetric analysis was also conducted and the phosphine oxide blends produced high char yields suggesting utilization in fire‐resistant applications. The miscibility of the phosphine oxide material has been attributed to specific hydrogen bonding interactions observed between the phosphine oxide bond and the secondary hydroxyl group in the polyhydroxy ether. This hydroxyl functionality is also present in the epoxy and vinylester precursors and it is suggested that these materials could be utilized as interface sizings for carbon fibers, which would produce a graded microstructure between the fiber and the polymer matrix systems.
Poly(aryl ether phenylquinoxalines) via anionic ring opening polymerization of macrocycles
Authors: Srinivasan S. , Hedrick J. L. , Chan K. P. , Hawker C. J. , Twieg R.
Published: March 2011

A cyclic poly(aryl ether phenylquinoxaline) was prepared via the self‐polymerization of 1 in an N‐methyl‐2‐pyrrolidone (NMP) solution containing base using a pseudo‐high dilution polymerization condition. The macrocycle formation of 1 was carried out in the presence of potassium carbonate in a NMP/toluene solvent mixture at a solids content of 1%. The water generated by phenoxide formation was removed as an azeotrope with toluene 170 °C. A concentrated solution of the macrocycle was added to the reaction mixture over an 8 hour period. The reaction was allowed to proceed for an additional 24h to ensure quantitative reaction. A number of characterization techniques were used to study the cyclization of 1 including GPC, HPLC, H NMR and matrix‐assisted laser desorption ionization (MALDI) mass spectroscopy. The MALDI‐TOF mass spectrum of the cyclization of 1 clearly showed that a mixture of macrocycles is obtained, with the expected distribution of molecular weights. Facile ring opening polymerization of the cyclic poly(aryl ether phenylquinoxaline) oligomers was accomplished with a nucleophilic initiator. High polymer was obtained for each polymerization temperature (η = 0.4–0.5 dl/g in NMP), however, prolonged reaction time resulted in significant gel formation. The Tg's were high and commensurate with the high molecular weight linear analog (250 °C).
TNT‐Based condensation monomers and polymers
Authors: Rusanov Alexander L. , Komarova Ludmila G. , Sheveleva Tatyana S. , Prigozhina Marina P. , Shevelev Svyatoslav A. , Dutov Michai L. D. , Vatsadze Irina A. , Serushkina Olga V.
Published: March 2011

New aromatic diamines were obtained on the basis of available and inexpensive 2, 4, 6‐trinitrotoluene (trotyl, TNT). Monomers obtained were used for the preparation of the new organo‐soluble polyimides containing thiophenoxy and phenoxy side groups.
Structure development during sol‐gel process in organic‐silica networks
Authors: Matêjka Libor , Pleštil Josef
Published: March 2011

Two types of the organic‐silica hybrid networks were prepared and their formation and structure were studied in dependence on reaction conditions. The silica phase was formed by the sol‐gel process from tetraethoxysilane (TEOS) or alkoxysilane endcapped prepolymers. The organic phase was composed of linear poly(oxypropylene) chain or the epoxide network arising by curing the diglycidyl ether of Bisphenol A (DGEBA) with poly(oxypropylene)diamine. Fast development of the structure during polymerization was followed by the in‐situ small‐angle X‐ray scattering measurement. One‐ and two‐stage polymerization procedures result in formation of heterogeneous but optically transparent nanocomposites with different structures.
Hyperbranched polyesters and polyamides by the ABX polycondensation process
Authors: Brenner Axel R. , Schmaljohann Dirk , Voit Brigitte I. , Wolf Dieter
Published: March 2011

Several hyperbranched polyesters with aliphatic and aromatic structural units and one hyperbranched polyamide were prepared by a ABX type polycondensation process in the melt or in highly concentrated solutions at temperatures above 150 °C. The structure of these polycondensates were determined and the polymer properties were analyzed. The hyperbranched polyesters have a degree of branching close to 50% and no indication of side reactions during polycondensation were found. The polyamide structures are more complex and analogous perfectly branched polyamides dendrimer segments up to generation four had to be used as model compounds in order to study structural defects. All hyperbranched polycondensates are fully soluble in polar solvents and exhibit low solution viscosities.
Polycondensation route leading to poly(alkylene phosphate)s
Authors: Pretula Julia , Kaluzynski Krzysztof , Szymanski Ryszard , Penczek Stanislaw
Published: March 2011

A polytransesterification method of preparation of the high‐molecular‐weight poly(alkylene H‐phosphonates) ‐ polymers bearing a reactive ‐OP(O)(H)O‐units, is described:

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Mechanism of transesterification involves mostly ‐OP(O)(H)O⊖, Mt⊕ “growing species”. The polyphosphonates were converted into a number of derivative polymers, like poly(alkylene phosphates), prepared by a direct oxidation, without decreasing of the DPn of the parent polymers.
Molecular composites of polyimide/poly‐n‐vinylpyrrolidone by in‐situ polycondensation
Authors: Wu Meiyan , Yuan Yumin
Published: March 2011

The molecular composites of polyimide (PI) with poly‐n‐vinylpyrrolidone (PVP) were successfully synthesized by in‐situ polycondensation of the rigid polymer in the matrix polymer solution. A strong acid‐base interaction between the polyamic acid (the precursor of PI) and the PVP was confirmed experimentally. By this specific interaction the miscibility of PI with PVP was substantially improved. The PI dispersed in the PVP matrix polymer on a molecular level or nearly molecular level.
Biodegradation of ldpe/cellulose blends by common fungi
Authors: Foust Christopher J. , Mills Richard R. , Haas Thomas , Castevens Charles , Ottenbrite Raphael M.
Published: March 2011

We have developed a cellulose‐polyethylene blend polymer film for degradative susceptibility to brown rot or cellulasic fungi. Paxon low‐density polyethylene (LDPE) polymer pellets were melt‐blended with 8855 cellulose. A pure polyethylene sample was melted, pressed and used as the control. Naturally occurring fungi were harvested from decaying wood and cultured on full nutrient agar until individual phenotypes developed. The discrete fungal colonies were isolated and transferred to bacteriological agar with carboxymethylcellulose as the only carbon source. Surviving fungi were subjected to an indirect cellulase assay to confirm cellulolytic properties. Trichoderma viride showed 100% surface area growth on low‐density polyethylene (LDPE) blended with 8% (w/w) cellulose in 90 days. Growth coverage by Gliomastix on LDPE blended with 8% cellulose reached 100 % in 150 days, and up to 72% growth activity on blends with 1.5% cellulose, 1% cellulose, and the control LDPE.
Microspheres by dispersion polymerization of lactides and ϵ‐caprolactone
Authors: Slomkowski Stanislaw , Sosnowski Stanislaw , Gadzinowski Mariusz
Published: March 2011

Polyester microspheres were synthesized by the ring‐opening polymerization of lactides (racemate or optically active L,L‐isomer) and ϵ‐caprolactone. Polymerizations were carried out in the 1,4‐dioxane‐heptane mixed solvents in the presence of poly(dodecyl acrylate)‐g‐poly(ϵ‐caprolactone) (poly(DA‐CL)) used as surface‐active agent. Polymerizations were initiated with tin(II) 2‐ethylhexanoate (lactides), diethylaluminum ethoxide or sodium trimethylsilanolate (ϵ‐caprolactone). In the studies of the polymerization of lactides, relations were determined between diameters, the distribution of diameters of synthesized microspheres, and the structure of poly(DA‐CL). It was found that it is possible, depending on thermal treatment of microspheres after synthesis, to obtain polylactide microspheres differing in the degree of crystallinity. Kinetics of the dispersion pseudoanionic and anionic polymerizations of ϵ‐caprolactone were also investigated and the results of these studies were compared with the data for the corresponding polymerizations of ϵ‐caprolactone in solution.
Quantitative comparison of selectivities in the polymerization of cyclic esters
Authors: Baran Jolanta , Duda Andrzej , Kowalski Adam , Szymanski Ryszard , Penczek Stanislaw
Published: March 2011

Chain transfer processes (ktr) taking place in the polymerization (anionic and pseudoanionic) of cyclic esters (lactones) are reviewed. These reactions are mostly responsible for the departure of these systems from the fully controlled (living) polymerizations. The ratios of kp/ktr have been determined for a number of initiating systems and the structures of the growing species are related to their selectivity, expressed by kp/ktr. It has been shown that the less reactive and more sterically crowded active species polymerize more selectively.
Ultrahigh‐strength self‐reinforced polylactide composites and their surgical applications
Authors: Törmälä Pertti , Pohjonen Timo , Rokkanen Pentti
Published: March 2011

Bioabsorbable lactide polymers and copolymers were self‐reinforced by die‐drawing to increase their strength and ductility. Self‐reinforced materials were applied in manufacturing ultrahigh‐strength implants, like pins, screws, tacks and stents, for tissue management in different disciplines of surgery.
Processing and in vitro degradation of poly(l‐lactic acid) fibres
Authors: Migliaresi Claudio , Fambri Luca
Published: March 2011

High‐strength poly(L‐lactic acid) fibres were produced by dry spinning from chloroform solution or melt spinning. Fibres were characterised by viscometric molecular weight, thermal analysis and mechanical properties. Different sets of fibres were subjected to in vitro degradation in Ringer solution at 37°C for up to 16 weeks.
Molecular designing of biodegradable copolypeptide membranes
Authors: Hayashi Toshio , Oka Masahito , Miyachi Yasuyoshi
Published: March 2011

Two‐component random copolypeptide membranes consisting of N‐(hydroxyalkyl)‐ L‐glutamine and L‐leucine or L‐alanine were prepared by carrying out aminolysis reactions with 3‐amino‐l‐propanol (P) together with crosslinking reaction with octamethylenediamine (OMDA) on membranes of the starting copolymers consisting of γ‐methyl L‐glutamate (M) and L‐leucine (L) or L‐alanine (A). The relation between their bulk structure and properties was investigated with regard to the swelling ratio in water (q), the rate of water vapor permeability (Vf), tensile properties, and enzymatic degradation behavior in a pseudo‐extracellular fluid (PECF). The tensile property of the membranes was highly dependent on q in PECF, and on the hydrophobicity of the side chains. It was shown that a common relation was obtained between Vf and q of membranes in PECF regardless of the difference of the nature of side chains. Biodegradation of the membranes in vitro by bromelain indicated that degradation took place in bulk rather than on a surface, and that the rate of degradation was also highly dependent on q of samples as well as on the hydrophobicity of side chains of samples.