bluuebunny/crossref_metadata_2025 huggingface dataset:
Heterogeneous anionic coordinated polymerization of propylene oxide: A quantitative 13c NMR analysis of the regio‐ and stereo‐selectivity of the catalyst via microstructure analysis of polymers
Authors: Goriot R. , Pétiaud R. , Llauro M. F. , Hamaide T.
Published: March 2011

Poly(propylene oxide)s synthesized with an heterogeneous catalytic system have been analyzed by 13C NMR spectroscopy by using DEPT experiments and sub‐spectrum editing techniques. The results have been compared with those obtained from commercial products, in order to reach a greater insight into the selectivity of the catalytic system. A quantitative and reliable determination of the inversion ratio is proposed, which implies each type of carbon as well. This inversion ratio was found to be much higher than that observed in commercial PPO. It is shown that when the inversion ratio is no longer negligeable, its accurate determination is a prerequisite to a reliable approach of the tacticity distribution in regular sequences. So, a quantitative determination of the configurational diad and triad distribution is proposed which takes into account the fraction of “defect” resonances (consequence of inverted addition) overlapping with “normal” resonances (unaffected by the inverted addition) in the different sub‐spectra. The main features of the catalyst activity are outlined and compared with results obtained with commercial PPO.
FTIR and micro‐Raman spectra of polymer nanostructures under pressure
Authors: Afanasyeva N. I. , Belogorokhov A. I. , Blank V. D. , Jawhari T. , Ovchinnikov A. A.
Published: March 2011

Studies of metastable C60 forms obtained at high pressures and temperatures and other polymer carbon structures up to nanostructures have been performed over a wide spectral range using FTIR and micro‐Raman techniques. FTIR spectra of carbon‐based polymer materials (pristine fullerenes, nanostructures, and diamond‐like C60 forms) were studied in the range from 1600 to 300 cm−1.

The micro‐Raman spectra of the carbon‐based materials and their new forms obtained under the conditions of high energy impacts allowed us to determine the level of disorder in these polymer forms of carbon and to study the formation of new structures up to superhard ones.
Spectroscopic characterization of the conversion of poly(p‐phenylene‐vinylene) precursor by ion irradiation
Authors: Davenas J. , Massardier V. , Tran V. H. , Nguyen T. P.
Published: March 2011

Different spectroscopic techniques show that poly(p‐phenylene vinylene) films can be derived from a sulphonium precursor by irradiation with ion beams at energies of the order of 100 keV. The comparison with the pyrolysis conversion shows less chlorine and sulfur residues in the irradiated thickness, whereas some ketone structures are evidenced. The formation of nanometric scale carbon clusters induced by the irradiation degradation of PPV is however indicated by UV spectrophotometry, leading to bandgap narrowing and increase of the conductivity. The irradiation with doping species allows the conversion and doping of PPV films in a single stage. The induced conductivity is limited by the formation of complexes with chlorine residues through a gettering process.
FTIR&ATR analyses on a polypropylene (pp) surface after plasma treatment in the study of chitosan surface grafting to improve PP dyeing behaviour
Authors: Rochery M. , Lam T. M. , Crighton J. S.
Published: March 2011

This study consisted in working on the treatment of a polypropylene (PP) film surface to improve its dyeing behaviour. A plasma treatment was carried out to try to create oxidizing groups on this surface, so that it could be then easier to apply a specific polysaccharide: chitosan which is reported to be much more reactive than PP and easy to dye. A study about the various parameters of the plasma instrument was necessary to find the optimal treatment. The possible formed oxidizing groups were emphasized by FTIR&ATR analyses. Chitosan was applied after the plasma treatment and the dyeing result which was then observed, was quite encouraging in certain conditions.
Use of fluorescent probes (pyrene and molecular rotor) for the detection of hydrophobic microdomains in amphiphilic polymers aqueous solutions
Authors: Benjelloun Abdesselam , Damas Christine , Dziadosz Laure , Adibnejad Mohammad , Brembilla Alain , Carré Marie‐Christiane , Viriot Marie‐Laure , Lochon Pierre
Published: March 2011

The purpose of the present investigation deals with a comparative study between the magnitudes of the local viscosity and/or the polarity of the hydrophobic microdomains generated by poly (3‐hexadecyl‐1‐vinylimidazolium bromide) in an aqueous medium using a cinnamylidene molecular rotor and pyrene as fluorescent probes. Moreover, the results are compared with the data obtained with micelles of conventional surfactants such as the homopolymer repetitive unit model and CTAB.
13C, 25Mg and 11B solid‐state NMR study of a fire retarded ethylene‐vinyl acetate copolymer
Authors: Pécoul Nathalie , Bourbigot Serge , Revel Bertrand
Published: March 2011

Flame retardance of ethylene‐vinyl acetate copolymer (EVA) can be achieved using magnesium hydroxide (Mg(OH)2) incorporated in the polymeric matrix. The adduct of small amount of zinc borate as synergistic agent in the formulation increases the fire‐proofing properties. Multinuclei solid‐state NMR appears as a powerful means to characterise materials before and after combustion. We show that endothermic dehydration, water vapour evolved and formation of a glassy coating provide the flame retardancy of interest to the polymeric matrix.
Characterization of a poly(ethersulphone) by on‐line coupling of size exclusion chromatography with NMR and FTIR spectroscopy
Authors: Eichhorn Klaus‐Jochen , Voigt Dieter , Komber Hartmut , Pospiech Doris
Published: March 2011

An on‐line detection „on the flow”︁ during the size exclusion chromatography run using FTIR and NMR spectrometers was applied to investigate the liquid chromatographic separation process of oligomers and to identify the separated chromatographic compounds. The FTIR and NMR detectors give real‐time information about the chemical structure and functional groups of the eluated species. The preferences and limits of the on‐line coupling were discussed using an oligomeric hydroxyl terminated poly(ethersulphone) as an example. Molecular weights could be calculated from the 1H‐NMR spectra of the separated species using the intensities of end‐group and main‐chain signals. Residues of N‐methylpyrrolidone which was used as solvent in the oligomer synthesis were identified by the FTIR detector.
NMR investigations on dynamical aspects of aging processes in elastomers
Authors: Denner Paul , Walter Bernd , Willing Theo
Published: March 2011

Proton spin relaxation measurements have been used to investigate the effect of aging on local and coherent segmental dynamics in cis‐1,4‐polybutadiene samples. The polymer chains in bulk polybutadiene were crosslinked by exposure to ionizing radiation. The transition of the 1H‐n.m.r. signal from a liquidlike spin system response to a solidlike one is due to crosslinking and network formation by the irradiation and depends on the radiation dose. It is shown that the radiation yields changes in the constrained defect diffusion processes modelling the chain dynamics. Correlation time and memory time for the local and coherent segmental motion strongly depend on radiation dose.
Molecular weight dependent antimicrobial activity by Chitosan
Authors: Tokura Seiichi , Ueno Keisuke , Miyazaki Satoshi , Nishi Norio
Published: March 2011

Chitosan oligomers of average molecular weight 9300(P9300) and 2200(P2200) were prepared by nitrous acid degradation followed by the reduction of 2,5‐anhydromannose terminal by sodium borohydrate. Although P9300 provided the growth inhibition of Escherichia coli, P2200 was not growth inhibitor but growth accelerator. The stacking of P9300 to cell wall of E. coli was confirmed by the use of FITC(Fluorescein isothiocyanate) labeled chitosan oligomer using the Confocal Laser Scanning Microscope. The permeation of P2200 was also observed through cell wall without stacking to cell wall. The effective growth inhibition of bacteria was assumed to be the prevention of delivery of nutrition through cell wall.
Biodegradation of chitin with enzymes and vital components
Authors: Takamori Yoshimori , Morimoto Minoru , Sashiwa Hitoshi , Shigemasa Yoshihiro , Okamoto Yoshiharu , Minami Saburo , Matsuhashi Akira
Published: March 2011

Chitin from squid pen was effectively degraded by the chitinase from Bacillus sp. PI‐7S, while the degradation of chitin with lysozyme proceeded very slowly. Among the various vital components studied, the degradation of chitin from squid pen was performed not by canine serum, canine tela subcutanea, canine tela liver, and equine serum but by bovine serum and caprine serum. Noteworthy is the fact that chitin sponge subcutaneously implanted in dog reported not to have chitinase was degraded in ca. 14 days.
Synthesis of two water‐soluble polysaccharides by Acetobacter sp. NCI 1005
Authors: Tajima Kenji , Uenishi Nobuto , Fujiwara Masashi , Erata Tomoki , Munekata Masanobu , Takai Mitsuo
Published: March 2011

A new polysaccharide was isolated from the culture of Acetobacter aceti subsp. xylinum (A. xylinum) NCI 1005 grown on sucrose. The structure of the polymer was analyzed by nuclear magnetic resonance (NMR) spectroscopy. The water‐soluble polysaccharide (WSP) was determined to be β(2, 6) linked polyfructan, which was structurally different from the polymer synthesized from glucose instead of sucrose by the same strain. The discovery of the new polysaccharide has elucidated that the bacterium has the ability to synthesize two different kinds of water‐soluble polysaccharides.
Starch biosynthesis and modification of starch structure in transgenic plants
Authors: Koßmann J. , Emmermann M. , Frohberg C. , Lloyd J. R. , Lorberth R. , Springer F. , Willmitzer L. , Büttcher V. , Abel G.J.W. , Duwenig E. , Welsh T.
Published: March 2011

Starch is synthesised through the ADP‐glucose pathway, involving the three enzymes ADP‐glucose pyrophosphorylase, starch synthase and starch branching enzyme. ADP‐glucose pyrophosphorylase is the key enzyme of the pathway, determining the flux of carbon into starch. It generates ADP‐glucose, which is the substrate for the starch synthases, from glucose‐1‐phosphate and ATP releasing pyrophosphate. The enzyme is stimulated by 3‐phosphoglycerate and inhibited through inorganic phosphate. The starch synthases, which catalyse the transfer of glucose from ADP‐glucose to the nonreducing end of a growing α‐1,4‐glucan, are divided into two classes, the granule‐bound starch synthases (GBSS) and the soluble starch synthases (SS). In both classes several isoforms have been described from many different plant species. The branching enzyme, which introduces branchpoints into the amylopectin, can also occur in different isoforms. Other enzymes present in plants, which also act on α‐1,4‐glucans, such as the starch phosphorylases, disproportionating enzyme and different starch hydrolases, might also be important for dertermining the starch structure and, therefore, its processibility. Many aspects of starch synthesis are not fully understood to date. Starch metabolism can be manipulated through genetic engineering, either by the ectopic expression of different heterologous genes, or through the repression of the expression of endogenous genes using antisense RNA technology. This not only allows the functional analysis of starch biosynthetic proteins, but also the manipulation of starch structure in order to widen its industrial applications.

In this way many different potato lines have been generated, containing either different amounts of starch, or which synthesize a structurally modified starch. These structural changes relate to the amylose content, the phosphate content, or the gelatinisation and gelation characteristics of the starch.
Solution properties of cellulose tris(3,5‐dimethyl‐phenylcarbamate)
Authors: Norisuye Takashi , Tsuboi Akihiko , Sato Takahiro , Teramoto Akio
Published: March 2011

The dilute‐solution behavior and liquid crystal formation of cellulose tris(3,5‐dimethylphenylcarbamate) (CTDC) in 1‐methyl‐2‐pyrrolidone (NMP) at 25°C are discussed by summarizing our recent studies, and its molecular characteristics are compared with those of cellulose tris(phenylcarbamate) (CTC) in the same solvent. The molecular weight dependences of optical anisotropy factor, radius of gyration, intrinsic viscosity ([η]), and isotropic‐cholesteric phase boundary concentration for CTDC are explained consistently by current theories based on the wormlike chain. An analysis of the newly measured [η] for CTC shows that the backbone conformation and chain stiffness are substantially the same for the two cellulose derivatives in NMP. However, a distinct difference in optical anisotropy is found and briefly discussed in relation to the higher optical resolution capacity of CTDC than that of CTC in chromatographic separation of racemic compounds.
Preparation and anticoagulant surface properties of glucoside‐ or sulfated glucoside‐bearing polymer grafted poly(ethylene) films
Authors: Sakamoto Nobuyuki , Shioya Tomoko , Kishida Akio , Akashi Mitsuru
Published: March 2011

Poly(GEMA) or poly(GEMA)‐sulfate grafted surfaces were prepared for the purpose of developing biomaterials with anticoagulant surfaces. Their functionalities were investigated as anticoagulant activity, proteins and cells adhesion activity, and complement activation activity. These results revealed that the adhesion of blood cells onto a GEMA‐sulfate grafted surface was due to protein adsorption and that complement activation onto a GEMA‐sulfate grafted surface was larger than that on a GEMA grafted surface. A GEMA‐sulfate grafted surface, however, exhibited good anticoagulant activity. These functions seemed to be due to the specific functionality of the SO3 groups in a GEMA‐sulfate.
Methyl‐hydroxypropyl cellulose ‐ shear induced birefringence measurements in the semi–dilute regime
Authors: Schmidt Jürgen , Weigel Richard , Burchard Walther , Richtering Walter
Published: March 2011

The present study was induced by unexpected findings with this and other not fully substituted cellulose derivatives. Although fully transparent aqueous solutions were prepared, static light scattering (LS) revealed a strong aggregation. A detailed analysis of the LS‐data as well as transmission electron‐microscope pictures gave evidence for fringed micelles as aggregate structure. These particles consist of several side‐by‐side aligned chains that form a compact core from which many dangling chains emerge. The core in this model has a geometrical anisotropic shape and flow birefringence became detectable when orienting the particles by the action of shear forces. Induced flow birefringence is a common feature of many other materials and therefore a set‐up was constructed that could be attached to a common constant stress rheometer of Bohlin. The reported experiments present first examples measured with this set‐up and demonstrate the efficiency of this technique. In the following the equipment is briefly described and the results obtained so far are tentatively interpreted.
Rheological properties of native and hydrolyzed starches in dependence on composition and concentration
Authors: Vorwerg Waltraud , Radosta Sylvia
Published: March 2011

The structure formation of starch polysaccharides in aqueous solutions is determined by the ratio of amylose to amylopectin and the molecular properties of these components. Our research is focused on establishing defined correlations between composition, molecular structure in diluted solutions and rheological properties of concentrated aqueous starch polysaccharide solutions. Diluted solutions were investigated by size exclusion chromatography with multi angle laser light scattering detector. Measurements of concentrated aqueous solutions were carried out by a Bohlin cs‐rheometer with programmed stress using a cone‐plate geometry of 40 mm diameter and a cone angle of 4 degrees. Gels were characterized by oscillatory measurements taking into account the frequency dependence of the storage and loss moduli and the influence of a stress sweep on the moduli. The concentration dependence was investigated with starches of potato, wheat, maize and wrinkled pea. Starches with quite similar amylose content as from potato, wheat and maize, show different behavior in rheological properties.

Further differences in structure formation were obtained by enzymatic hydrolysis of potato and wheat starch with bacterial α‐amylase. The hydrolyzing conditions were chosen such that the degradation led to molecular weights between 5*105 and 107 g/mol. Detailed information about molecular composition was obtained by fractionation of degraded starches. The amylopectin was found to be degraded more strongly than the contained amylose.

In comparison to native starch polysaccharide fractions the amylopectin hinders the gelation process in dependence on its molecular weight distribution and the length of the outer chains.
New developments in the analysis of the substitution pattern of polysaccharide derivatives
Authors: Mischnick Petra
Published: March 2011

The analysis of the primary structure of polysaccharide derivatives has to consider different structural levels. In the field of the monomer analysis anion exchange chromatography enables the investigation of some anionic derivatives and methyl ethers. Two analytical strategies for the analysis of the substituent distribution along the polymer chain are outlined, and the results from model studies on methyl amyloses prepared under homogeneous and heterogeneous conditions are discussed.
Deprotonation patterns of disaccharides in coordinating cellulose solvents: A status report
Authors: Kettenbach Gerhard , Klüfers Peter , Mayer Peter
Published: March 2011

Crystals of metal complexes of deprotonated open‐chain oligosaccharides which may serve as models for the action of coordinating cellulose solvents on the polysaccharide molecule, are generally harder to obtain in a quality suitable for X‐ray analysis than in the case of monosaccharides. Four preliminary crystal structure analyses are presented which settle the significance of intramolecular hydrogen bonds towards the metal ligating acceptors. The metal binding sites of sucrose include both 1,2‐ and 1,3‐diolato complex formation, whereas α,α‐trehalose has been found in the 1,2‐diolato coordination mode.
Temperature‐responsive hydrogels from cellulose
Authors: Nishimura Hiroshi , Donkai Nobuo , Miyamoto Takeaki
Published: March 2011

The aim of this work is to prepare the temperature‐responsive cellulosic hydrogels undergoing a large volume change in an aqueous solution on heating or cooling. To this end, we prepared 0‐methyl cellulose (MC) and O‐(Z‐hydroxy‐3‐butoxypropyl) cellulose (HBPC) which precipitate out of solution on heating without forming gel. MC and HBPC derivatives prepared by homogeneous reactions were proved to be promising raw materials for the cellulosic hydrogels mentioned above. The results on the phase separation of the derivatives were discussed in terms of the distribution of substituents along the cellulose chain and in the anhydroglucose units.
Photonic polymers for the devices of the 21st century
Authors: Hadziioannou Georges , van Hutten Paul F. , Malliaras George G.
Published: March 2011

This paper describes research activities towards the development of polymer materials and devices for optoelectronics. Electroluminescent devices, lasers and photovoltaic devices from polymers or oligomers are discussed.
Colloidal properties of star polymers
Authors: Roovers Jacques
Published: March 2011

Regular star polymers with functionality f = 64 and f = 128 have such high segment density that they resemble “hard sphere” objects in dilute solution. In semi‐dilute solution they form a macrocrystalline ordered phase with spacings of the order of 100 to 500Å. They are physical gels. Their melt properties are characterized by a long term relaxation process not found in stars with fewer arms.
Does compressibility affect the results obtained by small angle neutron scattering?
Authors: Joanny J.‐F. , Benoît H. , Stockmayer W. H.
Published: March 2011

Recently a few papers have been devoted to the scattering by polymer solutions and blends(1,2) assuming that the systems under investigation are compressible, contrarily to what is usually done. This is motivated by the fact that if one uses the theory of incompressible mixtures in scattering experiments, one obtains values of the Flory(3) χ parameter which are inconsistent with the values obtained by other techniques. In this paper we would like to show that, contrarily to what has been said, the effect of compressibility can be easily evaluated; it is very small and already corrected in the classical treatment of the data used in light or neutron scattering experiments.
Correlation hole effect in comblike copolymer systems obtained by hydrogen bonding between homopolymers and end‐functionalized oligomers
Authors: Huh J. , Ikkala O. , Ten Brinke G.
Published: March 2011

Monodisperse block copolymer systems in the homogeneous melt exhibit small angle X‐ray scattering peaks at finite nonzero angle due to characteristic correlation hole concentration fluctuations. Here we will address these fluctuations for comblike copolymer systems obtained by strong association between polymers and end‐functionalized oligomers. Experimentally, the dominant fluctuations have been found by us to vary between conventional long wave length fluctuations (for weak hydrogen bonding) as for simple mixtures, and finite wave length fluctuations (strong hydrogen bonding), characteristic for block copolymer systems. Monte Carlo computer simulations show that both regimes will occur in one and the same system depending on the temperature. The transition between both regimes is directly related to the fraction of free oligomers, which depends on the temperature and the interactions. The structure factors are analysed in terms of the Random Phase Approximation applied to a mixture of free oligomers and comb copolymers, using a uniform distribution of teeth along the polymer chains and a binomial distribution in the number of polymers with a given number of teeth, confirmed numerically, as input. The agreement is excellent both at high and low temperatures.
Mesophase structure and alignment under different fields of liquid crystalline main‐chain/side‐group block copolymers
Authors: Galli Giancarlo , Chiellini Emo , Francescangeli Oriano , Ferri Dino , Wolff Dietmar , Springer Jürgen , Laus Michele , Angeloni Annino S.
Published: March 2011

Liquid crystalline block copolymers are new materials in which multiple molecular interactions can provide the driving force for complex phase behaviors and states of order. Block copolymers containing both liquid crystalline main‐chain polyester and side‐group polymethacrylate blocks were investigated. They phase separated in the liquid crystalline state and their individual mesophases coexisted. The copolymers responded very differently when either a mechanical or a magnetic field was used for alignment. In the fibers the orientations of the side‐group and main‐chain smectic planes with respect to the fiber axis depended critically on the block lengths and on their distinct tendencies to align, whereas under a magnetic field the mesogens aligned collectively with their long molecular axis parallel to the field, independent of the copolymer structure.
Synthesis of poly(p‐phenyleneterephthalamide) in presence of polymer matrices
Authors: Russo Saverio , Mariani Alberto , Mazzanti Sabina L. E. , Ruggeri Giacomo , Conio Giuseppina
Published: March 2011

The direct syntheses of poly(p‐phenyleneterephthalamide) in presence of poly(vinylpyrrolidone) and poly(4‐vinylpyridine) as matrices have been carried out following the so‐called Yamazaki's and Higashi's methods. The intrinsic viscosity data of the resulting polyamide were found to be strongly dependent on the matrix used as well as on its molecular weight.
Star‐shaped and hyperbranched polyesters
Authors: Kricheldorf Hans R.
Published: March 2011

In contrast to a‐a/b‐b type monomers, the a‐b monomers(e.g. hydroxy‐ or amino carboxylic acids) possess a much greater synthetic potential. Using 3‐ or 4‐hydroxy‐benzoic acid and 4‐hydroxyphenylpropionic acid (phloretic acid) starshaped polyesters with controlled molecular weight were prepared. Analogously, starshaped liquid‐crystalline copolyesters were synthesized, and the influence of star‐centers on the stability of the nematic phase was studied. Three polycondensation methods were elaborated and compared for the synthesis of hyperbranched homo‐ and copolyesters. Both the degree of branching and the nature of the endgroups were varied and their influence on the solubility, crystallinity and melt rheology was investigated. Furthermore, A‐B‐A triblock co‐polymers with hyperbranched A‐blocks, and hyperbranched poly(ester‐amide)s were synthesized and characterized.
Block Copolymers by high temperature oligomer‐coupling reactions: Bis(5‐oxazolinone)/OH reaction
Authors: Lefébvre Hervé , Fradet Alain
Published: March 2011

High temperature chain‐coupling reactions in the bulk between amino‐, hydroxy‐ or carboxy‐terminated polymers and various coupling agents have been studied and applied to the synthesis of copolymers with aliphatic polyester, polyether or polyamide blocks. Thus, carboxy‐terminated oligomers can be coupled by bisoxazolines or bisimidazolines, while 4‐substituted and 4, 4‐disubstituted bis(5‐oxazolinones) are efficient coupling agents for amino‐ or hydroxy‐terminated oligomers. In the latter case, the use of a catalyst is necessary. The reaction has been optimized using a series of bisoxazolinones deriving from α‐amino‐acids and 1‐dodecanol and α, ω‐dihydroxy‐poly(ϵ‐caprolactone) as model compounds. High molar mass poly‐ϵ‐caprolactone containing α‐aminoacid moieties has been obtained in the presence of tetrabutoxytitanium as a catalyst.
Enzymatic condensation and polycondensation reactions in organic solvents
Authors: Gutman Arie L. , Knaani Dafna , Bravdo Tamar
Published: March 2011

Lipases in organic solvents catalyse lactonisation or polymerisation of ω‐hydroxyesters. Under these conditions the enzymes exhibit both enantioselectivity and prochiral selectivity. This approach was used to develop the synthesis of chiral γ‐lactones and A‐B type polyesters from racemic or prochiral hydroxyester substrate.
Effects of transformation phenomena on polymer synthesis
Authors: Pascault Jean‐Pierre
Published: March 2011

The chemistry and the reaction rates have been related to the phase transitions and transformations occuring during different polymer syntheses. Early cristallization of chain segments disturbs the synthesis of linear segmented polyureas or polyurethanes. The gelation process occuring during the epoxy‐amine network formation does not affect the reaction rate, but after vitrification, this reaction becomes diffusion‐controlled. In the case of modified thermoset a liquid‐liquid transition may induce a fractionation phenomenon which modifies the average functionality of the molecules and the appearance of the gel point.
Synthesis of thermotropic liquid crystalline all‐Trans‐p‐Phenylenevinylene oligomers via two‐step metathesis
Authors: Thorn‐Csányi Emma , Kraxner Peter
Published: March 2011

Liquid crystalline products of oligomeric p‐phenylenevinylene derivates were prepared metathetically using a stable molybdenum carbene complex (Mo(NArMe2)(CHCMe2Ph)[OCMe(CF3)2]2). The synthesis was conducted via two steps: 1. Metathesis polycondensation of 2, 5‐dialkyl‐1, 4‐divinylbenzenes to oligo‐(2, 5‐dialkyl‐1, 4‐phenylenevinylene)s, 2. Endcapping of the vinyl groups via cross‐metathesis using 3‐hexene. The products were characterized by1H‐NMR and UV/Vis spectroscopy, as well as by DSC.
New functionalized polycondensates
Authors: Ritter Helmut
Published: March 2011

Polyketones, polysulfones and polyamides are presented that contain different types of functional groups located in the main chain or in the side chain of the polycondensates. Functional groups are distyrylpyridine, cinnamic acids, and ester groups. One example is presented dealing with enzymatically catalyzed polycondensation of aniline derivative bearing a chalcon‐function. Some interest is focused on photochemical crosslinking of the materials that are suitable to prepare semipermeable membranes. The successful synthesis of polymerizable dendrimers based on aspartic acid is also described. Finally, the potential synthesis of polyamides with large ring‐components in the main chain is discussed.
Polyarylates based on 3, 4'‐disubstituted benzophenones
Authors: Stagnaro Paola , Valenti Barbara , Cavazza Barbara , Costa Giovanna , Trefiletti Vincenzo
Published: March 2011

New thermotropic aromatic poly(ketoesters) have been obtained by copolymerization of 3‐hydroxy‐4'‐carboxybenzophenone (3, 4'‐HCBP) or of the isomeric 4‐hydroxy‐3'‐carboxybenzophenone (4, 3'‐HCBP) with some commercial aromatic hydroxyacids. The polymers have been prepared both by direct polycondensation in solution and in bulk. Homopolymers of 3, 4'‐HCBP and 4, 3'‐HCBP melt to an isotropic liquid, while a nematogenic behaviour is shown by samples with a comonomer content higher than 30%. A preliminary investigation has been carried out to determine the influence of the liquid‐crystalline phase on their transport properties.
Transimination: An efficacious reaction for the synthesis of macrocycles
Authors: Madec Pierre‐Jean , Pérès Richard , Borgès‐Lopès Elizabeth , Jeanne‐Rose Valérie , Lafontaine Eric , Maréchal Ernest
Published: March 2011

A new family of main‐chain liquid crystal polymers containing azomethine units have been synthesized and characterized. Our attention has been focused on their strong tendency to generate macrocyclic dimers (AB)2 constituted with two mesogenic rods and siloxane spacers. In favourable conditions (diluted solution, acid catalysis) macrocycles may be rapidly formed and purely obtained by fractionation. Synthetic aspects and main thermotropic properties are discussed. In spite of their large size some macrocycles have been obtained as single crystals and then characterized by X‐ray diffraction.
Synthesis of a thermotropic polyester and the thermal behavior of its blends with poly(ethylene terephthalate)
Authors: Novack Kátia M. , Martins Jülia C. A. , Gomes Ailton S.
Published: March 2011

A thermotropic liquid crystalline polyester (LCP) with a flexible spacer group in the main chain has been synthesized by polycondensation and mixed with poly(ethylene terephthalate) (PET). The influence of the LCP's contents on thermal properties of the blends has been determined by Differential Scanning Calorimetry (DSC). LCP and blends were also characterized by Carbon 13 Nuclear Magnetic Resonance (NMR), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA).
Anisotropic polymeric networks with a controlled nanostructure
Authors: St Pourcain C. B. , Edwards S. F. , Griffin A. C.
Published: March 2011

The synthesis and properties of anisotropically ordered polymer networks with a controlled (molecular) nanostructure are reported. Polymer networks with only a single rigid segment (based on 1, 4‐distyrylbenzene or hydroquinone) between crosslink points were prepared by a simple polyesterification procedure. Unswollen polymer networks containing only one of these rigid segments or a combination of the two were birefringent and exhibited a reversible thermotropic phase transition. The ordering within these networks is attributed to a microphase separation of rigid aromatic and flexible aliphatic segments rather than strictly to a shape‐anisotropy driven liquid crystalline phase. The nature of ordering within these networks when swollen in 1, 2‐dichlorobenzene is also discussed.
Modification of polycyanurate networks with protic additives based on polydimethylsiloxane
Authors: Barthélémy Laurent , Boch Annie , Lafitte Jean , Mirco Valérie , Méchin Françoise , Pascault Jean‐Pierre
Published: March 2011

Hydroxy telechelic polycaprolactone / polydimethylsiloxane / polycaprolactone triblock copolymers were used to modify aromatic polycyanurate networks through a polycondensation‐induced phase separation. Model studies revealed that the cyclotrimerization mechanism in the presence of alcohol functions was complex. The additives, which activate the reaction, are finally chemically linked to the matrix. Both thermodynamic and kinetic features result in very finely divided morphologies, with highly interpenetrated phases which contribute to a great improve of the static mechanical properties.
Evolution of the dynamic mechanical relaxations during the gel formation
Authors: Durand Dominique , Nicolai Taco , Lefevre Patrice , Prochazka Frederic , Randrianantoandro Hery
Published: March 2011

Static and dynamic properties of a polyurethane system at different stages of the gelation process have been investigated. Shear modulus data were collected over a wide frequency range covering both the α‐relaxation and the internal modes relaxations. The evolution of the relaxation spectra in relation with the structural transformation occurring during the growth process is analysed within the percolation model.
Radiofrequency (27.12 MHz) activation of the curing reaction of epoxy resins of DGEBA type
Authors: Alazard Patrick , Gourdenne Albert
Published: March 2011

Radiofrequency (27.12 MHz) heating is used for the activation of the curing reaction of an epoxy resin of DGEBAa) type in presence of diaminodiphenylmethane as crosslinking agent. The principle of the activation process is based on the partial conversion as heat of the dielectric loss in the organic medium due to the forced dipolar relaxation at 27.12 MHz. The samples of thermosetting matter are positioned between two parallel steel plates or electrodes, and an electrical voltage is applied. When the temperature is sufficiently high, the step‐growth reactions starts working.
Hydrodispersible copolyesters: Relationship between chemical structure and physico‐chemical properties
Authors: Fleury E. , Vidil C. , Larcheres G.
Published: March 2011

Anionic copolyesters with sodium sulfonate functions and short polyethylene oxyde blocks are used for polyester filament sizing. These polymers were prepared using a three stages melting process at high temperature combining ester interchange, direct esterification, polycondensation and etherification reactions. A study on the relationship between chemical structure and physico‐chemical properties (glass transition temperature, solubility behaviour, hydrolytical and thermal stability) shows that the control of the ether bridges content is important.
Detailed kinetics of liquid crystalline copolyester synthesis: Copolyesterification between poly(ethylene terephthalate), terephthalic acid and hydroquinone diacetate
Authors: Ghadage Ramesh S. , Lodha Anjali , Mathew Johnson , Ponrathnam Surendra , Prasad Sudarshan D.
Published: March 2011

The kinetics of liquid crystalline copolyester synthesis via melt transesterification between poly(ethylene terephthalate)[PET], terephthalic acid [TA] and hydroquinone diacetate [HQDA] is examined. A number of assumptions are proposed and validated to simplify the kinetics and to make the analysis tractable. A key postulation is that the reaction originates between terephthalic acid [TA] and hydroquinone diacetate [HQDA] to form a dimer which slices PET chain. The subsequent coupling of PET segments reforms PET chain with random incorporation of TA‐HQDA units. Steady state approximation is invoked for the rate of generation of dimer. The kinetic analysis reveals the implicit simplicity of complex systems.
The mechanism of chain growth in oxidative polycondensation of phenols
Authors: Ionescu Mihail , Mihis Ana Bianca
Published: March 2011

A new mechanism of chain extension in oxidative polycondensation of phenols has been proposed. Between the two accepted mechanisms: quinol ether redistribution and quinol ether rearrangement, the second mechanism seems to be the most important for the chain growth. The first mechanism, quinol ether redistribution, preserves the system average degree of polymerization and assures a permanent equilibration of the polymeric chains, but has only a minor contribution to the molecular weight increase. The second mechanism, quinol ether rearrangement, proved to be the most important for chain extension and was interpreted as a repeated Claisen rearrangement (a particular case of a sigmatropic rearrangement), characteristic to allyl ethers of phenols. Experimental data proved that the above mentioned mechanisms probably take place simultaneously and the real growth of the molecular weight is a result of the cumulative contributions of both mechanisms.
The acid‐catalyzed polycondensation of furfuryl alcohol: Old puzzles unravelled
Authors: Choura Mekki , Belgacem Naceur M. , Gandini Alessandro
Published: March 2011

This paper describes mechanistic studies aimed at understanding the origin of two important side events accompanying the linear polycondensation of furfuryl alcohol in acidic media. The first process concerns the formation of conjugated sequences along the polymeric chains. The use of model monomers and compounds simulating the structure of the linear polymer provided for the first time a full understanding of the reactions leading to multiple unsaturations. The main culprits for this process are the labile hydrogen atoms on the methylene moiteties bridging the furan rings. The second anomaly in these systems concerns the formation of networks following a complex branching mechanism. Again, model structures helped to pinpoint the origin of this process and to propose plausible reactions to describe it.
Syntheses of poly(ester‐amide)s derived from optically active amino alcohols
Authors: Koyama Emiko , Sanda Fumio , Endo Takeshi
Published: March 2011

Syntheses of poly(ester‐amide)s derived from optically active amino alcohols are described. Poly(ester‐amide)s with M̄n 8,700–27,200 were obtained by the polycondensations of hydroxycarboxylic acids derived from maleic or succinic acid, and by those of dicarboxylic acids and diols derived from dicarboxylic acids and optically active amino alcohols using EDC·HCl in satisfactory yields. The radical additions of ethanethiol or mercaptoethanol to the polymers derived from maleic anhydride proceeded smoothly in satisfactory incorporation ratios (43∼98%). The polymer obtained from succinic anhydride and 2‐aminoethanol showed hydrolytic degradability. The Tg of the polymer derived from leucinol showed even‐odd effect with increase of methylene chain length of dicarboxylic acids.
Heterocyclic polyamides containing hexafluoroisopropylidene groups
Authors: Bruma Maria , Hamciuc Corneliu , Hamciuc Elena , Mercer Frank , Belomoina Nataliya , Schulz Burkhard
Published: March 2011

New heterocyclic polyamides have been synthesized by solution polycondensation of aromatic diamines containing phenylquinoxaline units with diacid chlorides having both imide and hexafluoroisopropylidene (6F) groups. These polymers are soluble in polar aprotic solvents, such as N‐methylpyrrolidone (NMP) or N, N‐dimethylformamide (DMF), and can be cast into flexible thin films from solutions. They show high thermooxidative stability with decomposition temperatures above 400°C and glass transition temperatures in the range of 225‐300°C. The polymer films exhibit good chemical resistance towards diluted acids and good electrical insulating properties with dielectric constants in the range of 3.2–3.7.
Dodecyl dodecanamide as a model for the study of polyamide n‐chlorination. Unusual behaviors of the reaction system
Authors: Girardon V. , Tessier M. , Maréchal E.
Published: March 2011

The N‐chlorination of dodecyl dodecanamide (DDA) by ter‐butyl hypochlorite (tBuOCl) was carried out at 25°C in methylene chloride. The conversion is determined by 1H‐NMR and iodometric titrations of N‐chlorinated DDA (N‐Cl DDA). Curves of conversion‐time plots present singular profiles whose shapes are strongly depending on the reagent and product concentrations.
New aromatic‐aliphatic polyesters based on N‐alkyl carbazole groups in the main chain. Synthesis‐structure‐properties relationships
Authors: Drzewinski Isabel , Adès Dominique , Bélorgey Georges , Siove Alain
Published: March 2011

Polyesters based on N‐butyl or N‐octylcarbazole units in the main chain were synthesized either by direct polycondensation between the carbazole dicarboxylic acids and ethylene glycol or from alcoholysis of the 2‐hydroxyethyl diesters in the presence of different catalytic systems. Depending on the reaction conditions together with the nature and the concentration of the catalyst, diethylene glycol (DEG) is formed as a side‐reaction product. DEG is incorporated in the polyester chain concurrently with EG and leads to the formation of ether links in the spacers. The DEG content as well as the length of the alkyl pendant group of the carbazole unit were found to have a drastical effect on the thermal properties. Furthermore, these materials form charge transfer complexes through carbazole nuclei with electron acceptor and electron donor molecules as well.
Synthesis and structure of elastomeric poly[ester‐block‐ether]s
Authors: Fray Miroslawa El , Slonecki Jerzy
Published: March 2011

Different poly[ester‐block‐ether] (PEE) elastomers have been prepared in a two‐stage process, namely transesterification followed by polycondensation in the melt. These terpolymers consisted of poly(butylene terephthalate) (PBT), poly(oxytetramethylene) (PTMO) and dimerized fatty acid (DFA). The content of PTMO and DFA blocks was changed at a constant PBT mass ratio of 50. Supermolecular structure of synthesized polymers was investigated using optical microscopy (OM) and transmission electron microscopy (TEM). Thermal and mechanical properties were examined by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMTA). An influence of dimerized fatty acid on the segment's comiscibility (phase separation) was estimated.
Synthesis and properties of polyamides derived from 1, 4‐bis(4‐aminophenoxy)‐2‐tert‐butylbenzene
Authors: Liaw Der‐Jang , Liaw Been‐Yang
Published: March 2011

1, 4‐Bis(4‐aminophenoxy)‐2‐tert‐butylbenzene was synthesized and used as a monomer to prepare a series of polyamides by the direct polycondensation with various aromatic dicarboxylic acids in N‐methyl‐2‐pyrrolidone using triphenyl phosphite and pyridine as condensing agents. All the polymers were obtained in quantitative yields with inherent viscosities of 0.75–1.75 dL g−1. All the polyamides showed amorphous nature and most of them were soluble in polar solvents. Polyamides derived from 4, 4'‐sulfonyldibenzoic acid and 4, 4'‐hexafluoroisopropylidenedibenzoic acid were even soluble in common organic solvent such as THF. All polyamide films could be obtained by casting from their DMAc or NMP solutions. The polyamide films had a tensile strength range of 35–84 MPa, an elongation range at break of 3–7%, and a tensile modulus range of 1.2–2.5 GPa. These polyamides had glass transition temperatures between 203–268°C and 10% mass loss temperatures were recorded in the range of 456–472°C in nitrogen and 453–470°C in air atmosphere.
Chain extension of ketonic resins
Authors: Kizilcan Nilgün , Akar Ahmet
Published: March 2011

Chain extensions of cyclohexanone‐formaldehyde (CF) and acetophenone‐formaldehyde (AF) resins via their hydroxyl groups were studied. The chain extension was regulated by the ratio of hydroxyl groups/reactive reagents. Dimethyl dichlorosilane, phosphorus oxychloride, toluene‐2, 4‐diisocyanate, phthalic anhydride, tetrahydro phthalic anhydride, trimellitic anhydride, 4, 4'‐oxydiphthalic anhydride were used as chain extender reagent. It has been shown that solubilites, melting point and molecular weight of extended resins depended upon the characteristics of chain extender reagents.
Approach of the mechanism of poly(3‐octyl thiophene) crosslinking under electron beam
Authors: Froyer Gerard , Louarn Gu Y. , Ciprelli Jean Louis , Clarisse Christian
Published: March 2011

Poly(3‐octylthiophene) was used as a negative resist in e‐beam microlithography. This conducting polymer fulfills the main requirements placed on materials which can be useful in this type of process. However, chemical modifications leading to crosslinking are not clearly established at this time. Approach of a mechanism is proposed in this paper which is supported by spectroscopic results obtained from the irradiated materials: it seems reasonable that crosslinking might occur between lateral alkyl groups eventually on carbon atoms in allylic position with the formation of a carbon ‐ carbon double bond between locally stacked Poly(3‐octylthiophene) chains.
Synthesis of new haemocompatible phospholipid polyurethanes for biomedical applications
Authors: Li Yu‐Jun , Nakaya Tadao
Published: March 2011

A series of new phospholipid polyurethanes with hydrogenated poly (isoprene) glycol and 4, 4'‐methylenediphenyl diisocyanate was synthesized using 2‐[bis(2‐hydroxyethyl)methylammonio]ethylalkylphosphate and 1, 4‐butanediol as chain extender. The polyurethanes exhibited favorable haemocompatibilities and excellent mechanical characteristics.
Synthesis of novel amphiphilic di‐block and multiarmed star‐shaped copolymers based on polyisobutylene and poly(ethylene oxide)
Authors: Lemaire C. , Tessier M. , Maréchal E.
Published: March 2011

The synthesis of polyisobutylene‐b‐poly(ethylene oxide) linear diblock copolymers and multiarmed star‐shaped copolymers (having one‐polyisobutylene‐arm and two, three, or four, ‐poly(ethylene oxide)‐identical length arms) is described. All these different structures were characterized by MALDI‐TOF mass spectrometry and Size Exclusion Chromatography.
Biodegradable synthetic and semisynthetic polymers
Authors: Chiellini Emo , D'Antone Salvatore , Solaro Roberto
Published: March 2011

As a part of our continuing interest in the preparation of multifunctional polymeric materials and evaluation of their potential in pharmaceutical, medical and environmental fields, a survey on new polymeric systems of synthetic and semisynthetic origin, susceptible to bioerosion and/or biodegradation attack is presented. In particular, attention has been focused on the design, preparation and characterization of the following classes of hydrophilic and/or water‐soluble polymeric materials: hydroxyl‐containing poly(ester)s, hydroxyl‐containing poly(amide)s, hydrophilic polymers containing carboxylic groups, perhydroxylated oligo‐ and poly(saccharide)s, oxidized poly(saccharide)s, and hybrid polymeric materials based on blends of carboxyl‐containing synthetic polymers and proteins. The rationale of the research activity undertaken over the years is illustrated by focusing on some specific achievements of practical significance.
Thermoplastic starch revisited. Structure/property relationship for “dialed‐in” biodegradability
Authors: Zdrahala Richard J.
Published: March 2011

Starch, totally biodegradable polysaccharide biosynthesized by numerous plants, is one of the most abundant renewable resources known to man. Composed mostly from linear amylose and highly branched amylopectin, the starch, in its granular form, is a crystalline material. When mixed with limited amount of water and subjected to heat and shear, starch undergoes spontaneous destructurization. Homogeneous melt, possessing thermoplastic character is formed, called thermoplastic starch. It absorbs between 5 and 30 % of water at relative humidity range 0 to 90 %. Water is principal plasticizer of this material changing its original stiffness from glass‐like to natural gumlike substance. This plasticization is accompanied by significant dimensional changes. Many polymers, both hydrophilic and hydrophobic, were blended with starch to modify its moisture sensitivity. To illustrate influence of admixed polymers on its moisture sensitivity and its effect on properties and biodegradability, poly(vinyl alcohol), poly(ethylene‐co‐vinyl alcohol) and poly(ethylene‐co‐methacrylic acid) were added to potato starch. This paper discusses results and observed trends.