bluuebunny/crossref_metadata_2025 huggingface dataset:
Applications of two‐dimensional correlation spectroscopy in depth‐profiling photoacoustic spectroscopy, near‐infrared dynamic rheo‐optics, and spectroscopic imaging microscopy
Authors: Noda Isao , Story Gloria M. , Dowrey Anthony E. , Reeder Robert C. , Marcott Curtis
Published: March 2011

Two‐dimensional infrared (2D IR) correlation spectroscopy has found diverse applications in characterizing polymers. The versatility of this powerful technique is demonstrated in the study of a polymeric laminate film by using depth‐profiling photoacoustic spectroscopy, mid‐ and near‐IR dynamic rheo‐optical measurements, and spectroscopic imaging microscopy. Spatial and temporal variations of near‐IR spectra are effectively analyzed by the 2D correlation technique. Step‐scanning FT‐IR spectrometers provide a unique opportunity to obtain desired spectral information often difficult to access by the conventional rapid‐scanning approach.
Synthesis of sulfated alkyl oligosaccharides with potent anti‐HIV activity
Authors: Uryu Toshiyuki , Katsuraya Kaname , Nakashima Hideki
Published: March 2011

Sulfated alkyl malto‐ and laminari‐oligosaccharides with potent anti‐human immunodeficiency virus (HIV) activities were synthesized. Present work focusses on the syntheses of high anti‐HIV active compounds from low molecular weight carbohydrates which will react selectively with AIDS virus protein only. A surface‐active agent type compound consisting of both hydrophilic sulfated oligosaccharide and hydrophobic alkyl group portion was prepared. Individual pure malto‐oligosaccharides from malto‐tetraose to ‐heptaose and laminarioligosaccharides from laminari‐pentaose to ‐nonaose were used as the starting carbohydrates. Synthesis of peracetylated alkyl oligosaccharide was carried out with β‐peracetylated oligosaccharides and corresponding alcohols by using Lewis acid catalysts. Sulfation was performed with sulfur trioxide‐pyridine complex. The anti‐HIV activity was assayed by means of MT‐4 cells and HIV‐1 or HIV‐2 viruses. Almost all sulfated alkyl oligosaccharides exhibited potent inhibitory effects on HIV infection. Sulfated alkyl laminari‐oligosaccharides which have various kind of aklyl portion such as fluoro alkyl, chiral alkyl, cyclic alkyl, and phenyl alkyl were also examined. In addition, this study also provides an assessment of activity levels of sulfated alkyl oligosaccharides in small mammals.
Microstructural analysis of microfibrils of bacterial cellulose
Authors: Horii Fumitaka , Hirai Asako , Yamamoto Hiroyuki
Published: March 2011

This paper reviews mainly our recent investigations of two allomorphs of native cellulose, celluloses Iα and Iβ, carried out based on the composite crystal model by high resolution solid state 13C NMR and electron microscopy. First the distribution of the two allomorphs in nature is described together with some deviations from the simple composite crystal model. Secondly, the influences of polymer additives on the crystallization of the two allomorphs are described in the bacterial system somewhat in detail. On the basis of these results, the mechanism of the crystallization of the two allomorphs is finally discussed also in the bacterial cellulose system.
Investigation of the supramolecular structure of never dried bacterial cellulose
Authors: Fink Hans‐Peter , Purz Hans Joachim , Bohn Andreas , Kunze Jürgen
Published: March 2011

Supramolecular structure of initially wet bacterial cellulose of Acetobacter xylinum has been investigated by X‐ray scattering including synchrotron radiation, transmission electron microscopy, and 13C‐CP/MAS‐NMR‐spectroscopy. As a result a model is given of never dried swollen microfibrillar ribbons consisting of 5 to 12 waterfree Iα‐crystalline subunits with a cross‐section of about 7 nm × 13 nm and of water solvating the subunits. Lateral aggregation of these crystalline units was found along the smaller (110)‐lattice planes with a layer of water between adjacent crystallites. The NMR‐spectrum of wet bacterial cellulose exhibits an additional C‐1 line component indicating cellulose‐water interactions. During drying lateral dimensions of the microfibrillar ribbons, crystallite sizes, as well as the overall crystalline order decrease, whereas the Iα/Iβ‐ratio of about 80/20 remains approximately unchanged. Conclusions were drawn with regard to the early states of structure formation of bacterial cellulose.
Hypolipidemic effects of hydrolyzed xyloglucan
Authors: Yamatoya Kazuhiko , Shirakawa Mayumi , Kuwano Kazutami , Suzuki Junko , Baba Osamu
Published: March 2011

Xyloglucan is found in the primary cell walls of higher plants, where it plays important biological roles. It also exists in certain seeds, for example tamarind, as a reserve polysaccharide. Some xyloglucan oligosaccharides possess plant growth promotion activity.

We prepared hydrolyzed xyloglucan from the tamarind seed xyloglucan using endo‐(1 → 4)‐ β ‐glucanase and examined its effects on lipid metabolism in rats fed a high fat diet. Among the plasma lipids, total lipid, cholesterol, triglyceride and β ‐ lipoprotein were each reduced 14 ‐ 17% by hydrolyzed xyloglucan. Hydrolyzed xyloglucan significantly reduced both adipose tissue weight and plasma GOT. Among the hepatic lipids, total lipid, cholesterol, triglyceride and phospholipid were significantly reduced by hydrolyzed xyloglucan.

These hypolipidemic effects may be important for the treatment and prevention of geriatric diseases, including diabetes and cardiac disorders.
Micellization of amphiphilic block copolymers and use of their micelles as nanosized reaction vessels
Authors: Antonietti Markus , Förster Stephan , Oestreich Sascha
Published: March 2011

Amphiphilic block copolymers made by a variety of techniques form in selective solvents micelles of well defined size and shape. We report on the underlying principles of micelle formation, as revealed by light scattering experiments.

In addition, we will delineate some applications of these block‐copolymer micelles where we focus on two technological relevant cases, namely the stabilization of polymer particles in low cohesion energy environments as well as the stabilization of metal and semiconductor colloids inside specially functionalized block copolymer micelles. In the latter case, stable hybride materials are obtained where the properties both of the polymer and the inorganic are added in a synergistic way. First data on special catalytic properties, the generation of superparamagnetic materials, and special colloids with optical functionality are presented.
Towards realistic rheological models for polymer melt processing
Authors: Feigl Kathleen , Christian Öttinger Hans
Published: March 2011

Greatly needed improvements to rheological models of polymer fluids can best be made by understanding and modifying a model on the molecular level, where the physics governing real fluids are created. For this purpose, stochastic simulations are an indispensible tool. The usefulness of stochastic simulations for kinetic theory models are well‐known. In this paper, we show that the class of Rivlin‐Sawyers, or K‐BKZ, integral models is also subject to a molecular interpretation and can be simulated using stochastic techniques. We also illustrate how an existing molecular model can be modified, resulting in better predictions of viscoelastic behavior. For this we formulate a stochastic simulation of a reptation model modified to account for double reptation and tube‐length fluctuations.
Diffusion in microstructured block copolymer melts
Authors: Lodge Timothy P. , Hamersky Mark W. , Milhaupt Jodi M. , Kannan Rangaramanujam M. , Dalvi Mukul C. , Eastman Christine E.
Published: March 2011

Forced Rayleigh scattering has been employed to measure tracer and self‐diffusion in block copolymer melts, for both entangled and unentangled systems, and in both the ordered and disordered states. It is shown that entanglements are particularly effective in retarding the motion of copolymers parallel to the interface between microdomains. The mechanisms of “activated reptation” and “block retraction” are proposed for parallel diffusion. The importance of large amplitude composition fluctuations in the disordered state near the ordering transition is also demonstrated, for both copolymer and homopolymer tracers; the results suggest that copolymer tracers are more affected than homopolymers of comparable molecular weight.
Synthesis of unsaturated polyesters from dipotassium salts of cis‐aconitic, itaconic and mesaconic acids and 1, 4‐dibromobutane
Authors: Sepulchre Marie‐Odile , Sepulchre Maurice
Published: March 2011

The polycondensation of dipotassium salts of cis‐aconitic, itaconic and mesaconic acids and 1, 4‐dibromobutane in 1‐methyl‐2‐pyrrolidone at 105°C led in all the cases to the formation of an unsaturated copolyester containing at least three different units: butylene itaconate, butylene mesaconate and butylene citraconate units. At the equilibrium, the relative molar portions of the three units were found to be equal to 36, 59, and 5%, respectively. The polycondensation of the cisaconitic acid salt was accompanied by a decarboxylation reaction which excluded the possibility of preparing unsaturated polyesters with pendant carboxylic acid groups. The study of model reactions carried out with hexyl bromide did not allow us to determine the structure of unexpected units resulting from side reactions occurring only in the polycondensation of cis‐aconitic and itaconic acid salts.
Biodegradation of poly(amino acid)s: Evaluation methods and structure‐to‐function relationships
Authors: Rypáček F. , Pytela J. , Kotva R. , Škarda V. , Cífková I.
Published: March 2011

Two poly(amino acid) systems were studied: (a) poly[N5‐(2‐hydroxyethyl)‐L‐glutamine] (PHEG) derivatives prepared by NCA polymerization; (b) poly‐α,β‐[N‐(2‐hydroxyethyl)‐DL‐aspartamide] (PHEA) derivatives prepared by thermal polycondensation of aspartic acid to racemic polysuccinimide followed by chemical modification reactions. The degradation of polymers by isolated enzymes and homogenate of kidney tissue was studied in vitro and the effect of polymer structure on the rate of degradation and the size of degradation products was evaluated. A PHEA derivative (modified by tyramine residues in 9.6 % of side chains) was accumulated in the lysosomes of kidney cells of rats and the molecular‐weight distribution of the polymer retained inside the lysosomes of living cells and that of the polymer excreted into urine was analysed by a high‐sensitivity size‐exclusion chromatography using the fluorescence and radioactive labelling. While PHEG derivatives were degraded by isolated mammalian enzymes and a tissue homogenate, no significant degradation of PHEA and derivatives was observed, either in vitro, with isolated enzymes and homogenate or in vivo, under a long‐term exposure to the lysosomal enzymes in living cells.
Bulk polymerization of lactides initiated by aluminum isopropoxide. I. Mechanism and kinetics
Authors: Degée Philippe , Dubois Philippe , Jérǒme Robert
Published: March 2011

Commercially available Al isopropoxide (Al(OiPr)3) has proved to be an efficient initiator for the bulk polymerization of lactide. The ring‐opening polymerization proceeds through a “coordination‐insertion” mechanism and the selective rupture of the acyl‐oxygen bond of the monomer. Polyester chains are selectively end‐capped with an aluminum alkoxide and an isopropoxy group. Therefore, substitution of Al tris(4‐penten‐1‐olate) for Al(OiPr)3 leads to the formation of macromonomers. In the temperature range from 110 to 150°C, polymerization is “living”, i.e. the molecular weight can be predicted by the initial monomer‐to‐Al molar ratio and the monomer conversion. The narrower polydispersity of poly(L,L‐lactide) compared to the amorphous poly(D,L‐lactide) (M̄w / M̄n 1.3 compared to 1.9, respectively), both prepared in the bulk, is thought to result from the restricted mobility of the crystallized isotactic polyester chains. When the temperature is increased up to 180°C, inter‐ and intramolecular transesterification reactions interfere with chain propagation.
Novel biodegradable ester‐based polymer blends
Authors: Tighe Brian J. , Amass Allan J. , Yasin Mohammed
Published: March 2011

We have found, within the polyester family, interesting and potentially useful patterns of three‐component compatibility. The bacterially produced biodegradable polyester, poly(hydroxybutyrate) (PHB) and its copolymers with hydroxyvalerate (HV) together with polymers such as cellulose acetate butyrate (CAB), polycaprolactone, poly(lactic acid), and a series of high‐molecular‐weight, non‐crystallizable ester‐based plasticisers have been identified as possible candidates in the production of blends in which aspects of performance can be varied with a degree of independence of cost. The compatibility ranges can be conveniently represented in the form of triangular graphs, with the relative weight fraction, or percentage, being represented along each of the three axes. The extent to which the modulation of the physical properties in general, but the stability in various environments in particular, is possible by the formation of three‐component blends, such as those formed between P(HB‐HV), cellulose acetate butyrate and poly(alkylene adipate) plasticisers, is discussed.
Single‐chain single crystals
Authors: Cao Jie , Gu Fangming , Liu Yongjian , Bi Shuguang , Bu Haishan , Zhang Ze
Published: March 2011

Single‐chain single crystals of isotactic polystyrene and poly(ethylene oxide) were studied by using transmission electron microscopy, high resolution electron microscopy, electron diffraction. Single‐chain single crystals were prepared by spreading a dilute solution of polymers on a water surface and collecting the resulting single‐chain particles on copper grids, followed by isothermal crystallization. A statistical analysis of the sizes of single‐chain crystals was found to match with the known molecular weight distribution of original sample, indicating the particles to be composed of single chain. Observation of the morphology and electron diffraction gave evidence of the single crystal nature. Regular‐shaped single‐chain crystals were obtained after isothermal crystallization for a longer time. By close observation, several types of morphologies were found for single‐chain crystals of isotactic polystyrene and poly(ethylene oxide); in addition to the conventional morphologies observed for multi‐chain crystals, new morphologies were observed in both cases. The morphologies of poly(ethylene oxide) were explained according to the crystal structure and twin modes. Tent‐like single‐chain crystals were often observed. Because of the small size of the crystals, they can avoid collapse on the substrate. The crystalline c‐axis of single‐chain crystals were found to orient preferably in the direction normal to the substrate. The investigation of electron diffraction and high resolution electron microscopy revealed that the structure of the single‐chain crystals of isotactic polystyrene is the same as for multi‐chain crystals. A reasonable explanation is given for the unusual resistance to electron irradiation and the missing of lower‐index reflections. Regular periodic stripes were found on the top surface of single‐chain crystal of isotactic polystyrene with an average periodic length in accordance with (220) spacing. In addition, a statistical thermodynamics theory was developed for single‐chain crystal. It is found that the equilibrium dimensions are related to molecular weight and annealing temperature, while the equilibrium melting temperature depends on molecular weight.
Shear mixing and phase diagram shift of polymer blends
Authors: Han Charles C.
Published: March 2011

For a low molecular weight polystyrene/polybutadiene blend, the effect of shear on the suppressing of critical fluctuations and the critical temperature has been studied and is in good agreement with the predictions of Onuki and Kawasaki. By assuming the symmetry of this critical scaling into the two phase region, together with the Taylor theory, the observed (phase separated) droplet break‐up and the formation of string pattern can be explained. The exact shear dependence of Tc(γ) can be obtained by the use of the fluorescence microscope under steady shear.
Morphologies and domain sizes of microphase‐separated structures of block and graft copolymers of different types
Authors: Matsushita Yushu , Noda Ichiro , Torikai Naoya
Published: March 2011

Well‐defined block and graft copolymers of different types with different compositions and molecular weights, such as styrene(S)‐2‐vinylpyridine(P) diblock copolymers, SP star‐shaped block copolymers, PSP triblock copolymers, styrene(S)‐isoprene(I) multiblock copolymers of the (SI)n type, ISP triblock copolymers, SPP graft copolymers and their deuterated samples were prepared. Variations of the morphologies with compositions, molecular weight dependences of the lamellar domain sizes and conformations and distributions of block chains in the lamellar domains were studied in the strong segregation limit.

Besides typical morphologies such as spherical, cylindrical and lamellar structures, ordered bi‐ and tri‐continuous structures were found between cylindrical and lamellar structures for SP diblock copolymers, PSP and ISP triblock copolymers, respectively. The composition ranges of morphologies are different for the block and graft copolymers of different types.

The molecular weight dependences of lamellar domain sizes are about the same, but their magnitudes are not always the same for the block and graft copolymers of different types. These results are well explained by the theories of Helfand‐Wasserman and Semenov.

Block chains in lamellae are extended along the direction perpendicular to lamellae, but they are contracted along the parallel direction. The former result is well explained by the theories, but the latter is not. Chains adjacent to the junction points between different block chains are localized near the domain interface, but chains at the free‐ends of block chains are widely distributed in the domain with the maximum at the center of domain.
Recent developments in molecular organic electroluminescent materials
Authors: Chen C. H. , Shi J. , Tang C. W.
Published: March 2011

A review of recent developments in the design and use of small molecular organic electroluminescent materials for display applications is presented. The material issues pertaining to transport properties, color, emission efficiencies, and operational stability are described.
Spiro linked compounds for use as active materials in organic light emitting diodes
Authors: Salbeck Josef , Weissörtel Frank , Bauer Jacqueline
Published: March 2011

Spiro‐linkage of low molecular weight entities as a new structural concept for the design of new active materials for electroluminescent applications is presented. These spiro linked compounds result in nonpolymeric organic glasses with high thermal stability as can be derived from their high glass transition temperatures (Tg), and characterized by differential scanning calorimetry. Blue emitters based on spiro linked oligophenyles are presented. These compounds are soluble in common organic solvents and show high photoluminescence quantum efficiency in the solid state and high morphologic stability with glass transition temperatures up to 250°C. Charge transport materials based on spiro linked versions of 2‐(4‐biphenyl)‐5‐(4‐tert‐butylphenyl)‐1,3,4‐oxadiazole (PBD) for electron transport, and spiro linked versions of triphenyldiamin derivatives (TPD) for hole transport show improved morphologic properties with nearly unchanged electronic properties compared to the parent compounds.

High quality amorphous films can be prepared with the spiro compounds by vapor deposition as well as by simple spin coating.
Aromatic polyethers with 1,3,5‐triazine units as hole blocking/electron transport materials in leds
Authors: Fink Ralf , Frenz Carsten , Thelakkat Mukundan , Schmidt Hans‐Werner
Published: March 2011

Various difluoro functionalized aromatic 1,3,5‐triazine monomers were prepared. A series of poly‐(1,3,5‐triazine‐ether)s was synthesized by polycondensation with 4,4′‐(hexafluoroisopropylidene)diphenol. The polymers have excellent thermal stability and are amorphous with glass transition temperatures in the range of 190–250°C. In order to examine the potential to apply these polymers in organic electroluminescent devices, the redox properties were studied by cyclic voltammetry. It was found that the monomers have high electron affinity and reach LUMO values in the range of −2.7 to −3.1 eV. This opens the possibility to utilize 1,3,5‐triazine containing materials as electron injecting/hole blocking layer in LEDs. First LED results are in accordance to these high electron affinities.
Ultrathin organic layers for corrosion protection
Authors: Maege Iris , Jaehne Evelin , Henke Axel , Adler Hans‐Juergen P. , Bram Christian , Jung Christian , Stratmann Martin
Published: March 2011

The adsorption and self‐organisation process of alkyl‐phosphonic acids and phosphoric acid monoalkyl esters on technical aluminium surfaces have been investigated by different surface sensible techniques: Grazing angle FT‐IR‐ spectroscopy, angle dependent XPS and Auger‐ spectroscopy. The aim of these studies was to replace the present technical procedure for pretreatment of aluminum surfaces with Chromate acid in order to improve the corrosion inhibition and the coating adhesion.

The ability for self‐assembly is given by substances which have a surface reactive group and a long‐aliphatic or aromatic spacer and a supramolecular order is built‐up between these spacers. The results show that these molecules are able to adsorb spontaneously onto the aluminum surface and subsequently a structured molecular order is formed.

These effects were confirmed by industrial linked adhesion and corrosion tests.
Interaction of Linear Polyelectrolytes with Oppositely Charged Lightly Cross‐Linked Networks
Authors: Zezin Aleksander B. , Rogacheva Valentina B. , Kabanov VictoR. A.
Published: March 2011

The processes proceeding at the contact of highly swollen lightly cross‐linked polyelectrolyte networks with aqueous solutions of oppositely charged linear polyions were studied. The reactions under discussion proceed as frontal processes and follow by strong (three orders of magnitude) contraction of the gel sample. The existence of sharp boundary between outer weakly swollen layer which is the reaction product—interpolyelectrolyte complex and the highly swollen inner part which is the initial unconverted gel is characteristic for the process. The kinetics of linear polyions absorption by polyelectrolyte networks and factors controlling the rate of sorption such as chemical structure of polyelectrolytes, nature and concentration of simple salts, pH, temperature were investigated. The “relay‐race” mechanism of linear polyelectrolyte transport was established.
Improvement of adhesive bonding of thermoplastic polymers by different surface treatments
Authors: Zeiler Thomas , Pfeffer Petra , Kürner Marcus , Münstedt Helmut
Published: March 2011

Injection moulded samples of six species of thermoplastic polymers were exposed to different surface treatments and successively glued together to form single lap shear joints. Lap shear strength and failure mode of these specimens were examined. The surfaces obtained after treatment were characterized by electron spectroscopy for chemical analysis, contact angle measurements and atomic force microscopy.
Fluorescent molecular rotors as probes for polymers
Authors: Carré Marie‐Christiane , Dorion Catherine , Rebizak Richard , Pla Fernand , Brembilla Alain , Viriot Marie‐Laure
Published: March 2011

The use of a molecular rotor (1,1‐dicyano‐4‐(4'‐dimethylaminophenyl)‐1,3‐butadiene) as a fluorescent probe was proved to be of great interest for the study of polymers. First, the rotor can detect the critical time of the glass effect in the bulk polymerization of MMA into PMMA due to viscosity change, this will allow a better control of the process and is complementary to the information issued from the use of the fluorescent pyrene probe which is sensitive to the gel effect. Second, the cinnamylidene rotor was able to detect the formation of hydrophobic microdomains for cationic amphiphilic polymers in their aggregation modes when they were solubilized in water, both polarity and viscosity changes are playing a role. The possibility of incorporation of various molecular fluorescent rotors in polymers beads was also studied.
The influence of processing conditions on the properties and the degradation of poly (3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)
Authors: Renstad R. , Karlsson S. , Albertsson A.‐C.
Published: March 2011

The influence of melt‐extrusion on the degradation behavior of poly(3‐hydroxybutyrate‐co‐7% 3‐hydroxyvalerate) in a small‐scale compost and in salt media with Aspergillus fumigatus has been studied. The degradation has been monitored by Size Exclusion Chromatography (SEC), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM) and X‐ray analysis. During the first 9 weeks of composting the degradation proceeds through surface erosion without any significant change in molecular weight or weight crystallinity. After 10 months the weight average molecular weight, Mw, has decreased by approximately 15–50%. It is suggested that degradation mechanism is converted from enzymatic to chemical hydrolysis as the porosity of the samples increases which facilitates water penetration. In addition, the acidic degradation products would accelerate the chemical hydrolysis inside the sample due to lowering of the pH. During degradation in media containing A. fumigatus the sample processed at low temperature exhibited extensive surface degradation and a 12% reduction of the Mw. In contrast the sample processed at high temperature showed an homogeneous surface degradation and no reduction in molecular weight. The differences in degradation are attributed to variations in the initial morphology of the samples caused by the processing conditions. Further investigations are, however, required to separate effects attributed to local differences in the compost environment and the structure of the samples.
Stereochemical aspects of the controlled ring‐opening polymerization of chiral cyclic esters
Authors: Spassky Nicolas , Pluta Christian , Simic Vesna , Thiam Mohamedou , Wisniewski Muriel
Published: March 2011

The stereochemical aspects of controlled polymerization of lactide and β‐butyrolactone are discussed. The physicochemical and thermal properties of these polymers are shown to be depending on the stereochemical structure of the macromolecular chain. Different types of processes involving change of enantiomeric composition in the course of the polymerization reaction are examined in function of different initiators used. The formation of stereocomplexes from stereocopolymers of various enantiomeric compositions is reported.
Cyclic and linear liquid crystalline functionalized polyesters with main‐chain ortho‐linked units. synthesis and characterization of cyclic lc unimers and dimers with “u”‐shaped rigid mesogenic units with alkyl side chains
Authors: Navarro Fernando
Published: March 2011

Although ortho‐diphenols had not been extensively used in the synthesis of LC esters, a great variety of molecular structures of low and high molecular weight LC esters containing high proportions of these units can be synthesized. In this paper we describe the synthesis and characterization of new series of low and high molecular weight cyclic and linear LC esters with mesogenic “U”‐shaped rigid units with terminal groups which are alkyl chains. Cyclic oligoesters and linear polyesters were formed by the polycondensation of 4,4'‐[1,10‐decamethylenebis(oxy)]bis(cinnamic acid) with monosubstituted catechols which are the alkyl esters of 3,4‐dihydroxybenzoic acid. Although the great importance that concomitant cyclization reactions have in polyesterifications involving high proportions of ortho‐diphenols does not seem to have been considered until now, we have found mat these polyesterifications produced linear polyesters along with high proportions of cyclic oligoesters even when reaction conditions disfavored cyclization. Copolymerization with p‐hydroxybenzoic acid decreased the amount of cyclic oligomers, however it was necessary to copolymerize with proportions of PB higher than 50 mol‐% to get copolyesters with low proportions of cyclic oligomers. As far as we know we describe the first examples of cyclic LC oligoesters and cyclic LC unimers and dimers which display enantiotropic LC mesophases stable over broad ranges of temperature. Cyclic dimers display mesophases whose isotropization temperatures ( > 300°C) are much higher than that of their linear high molecular mass homologues. Cyclic LC unimers and dimers, linear LC polyesters and model compounds were characterized by FAB‐MS, GPC, 1H NMR, DSC and hot‐stage polarized microscopy. All these compounds contain reactive C=C double bonds and can be crosslinked thermally and photochemically. Cyclic unimers and dimers can be polymerized termally to produce high molecular mass polymers.
Molecular and mechanistic aspects of the functionalization of polyolefins with ester groups
Authors: Ciardelli Francesco , Aglietto Mauro , Passaglia Elisa , Ruggeri Giacomo
Published: March 2011

In the present paper the functionalization reaction of polyolefins in the melt with diethylmaleate (DEM) in the presence of peroxide is revisited. The process was analyzed on the basis of several experiments carried out in the Brabender mixer with 30 min residence time and at constant temperature, 190° C for EPR and 200° C for LLDPE samples, while varying the number of branching in the starting polyolefin, the amount of DEM and of dicumyl peroxide (DCP). For reference purposes similar experiments were also examined as performed with EPDM and isotactic polypropylene (PP).

At the end of the reaction, the polymeric product was treated with boiling acetone to remove low molecular weight products. In general, the acetone insoluble polymer was soluble in heptane and the functionalization degree (FD) referred to this fraction was in the range 0.2–2.0% mol of DES groups per 100 moles of monomelic units.

The contemporary occurrence of the degradation and chain extension, including crosslinking reactions, provides a reasonable explanation of the results obtained. The analysis of the process performed in the present work helps to select proper conditions for controlling the characteristics and FD of the polyolefin and keep undesired secondary reactions under control.
Developments in the synthesis of maleated polyolefins by reactive extrusion
Authors: Bray Tracey , Damiris Sam , Grace Andrew , Moad Graeme , O'Shea Michael , Rizzardo Ezio , van Diepen Gary
Published: March 2011

The maleation of conventional and metallocene linear low density polyethylenes by reactive extrusion has been explored with a view to defining the conditions necessary for a robust process that provides both high grafting efficiencies (>80%) and minimal degradation or cross‐linking. The dependence of grafting efficiency on various operating parameters (maleic anhydride level, maleic anhydride:initiator ratio, throughput rate, direction of screw rotation, temperature) has been established. Literature methods for characterization of the grafted product based on FTIR or 1H NMR analysis have been critically examined with respect to their ability to distinguish between single unit and oligomeric maleic anhydride grafts and found to yield ambiguous results.
13C NMR Study of the grafting of 13C labeled maleic anhydride onto PE, PP and EPM
Authors: Heinen Wouter , van Duin Martin , Rosenmöller Carola H. , Wenzel Cornelia B. , De Groot Huub J.M. , Lugtenburg Johan
Published: March 2011

The chemical structure of polyolefins grafted with maleic anhydride (MA) has been the subject of much speculation, but thorough experimental studies are rare. MA with 99% 13C in the double bond was synthesized and grafted onto PE, EPM and PP in the melt and solution. 1D INADEQUATE 13C NMR spectroscopy was used to characterize the products. Saturated, monomeric MA graft structures are formed. Only for grafted PE short MA oligomers are demonstrated. Grafting occurs on secondary and tertiary carbons depending on the composition of the polyolefin. For PP a new, unsaturated MA graft structure on the polymer chain terminus is identified. All graft structures are rationalized using a simple grafting mechanism.
Macromolecule — Metal complexes based on salts of unsaturated mono‐ and dicarboxylic acids: Synthesis and characterization
Authors: Dzhardimalieva Gulzhian I. , Pomogailo Anatolii D.
Published: March 2011

The radical polymerization and copolymerization of salts of unsaturated carboxylic acids were used for the production of metal‐containing polymers. The kinetic peculiarities and copolymerization parameters were estimated. The synthesis and structure of transition metal acrylates, maleates, fumarates, and itaconates are discussed. The influence of the metal atom on salt reactivities and reaction rates is observed.
(Co)polymerization of metal‐containing monomers as a way of MMC synthesis
Authors: Pomogailo Anatolii D.
Published: March 2011

The principal advances and problems of the synthesis, of poly‐, co‐ and graft‐ polymerization of metal‐containing monomers (MCM) are analysed. The MCMs are classified on the type of the metal bond with the organic part of the molecule, viz. MCM with σ‐, nv‐, and π‐bonds. The effect of a transition metal on both the polymerization and on the properties of the products formed is of special interest. The basic fields of application of metal‐containing polymers have been summed up.
Addition — Fragmentation type initiators for cationic polymerization
Authors: Yaǧci Yusuf , Reetz Ivo
Published: March 2011

Addition — fragmentation reactions are a versatile and exceptionally interesting tool in preparative polymer chemistry. With the aid of specially designed allyl‐onium salts (addition — fragmentation agent, AFA) in conjunction with conventional radical initiators it is possible to very efficiently initiate cationic polymerizations. The mechanism involves (a) the formation of radicals by heating or irradiating the radical initiator, (b) the addition of these radicals to an AFA molecule and (c) the fragmentation of the AFA. In step (c) radical cations are produced, which with high rates initiate the polymerization of cationically polymerizable monomers (e.g., cyclohexene oxide, CHO). In order to show good performance in initiation reactions, AFAs have to be equipped with functional groups or substituents which either promote radical addition or facilitate the fragmentation of reaction intermediates.
Anionic polymerization and copolymerization of macromonomers: Kinetics, structure control
Authors: Ederle Y. , Isel F. , Grutke S. , Lutz P. J.
Published: March 2011

The present paper discusses the ability of macromonomers to undergo polymerization and copolymerization with acrylic and vinylic monomers. These macromonomers have been synthesized by classical deactivation reactions. Special interest was devoted to macromonomers fitted with polymerizable methylmethacrylate end‐groups. The anionic homopolymerization of ω‐methacryloyloxy‐polystyrene macromonomers was studied in detail and the influence of the molar mass of the macromonomer on the apparent propagation constant was determined. The anionic homopolymerization of ω‐methacryloyloxy poly(ethylene oxide) macro‐monomers was also examined. In both cases, lithium chloride has to be added in order to reach a better control of the reaction. The dilute solution properties of these polystyrene polymacromonomers have been studied. Some preliminary attempts to apply that anionic homopolymerization of macromonomers to the preparation of “dumbbell” and “palmtree” polymers were presented.
Preparation of uniform stereoregular polymer, stereoblock polymer and copolymer of methacrylate, and their stereocomplex formation
Authors: Hatada Koichi , Kitayama Tatsuki , Ute Koichi , Nishiura Takafumi
Published: March 2011

Isotactic (it‐) and syndiotactic (st‐) uniform poly(methyl methacrylate)s (PMMAs) were prepared by stereospecific living polymerizations followed by supercritical fluid chromatographic separation. The it‐and st‐uniform PMMAs were used to study the mechanism of stereo‐complex formation in solution with the aid of gel permeation chromatography and 1H NMR spectroscopy. The it‐ and st‐uniform PMMAs with hydroxy end‐group were prepared and reacted with sebacoyl dichloride to form uniform stereoblock PMMA. The stereoblock PMMA was found to form intra‐ and intermolecular stereocomplexes in acetone. A uniform stereoblock copolymer, it‐PMMA‐block‐st‐poly(ethyl methacrylate), was prepared and its stereocomplex formation was also studied.
Ionic polymerization in aqueous emulsion
Authors: De Gunzbourg Anémone , Maisonnier Sylvette , Favier Jean‐Claude , Maitre Catherine , Masure Michèle , Hémery Patrick
Published: March 2011

A kinetic study of the anionic polymerization of octamethylcyclotetrasiloxane (D4) in aqueous emulsion has been carried out in the presence of ionic additives. The rate of polymerization of several cyclosiloxanes has been compared, leading to additional evidence for an interfacial mechanism of polymerization. The emulsion process has been applied to the cationic polymerization of D4 and of tetramethylcyclotetrasiloxane (DH4) initiated by dodecylbenzenesulfonic acid. Very efficient for the synthesis of linear polymethylhydrogenosiloxanes (PMHS), these conditions did not seem suitable for the polymerization of D4. The extension of the process to other heterocyclic monomers is discussed through the anionic polymerization of phenylglycidylether.
New adventures with divalent carbon intermediates
Authors: Marchand Alan P. , Rajagopal D. , Kumar Kaipenchery A. , Eckrich Ralf , Ramanaiah K. C. V. , Namboothiri I. N. N. , Alihodžić Sulejman , Dong Eric Zhiming , Shukla Rajesh , Bott Simon G. , Mlostoń Grzegorz , Galindo Alberto , Bartnik Romuald
Published: March 2011

Part I: Reactions of 3‐substituted 1‐azabicyclo[1.1.0]butanes (1a and 1b) with dichlorocarbene proceed in each case via nitrogen ylide intermediates with concomitant ring opening to afford the corresponding dihaloimines (2a and 2b, respectively). Part II: Vinylidènecarbene‐cycloalkyne equilibria have been studied in three polycarbocyclic systems, i.e., 10a‐10b, 20a‐20b, and 27a‐27b. In all three systems, only the vinylidenecarbene intermediate can be trapped in situ by cyclohexene. The results of site‐specific 13C labeling studies that employ 9‐C(8)‐13CBr2 (enriched with 4 atom‐% 13C), 19‐C(4)‐13CBr2 (enriched with 5 atom‐% 13C), and 23‐C(4)‐13CBr2 (enriched with 10 atom‐% 13C) also support this conclusion and suggest that cycloalkyne intermediates, if formed in these systems, must rearrange very rapidly to the corresponding (thermodynamically favored) vinylidenecarbenes. Part III: Base‐promoted reactions of N‐tosyl‐ and N‐benzhydrylazetidin‐3‐ones (i.e., 30a and 30b, respectively) with diethyl diazomethylphosphonate (DAMP), when performed in the presence of cyclohexene, in each case afford exclusively the product that results via in situ trapping of the corresponding vinylidenecarbene.
Inner sphere and outer sphere electron transfer reactions in atom transfer radical polymerization
Authors: Matyjaszewski Krzysztof
Published: March 2011

The participation of electron transfer (ET) processes in atom transfer radical polymerization (ATRP) is discussed. Inner sphere electron transfer process (atom transfer) is the inherent part of ATRP. It includes the homolytic cleavage of C‐halogen bond in dormant macromolecular alkyl halides species by the Cu(I) activator with the rate constant kact≈︁100±1 M−1s−1. This process is reversible and the deactivation of growing radicals by X‐Cu(II) species is very fast with the rate constant of deactivation kact≈︁107±1 M−1s−1. However, in addition to the atom transfer process (inner sphere ET), outer sphere ET may also occur. Growing radicals can either be oxidized by Cu(II) species to carbocations or reduced by Cu(I) species to carbanions. These reactions were observed in the polymerization of p‐methoxystyrene and initiation with 2‐bromomalonates, respectively. In order to avoid these side reactions the catalyst structure should be fine tuned for the particular monomer and the range of targeted molecular weights. In addition, some side reactions can be avoided by slow addition of initiator (e.g. for benzhydryl halides), catalyst (for malonates and CCl4 as initiators) and by reducing polymerization temperature.
„Bonding”︁ electropolymerization: A new electron‐transfer strategy for the tailoring of performant polymer‐based composites
Authors: Baute Noëlle , Calberg Cédric , Dubois Philippe , Jérǒme Christine , Jérdme Robert , Martinot Lucien , Mertens Marc , Teyssié Philippe
Published: March 2011

Careful control of experimental conditions in the cathodic electropolymerization of acrylonitrile allows the grafting of thin polymer films, on conducting surfaces offering electrons easily mobilized at a relatively low potential. Matching relative polarity and donicity of solvent and monomer expands the applicability of this methodology to the whole class of (meth)acrylic monomers, paving the way to many new and useful multiphase materials
Recycling technology of poly(ethylene terephthalate) materials
Authors: Lin Chen Chong
Published: March 2011

Poly(ethylene terephthalate) (PET) has become one of major post consumer plastics wastes, in addition to polyethylene (PE), polypropylene (PP), polystyrene (PS) and poly(vinyl chloride) (PVC). The challenge to large‐volume plastics companies is to learn how to collect, separate, reprocess and market their low‐cost products and make a profit, too. The effort of PET recycling, however, is the most successful story in the plastic recycling technology, including both reclaim and upgrade of PET waste. Beverage bottles made of PET are recycled more than 20% of the total production. The technology of today can reclaim the post‐consumer PET bottles to produce high‐quality granulated PET with better than 99% purity. A practical reclaim process for recycling PET bottles (including bottle, HDPE base cup, aluminum cap, liner, label and adhesive) is available by the Center for Plastics Recycling Research in USA. PET recycling process, like for other plastics, can be divided into three categories: incineration, physical recycling, and chemical recycling. To make the plastic recycling business pay requires more than simple recovery and marketing. Greatest profit potential is in upgraded and value‐added reclaim products. Upgrading involves compounding with additives to make material more processable, adding reinforcement, or producing extrusions or finished parts from reclaim resins. For instance, a modified injection‐moldable resin made from PET bottle scrap is claimed to provide high impact and processability at less cost than competitive materials. It is foreseen that chemical recycling of waste PET bottle becomes feasible if the price of raw material goes up. Three economical processes are involved in this technology: pyrolysis, hydrocracking, and hydrolysis. The hydrolysis process is presently employed to recover the raw material for unsaturated polyester resin manufacture or polyols for the production of polyurethane resin. It is reported in this presentation that polymer concrete could be a huge potential market for chemical reclaim of PET materials, especially for green or mixed‐color PET, which are priced lower than colorless PET reclaim materials.
New trends in chemical recycling of poly(ethylene terephthalate)
Authors: Spychaj Tadeusz , Paszun Daniel
Published: March 2011

Chemical recycling of poly(ethylene terephthalate) (PET) by nonconventional transesterification and ammonolysis/aminolysis methods are discussed on the basis of literature and own experimental data. The obtained products of deep PET degradation using allylamine (N,N′‐diallylterephthaldiamide), triethanolamine and other alkanolamines were prepared and characterized by DSC and elemental analysis.
The role of additives in the recycling of polymers
Authors: La Mantia Francesco Paolo
Published: March 2011

The main problems in post‐consumer plastics recycling are due to the degradation undergone by the polymers during processing steps and by the products during their lifetime and, for heterogeneous recycling, to the incompatibility of different polymers. To reduce the negative effects of the recycling steps, two main ways can be adopted for homogeneous materials: restabilization during the recycling to avoid or at least to slow the degradation and addition of fillers and modifiers capable of improving the performance of thermoplastic polymers without increasing the final cost of the secondary material. In the case of mixed plastics, compatibilization is the necessary step to obtain secondary materials with acceptable properties.
The influence of recycling on the properties of wood fibre — Plastic composites
Authors: Balatinecz John J. , Sain Mohini M.
Published: March 2011

The manufacture of composites offers the greatest flexibility to convert and utilize waste plastics, paper and wood into high‐value products. This paper reports on two studies regarding the recycling of these materials. In one study, recycling was simulated by regrinding and injection‐moulding composites of polypropylene (PP), polyethylene (PE) and old newsprint (ONP) eight times. The results indicated that reprocessing had only minor deleterious effect on the mechanical properties (tensile and flexural). The viscosity of neat PP decreased with repeated recycling indicating some thermo‐oxidative degradation. The overall rheological character of PP composites did not change much. PE composites, on the other hand, showed increasing melt flow with reprocessing. The second study examined the effects of various coupling agents on the properties of multicomponent PP composites. Maleated polypropylene (MAPP) was the most effective coupling agent.
Polyelectrolytes bearing azobenzenes for the functionalization of multilayers
Authors: Fischer Peter , Laschewsky André , Wischerhoff Erik , Arys Xavier , Jonas Alain , Legras Roger
Published: March 2011

Thin polymeric films are assembled by the alternating adsorption of oppositely charged polyelectrolytes. The polyions are functionalized by azobenzenes, typically carrying donor‐acceptor substituents. The azobenzene chromophores are exploited as versatile analytical tools, to study the assembling process, and to control the film quality. A high concentration of ionic groups does not seem to be advantageous per se for good film growth, but rather the matching of the charge densities of the polyelectrolyte pair used seems to be important. Also, the influence of the strongly interacting, form‐anisotropic character of the azobenzenes on the internal film structure was investigated. Although even high concentrations of azobenzenes and of other mesogens do not induce particular ordering, a few polymer pairs allowed the construction of real multilayer films, exhibiting e.g. Bragg peaks.
Molecular hybrids of azobenzene polymer and liquid crystal molecule. A new approach for understanding the command surface system
Authors: Ubukata Takashi , Seki Takahiro , Ichimura Kunihiro
Published: March 2011

Langmuir‐Blodgett (LB) films consisting of the hybrid of a polymer having the azobenzene (Az) side chain and 4î‐pentyl‐4‐cyanobiphenyl (5CB) are prepared. Microscopic observations and spectroscopic data both indicate that the Az side chain and 5CB are homogeneously mixed at a molecular level without phase separation in the layer. This provides a satisfactory model of the command surface system. Time course accumulation of spectroscopic data for multilayered hybrid films reveals the cooperative nature of the photo‐motivated molecular motions.