bluuebunny/crossref_metadata_2025 huggingface dataset:
Poly(styrene‐co‐p‐(hexafluoro‐2‐hydroxy‐2‐propyl)‐styrene) blends with syndiotactic and/or isotactic poly(methyl methacrylate)
Authors: Luo Dexin , Kwei T. K. , Pearce Eli M.
Published: March 2011

A modified polystyrene, poly(styrene‐co‐p‐(hexafluoro‐2‐hydroxy‐2‐propyl)styrene) (FPS), was blended with syndiotactic and/or isotactic poly(methyl methacrylate) (PMMA) in toluene. Blends were prepared under different conditions to control the self‐aggregation of the PMMA segments. The formation of hydrogen bonding and the attendant changes in the aggregation or crystallization of PMMA segments were determined in the solid state by means of FTIR and DSC. The results indicate that for the binary blends, the aggregation of PMMA segments is diminished by hydrogen bonding interaction with either s‐PMMA or i‐PMMA, and that the interaction is stronger with the s‐PMMA blends. For the ternary blends, FPS/s‐PMMA/i‐PMMA, the preference for stereocomplexation in the system with hydrogen bonding may be attributed to the “kink‐nucleated” mechanism, which needs relatively short chain lengths of PMMA segments. Regardless of the order of addition of the components, the formation of crystalline stereocomplexes of s‐ and i‐PMMA could be readily detected. Therefore, the miscibility of the polymer blends is dependent on the competition between the self‐aggregation of the s‐ or i‐PMMA segments, stereocomplexation and the hydrogen bonding interaction of PMMA segments with FPS.
Ion conduction in poly(crown ethers), polyglucosan gels and macroporous polyethylene films
Authors: Cowie J.M.G.
Published: March 2011

Much work has been reported on ion conduction in solid solutions of salts dissolved in linear and comb‐branched poly(ethylene oxide) analogues. There appears to be a limit to the conductivity levels achieved in such systems, and conductivity values rarely exceed σ ∼ 10−4 Scm−1 at room temperature. To overcome this there has been a move towards more mobile plasticized systems and polymer gel electrolytes are receiving some attention. Gels prepared from N‐methyl‐2‐pyrrolidinone/LiCl and polyglucosans such as cellulose and amylose have been studied and show some promise with ambient σ Ge; 10−4 Scm−1. Macroporous polyethylene has also been used to support fluid polyethylene glycol/salt systems, but these only reached σ ≥ 10−5 Scm−1 at ambient temperature.

Comb‐branch polymers with crown ethers provide systems with respectable room temperature conductivities of between 10−4 and 10−5 Scm−1, but these might be improved if the crown ethers could be arranged in regular channels. Ways to achieve this are briefly discussed.
The solubility and transport properties of small molecules in polymers — A modeling approach
Authors: Suter U. W.
Published: March 2011

The molecular mechanisms acting in the transport of “guest” molecules through polymeric solids still pose considerable difficulty: despite a manifest technological demand there has been a considerable lack of fundamental understanding of the mechanisms underlying the solubility and diffusion of even the smallest molecules in macromolecular substances. It is well known that the transport coefficients of low‐molar‐mass substances in polymers are strongly dependent on a number of factors, prominent among them the chemical structure of macromolecules. Nevertheless, the models applied for interpretation of transport of small molecules through macromolecular systems have been usually of a rather unspecific nature.

Recently, modeling of the transport of gases through polymers in atomistic detail has been rather successful in elucidating the mechanisms as well as in predicting, without adjustable parameters, the transport coefficients. For the solubility, the quantitative estimate is rather rough since the estimation of the free energy of residence of guest molecules in a host matrix is plagued by the usual inaccuracies, the topological information is accurate, however; on the other hand, it is possible to estimate the diffusion coefficient to within a factor or ca. 2–5 over the entire range investigated (105 < D/(cm2/s) 10< −10).

Mechanistically, one can state that the interstitial unoccupied column in the polymer can accommodate gas molecules with only small effects on the matrix. The solubility isotherm follows Fermi‐type statistics as long as the solute concentration is not too high. The gas transport through polymers occurs by a hopping mechanism in a matrix of macromolecular material that executes rapid thermal motion not coupled to large‐scale changes in the polymer. Consequently, the mechanism for gas transport in glasses and melts (or rubbers) is the same. On a short time scale, typically for times between 1013s and ns (or more), the diffusion is anomalous, due to the interstitial structure of the polymer. Einstein diffusion occurs only on time scales that are significantly longer (sometimes up to ms).
Preparation of polysaccharide derivatives and their chiral recognition mechanism
Authors: Okamoto Yoshio , Yashima Eiji
Published: March 2011

Several new phenylcarbamate derivatives of cellulose and amylose having fluoro and methyl groups or 4‐trimethylsilyl substituent on the phenyl groups were prepared and their chiral recognition abilities as chiral stationary phases for HPLC were evaluated. These derivatives are soluble in chloroform and exhibit chiral discrimination in 1H NMR spectroscopy. Based on the above results and molecular mechanics calculation of interaction energies between the derivatives and enantiomers, the mechanism of chiral discrimination is discussed.
Molecular characteristics of functional polysaccharides
Authors: Norisuye Takashi
Published: March 2011

The molecular characteristics of sodium hyaluronate and amylose in various solvents are discussed by summarizing our recent studies. Data for the intrinsic viscosity and the radius of gyration are analyzed on the basis of the wormlike or helical wormlike chain, with excluded‐volume effects taken into account by the Yamakawa‐Stockmayer‐Shimada theory. The unperturbed hyaluronate molecule in 0.2 M or 0.5 M aqueous NaCl is shown to behave like a wormlike chain with Kuhn's segment length of about 8 nm. Amylose in the unperturbed state is more flexible, regardless of the kind of solvent, its stiffness parameter being about one half that for the hyaluronate chain, but it assumes an irregular helical conformation similar to what is predicted by conformation analysis.
Gelation and its relevance to the function of polysaccharides
Authors: Mimura Mitsuru , Urakawa Hiroshi , Kajiwara Kanji , Kitamura Shinichi , Takeo Kenichi
Published: March 2011

(1→4)‐α‐ and (1→4)‐β‐D‐linked glucosidic oligosaccharide chains were generated by the Monte Carlo method, and the scattering from the systems composed of simulated chains was calculated to compare with the results of small‐angle X‐ray scattering from the oligosaccharides in aqueous solution. By extending the simulation to a longer chain, a single chain conformation of (1→4)‐α‐ and (1→4)‐β‐D‐linked polysaccharides was evaluated. On the basis of the simulation, the suprastructure of (1→4)‐α‐ and (1→4)‐β‐D‐linked polysaccharides and their gel formation mechanism were discussed in some detail by analyzing the small‐angle X‐ray scattering from the aqueous solutions of (1→4)‐α‐ and (1→4)‐β‐D‐linked polysaccharides.
Preparation of new types of temperature‐responsive cellulose derivatives
Authors: Miyamoto Takeaki , Long Mingfang , Donkai Nobuo
Published: March 2011

This paper reviews briefly our preliminary results concerning thermoplastic hydrogels and thermotropic aqueous gels from cellulose. Several kinds of thermoplastic hydrogels and thermotropic aqueous gels were prepared from cellulose and their thermal properties were examined. The former aims at preparing water‐insoluble cellulose derivatives having a high water absorbency and a thermal flow temperature of approximately 130°C, while the later aims at preparing water‐soluble cellulose derivatives which show a solubility behavior similar to that of synthetic polymers with a lower critical solution temperature (LCST) in aqueous solution. The results will be discussed in terms of the chemical structure of the prepared derivatives and their substituent distributions along the cellulose chain.
Novel pharmaceutical applications of polysaccharides
Authors: Franz Gerhard , Alban Susanne , Kraus Josef
Published: March 2011

The role of chemically characterized polysaccharides will be discussed in view of their immunostimulating activities. A possible correlation of fungal β‐1.3/1.6‐glucans differing in the branching pattern is demonstrated with in vivo tumor models. In a second part the possible role of sulfated polysaccharide structures as anticoagulating compounds is again correlated with polysaccharide structures and sulfate substitution pattern of these biopolymer derivatives.
Novel drug delivery system by chitin derivative
Authors: Tokura Seiichi , Nishi Norio , Takahashi Kiyohisa , Shirai Akihiro , Uraki Yasumitsu
Published: March 2011

A porous chitin foam was regenerated from chitin dope in calcium chloride dihydrate saturated methanol. The porous chitin foam was shown to have cationic property, because chitin foam tended to adsorb anionic dyes through ionic binding and hydrophobic interaction. A pendant type of polymeric drug was prepared applying peptide spacer composed of phenylalanine at amino end and two step hydrolyses of polymeric drug were shown to release active drug at the final step using lysozyme and chymotrypsin in vitro.
Antiviral activity of polysaccharides against infection of tobacco mosaic virus
Authors: Sano Yoh
Published: March 2011

In the course of searching for antiviral substances to tobacco mosaic virus (TMV), it was found that polysaccharides have a high inhibitory activity against TMV infection. The leaves of Xanthi NN tobacco were rubbed with the mixtures of TMV and polysaccharides such as chondroitin sulfate C‐ and A‐ types. The addition of polysaccharides to the inoculum solution greatly reduced the number of local lesions formed on the inoculated leaves. Here the polysaccharide did not completely prevent virus entry into the leaves and the virus particles may penetrate and multiply in leaves without forming lesions. Although the electron micrograph showed that the virus suspension was almost monodisperse, the addition of polysaccharides caused TMV to form large raft‐like aggregates. The TMV solution became turbid after the addition of a large amount of polysaccharides. A threshold concentration of polysaccharides exists for virus precipitation, which is independent of the virus concentration. The size of polysaccharide at the threshold concentration agreed well with that obtained by light scattering method. The strength of the interaction between TMV and polysaccharides was found to be related to the degree of inhibitory activity of polysaccharides.
Polymers for medical uses
Authors: Höcker Hartwig
Published: March 2011

A brief survey of biomaterials and of the approaches to modify their surface is given. By means of specific examples of polymers and polymer blends the chemical modification of the surface by means of wet‐chemical processes as well by plasma treatment and the consequences for endothelial cell proliferation, fibronectin adsorption, hydrophilicity, surface tension and zeta‐potential are described. The results are correlated with standard parameters of measuring hemocompatibility and a compatibility window is indicated.
The state of water in swollen polymers
Authors: Rault Jacques
Published: March 2011

It is shown that by low frequency measurements in hydrophilic polymers only one state of water is observed. Water behave as a classical plasticizer and ice melting in polymer is similar to ice melting in binary simple mixture. The non crystallizable water in these systems is explained by the Tg regulation effect. In oriented swollen polymers, only one state of water is observed in the time scale ∼ 1/ωq = 10−5 s by deuterium NMR. This technique gives information on the mean orientation of D2O molecules in the oriented polymer and on the fraction of mobile water molecules. The concept of bound and unbound water is not relevant for explaining the DSC and D‐NMR results.
Use of hydrogels as corneal inlays for refractive surgery
Authors: Laroche Laurent , Honiger Jiri. E. , Borderie Vincent
Published: March 2011

A novel hydrogel has been used for intracorneal implantation, in order to correct refractive errors of the eye. Our hydrogel is a polyanionic copolymer of acrylonitrile and sodium methallylsulfonate material (AN 69, made by HOSPAL, France). We describe here its formation, chemico‐physical and biological properties (in vitro and in vivo), and its biomechanical behaviour when implanted into the cornea.
Optical polymers for telecom applications
Authors: Lösch Kurt
Published: March 2011

An attractive application field for optical polymers is seen in telecom systems, both for interconnection and switching. Based on selected system applications specific requirements for materials selection and processing of polymer based optical devices are given.
The study of stabilizer action modes by means of time‐resolved techniques: Intermediate radical cations
Authors: Brede Ortwin
Published: March 2011

In organic systems, radiation‐ and photo‐induced electron transfer reactions result in the first step in the formation of radical cations. With pulse radiolysis and laser photolysis experiments radical cations of phenols could be indirectly characterized whereas radical cations of sterically hindered amines (HALS compounds) could be directly observed.
Copolymerization and copolymers of brominated phenylmaleimides with some vinyl monomers
Authors: Janović Zvonimir
Published: March 2011

The kinetics of the free radical copolymerization in solution of N‐(4‐bromophenyl)maleimide (MBPMI), N‐(2, 4‐dibromophenyl)maleimide (DBPMI) and N‐(2, 4, 6‐tribromophenyl)maleimide (TBPMI) with styrene (St), methyl acrylate (MA), methyl methacrylate (MMA) and acrylonitrile (AN) at low and high conversions were described. Some characteristic properties of the copolymers obtained, particularly their thermal behaviour were also presented.
Plasma modification of polymer surfaces
Authors: Friedrich Jörg , Unger Wolfgang , Lippitz Andreas
Published: March 2011

To avoid chemical destructions of macromolecules at the polymer surface and to obtain maximum improvement in adhesion properties the short‐time exposure to plasma is a good choice. Enhanced quality of surface functionalization can be reached by chemical conversion of plasma introduced functional groups. Additionally, molecular and supermolecular orientations of the macromolecules and their re‐arrangement by plasma exposure influence the adhesion properties of polymers. Atmospheric pressure plasma is generally suitable for high‐speed surface modification of polymers.
New engineering polymers for blow‐moulding
Authors: Kirchner Olaf
Published: March 2011

The combination of using high performance flexible engineering polymers and their processing by blow moulding technology allows traditional rubber and rubber‐metal composite parts to be replaced to obtain improved performance, lower cost and greater design freedom. Two examples of automobile applications are detailed to support this concept ‐ constant velocity joint boots and engine air ducting.
Simulation of polyelectrolytes in solution
Authors: Seidel Chr.
Published: March 2011

We present results of a Monte Carlo Simulation of weakly charged chains. The Coulomb interaction between charged beads is modelled by a Debye‐Hückel potential. The stretched charged chains are shown to be not wormlike and to exhibit strong chain end effects.
Metalloporphyrin catalysts for living and immortal polymerizations
Authors: Inoue Shohei , Sugimoto Hiroshi , Aida Takuzo
Published: March 2011

The living polymerization of methyl methacrylate with aluminium porphyrin (1) proceeded dramatically rapidly at room temperature in the presence of sterically crowded organoaluminium compounds such as methylaluminium ortho‐substituted diphenolates (3a − 3g), bis(triphenylmethanolate) (4a), and triphenylaluminium, where undesired reaction between the growing species and the Lewis acids was sterically suppressed. On the basis of this Lewis acid ‐ assisted high‐speed living polymerization, various monomers such as ethyl, propyl, butyl, and dodecyl methacrylates, methacrylonitrile, and 1,2‐epoxypropane were polymerized very rapidly with the aluminium porphyrin ‐ Lewis acid systems.
Recent developments in living cationic polymerization
Authors: Nuyken Oskar , Kröner Hubertus , Rieß Gisbert , Oh Saehoon , Ingrisch Stefan
Published: March 2011

Scope and limitation of the vinyl ether polymerization initiated by NR4ClO4(KClO4;LiClO4)/CH3CHI‐OR was discussed. Besides isobutyl vinyl ether (IBVE), N‐vinylcarbazole (NVC) and 2‐chloroethyl vinyl ether (CEVE) were initiated by NR4ClO4/CH3CHI‐OR. These polymerizations exhibited the characteristics of a living polymerization. However, in order to observe narrow molar mass distribution NVC was initiated with CH3CHI‐OR, without salts. Block copolymers were synthesized by the method of sequential monomer addition (NVC, IBVE, CEVE). The PCEVE segment was modified by nucleophilic substitution, which allowed the synthesis of amphiphilic block copolymers.
Polymerization of acrylamide in inverse microemulsions under special conditions
Authors: Bartoň Jaroslav
Published: March 2011

Increasing of Φaw, the volume fraction of the aqueous phase (water + acrylamide) in inverse microemulsion systems toluene / sodium bis(2‐ethylhexyl) sulfosuccinate (AOT) / water / acrylamide (Set A); toluene / AOT / water / acrylamide / sodium dodecyl sulfate (SDS) (Set AD) and toluene / styrene/ AOT / water / acrylamide (Set AS) leads to an increase of the viscosity. The dependence of the viscosity on Φaw in the temperature range 20–45°C is characterized by three maxima (at ΦawΦ25, 45 and 65%). These maxima can be eliminated by an increase of temperature to 50°C (Sets A and AS). The most prominent peak (at ΦawΦ45%) is preserved at 50°C only for systems of Set AD.

The acrylamide polymerization behaviour in Sets A and AD is very similar irrespective of the nature of initiator used (dibenzoyl peroxide and ammonium peroxodisulfate). The rate of polymerization is a complex function of Φaw. In the presence of styrene (Set AS) a significant retardation of polymerization was observed. The rate of polymerization increases with increasing Φaw. Viscosity of the inverse dispersion system (Set AD) has no effect on the polymerization rate of acrylamide.
2H NMR studies of oriented bacteriorhodopsin membranes to determine single bond orientations
Authors: Ulrich Anne S.
Published: March 2011

For the structural analysis of oriented polymers and other macromolecular systems, we present a solid state 2H NMR technique capable of measuring the orientations of individual chemical bond vectors with high accuracy. When an immobilized uniaxially oriented sample is aligned along the spectrometer magnetic field direction, the angle between a deuterium‐labelled methyl group and the axis of ordering can be calculated from the spectral quadrupole splitting. However, since positive and negative splittings are indistinguishable, there may be two solutions. We show how these may be discriminated by acquiring additional spectra at different sample inclinations (Ref 1). The analysis of the resulting complex lineshapes is aided by computer simulation, which furthermore allows a characterization of the orientational distribution function of the sample. The 2H NMR method has been developed around the membrane protein bacteriorhodopsin as a biological model system that can be prepared in uniaxially oriented films. The overall orientation and molecular conformation of the retinal chromophore were resolved from the individual orientations of its five labelled methyl groups (Refs 2, 3). Structural changes were detected in an intermediate of the photocycle (M), which provide insight into the mechanism of the protein as a proton pump (Ref 4).
Interfacial interactions and structure of polyolefins
Authors: Lotz Bernard , Wittmann Jean‐Claude
Published: March 2011

The elucidation of structural aspects of polyolefins (isotactic and syndiotactic polypropene and isotactic poly(1‐butene)) oriented by epitaxial crystallization is briefly described. Investigations are performed by a combination of electron and Atomic Force Microscopy. AFM helps assess submolecular details in well defined crystallographic planes selected via the epitaxial crystallization.
Dynamic light scattering method of polymer solutions
Authors: Burchard Walther
Published: March 2011

The main features of dynamic light scattering are briefly outlined. The capability of this method to characterizing molar mass distributions and to distinguishing different molecular architectures is demonstrated with some examples. Special attention is given to the question of internal mobility and the spectrum of relaxation times. Recent results on asymptotic behavior are presented and discussed. Scaling behavior of the first cumulant with respect of space and of the time correlation function with respect of time (shape function) is found. All examples studied so far demonstrate the dynamic scaling of Zimm‐Rouse chains, but the prefactors strongly depend on branching and crosslinking.
Viscoelastic properties of liquid crystalline polymers
Authors: Marrucci Giuseppe
Published: March 2011

The viscoelastic properties of main‐chain liquid‐crystalline polymers are reviewed with an emphasis on the main differences that these materials show with respect to the behaviour of ordinary polymers. The distinction between the anomalies directly arising from the material anisotropy and those which are related to the polydomain structure is also emphasised.
Probe rotation near and below the glass transition temperature: Relationship to viscoelasticity and physical aging
Authors: Ediger M. D. , Inoue T. , Cicerone M. T. , Blackburn F. R.
Published: March 2011

Reorientation times ťc for two probes in several amorphous polymers near the glass transition temperature Tg are reported. Tg for these polymers ranges from 205 to 459 K. Probe reorientation was measured in the time window from 10−2 to 104 s with a recently developed photobleaching method. ťc for a given probe at the Tgs of the different polymers varies more than three decades. Viscoelastic relaxation times characteristic of the Rouse modes of the matrix polymers are closely related to probe rotation times and thus also not constant at Tg. The characteristic length scale of motions responsible for the glass transition varies significantly for the three polymers studied. Preliminary physical aging results indicate that probe reorientation in polystyrene ages slightly faster than the volume.
Orientation‐dependent interactions in polymer systems: Segmental orientation, miscibility, and self‐organization
Authors: Fukuda Takeshi , Fujimoto Kouji , Murakami Mauro M. , Kawabata Kenji , Miyamoto Takeaki
Published: March 2011

Three co‐operative phenomena that are supposed to originate in the orientation‐dependent interactions among polymer segments are discussed and attempted to be interpreted in terms of a common set of polymer models.
Computer simulation and control for product quality in injection molding
Authors: Kamal Musa R.
Published: March 2011

The use of computers in plastics processing has continued to grow in parallel with rapid expansion of computer availability and computing power. One of the main areas of application is in computer simulation of the injection molding process where more demanding applications relate to the simulation of molding of complex‐shaped moldings. Recent development include the use of boundary fitted curvilinear coordinates, the incorporation of fountain flow, and the coupling of crystallization kinetics within the transport equations. Applications in computer control relate to the control of pressure and temperature throughout the injection molding process, self‐tuning control, physically‐based dynamic models, and the control of properties of the molding, e.g. the weight of the article. Recent developments relate to the application of inverse modeling. An example is given of the use of inverse modeling of thermal stresses to predict or optimize thermal or pressure history during molding.
Recent development of the nonlinear optical active material system
Authors: Kim Nakjoong
Published: March 2011

New nonlinear optical active materials have been highlighted to apply them to practical applications since about two decades ago. During this period, a number of materials have been developed and studied in academic and industry field. Particularly, the second‐order nonlinear optical properties are facile to approach in the laboratory. We can consider the possibility of the device application by investigating the macroscopic second‐order nonlinear optical properties using the second harmonic generation and linear electro‐optic study. Nowadays, the absolute value of the nonlinear optical coefficient of organic material overcame the value of conventional inorganic materials due to quick research progress. Therefore, the new organic materials systems showed some promising motives to fabricate the optical device.
Starburstr̀ dendrimers — Nanoscopic supermolecules according to dendritic rules and principles
Authors: Tomalia Donald A.
Published: March 2011

Construction of dendritic macromolecules based on the mimicry of macroscopic branching patterns found in trees is reviewed. From this mimicry, synthetic strategies have been developed for the preparation of precise macromolecular building blocks referred to as Starburstr̀/Cascade dendrimers. These dendrimer constructions involve the amplifications of matter (mass) by organizing monomer units around initiator cores according to geometrically driven mathematical rules and principles. The predictable precision of mass and valency (i.e., number of reactive surface groups) displayed by these dendrimers, as a function of generation, validates their proposed role as fundamental nanoscopic building blocks (i.e., particle sizes of 10 −1000Å). This emerging area of “structure‐controlled polymers” is defining a fourth new major class of macromolecular architecture. Ideal, defect free structures of Starburstr̀ polyamidoamine (PAMAM) dendrimers (e.g., NH3 core; generation = 2.0, MWt. 2,414) have been synthesized in kilogram quantities with overall yields of 60‐70%. The precise masses and surface valencies associated with these dendrimer structures allow one to view these entities as “nanoscopic analogues” to atoms. As such, basic rules of chemical combination between dendrimers to give definite, stoichiometric compositions can be defined much as first noted by Dalton for atoms. The use of these nanoscopic building blocks (i.e., 10–1000Å species) to construct supramolecular/supermolecular structures such as nanoscopic compounds, clusters and macro‐lattices will be reviewed.

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Morphology and strength of high performance main‐chain liquid crystal polymers
Authors: Wegner Gerhard
Published: March 2011

The impact of chain‐length on formation and properties of thermotropic LC‐phases is described for poly(didocecyl‐p‐phenylene). Isotropic, biphasic or anisotropic melts are observed. The zero‐shear viscosity scales as η≈︁Mw2.9 in the isotropic and as η=Mw3.2 in the anisotropic melt. If quenched from the LC‐melt, the material exhibits a smectic superstructure dominated by disclinations. The same feature is seen with the poly(diacetylene) P‐4BCMU crystallized from lyotropic solution. The LC‐phase consists of lamellae the thickness of which scales with the extended chain length. Segregation of the chains allows the lamellae to adapt to the strain field in the vicinity of the core of the disclinations. A banded texture observed when the LC‐phase is subject to shear is resolved by TEM as composed of periodically distorted stacks of lamellae. Small modifications of the chain structure by comonomers has a substantial impact on the mechanical properties. Introducing only 5 mol percent of comonomers with sterically assuming substituents into lyotropic poly(p‐phenylene terephthalamide) improves the compressional strength (Elastica test) of fibers by 25 percent.
Rubber toughening of plastics: Rubber particle cavitation and its consequences
Authors: Bucknall C. B. , Soares V. L. P. , Yang H. H. , Zhang X. C.
Published: March 2011

A newly‐developed energy‐based model for cavitation in rubber particles provides a quantitative basis for understanding the factors controlling toughness in rubber‐modified plastics. Cavitation of the rubber is the initial step in the toughening mechanism, and is shown to accelerate yielding of the matrix, either by the formation of dilatation bands or by multiple crazing. Cavitation is thus a strain‐softening effect. However, in some cases the cavitated rubber forms fibrils which become highly stretched as local strains increase, and thus begin to carry a significant fraction of the applied stress. The resulting strain‐hardening ensures that yielding is not limited to a small deformation zone at a crack tip, but spreads outwards.
Modification of metallocene catalysts for olefin polymerization
Authors: Soga Kazuo
Published: March 2011

The metallocene catalyst developed by Kaminsky and Sinn has been demonstrated to permit the synthesis of any kind of stereoregular polymers as well as uniform copolymers with very narrow compositional and molecular weight distributions. The catalyst is, thus, expected to comprise a revolution in the polyolefin industry.

More recently, a great deal of research effort has been devoted to modify it for practical applications, which has yielded a new generation of metallocene catalysts.

This paper summarizes the results reported so far in the field. Some of our original data will be also reported.
Recent advances in olefin polymerization
Authors: Shiomura Tetsunosuke , Kohno Masahiro , Inoue Norihide , Asanuma Tadashi , Sugimoto Ryuichi , Iwatani Tsutomu , Uchida Osamu , Kimura Shigeru , Harima Shigeru , Zenkoh Hirofumi , Tanaka Eishi
Published: March 2011

Various metallocenes were tested for syndiotactic polymerization of propylene. Reduction in the amount of costly methylalumoxane (MAO) or replacement with the other components was accomplished. Small modifications in the metallocene ligands brought about remarkable differences in the resulting catalysts concerning their storage stability, H2 response as well as stereo‐specificity. Syndiotactic polypropylene (SPP) in the melt state behaves very differently compared to isotactic polypropylene (IPP). The notion that these polymers have different distributions of molecular entanglements are pursued, and verified for the first time. Excellent dispersibility of other olefin polymers in SPP matrix contributed to improve the usefulness of SPP.
Organosilicon polymers with bis‐acetylenic units: Conductivity and ceramisation studies
Authors: Corriu R. , Gerbier P. , Guerin G. , Henner B.
Published: March 2011

The transformation poly[(silylene)diacetylene] into ceramic have been studied and SiC obtained with a quantitative yield: all the silicon atoms present in the starting material are converted into SiC. The key step is the crosslinkage of C4 units into a carbon matrix in which the R1SiR2 moieties are in the vicinity one to each other allowing the quantitative transformation into SiC. The carbon content of the resulting ceramic depends on the nature of R1 and R2 groups. The excess of carbon has been used for the carboreduction of oxides (TiO2, ZrO2, HfO2, etc…) and mixed ceramics with interpenetrating network have been obtained: SiC / TiC, SiC / ZrC, etc… Under nitrogen atmosphere, the ceramisation leads to different systems such as SiC / TiN, SiC / AlN, etc…
Synthesis, characterization, and application of helical polymers
Authors: Okamoto Yoshio
Published: March 2011

This review mainly describes the asymmetric synthesis of optically active polymers with helical conformation. Bulky methacrylates such as triphenylmethyl methacrylate and 1‐phenyldibenzosuberyl methacrylate give one‐handed helical and optically active polymers with almost perfectly isotactic main chain conformation by polymerization with chiral anionic initiators. The radical polymerization and copolymerization of these monomers under chiral conditions also afford optically active polymers with prevailing one‐handed helicity. N, N‐Disubstituted acrylamides also give optically active, helical polymers in the asymmetric anionic polymerization. Optically active polyisocyanates with a prevailing one‐handed helical structure have been prepared in the copolymerization of an achiral isocyanate with a small amount of an optically active isocyanate and also in the polymerization of alkyl and aromatic isocyanates with optically active lithium alkoxide or amide compounds. The existence of a stable helical structure for polychloral has been successfully proved with the helical oligomers of chloral. One‐handed helical polyisocyanides have been prepared by helix‐sense‐selective polymerization of bulky isocyanides and also by the cyclopolymerization of a 1, 2‐diisocyanobenzene derivative with the Pd complex of a one‐handed helical oligomer.
Template‐induced control of stereochemistry for the synthesis of linear vinyl polymers
Authors: Wulff Günter , Gladow Stefan , Kühneweg Bernd , Krieger Stephan
Published: March 2011

Asymmetric cyclocopolymerization of judiciously designed bifunctional monomers with a number of common comonomers affords optically active vinyl polymers with main chain chirality. Tacticity and sequence of comonomeric units can be controlled and thus complicated structures built up. Under different reaction conditions the same bifunctional monomer 1 can undergo cyclization involving a 19‐, a 21‐, or an 18‐membered ring. With monomer 3 an 11‐membered ring is formed.
Following the polyisocyanate helix reversal from dilute solution through the liquid crystal and into the solid state
Authors: Green Mark M. , Sato Takahiro , Teramoto Akio , Lifson Shneior
Published: March 2011

The absence of a predetermined helical sense in the polyisocyanates causes the formation of helix reversals which enforce a strong cooperativity for the amplification of chiral effects. The helix reversals though also place a limit on this amplification, a limit which would be eliminated by reducing the helix reversal population. Approaching the liquid crystal state of the polyisocyanates in both dilute and concentrated solutions appears to cause the exclusion of the helix reversals which is consistent with theoretical expectations.

Since the linear birefringence of the polyisocyanate solid state precludes optical activity measurements associated with the polymer, we have synthesized hydrogen bonding side chain adapted polyisocyanates which appear by DSC and infra‐red criteria to form equilibrium molecular composites with copolymers of vinyl phenol and styrene. The optical activity properties of these composites may offer a new way to probe polymer motion in the solid state.
Helix change of polypeptides in the solid state as studied by NMR spectroscopy
Authors: Ando Isao
Published: March 2011

The conformational characterization of solid polypeptides has been carried out by means of high‐resolution solid‐state NMR. It has been demonstrated that high‐resolution solid‐state NMR spectroscopy is a very useful means for elucidating the structure of polypeptides and proteins in the solid state.
Biological activities of biodegradable polysaccharide
Authors: Tokura Seiichi , Nishimura Shin‐Ichiro , Sakairi Nobuo , Nishi Norio
Published: March 2011

A low toxicity of chitin was demonstrated to be mostly due to biodegradability and the fast metabolization of hydrolysate in animal body. Chitosan, a deacetylated derivative of chitin, is also known to be a biocompatible polymer in spite of a slight immunoadjuvant activity in animal body. Chitosan is easily regenerated to fiber, film, beads and non woven fabrics owing to its high solubility toward diluted aqueous organic acids such as formic acid, acetic acid, glutamic acid and ascorbic acid. The regeneration of chitin was achieved into fibers, gels, porous foams and non woven fabrics following to dissolution of chitin with formic acid or calcium chloride dihydrate saturated methanol. Chitin and its derivatives have been applied as biomedical materials due to remarkable advantages such as antimicrobial activity, acceleration of epidermal cell assembly, low toxicity, and biodegradability.
Simulations on polymer networks and their elastomeric properties
Authors: Mark J. E.
Published: March 2011

A variety of examples are given to illustrate how computer modeling techniques are being used to elucidate the structures of elastomeric polymer networks and the rubberlike elasticity they exhibit.
The molecular dynamics of poly(1, 4‐Trans‐butadiene) in the amorphous state and in an inclusion complex
Authors: Haliloǧlu Türkan , Mattice Wayne L.
Published: March 2011

The molecular dynamics of poly(1, 4‐trans‐butadiene) in the amorphous state at bulk density and in its inclusion complex with perhydrotriphenylene are compared here. The internal motions differ in the two systems, due to the occupation of gauche states at CH2‐CH2 of the amorphous polymer, but the exclusion of gauche states at these bonds in the inclusion complex. This difference in conformational preferences at CH2‐CH2 has consequences for the decay rates for the orientation autocorrelation functions.
Surface modification of biomedical polymers
Authors: Ikada Yoshito
Published: March 2011

Surface modification of biomedical polymers by the technique of surface grafting was briefly overviewed, mostly based on our results. It was shown that surface grafting of water‐soluble polymer chains onto polymeric biomaterials was effective in producing mechanically non‐stimulative, blood‐compatible, antibacterial, tissue‐bonding, and cell‐adhesive surfaces. In addition to the improvement of the interfacial biocompatibility, the surface grafting was useful also for obtaining a biofunctional surface such as immunoadsorbent.
The surface and interfacial chemistry of polyimide films
Authors: Coulman D. , Edman J.
Published: March 2011

The surfaces of polyimide films and the structure just below the surfaces have been extensively studied as people have sought to improve and understand the key factors controlling adhesion. Treatments of all types from primers to plasma etching to sand blasting have been evaluated with varying efforts depending on the application. In recent years, the emphasis has been on understanding the chemical and morphological changes effected by these treatments and then correlating chemistry and morphology with adhesion. The picture that emerges is that surface energy alone, as is the case with most polymers, usually is insufficient to predict adhesion to polyimides. Instead, initial bond strength and bond durability, whether with adhesives or metals directly deposited on the film, depend on chemical bonding, diffusion between deposited layers and the polyimide, formation of a micro composite region controlled in part by topography and the viscoelastic properties of the polymer below the surface. Poor viscoelastic behavior frequently is characterized as a weak boundary layer. Recent work has shown that small amounts of organometallics that diffuse to the surface during the film forming process can significantly affect bondability both to adhesives and to vacuum deposited metals. The possible effect of these additives on bond formation, viscoelastic properties, diffusion and topography is under investigation and will be discussed along with an over view of the primary film forming steps that might affect surface chemistry and structure.
New surface improvement techniques for engineering plastics
Authors: Moriuchi Takahiko , Yamamoto Suguru
Published: March 2011

Sputter etching process and reactive sputter etching process in radio frequency(RF)glow discharge for surface improvement technique of engineering plastics, especially P T F E (polytetrafluoroethylene) were studied. In the case of sputter etching in Ar gas. characteristic cone like structures were developed on the P T F E surface, resulting in improvement of adhesive property. In reactive sputter etching in H2O gas, the P T F E surface changed chemically and showed wettability.
Production of micron‐sized monodispersed cross‐linked polymer particles having hollow structure
Authors: Okubo Masayoshi , Minami Hideto , Yamashita Tsuyoshi
Published: March 2011

4 μm‐sized monodispersed cross‐linked polymer particles having hollow structure were produced as follows. First, 1.7 μm‐sized monodispersed polystyrene (PS) seed particles produced by dispersion polymerization were dispersed in ethanol/water (7/3, w/w) solution in which divinylbenzene (DVB), benzoyl peroxide (BPO), poly(vinyl alcohol), and toluene was dissolved. The PS seed particles were swollen with DVB, toluene and BPO maintaining high monodispersity throughout the dynamic swelling process where water was slowly added continuously. And then, the seeded polymerization of the (toluene/DVB)‐swollen PS particles was carried out.
Designs of latex particles' morphologies for toughening polymer matrices
Authors: El‐Aasser Mohamed S. , Segall Iris , Dimonie Victoria L.
Published: March 2011

The performance of the designed structured core/shell latex particles in toughening polycarbonate (PC) matrix was examined. The influence of parameters related to the core/shell latex particles on toughening PC such as: the particle size and levels of crosslinking of the core rubber particles, composition and molecular‐weight of the shell polymer, the weight ratio of shell and core polymers as well as the particle morphology was evaluated. Core/shell structured latex particles with thinner shells of higher molecular‐weight polymers were found to improve the impact resistance of PC. The role of chain entanglements in increased adhesion between the discrete rubbery phase and the continuous glass matrix are discussed.
Photoresponsive liquid crystalline and amorphous polymers
Authors: Anderle K. , Bach H. , Fuhrmann TH. , Wendorff J. H.
Published: March 2011

Isomerization processes of azobenzene dyes dissolved in a glassy polymeric matrix or attached in glassy amorphous or liquid crystalline polymers to the backbone as side groups are induced by light. The isomerization process, in turn, causes the dye to reorient provided that polarized light is used: the long axis of the dye is oriented perpendicular to the polarization direction in the stationary case. Such a reorientation gives rise to strong modifications of the optical properties. This contribution is concerned with the analysis of the correlation between the nature of the azobenzene dyes, the isomerization, reorientation and modulations discussed above and with possible applications in the optical holographic storage. Considered are, in particular, dye/matrix combinations giving rise to nonlinear holographic responses, two photon holography, transient holographic modes applicable for holographic displays and the optical switching of other than optical properties.
Development of new cyclic olefin polymers for optical uses
Authors: Kohara Teiji
Published: March 2011

New cyclic olefin polymers (COP) with a better balance of properties than those of conventional optical plastics have been developed by using norbornene monomers. The COP are prepared by ring‐opening metathesis polymerization of norbornene monomers followed by complete hydrogenation of double bonds. The COP have practically been applied for optical uses such as lenses, prisms and optical discs.
Towards supramolecular polymers
Authors: Huff Jürgen , Preece Jon A. , Fraser Stoddart J.
Published: March 2011

The natural phenomenon of self‐assembly has been used to make complex unnatural products. These new compounds have taken the form of catenanes and rotaxanes. We have identified several polymeric architectures containing the catenane and rotaxane motifs, and then described how the model structures, which we have identified and actually realized as chemical compounds, can be employed to assess the feasibility of introducing mechanical linkages into novel polymers by means of self‐assembly processes.
Bengal rose@dendritic box
Authors: Jansen Johan F.G. A. , Meijer E. W. , De Brabander ‐ Van Den Berg Ellen M. M.
Published: March 2011

Bengal Rose was succesfully encapsulated and liberated from a dendritic box. Bengal Rose@DAB‐dendr‐(NH‐t‐BOC‐L‐Phe)64 was investigated with several different techniques such as ultraviolet, circular dichroism and fluorescence spectroscopy.
Degradable dendritic polymers — A template for functional pores and nanocavities‐
Authors: Muzafarov Aziz M. , Rebrov Evqueniy A. , Gorbacevich Olga B. , Golly Monika , Gankema Harold , Möller M.
Published: March 2011

Degradable dendrimers are prepared as a template to create utrasmall cells when they get embedded in a polymer resin and to obtain well‐defined cavities with particular chemical groups at their walls if the endgroups remain attached to the matrix. In a first approach cascade: (13‐oxa‐1‐methylsilaundecenylidene): undecene was synthesised by the polyaddition reaction of methyl‐di‐undecenoxysilane as basic repeat unit. A multimodal weight distribution was found which appeared to be selfcontrolled to a limited molecular weight. Degradation was done with dry methanol and methanol with aqueous hydrochloric acid. In the case of dry methanol, the degradation products yielded only low molecular weight compounds while siloxane bonds were formed in the case the degradation was performed with methanol and aqueous hydrochloric acid. In order to create films with nanocavities, the degradable dendritic macromolecules were embedded in a methacrylate resin. Hole formation was illustrated by transmission electron microscopy for the case of 0.5 wt.‐%, 5 wt.‐% and 30 wt.‐% of dendrimer content. However, aggregation of the dendritic molecules during the curing of the methacrylate resin could not be avoided. In order to suppress aggregation, cascade: (1‐methylsilapropylidene): propene with methacrylate endgroups have been prepared which can be covalently linked to the embedding resin molecules. In a first approach the compatibility with the methacrylate resin was indicated by the optical transparency, while microscopy techniques were not capable to resolve the fine structure.
Block copolymers and telechelic oligomers by end group reaction of polymethacrylates
Authors: Esselbom Eberhard , Fock Jürgen , Knebelkamp Arno
Published: March 2011

Block copolymers and telechelic oligomers bearing methacrylate moities were obtained by means of a new highly selective end group reaction. Starting from polymethacrylates that were prepared by radical polymerization in the presence of mercaptanes as chain transfer agents, the resulting ester end group linked to the terminal tertiary carbon atom of the polymer backbone can be either transesterified or saponified selectively. The selectivity of the end group reactions was determined by MALDI‐TOF‐mass spectrometry. Polymethacrylate‐b‐poly(ethylene oxide)‐, polymethacrylate‐b‐poly(methacrylic acid)‐ and polymethacrylate‐b‐polysiloxane‐b‐polymethacrylate‐copolymers as well as α,ω‐dihydroxy‐ and α,ω‐dicarboxy‐telechelic polymethacrylates were prepared by applying end group transesterification or end group saponification.
Synthesis and characterization of syndiotactic polystyrene and poly[styrene‐co‐(p‐methylstyrene)]
Authors: Cardi Nicoletta , Po′ Riccardo , Abbondanza Luigi , Abis Luigi , Conti Giuseppina
Published: March 2011

Syndiotactic polystyrene and copolymers of styrene and p‐methylstyrene were synthetized in bulk by using a titanium tetraethoxide/methylaluminoxane catalytic system. The polymers were analyzed by 13C and 1H Nuclear Magnetic Resonance, Infrared Spectroscopy, Gel Permeation Chromatography and Differential Scanning Calorimetry and their properties were compared.