bluuebunny/crossref_metadata_2025 huggingface dataset:
α‐Olefin polymerization by various alumoxanes containing isobutyl group and metallocene
Authors: Kurokawa Hideki , Sugano Toshihiko
Published: March 2011

Ethylene or propylene polymerization was carried out by use of Me2Si(H4Ind)2ZrCl2 and alumoxanes containing isobutyl group. Polymerization activity of ethylene decreased with an increase of the isobutyl group content. On the contrary, the alumoxane having isobutyl group content of about 50% gave a maximum activity for propylene polymerization.
Mao based catalysts for syndiotactic polystyrene (sPS)
Authors: Campbell Richard E. , Newman Thomas H. , Malanga Michael T.
Published: March 2011

Several non‐metallocene (Ti, Zr) and substituted mono‐Cp titanium metallocenes have been tested in the presence of methylalumoxane (MAO) as catalyst for syndiospecific polymerization of styrene. Effect of substitutions on the titanium and Cp ligand, molar ratio of Al/Ti, TMA and temperature on activity, Mwt. and % sPS were studied. CpTi(OiPr)3 gives a less active catalyst than Cp*Ti(OiPr)3 and the resulting sPS is less stereoregular and of lower molecular weight.
Copolymerization of poly(propylene) macromonomer and ethylene with metallocene catalysts
Authors: Shiono Takeshi , Moriki Yuji , Soga Kazuo
Published: March 2011

Copolymerization of ethylene and poly(propylene) macromonomer(PPM) with Mn⇋710 was conducted with the (t‐butylamido)dimethyl(tetramethyl‐η5‐cyclopentadienyl)silanetitanium dichloride(CGC‐Ti), ethylenebis(tetrahydroindenyl)zirconium dichloride(Et[IndH4]2ZrCl2), bis(cyclopentadienyl)zirconium dichloride(Cp2ZrCl2) and bis(cyclopentadienyl)titanium dichloride(Cp2TiCl2) catalysts using methylaluminoxane as cocatalyst. From the detail analysis of resulting copolymers by DSC, IR and 13C NMR, it was proved that PPM is copolymerized with ethylene to give poly(ethylene‐co‐PPM). The ability of incorporating PPM in the copolymer was found to increase in the following order: Cp2ZrCl2 «Cp2TiCl2 < Et[IndH4]2ZrCl2 «CGC‐Ti.
Mixed cocatalyst systems in metallocene ethylene polymerization
Authors: Michiels Wilfried , Muñoz‐Escalona Antonio
Published: March 2011

The effect of the cocatalysts resulting from mixing AIR3 (R = Me (TEA), Et (TEA) and iBu (TIBA)), and B(C6F5)3 with MAO at different molar ratios on ethylene polymerization activities and on the molecular weight and microstructures of the resulting polymers using the catalyst Cp2ZrCl2 was explored. It has been observed that activities increase at low TMA concentrations with increasing TMA/MAO ratios, reaching a maximum at the TMA/MAO ratio of 0.3‐0.5. A decrease of the polymerization activities was observed at higher TMA/MAO ratios. Addition of TEA or TIBA to the MAO brings about a decrease in the polymerization activities, being the effect stronger for TEA. The use of B(C6F5)3 in the mixed cocatalyst systems leads to higher activities stabilizing also the active centers. The molecular weights of the polyethylenes follow the same trend, i.e. they decrease with increasing AIR3/MAO ratios (TIBA, with bulky R, gives the highest molecular weight because of the reduction of chain transfer reactions to the aluminium compound) but they are little affected by the presence of B(C6F5)3.
Microstructure of poly(cycloolefins) produced by metallocene/methylaluminoxane (mao) catalysts
Authors: Arndt Michael , Kaminsky Walter
Published: March 2011

[1]: The microstructures of poly(norbornenes) and poly‐(cyclopentenes) produced by metallocene/mao catalysts are investigated. Hydrooligomerizations have been performed and the products were identified by NMR spectroscopy. Using these hydrooligomers as models assignments for CPMAS spectra of the polymers were made. Regio‐ and stereoselectivity of the polymerization of cyclic monomers are discussed and compared to those observed in propene polymerization.
In search of the plastic enzyme
Authors: Guillet James E. , Burke Nicholas A. D. , Nowakowska Maria , Reese Howard , Gravett David M.
Published: March 2011

Photozymes are novel polyelectrolytes made from mixtures of hydrophobic and hydrophilic comonomers. They often contain a relatively high concentration of bound chromophores as photon harvesting or antenna groups, which transport excitation energy to organic substrates located in the interior of the macromolecular coil in aqueous solution. Previous studies have shown that the photocatalytic behavior of these polymers has many similarities to natural enzymes which carry out thermal reactions in biological systems. Mechanistic studies of four photozyme reactions are discussed: (1) the oxidation of perylene to perylenequinones; (2) the dehalogenation of hexachloro‐ and pentachlorobenzene; (3) the high‐yield synthesis of Vitamin D; and (4) the selective photolysis of aliphatic and aromatic ketones.
Preparation of elastomeric polypropylene using metallocene catalysts: Catalyst design criteria and mechanisms for propagation
Authors: Gauthier William J. , Collins Scott
Published: March 2011

A series of unsymmetrical metallocene catalysts were prepared and used to polymerize propylene under a variety of conditions using methylaluminoxane as a cocatalyst. Zirconium and hafnium‐based catalysts were more active and more importantly, much more stable at conventional polymerization temperatures than titanium catalysts. By adjusting experimental conditions, it is possible to vary both the molecular weight of the polymer and also the degree of crystallinity. These properties significantly impact on the tensile properties of elastomeric poly(propylene) (ELPP) in a predictable manner. The microstructure of ELPP was characterized by 13C NMR spectroscopy and the pentad distributions were analyzed using several statistical models for propagation. This work has demonstrated that the microstructure of ELPP is probably not that of an isotactic‐atactic block copolymer.
Polymers with indan units
Authors: Nuyken Oskar , Maier Gerhard , Leitner Michael , Yang Dazhong , Wolf Martin
Published: March 2011

Cationic polymerisation of 1, 4‐diisopropenyl benzene, 1, 4‐(2‐chloro‐isopropyl)benzene and related compounds yields soluble polymers with repeating units of indan.

High performance polymers with indan units are available via nucleophilic substitution of halogenated aromatic monomers containing a central indan element, which are synthesized from 1, 1, 3‐trimethyl‐3‐phenylindan via Friedel‐Crafts‐reaction with corresponding halogenated acyl‐ and sulfonyl chlorides.
Mesomorphic properties and sans conformational study in different liquid crystalline polymers
Authors: Hardouin F.
Published: March 2011

We report an overview about chain‐conformation informations given by small angle neutron scattering (SANS) studies of different kinds of Liquid Crystalline Polymers. We conclude that in the prolate nematic phase the chains are directly connected to the orientational order and the chain extension strongly depends on microscopic considerations concerning the coupling mesogen‐chain. The behavior is markedly different when the backbone anisotropy is oblate because the chains are hence affected by the smectic layering order (even at the scale of fluctuations in a high temperature nematic phase). In this latter case, since the chains are more or less confined in a 2D Gausssian geometry, they locally do not follow the director and the chain anisotropy mainly depends on the strength of the smectic layering.
Nanoscopic supermolecules with linear‐dendritic architecture: Their preparation and their supramolecular behavior
Authors: Frechet Jean M. J. , Gitsov Ivan
Published: March 2011

The design, synthesis, and properties of supermolecules consisting of well defined assemblies of linear and globular macromolecules is studied. Therefore, several families of hybrid block polymers based on polyether dendrimers linked to well‐defined blocks of polyethylene oxide, polyethylene glycol, polyester, or polystyrene have been prepared. The unique topological macromolecules that result from the assembly of such components having different shapes and internal densities can assemble in highly stable supramolecular micelles whose characteristics vary as a function of the medium. The hybrid macromolecules are usually prepared by the nucleophilic displacement of a reactive functionality located at the focal point of a convergent polyether dendrimer, with a nucleophilic anion located at one or both chain ends of a linear polymer. Alternately, the focal point of the dendrimer may be used to attach a polymerizable vinyl group affording a dendritic macromonomer that may be used to create variety of copolymers. Finally, the focal point of the convergent dendrimer may serve as an initiator in the polymerization of a linear chain thereby affording the hybrid linear‐dendritic entity. In the latter case the unique microenvironment provided by the dendrimer is useful in the prevention of undesirable side‐reactions during growth of the linear block. This demonstrates that the differences between the globular and linear fragments of these unique molecules can be used to design nanoscale reactors that perform functions not normally achieved with small molecules. The very unusual solution properties of the dendritic‐linear supermolecules are a direct result of the forced combination of their dissimilar building blocks.
Multifunctional bioerodible/biodegradable polymeric materials
Authors: Chiellini Emo , Solaro Roberto
Published: March 2011

As a part of our continuing interest in the preparation of multifunctional polymeric materials and evaluation of their potential in biomedical and environmental field, a survey on new polymeric systems susceptible to bioerosion and/or biodegradation attack is presented. In particular attention has been focused on the preparation and characterization of the following classes of polymeric materials: 1) hydroxyl‐containing polyesters; 2) functionalized cyclodextrins; 3) hydrophilic polymers containing carboxylic groups; 4) hydrogels for the release of phytodrugs; 5) hybrid polymeric materials; 6) synthetic and semisynthetic polyfunctional polymeric materials for the removal of uremic toxins. A few examples of the use of these polymers in the controlled release of drugs and as coadjuvants in the chronic renal failure treatment will be also presented.
Synthesis and electro‐optical properties of some ferroelectric liquid crystalline polymers
Authors: Hsu Chain‐Shu , Shih Li‐Jen , Hsiue Ging‐Ho
Published: March 2011

The synthesis and characterization of several series of ferroelectric side‐chain polymers were presented. Differential scanning calorimetry, optical polarizing microscopy and X‐ray diffraction measurement were used to determine their thermal transitions and analyze their anisotropic textures. The influence of polymer backbones, flexible spacers, mesogenic cores as well as chiral end groups on the mesomorphic properties of the polymers was discussed. Furthermore, the dielectric relaxation properties of the obtained polymers were also evaluated.
Rheological investigation of starch polysaccharide gelation
Authors: Vorwerg Waltraud , Radosta Sylvia
Published: March 2011

Small‐amplitude dynamic measurements of aqueous starch polysaccharide solutions are performed by a Bohlin controlled‐stress rheometer with air bearing. Three classes of starch polysaccharides–native starches, fractions of starches and hydrolysed starches–are compared in their molecular composition and rheological properties during and after the gelation process. Viscoelastic properties of solutions and gels are recorded in dependence on temperature and time, yielding storage and loss moduli during and after sol‐gel transition. Hot concentrated aqueous solutions are cooled down from 90 °C to 5 °C at a rate of 1 °C/min. Measurements are carried out at 0,1 Hz and 5% strain amplitude deformation. The typical course of the moduli of gelling starch polysaccharide solutions shows a liquid‐like behavior (G” > G') in the upper temperature level between 60 and 90 °C, a jumpwise increase with ensuing intersection of G' and G” below 60 °C and a solid‐like behavior (G' > G”) at lower temperatures with a slightly in time growing storage modulus. Storage and loss moduli depend on molecular composition and concentration of the substance. The process of starch polysaccharide aggregation is discussed with regard to theories of physical gelation by Ross‐Murphy and Winter.
Polyglucane derivatives with regular substituent distribution
Authors: Klemm Dieter , Heinze Thomas , Stein Armin , Liebert Tim
Published: March 2011

6‐O‐trialkylsilyl celluloses, 2,3‐O‐carboxymethylcelluloses, cellulose‐3‐O‐sulfate, and carboxymethylcellulose block copolymers were synthesized by regioselective functionalization of cellulose and of soluble cellulose intermediates like silyl and methoxy‐substituted trityl ethers as well as formates and trifluoroacetates. The preparation and structure characterization (NMR, FTIR, HPLC after chain degradation) of those polyglucane derivatives with regular substituent distribution is of importance to design self‐assembly systems and supramolecular structures (liquid‐crystalline media, ultrathin films, recognition and bioactive materials).
Defined carrageenan derivatives as angiogenesis inhibitors
Authors: Paper Dietrich H. , Vogl Horst , Franz G. , Hoffman Richard
Published: March 2011

Three carrageenans derived from red algae and three partially modified carrageenans were tested for their ability to inhibit the formation of new blood capillaries on the chorionallantois membrane of the hen egg. It could be clearly demonstrated that they were better angiogenesis inhibitors than the standard compound suramin.
Investigation on color change reaction during laser marking of plastics
Authors: Herkt‐Maetzky Christian , Robers Wilfried
Published: March 2011

Laser inscription of thermoplastic materials is a rapidly growing field. Therefore, materials must be developed, which were laser‐markable. For doing this in an efficient way, analytical techniques must be used to understand the mechanism of different processes during laser inscription.
Trends in non‐polluting organic surface coatings chemistry
Authors: Mezger T.
Published: March 2011

Paint application is a sector of human activity, where the common use according to product determination by the end user or small craftmans business contributes most obviously to environment pollution, In first instance of course by solvent evaporation.

There is a steadily increasing pressure by governmental authorities on the plant industry to reduce solvent emission from its products.

At the same time, more integral approaches of environmental impact assessments ‐ so called life cycle analysis ‐ become more and more important.

The paint industry answers these challenges by development of new types of coatings, which mainly means new types of binder polymers and new types of crosslink chemistry.

Advances in the understanding of polymer physical chemistry as well as the advent of new synthesis concepts lead to a number of emerging technologies expected to contribute significantly to reduction of pollution by paint application.

While in industrial paint application end‐of‐the‐pipe technology is still economically favourably competing with the advanced paint chemistry concepts (e.g. high‐solids, waterborne, UV‐curing, electrocoating, powder coating and supercritical CO2‐application), the situation in the large sector of end‐user and craftsman application of paint is much more difficult, at least in the sector of high performance and particularly high gloss coatings. End‐of‐pipe‐technology is unapplicable and, on the other hand, degrees of freedom in application equipment and curing conditions are limited. Furthermore, labour safety requirement further restrict the scope of applicable new chemistry.
Einige wesentliche Trends bei der Verarbeitung der thermoplastischen (Massen‐) Kunststoffe
Authors: Menges G.
Published: March 2011

The major application of plastics has to obey strong economical restrictions. By this reason users are carefully selecting new machinery. Later‐on high standards in user‐friendly handling and maintenance in high quality of the machinery is required. These wishes are fulfilled by all machinery suppliers worldwide, which are producing in bigger quantities. The technological progress, too follows these rules. Absolutely new technologies are not to see in the fields of mass production, especially with thermoplastic materials and commodities. The development of resin follows, too, the same rules and one can feel a concentration to fewer materials. The most preferred material seems to become polypropylene. One reason for this tendency bases on recycling necessities.
Use of transparent polymers in solar energy conversion systems
Authors: Wittwer V. , Goetzberger A.
Published: March 2011

Solar energy can deliver a large amount of the worldwide demand of energy

For large scale application of solar energy, the rational and intelligent use of energy is necessary. In both cases new improved materials and systems are needed. Transparent polymers can play an important role to fulfil this goal.
Directed polymer synthesis for industrial application
Authors: Höcker Hartwig
Published: March 2011

In the present survey the limitations for the industrial application of polymer syntheses are discussed as well as the directions, syntheses may go. As particular examples the living anionic polymerization and the respective ring‐opening polymerization and copolymerization are discussed.

Under the aspect of future developments some examples of biotechnological polymerization and particular features of biopolymers are given
Conformation and dynamics of fibrous and membrane proteins as revealed by high‐resolution solid‐state nuclear magnetic resonance
Authors: Saitǒ Hazime , Tuzi Satoru , Nishimura Katsuyuki , Fukutani Akira , Naito Akira
Published: March 2011

We examined conformation and dynamics of a variety of fibrous and membrane proteins by means of the conformation‐dependent displacements of 13C nuclear magnetic resonance (NMR) chemical shifts and their relaxation parameters, respectively, as recorded by high‐resolution solid‐state 13C NMR. Determination of three‐dimensional structure of atomic resolution is also briefly described for a simple peptide on the basis of precise measurements of interatomic distances.
Conformation and dynamics of polymer chains in condensed systems
Authors: Kotaka Tadao , Adachi Keiichiro
Published: March 2011

A Stockmayer's type‐A chain such as cis‐polyisoprene (PI) having dipole components parallel to the chain contour exhibits slow dielectric response, reflecting fluctuation of its end‐to‐end vector (dielectric normal modes). This article reviews our own work on dielectric spectroscopy for studying dynamics and conformational properties of probe PI chains in binary blends with PI or polybutadiene (PB) that does not exhibit normal modes. Through such studies we were able to see the crossover of the probe‐chain dynamics from Rouse behaviour in low‐molecular‐weight (lmw) matrices to pure reptation behaviour in high‐molecular‐weight (hmw) matrices. We were also able to confirm experimentally Flory's earlier prediction on excluded volumes in dilute blends of hmw probe chains in lmw matrices, for which a proof has never been given before.
Recent developments and future trends in injection molding technology
Authors: Takahashi Hideroh
Published: March 2011

The amount of plastic components of passenger cars in Japan has increased extremely past 25 years. Many of them are produced by injection molding. There are a number of significant developments in injection molding technology. These developments involve CAE (Computer Aided Engineering) including the prediction of the properties of molded parts, innovative experiments to analyze processing, new machineries (processing) and recycling plastics.
Dispersive mixing in immiscible polymer blends
Authors: Gogos C. G. , Esseghir M. , Todd D. B. , Yu D. W.
Published: March 2011

Dispersive mixing of immiscible polymer blends as well as polymer systems containing solids is achieved in compounding equipment at two stages of the system's processing experience: first, while one or more of the polymer components are melting, and second, after all polymer components have melted. That is, the first mode of dispersive mixing occurs during the melting mechanism of “dissipative mix melting” (Ref. 1), while the second is melt‐melt mixing.

During the compounding of a given blend system, there are a number of processing parameters that can be changed in order to improve mixing. These range from machine operating variables to the addition of processing aids. If such processing changes fail to produce the desired morphology, the most common change to consider is the screw geometry. This, in practice involves a trial and error procedure, or the use of an existing database built from prior experience.

The role which the thermomechanical and rheological properties of the blend component play in dissipative mix melting and melt‐melt mixing has not yet been well understood. The reason for this is that although most blend systems have components which are strongly non‐Newtonian and strongly viscoelastic, the thinking and rules of thumb for mixing such materials has been heavily influenced by the analysis of G. I. Taylor (Ref. 2), who in 1932 addressed the phenomenon of the dispersion of a single Newtonian droplet by a Newtonian matrix flowing in laminar shear flow.

This paper addresses the strong role that the rheology of blend components, under processing conditions, play in laminar dispersive mixing of polymer blends. From a practical point of view, if the dispersion mechanisms and rates of dispersion depend on the component rheology, then such knowledge can lead us to the selection of advantageous mixing element designs and processing conditions.

The experimental results were obtained in dispersive mixing carried out in devices developed in the Polymer Mixing Study (Ref. 3). Such model devices include the Couette Flow Intensive Mixer (CIM) (Ref. 4), where a constant shear stress is applied on the blend components and the Twin Screw Mixing Element Evaluator (TSMEE) (Ref. 5), where the mixing flows are those encountered in actual mixing/compounding operations. The TSMEE will be described in the body of this paper together with its on‐ and off‐line morphology determination capabilities and its in‐line rheology sensor.

The low‐density polyethylene (LDPE) and polystyrene (PS) polymers studied were selected because they cover a wide spectrum of rheological properties.
Synthesis and properties of disilanylene‐containing polymers
Authors: Ishikawa Mitsuo , Kunai Atsutaka , Ohshita Joji
Published: March 2011

Alternating polymers, poly[(disilanylene)ethynylene]s and poly[(1, 2‐diethynylenedisilanylene)(1‐silacyclopenta‐2, 4‐diene‐3, 4‐diyl)]s were prepared by the anionic ring‐opening polymerization of 1, 2, 5, 6‐tetrasilacycloocta‐3, 7‐diynes and 4, 5, 10‐trisilacyclo[6.3.0]undeca‐1(11), 8‐diene‐2, 6‐diynes, respectively.

Poly[(disilanylene)butenyne‐1, 4‐diyl]s were synthesized by the reaction of 1, 2‐diethynyldisilanes with a catalytic amount of RhCl(PPh3)3. Photochemical and conducting properties of the polymers are described.
Protein de novo design: Macromolecules with tailormade properties
Authors: Eggleston Ian M. , Mutter Manfred
Published: March 2011

In the absence of a detailed knowledge of the folding mechanism of natural proteins, the general design of polypeptide sequences with a high propensity to fold into a predetermined three dimensional structure still appears to be out of reach. The concept of Template Assembled Synthetic Proteins (TASP) represents a means by which one can nonetheless construct macromolecules with native‐like structural features, with the result that systems with tailormade structural and functional properties are now becoming attainable.
Wetting phenomena on polymeric surfaces
Authors: Shanahan Martin E. R.
Published: March 2011

Classic theory predicts a unique value of equilibrium contact angle, θo, for a given solid/liquid/fluid system. However, wetting phenomena are often very complicated in practice, with contact angle hysteresis being a major source of problems in interpretation. Contact angle variability is related to several factors, but we consider two which are particularly relevant to polymeric substrates ‐ effects of orientation of molecular chains near the surface and local solid strain at the wetting front. A model is proposed to explain “stick‐slip” motion of the triple line.
Photochemical hole burning in polymers
Authors: Horie Kazuyuki
Published: March 2011

The possibility of photochemical hole burning (PHB) for various organic dyes is studied in relation to their Stokes shifts. Dyes with a Stokes shift smaller than 1000 cm−1 show the capability of hole formation. Based on this measure, the first observation of hole burning on the Soret (So→S2) band of a zinc tetrabenzoporphin has been realized, showing strong correlation between So‐S1 and So‐S2 transitions. Low‐temperature structural relaxation of various methacrylate polymers is also studied with PHB temperature‐cycle experiments.
Resonant opto‐optical switching in organic polymer waveguides
Authors: Franke H.
Published: March 2011

Photochromic polymer films are prepared by doping a polymer matrix like PMMA up to a few wt% with the fulgides “Aberchrome”. Opto optical switching is achieved in planar waveguides. Optical switching with gratings in waveguides and in transparent films is reported for latent gratings activated by uniform exposure.
Photoinitiated cationic polymerisation of multifunctional systems
Authors: Decker Christian , Decker Danielle , Viet Trieu Nguyen Thi , Le Xuan Hien
Published: March 2011

Different types of tridimensional polymer networks have been synthetised by photoinitiated cationic polymerisation of vinyl ether and epoxy‐functionalised oligomers and polymers. The polymerisation kinetics was followed by real‐time infrared (RTIR) spectroscopy, a technique that records directly conversion versus time profiles in a timescale as short as 1 s. The addition of a diacrylate monomer was shown to accelerate the ring‐opening polymerisation of epoxidized polyisoprene, with formation of interpenetrating polymer networks having well contrasted properties. A dual polymer network has been generated by photocrosslinking of a polyisoprene functionalised with both epoxy and acrylate groups.
A novel polar polymer via romp
Authors: Davies Geoffrey. R. , Almond Peter. J. , Hubbard Hugh.V.St. A. , Ward Ian. M. , Feast William. J. , Gibson Vernon. C. , Khosravi Ezat , Marshall Edward. L.
Published: March 2011

We have synthesised poly(2,3‐bis(trifluoromethyl)norbornadiene) (PBTFMND) via ring‐opening metathesis polymerisation (ROMP) to yield a glassy, highly polar polymer. The high trans polymer is ∼92% tactic and the high cis polymer is ∼75% tactic but the type of tacticity cannot be determined by NMR techniques. Thermally Stimulated Depolarisation (TSD) measurements give relaxed susceptibilities as high as 45 for the high trans material but as low as 3 for the high cis material. These data suggest that both the trans and cis materials are syndiotactic. The high trans material can be poled to yield a maximum polarisation of about 20 mC m−2 and a pyroelectric coefficient of 6 μC m−2. Though this is less than that of PVDF, the low room temperature permittivity and loss of PBTFMND results in a pyroelectric figure of merit comparable with that of PVDF.
Synthesis strategies and properties of smart amphiphilic networks
Authors: Iván Béla , Feldthusen Jesper , Müller Axel H. E.
Published: March 2011

This paper briefly surveys recent developments in the field of amphiphilic networks (APN) which are a new class of crosslinked polymer systems consisting of covalently bonded hydrophobic and hydrophilic chain segments. The covalent bonds between immiscible hydrophobic and hydrophilic polymer chains prevent demixing and yield polymer networks with unique structure and properties. Telechelic macromonomers provide the basis for the first generation of APNs obtained by copolymerization of the macromonomer with selected low molecular weight monomers. Synthesis of a variety of APNs using methacrylate‐telechelic polyisobutylene (PIB) macromonomers prepared by living carbocationic polymerization (LCCP) and quantitative chain end derivatization is reviewed. The second generation of PIB‐based amphiphilic networks is prepared by crosslinking of well‐defined hydroxy‐telechelic PIB and partially deprotected silylated poly(2‐hydroxyethyl methacrylate) (PHEMA) precursor chains. Other opportunities providing better structural control of APNs by crosslinking of functional amphiphilic block copolymers (or precursors) obtained by combining living carbocationic and anionic polymerizations are outlined as well. Properties of APNs, such as control of swellability by composition, pH‐response of swelling, fast surface structure reorganization by contacting with solvent, morphology, sustained release of drugs and bio‐ and blood compatibility, are also summarized.
Nonlinear optical polymers. Second harmonic generation in corona‐poled thin films
Authors: Samyn Celest , Claes Goedele , van Beylen Marcel , De Wachter Anneleen , Persoons Andre
Published: March 2011

The synthesis and second harmonic coefficients, d3,1 and d3,3 as well as the related susceptibilities χ(2)zzz of five series of (NLO‐dye methacrylate)‐(methyl methacrylate) copolymers were investigated. The NLO‐chromophores bound covalently to the polymer backbone were 5‐(2,2‐dicyanovinyl)‐or 4‐(2‐cyano‐2‐methoxycarbonyl)vinyl‐1‐piperidino‐2‐thiophene (P1 and P2), 4‐nitro‐4′‐alkoxy‐stilbene (P3), 4‐nitro‐3′‐methoxy‐4′‐alkoxystilbene (P4) and 4‐nitro‐4′‐alkoxy‐α‐cyano stilbene (P5). The second order nonlinear optical properties of corona‐poled aligned thin polymer films, using a needle electrode in order to induce noncentrosymmetry, were evaluated.

Nonlinear susceptibilities, χ(2)zzz, of the films were derived from the analysis of full‐angle Maker fringe patterns at 1064 nm, χ(2)zzz values as high as 1.98×10−7 esu for P2 copolymers and of 1.19×10−7 esu for P3 copolymers could be achieved.
Orientational effects in novel side‐chain liquid crystalline polyolefin blends
Authors: Mucha Maria , Wolski Adam , Ganicz Tomasz , Stanczyk Wojciech
Published: March 2011

The paper is concerned with an analysis of the dynamic properties of novel comb‐like liquid crystalline polycarbosilane, which are related to the reorientational processes responding to the applied ac electric field. Electro‐optical and switching effects of the polymer are estimated basing on the measurements of the transmitted light intensity as a function of temperature and ac electric field. The threshold voltage, rise and decay times are measured and discussed.
Well defined columnar liquid crystalline polydiethylsiloxane
Authors: Molenberg Aart , Siffrin Stefan , Möller Martin , Boileau Sylvie , Teyssié Dominique
Published: March 2011

The kinetics of the anionic ring opening polymerization of hexaethylcyclotrisiloxane (D3Et) with the cryptate Li+/[211] as counterion have been studied by means of 13C NMR spectroscopy. The propagation reaction was found to be of first order in monomer as well as living end concentration. It proceeds by two decades slower than the corresponding reaction with hexamethylcyclotrisiloxane (D3Me) as monomer. The Li+/[211] system could be used to synthesize well defined polydiethylsiloxane (PDES) samples (M̄w/M̄n <1.2). However, when the polymerization was aimed at high molecular weights (≥ 600 000 g/mol), the obtained molecular weights were lower than expected, and the molecular weight distributions became broader. All PDES samples were capable of forming a columnar mesophase. The temperature range in which this phase exists was found to be strongly molecular weight dependent. Initiation of the D3Et polymerization with polybutadienyllithium and coupling of the living chain ends yielded a PB‐PDES‐PB triblock copolymer, which could be crosslinked, resulting in a mesomorphic network.
Structure and mesophase of a new series of aromatic polyesters
Authors: Zhu Zhen
Published: March 2011

A new series of aromatic polyesters in which the polymethylene flexible spacers are connected with the rigid main chain containing benzene ring were prepared by interfacial polycondensation. The polymers were characterized by hotstage polarized microscopy, differential scanning calorimetry, wide‐angle X‐ray diffraction and Fourier‐transform infrared spectroscopy. The structure and properties of polyesters were investigated. The results showed that the textures of the thermotropic liquid‐crystalline polyesters are smectic and/or nematic. The dependence of melting point, clearing point and transition enthalpy of polyesters on length of the alkylene group revealed a regular zig‐zag trend. The thermal analysis of polyesters revealed that the clearing transition is an equilibrium process, so the entropy of this transition may be taken as an indication of the degree of the order in mesomorphic state presented in the system. Furthermore, the thermal history of polymer had a significant effect on its thermal behavior. The regular arrangement of methylene segments changed when polymer melted from the crystal state to the liquid‐crystalline state. The research also implicated that the conformational change of the methylene flexible spacer was one of the reasons for this thermal effect.
Modification of the physical properties of polymers by supramolecular interactions
Authors: Rowan Alan E. , van Nunen Johanna L. M. , Schenning Albert P. H. J. , Nolte Roeland J. M.
Published: March 2011

Using molecular recognition, receptors based upon diphenylglycoluril have been clipped onto paraquat polymers and styrene copolymers. In the case of the former polymers, the viscosity and electrochemical behaviour was modified. In the case of the latter, liquid crystallinity was induced upon complexation.
Graft‐copolymerization of styrene on polypropylene in the solid phase
Authors: Beenen Welmoed , Wal Douwe J. v. D. , Janssen Léon P.B. M. , Buijtenhuijs Ab , Hogt André H.
Published: March 2011

The graft‐copolymerization of styrene on PP in the solid phase has been studied under various reaction conditions using a radical initiator. Polymerization kinetics were investigated by DSC experiments and reactions in glass ampoules. The conversion rate and grafting efficiency of styrene appeared to be strongly influenced by the presence of the PP matrix and the styrene/PP ratio. From reactions in a lab scale reactor the concentrations of styrene and initiator, the dosing rate and the temperature were investigated to be critical parameters determining the grafting efficiency and the average length and number of grafts. The phenomena observed were explained by describing the process in relative rates of diffusion and polymerization, including swelling of the polymer by styrene monomer and diffusion limitations (Trommsdorff effect).
The increase of conductivity of ethylene/acetylene copolymers by rolling
Authors: Aleshin Andrei.N. , Guk Elena.G. , Marikhin Vyacheslav.A. , Myasnikova Liubov P. , Belov Gennadii.P. , Belov Dmitrii.G.
Published: March 2011

Rolling of compact nascent PE/PA copolymer powder allows to increase the dc conductivity of rolled films by two order of magnitudes and to receive the oriented films of good quality with dc conductivity about 10−2S/cm.
Pressure dependence of the demixing behaviour in polymer blends: I. Experimental procedure
Authors: Zeuner Volker , Lentz Harro , Kleintjens Ludo A.
Published: March 2011

The most common way to influence the liquid‐liquid phase behaviour in partially miscible (co‐)polymer blends is changing the blending temperature. Since most extruders can handle pressures, up to 300 bar, pressure may also be used to influence the miscibility of polymers during blending.

We have developed equipment and an experimental procedure to study the pressure dependence of the liquid‐liquid demixing behaviour of high‐viscous polymer blends under equilibrium conditions.

Small amounts (1–4 grams) of specially made polymers are blended in the ‘DSM MINI EXTRUDER’. After a chosen mixing time, a small portion of the blend is injected into a small capillary tube and kept at the blending temperature.

The phase behaviour of the blends as a function of temperature and pressure is studied via laser light scattering (at a scattering angle of 90°) in a specially made 400 bar/250°C window autoclave, where the capillary cell is placed in a high temperature grade silicon oil.
Nonlinear optical properties of polymeric materials and polymer films: Recent developments and future trends
Authors: Verbiest Thierry , Persoons André
Published: March 2011

An overview of recent developments in the field of nonlinear‐optical properties of polymers is presented. The emphasis is placed on frequency doubling, the electro‐optic effect, and photorefractive properties of polymers.
Gas separation membranes from tailor‐made polymers
Authors: Hensema Edwin René , Boom Jeroen Pieter
Published: March 2011

The development of tailor‐made polymers as new gas separation membrane materials has lead to membranes allowing both higher selectivities as well as higher permeabilities. The increased productivity of these new membrane materials is explained in terms of a higher free volume available for gas transport.
Polymers for medical uses
Authors: Höcker Hartwig , Klee Doris
Published: March 2011

An increasing demand for biomaterials corresponds to the deficiency in the knowledge on biocompatibility. To increase this knowledge the modification of polymer surfaces, their characterization, and the investigation of the response of the biosystem is considered to be a suitable approach.

Surface modification may be performed in the wet‐chemical way (heterogeneous reaction) or by means of treatment with a suitable plasma (glow discharge). Surface sensitive methods such as X‐ray photoelectron spectroscopy, infrared spectroscopy in the attenuated total reflexion mode as well as surface energy measurements are useful for surface characterization.

To determine the bioresponse to the polymer surface, enzyme‐linked immunosorbent assays, cell growth and full blood tests may be used.

In the present paper several systems are described with respect to their surface modification, characterization, and bioresponse. It is shown that the protein adsorption is triggered by the surface, that SO2 plasma treatment enhances cell growth and that there seems to be a biocompatibility window for a surface characterized by a ξ‐potential between −4 and −8 mV and a ratio of dispersive to polar contributions of surface energy around 12.

It is stressed, however, that the final solution for a biomaterial is a material which, in the course of degradation, constantly presents a new biocompatible surface.
Porosity control in nylon‐6/nylon‐6, 6 membranes
Authors: Tanaka Nobuyuki
Published: March 2011

The possibility of porosity control in N6/N66 membranes prepared from N6/N66 blend solutions of calcium chloride – methanol mixture was investigated. For N6/N66 blend solutions at 10 °C and 20 °C, the four‐phase structure of solid, gel 1, gel 2 and solution was observed clearly in the pore formation process after adding water on a solution surface. In the boundary part between gel 1 and gel 2, the phase separation of N6 and N66 was predicted. The macroscopic pores of blend membranes prepared at 10°C and 20 °C were almost spherical.
Polymer derivatives of glucocorticoid hormones
Authors: Panarin E. F. , Baikov V. E. , Timofeevsky S. L. , Nezhentsev M. V. , Vinogradov O. V. , Kalinin G. V.
Published: March 2011

The activated derivatives of hydrocortisone, prednisolone, and dexamethasone, crotonates, methacrylates, and haloacetates were synthesized by acylating native hormones with chloroanhydrides of the corresponding acids. Water‐soluble conjugates of steroids which bear a positive sign were obtained by reactions in chains of copolymers of vinylpyrrolidone and vinyl‐, allylamine, diethylaminoethyl methacrylate and diethylaminoethyl crotonate with steroid haloacetates. Water‐soluble derivatives bearing a negative sign were obtained by the acylation of steroids using vinylpyrrolidone copolymer with maleic anhydride. Non‐ionogenic water‐soluble polymers were synthesized by the copolymerization of vinylpyrrolidone with steroid methacrylates and crotonates. Cationic and anionic polyelectrolytes bearing steroid units were also obtained by the ternary copolymerization of vinylpyrrolidone with steroid crotonates, diethylaminoethyl crotonate and crotonic acid. The polymer steroids exhibit high specificity in the interaction with trans‐cortine and antybodies to cortisol and to target cells, thymocytes. The in vivo experiments revealed anti‐inflammatory activity on the level of native hormones. The antishock activity of polymer conjugates exeeds that of native hormones. It was detected that negative side effects characteristic of native hormones decrease markedly after they are bonded to a molecule of water‐soluble polymer. No effect of the sign of the macromolecule on the biological activity of modified hormones was detected.
From organic conductors to bio‐conductors
Authors: Inokuchi Hiroo
Published: March 2011

Two major categories of organic solids are known to offer the prospect of electrical conduction. One of them consists of charge‐transfer complexes such as BEDT‐TTF salts. A large number of studies on charge‐transfer complexes have been carried out and their conductivity ranges from semiconductor to superconductor. The other group comprises single component materials. Typical examples are polycyclic aromatic compounds and also phthalocyanines; their conductivities are not as good as those of the donor‐acceptor kinds.1) As one of those single component organic semiconductors, a group of cytochromes, electron carrier in biological system, was offered. Cytochrome c3 (molecular weight = 13,995, 107 amino acid residers), an electron carrier in the reactions of very negative potentials in cells of Desulfovibrio, has four homes in the molecule.
Structure development under transient shear flow in semidilute polystyrene solution
Authors: Murase Hiroki , Kume Takuji , Hashimoto Takeji , Ohta Yasuo , Mizukami Tohru
Published: March 2011

The shear‐induced concentration fluctuations or phase separation of a semidilute solution comprised of polystyrene (PS) as a solute and dioctylphthalate (DOP) as a solvent (PS/DOP) was investigated by using real‐time and in‐situ shear‐small‐angle light scattering and shear‐phase‐contrast optical microscopy. When a transient shear flow with a fixed shear rate γ greater than a critical value γC was imposed on the solution, a unique anisotropic scattering pattern was observed some time after onset of shear. This pattern was found to be identical to the “butterfly pattern” previously reported for the same solutions under steady shear flow with γC. When the shear flow was ceased before the scattered intensity reached a steady state, the scattered intensity rapidly increased toward a maximum intensity, and then decreased toward the intensity of the quiescent solution with time. From the phase‐contrast microscopy, this immediate increment of the scattered intensity after the shear cessation was found to arise from the increment in amplitude of the concentration fluctuations along flow direction. The characteristic length scale of the fluctuations was about 2.5 μm in this experiment, almost independent of the shear rate imposed on the solution.
Morphology and kinetics of crystallization of polyethylene from chain disentangled melt
Authors: Galeski A , Psarski M.
Published: March 2011

Short description of crystallization processes in linear polyethylene with applied reptation concept and emphasized role of chain entanglements is presented. The influence of chain entanglements in Regimes of crystallization is discussed. The estimation of time of self‐diffusion and time required for complete pull‐out of a macromolecular chain from melt by crystallization forces on the basis of reptation friction leads to the conclusion that a crystallizing macromolecule is reeled out of the melt very quickly (order of microseconds) while other macromolecules are relatively motionless.

Fast crystallization of polyethylene does not change end‐to‐end distance of macromolecules while slow isothermal crystallization causes partial disentaglement of chains as it could be concluded from an increased end‐to‐end distance.

The route to complete disentanglement is a slow crystallization at elevated temperature (∼230°C) and under high pressure (∼6 kbars). High pressure crystallization delivers polyethylene samples with a high melting point (∼145°C) and completely extended chains (end‐to‐end distance − 1.0). Macromolecular chains in such samples after melting exhibit for a period of several minutes complete or partial disentanglement and can be used for studies of chain entanglements dynamics and also for studies of crystallization from chain disentangled melt.

The studies of crystallization of linear polyethylene in disentangled melt showed almost 4 fold increase in the growth rate of spherulite at 126°C (end of Regime II of crystallization) and only 1.1 fold increase at 123°C (beginning of Regime II of crystallization). The results concerning the kinetics of crystallization and nucleation in chain disentagled PE melt as well as resulting morphology are discussed further in terms of Regimes and reptation concepts.
Charge carrier photogeneration and transport in poly(methyl‐phenylsilylene)
Authors: Nešpůrek S.
Published: March 2011

Optical excitations in poly(methyl‐phenylsilylene) can be realized within the framework of a chemical bond in the polymer backbone or a side group skeleton. A charge transfer of the electron from the main chain to a side group is necessary to form stable ion‐pairs. Dissociation of the ion‐pairs can be described in terms of the Onsager theory of geminate recombination. The photogeneration efficiency can be improved by an electron acceptor doping. The charge carrier transport is influenced by two factors: delocalized movement inside the conjugated domains and intra‐ and interchain hopping. The electrostatic interactions of polar additives with polarons influence the polaron binding energy and the charge hopping.
Macromolecule‐metal complex interactions as precursors for the catalytic chemical modification of polymers
Authors: Rempel Garry L.
Published: March 2011

Chemical modification of polymers via catalysis has recently emerged as an area of increasing importance in macromolecular chemistry. It provides an efficient synthetic route for the production of novel polymers with desirable physical properties and functional groups which are often inaccessible by conventional polymerization techniques. Diene‐based polymers and copolymers are ideal for chemical modification because of the technological importance associated with the parent materials and the reactivities of the double bonds in the polymer chain. In employing organometallic catalysts for such modifications, it has been found that the ligand environment of the catalyst as well as the functionality of the polymer has a profound effect on the nature of the macromolecule‐metal complex interaction and the resulting polymer modification. The importance of the macromolecule metal complex interactions and the design of appropriate catalyst systems is illustrated for the hydrogenation, hydroformylation/hydroxymethylation and hydrosilylation of a number of polymers.