bluuebunny/crossref_metadata_2025 huggingface dataset:
Self‐assembly of main chain liquid crystalline polymers via heteromeric hydrogen bonding
Authors: Alexander C , Jariwala C P , Lee C M , Griffin A C
Published: March 2011

Complexation between pyridines and carboxylic acids is driven by hydrogen bonding. This simple, single hydrogen bond is shown to be capable of serving concomitantly as both the agent of liquid crystallinity and as the coupling bond generating an extended linear chain structure. Three such complexes made from an aromatic diacid and three structurally different bis pyridyls were prepared. In each case the association complex self‐assembles into an organized liquid crystalline phase. Discussion of this complexation as a step‐growth polymerization process is presented along with an examination of the suitability of various methods for characterizing these materials.
Hybrid thermotropic liquid‐crystalline block copolymers
Authors: Chiellini Emo , Galli Giancarlo , Angeloni Amino S. , Laus Michele , Bignozzi Maria Chiara , Yagci Yusuf , Serhatli Ersin I.
Published: March 2011

A new approach to the preparation of two classes of block copolymers containing liquid‐crystalline segments is reported. Copolymers 1 and 2 are constituted by polytetrahydrofuran and side‐chain liquid‐crystalline polymethacrylate blocks, whereas block copolymers 3 consist of polystyrene and main‐chain liquid‐crystalline polyester blocks. The synthetic procedures leading to copolymers 1‐3 are extremely versatile and can be used to prepare a great variety of block copolymer architectures. In both copolymer classes the chemically different blocks are strongly segregated in the solid and melt phases and undergo individual phase transitions. The mesophase transition temperatures of the liquid‐crystalline blocks are very similar to those of the corresponding homopolymers, and their enthalpies are directly proportional to the content of the liquid‐crystalline block.
Synthesis of planar poly(p‐phenylene) derivatives for maximization of extended π‐conjugation
Authors: Tour James M. , Lamba Jaydeep J. S.
Published: March 2011

Described is the synthesis of a ladder polymer with a poly(p‐phenylene) (PPP) backbone. The main PPP backbone was synthesized via palladium‐catalyzed coupling of an arylbis(boronic ester) with an aryl dibromide. Imine bridges, formed by exposure of the polymer to trifluoroacetic acid, are used to force the consecutive units into planarity. The bridging units are sp2 hybridized thus allowing for greater π‐electron flow between the consecutive phenyl units by lowering the band gap between the hydroquinoidal and the quinoidal forms of the phenylene backbone. When the bridges are n‐dodecyl substituted, the fully planar structures (with Mn < 5 000) are soluble in hot chlorobenzene from which flexible free standing films can be cast. The n‐butyl substituted polymers and the higher molecular weight n‐dodecyl substituted polymers are soluble in CH2Cl2/trifluoroacetic acid mixtures. The optical spectra of the planar systems are compared to that of the parent nonplanarized polymers, some analogous planar oligomers, and oligo(p‐phenylenes).
Thermodynamics of polymer blends
Authors: Koningsveld Ronald
Published: March 2011

The general principles of thermodynamic equilibrium in binary liquid systems are reviewed briefly, and extended to quasi‐binary mixtures of polydisperse polymers. Molecular models allowing actual phase behaviour to be discussed in terms of molecular parameters are exposed to data on the system polystyrene/polyvinylmethylether. Disparity in size and share between the repeating units must be introduced to obtain reasonable agreement between theory and experiment. The neccessary introduction of the molar‐mass distribution detracts from this agreement which makes clear that other aspects exist that must be taken into account. For example, cross association between repeating units has a marked effect on phase behaviour. Blends are subject to two kinds of thermodynamic aging which lead either to considerable mutual solubility in supposedly immiscible blends, or to metastable equilibria transforming into states of lower Gibbs energy. In both cases physical proerties of the blend will change with time.
PC/ABS blends: Compatibilization and mechanical behaviour
Authors: Greco Roberto , Dong Lisong
Published: March 2011

PC/ABS(M) blends, encompassing the whole composition range between pure PC and ABS(M), were prepared by melt‐mixing in a Brabender‐like apparatus. Thermal, mechanical and impact tests were performed on compression moulded specimens. Inward Tg shifts were detected for PC and ABS(M) in the blends with respect to pure PC and ABS(M) values, indicating an interaction between the component domains. This finding was confirmed by the comparison of the experimental tensile moduli with the Kernels model predictions, showing an evidence of a good adhesion between the phases. A synergistic effect was observed for the impact strength as well as for the maximum stress at an ABS(M) blend content of about 25 weight %. All the results are interpreted on the basis of an interlayer existing at the boundary between the PC and ABS phases. A preliminary investigation on the influence of the ABS internal composition, keeping constant all the other conditions (mixing, processing, specimen preparation), was carried out as well. Differences in the properties of PC/ABS(M) and PC/ABS(B) blends are thoroughly discussed. The compatibility between PC and ABS domains seems to be scarcely influenced by such a parameter in these blends.
Reactive blending of bioaffine polyesters through free‐radical processes initiated by organic peroxides
Authors: Immirzi Barbara , Malinconico Mario , Martuscelli Ezio , Volpe Maria G.
Published: March 2011

Reactive polymer blending of poly(β‐hydroxybutyrate) (PHB) and its valerate copolymers (PHBV) are reported, following two different methodologies, namely polymerization of rubber inclusions in the preformed matrix or reactive melt blending of preformed polymers. As second phase, poly(butyl acrylate) (PBA) and polycaprolactone (PCL) are used. The results of spectroscopic, thermal, mechanical and morphological analysis indicate the existence of chemical interactions between the blend components. Such interactions are also responsible of a drastic change in the morphology.
Intercrosslinked polymer networks by simultaneous curing of unsaturated polyesters and bismaleimide resins
Authors: Abbate M. , Di Liello V. , Martuscelli E. , Musto P. , Ragosta G. , Scarinzi G.
Published: March 2011

The modification of an unsaturated polyester resin by incorporating a second co‐reactive monomer as a thermosetting bismaleimide is described The bismaleimide was readily dissolved in the uncured polyester matrix up to a concentration of about 20% wt. FTIR isothermal measurements indicated that the kinetics and the mechanism of the curing process were strongly affected by the presence of the bismaleimide. The resulting inter‐crosslinked network showed a gradual enhancement of the elastic modulus in a wide range of temperatures by increasing the bimaleimide amount in the system. This enhancement was obtained without altering the intrinsic toughness of the matrix.
The reactor granule technology: A revolutionary approach to polymer blends and alloys
Authors: Galli P.
Published: March 2011

The new plastic materials frontier in general and in thermoplastic polyolefins in particular developed in the last years and into next century are and will be represented by polymer alloys. The new trend in polymer alloy is to obtain them from monomer directly in the reactor, replacing the polymer blends previously made by mechanical melt extrusion of preformed polymers. It discloses new opportunities in term of properties together with better economics. The reactor granule technology developed by Himont/Montecatini produces spherical form alloys that are a synergistic combination of morphological, chemical, rheological and thermomechanical properties, by which the polymer finds many applications not previously suitable for polypropylene or polyethylene. In reactor granule technology the multimonomer random and heterophasic copolymers can be produced primarly within the granule enclosed by a solid polymer skin free from sticky nature, typical of polymers obtained by gas‐phase technology and causing many problems like particles agglomeration and fouling.
Blends of natural and synthetic polymers: A new route to novel biomaterials
Authors: Giusti Paolo , Lazzeri Luigi , Barbani Niccoletta , Lelli Letizia , De Petris Silvano , Cascone Maria G.
Published: March 2011

Blends of natural and synthetic polymers were studied for potential applications in the biomedical field. Collagen and hyaluronic acid were mixed in aqueous solution with poly(vinyl alcohol) and poly(acrylic acid). The properties of the blends were studied by differential scanning calorimetry and dynamic mechanical thermal analysis. Some methods were also investigated to enhance the miscibility of the polymers in these blends.
Diffusion of spherical micronetworks in polymer diluent systems and melts studied by dynamic light scattering techniques
Authors: Bartsch Eckhard , Frenz Volker , Renth Falk , Sillescu Hans
Published: March 2011

Spherical polystyrene (PS) micronetworks can be prepared in microemulsion with bulk radii of 5–60 nm and different cross‐linking densities. The diffusion of these PS spheres has been studied in polymer diluent systems ranging from dilute solutions to plasticized melts by using forced Rayleigh scattering and photon correlation spectroscopy. On increasing the PS concentration, a colloid glass transition is observed at a volume fraction ΦC ≈ 0.64 of the swollen spheres. At higher concentration inside the “colloid glass” state the sphere diffusion is slowed down and becomes very complex but can be observed up to the limit of a melt of collapsed spheres.
Polarized and depolarized dynamic light scattering of concentrated polystyrene solutions
Authors: Brown Wyn , Nicolai Taco
Published: March 2011

Polarized and depolarized dynamic light scattering have been used to examine the dynamics of concentrated polystyrene solutions in dioctyl phthalate and toluene. Time‐temperature superposition of the depolarized intensity correlation functions gave master curves covering more than 10 decades on the time scale. Polarized correlation functions are resolved into relaxational and diffusive components having different temperature dependences. When the relaxation rate of the concentration fluctuations approaches the reorientational relaxation rate, the concentration fluctuations become q‐independent i.e. the diffusional relaxation is rate‐determined by the backbone mobility. With a small molecule solvent as toluene, however, a part of the concentration fluctuations relaxes faster than the orientational relaxation, i.e., the diffusion occurs in the free volume within the “frozen” network.
Static and dynamic scattering from cyclic diblock copolymer chains in solution
Authors: Borsali Redouane , Benmouna Mustapha
Published: March 2011

This work discusses the static and dynamic scattering properties of (A‐B)r ring diblock copolymer chains in the semi‐dilute solutions. The case of a symmetric diblock is considered in details. The results show substantial differences with respect to linear diblock copolymers. This is mainly due to the effect of connectivity of the chain extremities A and B leading to different conformations for both types of architectures. The additional entropic interaction in cyclic chains induces a decrease of the elastic scattering intensity and a shift of the location of its maximum to a higher q value. As for the dynamics, the fact that the two extremities are connected speeds up the frequency of the interdiffusion mode and shifts its minimum to higher q value. A discussion of hydrodynamic interactions is also included.
The zeolate ligand; zeolite encapsulated semiconductor nanomaterials
Authors: Ozin Geoffrey A. , Steele Mark R.
Published: March 2011

Consolidation of the results of structural, spectroscopic and kinetic studies of a range of intrazeolite guests and their reactions have led to the development of the “crown ether‐zeolite ligand analogy” and the concept of the “zeolate” as a macrospheroidal or macrocylindrical multidentate anionic ligand. This view of a zeolite cavity or channel as a collection of interconnected aluminosilicate crown ether‐like building blocks, permits a coordination chemistry approach to the understanding of metal‐ligand bonding (capping, anchoring, complexing, stabilizing and structure‐directing phenomena) in a variety of zeolite guest‐host inclusion systems. In this paper we focus attention on the role that the zeolate ligand plays in the organization of semiconductor precursors and their assembly to semiconductor nanoclusters with particular reference to II‐VI nanomaterials.
Polymeric porphyrin and metalloporphyrin assemblies in bulk solution
Authors: Fuhrhop Jürgen‐Hinrich , Bindig Uwe , Demoulin Corinna , Rosengarten Bianca , Siggel Ulrich
Published: March 2011

Some water‐soluble porphyrins aggregate in aqueous media to form fibrous assemblies. When polynucleotides are used as matrices, porphyrin monomers are aligned at the periphery or intercalated. Porphyrin‐porphyrin interactions hardly occur. Metal‐metal or metal‐ligand‐metal interactions have been observed in oxo‐oligomers, pyrazine‐bridged dimers and radical dimers. β‐Substituted metallo‐porphyrins, however, form no polymers. The only linear polymerization, which has so far been observed in molecular asemblies, occurs with amphiphilic porphyrin amides, amines and carboxylates and their metal complexes in water and of bacteriochlorophyll in DMF/water. These compounds form long‐lived high molecular weight micellar, inverse micellar and vesicular fibers spontaneously in aqueous media. The porphyrin fibers in water are about 4‐6 nm thick and up to several of μm long.
Metal coordination by natural biomacromolecules
Authors: Reedijk Jan
Published: March 2011

An overview is presented of the role of metal ions in living systems, with special attention to the coordination of the metal ions to the ligands in biologically occurring macromolecules. After a discussion of the commonly occurring ligands in biological systems, the several roles of the metal ions will be discussed (storage & transport, structure generation & stabilisation, catalysis and roles as drugs).
O2/n2‐separation by polymer‐bound cobalt complexes
Authors: Nishide Hiroyuki , Suzuki Takayuki , Soejima Yuji , Tsuchida Eishun
Published: March 2011

Facilitated or complexation‐mediated transport of oxygen in the solid membrane containing a fixed carrier was described, by using the polymer‐bound cobalt Schiff's base chelate (CoS) and cobaltporphyrin (CoP). α3 β‐Substituted cobaltporphyrin derivatives were synthesized: The oxygen‐binding reaction to cobalt was affected by the cavity structure on porphyrin, i.e., unbulky amido‐substituted groups such as acetylamido‐ and acrylamido‐substituents enhanced oxygen‐binding and ‐dissociation rate constant or provided an oxygen‐binding pathway. Oxygen transport through the membranes of these polymer‐bound CoP derivatives was selectively augmented due to the rapid and reversible oxygen‐binding. Diffusion constants via the fixed CoPs correlated to the characteristics of oxygen‐binding reaction.
A critical overview of the catalytic potential of zeolite supported metal complexes
Authors: De Vos D. E. , Thibault‐Starzyk F. , Knops‐Gerrits P. P. , Parton R. F. , Jacobs P. A.
Published: March 2011

This paper reviews some important items for the design of new zeolite‐metal complex supramolecules. After an overview of the synthesis methods for these systems, complexation reactions inside zeolites are discussed in detail. The last part is focused on the effects of encapsulation on the reactivity of the complexes.
Transition metal complexes in inorganic polymers as enzyme mimics
Authors: Romanovsky Boris V.
Published: March 2011

Features of a new family of catalytic systems which represent transition metal chelates entrapped within zeolite matrices are discussed. There exists strong similarity between the behavior of these catalysts and that of natural enzymes.
Selective hydrogenation of chloronitrobenzenes catalyzed by palladium complex of silica‐supported chitosan
Authors: An Ying , Yuan Ding , Huang Mei‐Yu , Jiang Ying‐Yan
Published: March 2011

A palladium complex of silica‐supported chitosan has been found to catalyze the hydrogenation of p‐, m‐ and o‐chloronitrobenzene, and of 4‐chloro‐1,3‐dinitrobenzene to p‐, m‐ and o‐chloroaniline, and 4‐chloro‐3‐aminoaniline in 100% yield, respectively, at room temperature and under atmospheric pressure, and the side reaction, dechlorination, has not been observed. This catalyst was very stable, the turnover numbers (p‐chloronitrobenzene to p‐chloroaniline cycles / palladium atom) reached 9000 in 17 hours.
The effects of structures and compositions of polymer‐metal complexes on the hydroformylation of olefins
Authors: Pan Caiyuan , Zong Huijuan
Published: March 2011

A number of linear and crosslinked polymer ligands containing P or N or S as coordinative atoms were prepared. The hydroformylation of olefins was carried out at mild conditions in the presence of complexes as catalysts which were made by complexation reactions of these ligands with various homogeneous complexes or metal salts. The obtained results were explained in terms of the influences of the polymer matrix, or the structures and compositions of the polymer chain, and the properties of polymer‐metal complexes on activity and selectivity. The most important factor for enhancing the selectivity towards linear aldehyde lies in the properties of the polymer‐metal complex. High selectivity up to 95% was obtained by using polymer phosphine ligand‐Pt‐Sn complexes as catalyst in the hydroformylation of olefins. The hydroformylation mechanisms were discussed.
Macromolecule complex for advanced optoelectronic devices
Authors: Mizoguchi Katsuhiro
Published: March 2011

This paper describes reviews about characterizations of optical and electronic (opto‐electronic) organic materials including macromolecule complex, and their applications for advanced key devices used for computers and communications technologies. On the basis of the author's recent investigations, discussions are made on organic electroluminescent thin film materials for emissive display devices, polymer dispersed liquid‐crystal materials for passive display devices, organic photoconductive materials for electrophotographic printer devices, and highly electroconductive polymers for solid tantalum capacitors. Finally, the technical issues and development prospects for the opto‐electronic organic materials in the 21st century are suggested.
Macromolecular dynamics in anisotropic viscoelastic liquids
Authors: Volkov V. S. , Kulichikhin V. G.
Published: March 2011

The non‐Markovian dynamics of a macromolecule in a nematic viscoelastic liquid is studied.
Brownian dynamics of polymeric chain in strong external field
Authors: Neelov Iqor M. , Clarke Julian H. R.
Published: March 2011

The cooperativity of conformational transitions in strained linear polymer chain was investigated by the method of Brownian dynamics. Deformation of a chain consisting of N=32 and 64 bonds was created by strong external field of dipole type. Correlations are discussed in terms of hazard‐plot analysis.
Evaluation of the tension on dna‐segments in the lakes‐straits model
Authors: Loomans Dirk , Blumen Alexander
Published: March 2011

We consider DNA gel electrophoresis in the framework of the lakes‐straits model, proposed by Zimm in Phys. Rev. Lett. 61, 2965 (1988) and J. Chem. Phys. 94, 2187 (1889). Here we evaluate the tension on a Gaussian chain‐fragment confined in a lake, by accounting for its variable length. Through numerical simulations we find that the precise form of the tension is very important for the calculation of the absolute value of the mobility of the chain and that it is of minor importance for establishing the frequency‐dependence of the mobility.
Monte carlo simulation of many‐arm star polymers
Authors: Ohno Kaoru
Published: March 2011

The statistics of many‐arm star polymers in dilute solution is studied by means of the enrichment algorithm [K. Ohno and K. Binder, J. Stat. Phys. 64, 781 (1991)] using a Monte Carlo simulation technique. In this study, typically 50,000 samples of star polymers with 12–32 arms each of which has 50 bonds are generated. The results for the configuration‐number exponent γ(f) are γ(12) = ‐3.4 ± 0.3, γ(18) = ‐8.9 ± 0.2 and γ(32) = ‐29 ± 2.
Influence of microscopic non‐affinity and functionality on the deformation of polymeric networks
Authors: Glatting Gerhard , Winkler Roland G. , Reineker Peter
Published: March 2011

A non‐affine model for the description of the stress‐strain behavior of polymer networks is introduced. We assume that the network consists of a gas of phantom chains. The deformation of the chains is taken into account by macroscopic constraints, where the macroscopic deformation is affine and the microscopic one non‐affine. In contrast to existing models, the number of parameters is reduced; nevertheless the main experimental features are reproduced.
Kinetics of network formation by end‐linking: A monte carlo study
Authors: Trautenberg Hans Ludwig , Sommer Jens‐Uwe , Göritz Dietmar
Published: March 2011

End‐linked tetrafunctional model networks were simulated using the bond‐fluctuation algorithm. The kinetics of network formation was studied and compared with the solution of the rate equation for a four‐step process. A crossover from diffusion‐controlled to reaction‐controlled time behavior depending on the reaction speed was observed. For a reaction probability of 10−3 per movement of an unreacted chain end and a cross‐linker into nearest neighbor position, the rate equation gives a satisfactory description of the kinetics of the reaction.

The evolution of the largest cluster as well as local imperfections of the network were considered in detail. The evolution of the cyclic rank differs from the model of Queslel and Mark.

The mobility of cross‐links of different functionality was measured.
Polymers on anisotropic lattices
Authors: Stilck Jürgen F.
Published: March 2011

The study of the thermodynamic behavior of polymers on anisotropic Bethe lattices shows a phase diagram for the fourcoordinated lattice which is different from the ones for lattices with larger coordination number. Two distinct polymerized phases appear, one of them having the density of sites incorporated into chains equal to one. The solution of the model on the anisotropic q=4 Husimi lattice leads to similar results. Finally, preliminary phenomenological renormalization group calculations, using the solution of the model on strips of finite widths via transfer matrix calculations, are consistent with a similar phase diagram for the model on the square lattice.
Onsager chains: Semi‐flexible polymers revisited
Authors: Mulder Bela
Published: March 2011

Using a density functional approach we derive the equations describing the equilibrium orientational distribution of a system of chains composed of elongated segments that interact with segments located on other chains through excluded volume interactions and with neighbouring segments of the same chain through a potential that determines the chain flexibility. We analytically determine the limit of stability of the low density isotropic phase as a function of the number of segments and the chain stiffness. The approach turns out to be formally equivalent to a recently proposed mean‐field theory by Petschek and Terentjev. Comparison with the Khoklov‐Semenov theory shows that the latter is based on an additional assumption that is not valid in an orientationally ordered phase.
Configuration‐dependent properties of polyoxyethylene chains in the third‐order interaction approximation
Authors: Linxi Zhang , Tao Jin , Jianmin Xu
Published: March 2011

Conformational energies of polyoxyethylene chains in the third‐order interaction approximation are calculated using a semiempirical potential energy function in the usual manner. Configuration‐dependent properties of POE in the third‐order are also calculated, and more close to the experimental data.
Free energies and phase equilibria of chain molecules
Authors: Smit Berend , Karaborni Sami , Ilja Siepmann J.
Published: March 2011

In this Article, a review is presented of recent developments in Monte Carlo simulations of chain molecules. The Rosenbluth chain insertion technique is used to calculate the free energy of the chain molecules. Furthermore, this insertion method is used to generate biased Monte Carlo moves. It is shown that this bias can be removed by adjusting the acceptance rules such that configurations are generated with their correct Boltzmann weight. This configurational‐bias Monte Carlo method can be combined with the Gibbs‐ensemble technique which results in an efficient method to simulate phase equilibria of chain molecules.
A model for isotropic, nematic, and columnar ordering in a self‐assembling system ‐ comparison with the phase behavior of 2,3,6,7,10,11‐hexa‐(1,4,7‐trioxaoctyl)‐triphenylene in water
Authors: Hentschke Reinhard , Edwards Patrick J. B. , Boden Neville , Bushby Richard J.
Published: March 2011

Many amphiphilic molecules in aqueous solution spontaneously self‐assemble into labile anisotropic aggregates. At large enough concentration, this shape anisotropy may lead to complex liquid‐crystalline mesophases. Here we compare the results of a recent excluded volume model for reversible assembling flexible linear aggregates to a corresponding experimental amphiphilic system, 2,3,6,7,10,11‐hexa‐(1,4,7‐trioxaoctyl)‐triphenylene, in water. Our comparison emphasizes the importance of including aggregate flexibility into theories of micellar assembly.
Amorphous fluoropolymers ‐ a new generation of products
Authors: Korinek P. M.
Published: March 2011

Poly(tetrafluoroethylene) (PTFE) already known since 50 years, Is a unique material among plastics due to its chemical inertness, heat resistance, electrical insulation properties and low coefficient of friction. Its high melt viscosity needs special ways of processing. That fact led to the development of melt‐processible fluoropolymers such as Perfluoroethylene‐propylene (FEP) and Perfluoroalkoxy (PFA). Now we have a third generation which is an amorphous fluorpolymer made by copolymerizing tetrafluoroethylene with 2,2‐bis (trifluoromethyl) ‐ 4,5 ‐ difluoro ‐1,3 ‐ dioxole. The bulky cyclic structure prevents the normal crystallisation as with PTFE polymers. The amorphous fluoropolymers have high clarity and dissolve in selected solvents. Having C‐F, C‐C and C‐O bonds the well known properties as high temperature and chemical resistance are retained. Dielectric constant is in the range 1.83 ‐ 1.93 up to 10.00 MHz the lowest of any plastic material. Optical properties are also very special. Refractive index is very low, in the range 1.29 ‐ 1.32. Transmission is high from UV to IR and the polymer is not photo‐degraded. The unique electrical and optical properties, coupled with high chemical and thermal stability, plus the ability to work from solution offers a powerful tool for those working on the frontiers of technology.
Anionic polymerization of hexafluoro‐1,3‐butadiene and characterization of the polymer
Authors: Narita Tadashi
Published: March 2011

The present review describes the anionic polymerization of hexafluoro‐1,3 ‐butadiene (HFBD) and the characterization of the polymer. HFBD which is hardly polymerized under radical polymerization conditions yielded the polymer with cesium and rubidium compounds as initiators in moderate conditions. X‐ray photoelectron spectra and Raman spectra showed the structure of the polymer was similar to that of poly(hexafluoro‐2‐butyne). The polymerization mechanism, an addition reaction of the propagating anion to the 2‐carbon of HFBD followed by isomerization of the propagating end group to yield the polyene structure, is proposed from the results of the investigation of initiation reaction and the structure of the polymers. Poly(HFBD) shows higher thermostability than poly(tetrafluoroethylene) in spite of bearing functional ‐CC‐groups in the polymer main chain.
Perfluorinated and partially fluorinated organic compounds. Preparation, characterization and application
Authors: Meinert H.
Published: March 2011

Electrochemical fluorination (ECF) of various heterocyclic compounds has been investigated. α,ω‐Dimorpholinoalkanes of different chain length (n = 1‐6) and of morpholinocyclohexene gave the perfluoro derivatives in yields up to 45%. The crystal and molecular structures of the perfluorinated compounds are presented.

The mechanism of ECF for these compounds is discussed on the basis of a steric model. Perfluorocarbon emulsions of second generation were prepared by means of F‐dimorpholines and F‐cyclohexylmorpholine, acting both as oxygen carriers and as interfacial active compounds (IFACs). The stabilizing effect of these IFACs is interpreted. Semifluorinated alkanes, RfRh, are chemically inert and non‐toxic. They are useful for blood substitutes in two ways: as co‐surfactants to stabilize emulsions with perfluorocarbons and as oxygen carriers instead of perfluorocarbons. The high density of perfluorocarbons cause problems in some field of application in medicine. Therefore symmetrical diethers of the type RF(CH2)mO(CH2)nO(CH2)mRF were synthesized. These are inert and biocompatible compounds. Diethers with long RF‐tail and long hydrocarbon spacer are ideal solubilizers for perfluorocarbons with hydrocarbons and vice versa. The diethers with short hydrocarbon spacer and long RF‐tail can be applied in biological systems, because they are not soluble in lipid tissues. Perfluorocarbons (e. g. F‐decalin, F‐octane) are used as medical tools in ophthalmology, their purity is essential. Not totally fluorinated compounds (1 H‐perfluoroalkanes, α,ω‐dihydrogenoperfluoroalkanes) are characterized and discussed. 1H‐perfluoroalkane is also formed by nucleophilic attack on perfluoroalkyl halide.
New pH sensitive network: Combination of an amphiphilic degradable polyester with a β‐cyclodextrin copolymer
Authors: Moine Laurence , Cammas Sandrine , Amiel Catherine , Renard Estelle , Sébille Bernard , Guérin Philippe
Published: March 2011

A novel hydrophobic monomer, ethyladamantyl malolactonate, has been synthesized and copolymerized with benzyl malolactonate by anionic ring‐opening polymerization. The ratio of adamantyl monomer varied from 0 to 100 mol%. Deprotection of benzyl groups leads to a water soluble copolyester with carboxylic acid lateral functions which give a polyelectrolyte character to the corresponding polymers. The mixture of a copolyester containing 10% of adamantyl groups and a β‐cyclodextrin/epichlorohydrin copolymer in aqueous solution leads to a new pH‐dependant associating system. The solution behavior of this system was studied by viscosimetry as a function of pH, concentration and ratio of both copolymers. At the initial solution pH (pH=2), the copolyester adopts a coiled structure as a result of hydrophobic interactions between the pendant adamantyl groups. Consequently, no network formation is observed as shown by a very low viscosity. As the pH increase, the viscosity of the medium increases and reaches a maximum at pH=5. At this pH, the copolyester expands because of electrostatic repulsions between the carboxylate pendant functions. Consequently, the adamantyl groups are accessible and can be encapsulated into the β‐cyclodextrin cavities resulting in a significant increase of the viscosity.
Synthesis and controlled photo‐ and biodegradabilities of poly[(hydroxybutyrate ‐Co‐hydroxyvalerate)‐G‐styrene]
Authors: Park Jin , Choi Won‐Moon , Ha Chang‐Sik , Kim Won‐Ho , Cho Won‐Jei
Published: March 2011

The graft copolymer, P(HBV‐g‐St), was synthesized by graft polymerization of styrene (St) onto poly(3‐hydroxybutyrate‐co‐3‐hydroxy valerate) [PHBV] under nitrogen atmosphere using benzoyl peroxide (BPO). The structure of poly[(hydroxybutyrate‐co‐hydroxyvalerate)‐g‐styrene] [P(HBV‐g‐St)] was identified by FT‐K, 1H‐NMR, and 13C‐NMR spectra. The effects of weight ratio of St to PHBV in feed, initiator concentration, reaction time and reaction temperature on the grafting ratio and grafting efficiency were investigated. The thermal decomposition temperature of P(HBV‐g‐St) was 273°C. The tensile strengths of P(HBV‐g‐St) before and after photo‐ or biodegradation were also measured. The photodegradability of P(HBV‐g‐St) was better than that of PHBV. The film surface of P(HBV‐g‐St) treated with Aspergillus nigger showed extensive grooves and pits as compared with the untreated P(HBV‐g‐St). It was found that the photo‐ and biodegradation rates of P(HBV‐g‐St) and tensile strength of P(HBV‐g‐St) can be “controlled” by changing the weight ratio of St to PHBV in feed.
Morphologies and enzymatic degradability of melt‐crystallized poly(3‐hydroxybutyric acid‐Co‐6‐hydroxyhexanoic acid)
Authors: Abe Hideki , Aoki Hiromichi , Doi Yoshiharu
Published: March 2011

The films of poly[(R)‐3‐hydroxybutyric acid‐co‐10mol% 6‐hydroxy‐hexanoic acid] (P[(R)‐3HB‐co‐6HH]) were prepared by melt‐crystallized method at various crystallization temperatures. The morphologies and properties of melt‐crystallized films were characterized by means of x‐ray diffraction, differential scanning calorimetry, optical microscopy, and scanning electron microscopy. All of the melt‐crystallized films showed the banded spherulite morphology. The enzymatic degradation of melt‐crystallized films was carried out at 37 °C in an aqueous solution (pH 7.4) of PHB depolymerase from Alcaligenes faecalis. The rate of enzymatic erosion was strongly dependent on the crystallinity of films, and the highest rate was as large as 2.15 mg·h−1·cm−2. After enzymatic degradation, the banded morphology of P[(R)‐3HB‐co‐6HH] spherulites was visible, suggesting that PHB depolymerase predominantly hydrolyzes polymer chains on the edges of crystalline lamellar stacks.
Synthesis and structures of cooligo(lactone) macromonomers
Authors: Gopp Udo , Sandner Barbara , Schöch Martin , Schlothauer Klaus , Pasch Harald , Ghahary Reza
Published: March 2011

Cooligo(lactone) macromonomers were prepared by cooligomerisation of (S,S)‐3,6‐dimethyl‐1,4‐dioxane‐2,5‐dione (L‐lactide), 1‐oxacyclohexane‐2‐one (δ‐valerolactone) or 1‐oxacycloheptane‐2‐one (ε‐caprolactone), initiated by 2,2‐bis[4‐(2‐hydroxy‐3‐methacryloyloxypropoxy)phenyl]‐propane (BisGMA). Two different reaction ways were used for the synthesis: parallel reaction and step reaction of lactones and L‐lactide. The macromonomers were characterised by differential scanning calorimetry (DSC), size exclusion chromatography (SEC), 1H‐ and 13C‐NMR spectroscopy and MALDI‐TOF mass spectrometry. Cooligo(lactone) macromonomers prepared by parallel and by step reaction show different molecular structures resulting in different properties. Their glass transition temperatures depend on the molar ratio of lactide and lactone as well as on the degree of oligomerisation. Macromonomers with high amounts of L‐lactide units are partially crystalline.
Thermal properties of polyurethanes derived from molasses before and after biodegradation
Authors: Hatakeyama Tatsuko , Tokashiki Tadaski , Hatakeyama Hyoe
Published: March 2011

Polyurethane (PU) foams derived from molasses were placed in soil for various periods from 3 to 12 months. Thermal properties of PU's before and after biodegradation were investigated by differential scanning calorimetry (DSC) and thermogravimetry (TG). Glass transition of PU's after 3 month's degradation was separated into two stages indicating that molecular chains of the original and decomposed portions move independently. Based on variation of glass transition temperature (Tg), heat capacity difference at Tg (δCp), thermal degradation temperature and mass loss, the degradation mechanism of PU was established.
Biodegradation of polycaprolactone in plant treatment active sludge
Authors: Rutkowska Maria , Dereszewska Alina , Jastrzȩbska Mariola , Janik Helena
Published: March 2011

The object of this study was the degradation of polycaprolactone films in a living composting environment with plant treatment active sludge. The incubation of polymer samples took place in the compost for a period up to 3 months. There are presented the characteristic parameters of plant treatment active sludge: temperature, pH, dry mass and activity of dehydrogenesis and their influence on degradation of polycaprolactone is discussed. The changes of weight, tensile strength, microhardness and morphology during experiment were tested. Enzymatic activity is resulted in surface erosion. Microscopical observations show deterioration of polycaprolactone surface. Hydrolysis (“bulk process”) is also contributed (onset of weight loss). The decreasing of weight and mechanical properties are observed after each period of incubation. The increase in the microhardness during first period of biodegradation can be directly proportional to the increase in crystallinity, because amorphous regions are degraded first what is confirmed by microscopical observation. The complete degradation of polycaprolactone in compost with plant treatment active sludge in living environment takes place after short period of time (3 month).
Ring‐opening polymerization of 1,4,8‐trioxaspiro‐[4.6]‐9‐undecanone: A route to novel molecular architectures for biodegradable aliphatic polyesters
Authors: Tian Dong , Dubois Philippe , Jérǒme Robert
Published: March 2011

The ring‐opening polymerization of 1,4,8‐trioxaspiro‐[4.6]‐9‐undecanone (TOSUO) initiated by aluminum isopropoxide, Al(OiPr)3, is typically “living” and allows random and block copolyesters of predictable molecular weight and composition to be prepared. Deacetalization of the polyester chains is complete, and reduction of the accordingly formed ketone groups into hydroxyl groups as well. No chain scission is observed when these two derivatization reactions are carried out. The potential of these novel functional aliphatic polyesters has been discussed as drug colloidal vectors and macroinitiators for the synthesis of biodegradable and biocompatible comb, graft and even hyperbranched polymers.
Acid‐catalyzed copolymerization of aspartic acid with ω‐amino acid. ‐Biodegradability and Ca2+ chelating ability of poly(aspartic acid ‐Co‐ ω‐amino acid)‐
Authors: Shibata Minako , Kusuno Atsushi , Kakuchi Toyoji , Nakato Takeshi , Yoshikawa Masako , Tomida Masayuki
Published: March 2011

The polycondensation of L‐aspartic acid (1) with various ω‐amino acids (2) using phosphoric acid catalyst produced poly(succinimide‐co‐ω‐amino acid)s (3), which was followed by alkali hydrolysis to poly(aspartic acid‐co‐ω‐amino acid) (4). The Ca2+ chelating abilities of 4 depended on the content of comonomer unit in the copolymer and on the kind of amino acids. For the copolymer using 11‐aminoundecanoic acid (2d) as a comonomer, the Ca2+ chelating ability was higher than that of poly(sodium acrylate). For poly(aspartic acid‐co‐6‐aminocaproic acid) (4c), there was a tendency to increase according to the increase of 6‐aminocaproic acid (2c) unit in the copolymer. The biodegradability of the copolymer in the case of 2c as a comonomer, evaluated by TOC measurement, was 63%, which was the highest degradability among the copolymers having different methylen length. The biodegradability of 4c decreased with increasing the 2c unit in 4c.
Polyesters of phosphoric acid: Synthesis and kinetics of hydrolysis
Authors: Penczek S. , Pretula J. , Kaluzynski K.
Published: March 2011

Three major methods have been elaborated in our laboratory for preparation of polymers with poly(alkylene phosphates) backbones: ring‐opening polymerization, poly‐condensation and transesterification, and polyaddition. The second method is based on the reaction of the commercially available compounds, namely dialkyl (or diaryl)‐H‐phosphonates and glycols. Reaction of the aliphatic H‐phosphonates with aliphatic glycols is a reversible process, whereas polycondensation of diphenyl H‐phosphonates with aliphatic and cycloaliphatic diols is practically irreversible. This latter method has recently been developed and is described in this paper.

Poly H‐phosphonates with M̄n up to 40–103 were prepared. Polymers are easily oxidized and quantitatively converted into the relatively stable poly(alkylene phosphates). Some physical properties of these polymers and kinetics of their hydrolysis is discussed.
Aromatic components in copolyesters: Model structures help to understand biodegradability
Authors: Rantze Elke , Kleeberg Ilona , Witt Uwe , Müller Rolf‐Joachim , Deckwer Wolf‐Dieter
Published: March 2011

Copolyesters build of aliphatic and aromatic components have been shown to be degraded by microorganisms in a certain range of composition. While aliphatic polyesters of diol and dicarbonic acid often are hydrolyzed e.g. by lipases, pure aromatic polyesters like polyethylene terephthalate are not biodegradable. To understand the degradation mechanism of complex aliphatic/aromatic copolymers, we performed degradation experiments with different enzymatic systems and also especially screened highly active microorganisms. Several polymers and monomeric esters representing distinct structure elements within the polymer‐chain have been synthesized. These model structures were investigated in terms to understand the correlation of the stereo selectivity of the tested enzymes and the biodegradability of the polymer structure.
Molecular design strategies for biomaterials that heal
Authors: Ratner Buddy D.
Published: March 2011

Biomaterials are widely used in medical devices with good success. However, the surface chemistries of our present generation of biomaterials are not specifically recognized by living organisms. Thus, biological reactions to biomaterials in use today are primarily influenced by non‐specific interactions occurring at their surfaces. This paper develops a hypothesis for the development of a future generation of biomaterials. A discussion of the meaning of biocompatibility is followed by a strategy for developing biomaterials that actively induce healing and reconstruction by turning on specific biologic pathways. Materials strategies for encouraging specific reactions and inhibiting non‐specific bioreaction are presented.
Water‐soluble biodegradable polymers: Synthetic or natural‐based raw materials?
Authors: Swift Graham
Published: March 2011

In this paper, we review some of the significant synthesis approaches that we and others have evaluated for producing commercially viable water‐soluble biodegradable polymers. The goals set for these polymers, cost/performance equivalent with current non‐biodegradable polymers and complete biodegradation or a high degree of certainty that they are free from potential adverse environmental impact, are realistic but very difficult to achieve. Hence, we believe that few new polymers are emerging or are likely to emerge in the near future because of the radical directional changes needed in the synthesis and environmental testing procedures for water‐soluble biodegradable polymers. We consider polymers with structures and compositions that mimic nature most likely to eventually be successful in the market place regardless of raw material origin, provided that cost/performance comparable with current commercial polymers can be achieved. Poly(aspartic acid), recently developed, may be considered as a prototype of things to come.
Ring‐opening polymerization of L‐lactide by means of different iron compounds
Authors: Södergård Anders , Stolt Mikael
Published: March 2011

L‐lactide was bulk‐polymerized in the presence of various commercially available iron compounds. The polymerization temperature was in the range of 140 and 230 °C, the monomer to initiator/catalyst ratio varied between 100 and 10 000, and the polymerization time between 30 minutes and 24 hours.

Iron oxides, iron chlorides and sulfuric iron compounds were low efficient and are not suitable for melt polymerization of lactide. The oxidation state was noticed not to affect the efficiency. Ferrocene required long polymerization times and a high concentration of the compound before a high molar mass polymer was received. Organic iron salts were also found to be efficient initiators/catalysts, except for the hydrated iron(III)citrate. Especially iron(II)acetate caused a rapid polymerization with a high conversion and molar mass.
The novel benzimidazole derivative, MPTB, induces cell apoptosis in human chondrosarcoma cells
Authors: Li Te‐Mao , Lin Tsang‐Yu , Hsu Sheng‐Feng , Wu Chi‐Ming , Su Yi‐Chang , Kao Shung‐Te , Chang Chih‐Shiang , Fong Yi‐Chin , Tang Chih‐Hsin
Published: March 2011

Chondrosarcoma is a malignant primary bone tumor that responds poorly to both chemotherapy and radiation therapy. This study is the first to investigate the anti‐cancer effects of the new benzimidazole derivative (5‐methyl‐2(pyridine‐3‐yl)‐1‐(3,4,5‐trimethoxybenzyl)benzimidazole; MPTB) in human chondrosarcoma cells. MPTB‐induced cell apoptosis in two human chondrosarcoma cell lines, JJ012 and SW1353 but not in primary chondrocytes. MPTB‐induced upregulation of Bax and Bak and dysfunction of mitochondria in chondrosarcoma. MPTB triggered endoplasmic reticulum (ER) stress, as indicated by changes in cytosol calcium levels, and increased glucose‐regulated protein (GRP) expression. MPTB also increased calpain expression. Transfection of cells with GRP78 or calpain siRNA reduced MPTB‐mediated cell apoptosis in JJ012 cells. Importantly, animal studies have revealed a dramatic 44% reduction in tumor volume after 21 d of treatment. This study demonstrates novel anti‐cancer activity of MPTB against human chondrosarcoma cells and in murine tumor models. Mol. Carcinog. ©2011 Wiley‐Liss, Inc.
Chemoprevention of lung carcinogenesis by the combination of aerosolized budesonide and oral pioglitazone in A/J mice
Authors: Fu Huijing , Zhang Jingjie , Pan Jing , Zhang Qi , Lu Yan , Wen Weidong , Lubet Ronald A. , Szabo Eva , Chen Ruth , Wang Yian , Chen Da‐Ren , You Ming
Published: March 2011

Budesonide, a synthetic glucocorticoid used for treating asthma, and pioglitazone, a synthetic peroxisome proliferator‐activated receptors γ ligand used for the treatment of diabetes, were evaluated for their combinational chemopreventive efficacy on mouse lung cancer using female A/J mice with benzo(a)pyrene used as the carcinogen. All chemopreventive treatments began 2‐wk post‐carcinogen treatment and continued daily for 20 wk. Budesonide was administered by the aerosol route using an improved aerosol delivery system. Pioglitazone was introduced by oral gavage. The characterization of drug distribution showed that budesonide introduced by aerosol delivery accumulated only in the lung. Budesonide alone reduced tumor load by 78% and pioglitazone alone reduced tumor load by 63%. By combining aerosolized budesonide with pioglitazone, the inhibition on tumor load was 90%. In vitro experiments using human cancer cells showed that budesonide and pioglitazone exhibited independent, additive inhibitory effects on cell growth. Our results provide evidence that aerosolized budesonide and oral pioglitazone could be a promising drug combination for lung cancer chemoprevention. © 2011 Wiley Periodicals, Inc.