bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthetic and natural polymers as drug carriers for tuberculosis treatment
Authors: Batyrbekov Erkesh O. , Iskakov Rinat , Zhubanov Bulat A. 
Published: March 2011

AbstractDrug forms based polymer carriers of prolong action were created for toxicologic effect of drug to be reduced in spite of long treatment of diseases. In present work a number of synthesis and natural polymers have been studied as carriers of antituberculous drugs for controlled delivery application. Following as drugs as isoniazid and ethionamide were incorporated into polymeric matrix (segmented polyurethanes, polyvinyl alcohol) and chemically bound with the polymer chain by covalent or electrostatic forces (aldehyde‐ and carboxymethylderivatives of polysaccharides). Biodegradation of polymeric systems and the release of drugs were studied by various physico‐chemical methods. It was shown that the drug release depends of method of the immobilization, type of the drug/polymer bonding, drug loading. The bacteriostatic activity of obtained systems was determined. The possibility of tuberculosis treatment was proved in experiments of animals.
Solid state interchain transesterification reactions in macromolecules
Authors: Economy J. , Schneggenburger L. A. 
Published: March 2011

AbstractInterchain transesterification reactions (ITR) play an important role in high temperature synthesis of most linear polyesters. For example, polyethylene terephthalate (PET) is prepared commercially by heating and distillation of ethylene glycol from a glycol capped oligomer of PET. In this paper, the potential importance of ITR to effect a much wider range of reactions and process is examined. For example, the ability to control the sequence distribution in linear copolyesters is described. In particular, it is shown that one can induce a random sequence distribution in copolyesters by ITR or, conversely, develop an ordered sequence from a random copolyester again by ITR. In one family of liquid crystalline copolyesters an unusual competition between ordering and a thermal Fries rearrangement is described. A whole new family of crosslinked copolyesters has been developed based on this knowledge of ITR. Solid state processing of cured copolyesters into finished articles by ITR has also been demonstrated. These crosslinked copolyesters can be depolymerized back to the starting oligomers by a reverse ITR, providing for the first time a recyclable thermosetting resin.
Synthesis of hyperbranched aromatic polyamides by direct polycondensation
Authors: Russoy Saverio , Boulares Alya , Mariani Alberto 
Published: March 2011

AbstractSome hyperbranched aromatic polyamides have been synthesized by direct polycondensation using the modified Higashi's method. Structures of the above polymers have been realized taking in proper account the analogies with amide group sequences of poly(p‐phenyleneterephthalamide) (PPDT) and poly(p‐benzamide) (PBA). Therefore, AB2‐ type monomers as well as suitable combinations of different bi‐ and trifunctional reactants (AA + B3) (e.g., p‐phenylenediamine + trimesic acid or other trifunctional acids) have been considered. For the latter systems, network formation has been minimized. In the present paper, our results on their direct polyamidation together with some preliminary characterization data on the resultant hyperbranched aramids are given.
Macrocyclic polymerization ‐ a new approach to molecular engineering
Authors: Kricheldorf Hans R. , Lee Soo‐Ran , Eggerstedt Sven , Hauser Karsten 
Published: March 2011

Abstract2,2‐Dibutyl‐2‐stanna‐1,3‐dioxacycloalkanes were used as cyclic initiators for the ring‐opening polymerization of various lactons. This method exclusively yielded series of macrocyclic polylactones without any competition with linear polymers. Under optimized reaction conditions these macrocyclic polymerizations obey the pattern of “living polymerizations”. The living chain ends allow the syntheses of macrocyclic blockcopolymers. The macrocyclic polylactones react with carboxylic acid chlorides by ring‐opening yielding telechelic oligo or polylactones. Furthermore, the tin containing macrocyclic polylactones can be used as difunctional “monomers” for polycondensations with dicarboxylic acid dichlorides.
The synthesis of mesogenic polymers provoked by molecular mobility. polysiloxanarylenes
Authors: Skorokhodov Serguei 
Published: March 2011

AbstractAn approach to the synthesis of potentially thermotropic liquid crystalline polymers based on parallel investigation of their molecular mobility was realized. The initial idea was provoked by the observation that there exists some correspondence of molecular mobility data and the ability of a polymer to form a liquid crystalline phase. Previously this phenomenon was demonstrated on the example of a series of thermotropic main chain polymers with flexible dimethylsiloxane spacers of variable length. The relation between the structure of the main chain and local molecular mobility of different fragments was investigated in a series of regular polysiloxane‐silarylenes containing rigid aromatic sequences. Molecular mobility was studied by dielectric spectroscopy in solution and in solid state. The structure of the main chain has been changed by variation of the repeated fragments' length, substituents and joint groups. The data of molecular mobility and their conformity with the chain structure were used for directed synthetic search of desired mesogenic polymers.
New aspects in chemistry and characterization of poly(ethylene oxide) hydrogels
Authors: Kazanskii Konstantin S. 
Published: March 2011

AbstractTo extend the variability of poly(ethylene oxide) (PEO) hydrogels in their swelling behaviour, ability to bind various subjects, and possible applications, some new synthetic approaches have been elaborated recently: (i) PEO networks with ionic and reactive groups were prepared by the reaction of P‐OH groups of poly(oligoethylene glycol phosphate)s with diepoxide. The swelling degree of these hydrogels is strongly affected by salts, what is typical of polyelectrolyte networks. The structure parameters of the network evaluated from the swelling data are discussed.(ii) A series of hydrogels with controlled structure was obtained by radical polymerization of methacrylate PEO macromonomers of various molecular weights and average functionality (0.99–1.85) in aqueous media. The networks prepared are characterized by means of elastic modulus and swelling pressure measurements as well as with the help of microparticles of liquid‐crystalline dispersion of DNA as probes highly sensitive to the network structure and state.
Structural influences on the properties of aromatic polyamidines
Authors: Böhme Frank , Kunert Christoph , Klinger Christian , Komber Hartmut 
Published: March 2011

AbstractPolyamidines with both nitrogens in the main chain (‐X‐NH‐CR=N‐) were obtained by polycondensation of diamines with different orthoesters. The thermal properties could be tailored by the choice of diamine and orthoester. Quantitative formation of a cyclic trimer could be observed when 2,6‐diamino‐pyridine was converted with triethyl orthoformate. 1H, 13C and 15N NMR spectroscopic investigations in solution and in solid state showed that the configuration of the amidine group was strongly dependent on the residue R. In polyformamidines, strong interactions caused by hydrogen bonds could be evidenced.
Novel branched blockcopolymers from poly(vinylpyridine) by chromium allyl compounds
Authors: Novakov Petar P. , Kuckling Dirk , Fedorova Ljubov , Adler P. Hans‐Juergen 
Published: March 2011

AbstractNovel branched blockcopolymers from polyvinylpyridine are formed by chromium allyl compounds. Our present work shows results for the homopolymerization of vinylpiridine (VP), dimethylacrylamide (DMAA), tert ‐ butylacrylate (t ‐ BA) as well as the graftcopolymerization of poly(vinylpyridine) (PVP), using tris (π ‐ allyl) chromium (TPC) as initiator. PVP activated by TPC was used for grafting with DMAA ‐ “grafting from”. On the other hand living PDMAA polymerized by TPC, was able to react with PVP chain ‐ “grafting onto”.
Acid‐catalyzed reactions in polyimide synthesis
Authors: Kuznetsov Alexander A. , Tsegelskaya Anna Yu. , Belov Michael Yu. , Berendyaev Vladimir I. , Lavrov Sergey V. , Semenova Galina K. , Izyumnikov Anatoly L. , Kozlova Nina V. , Kotov Boris V. 
Published: March 2011

AbstractMelts of aromatic carboxylic acids are found to be excellent reaction media for 1‐pot high molecular weight polyimide synthesis from diamines and tetracarboxylic acid dianhydrides. No reversible reaction of polyamic acids (PAA) formation was observed. The effect of the reactivity equalization was observed for low‐ and high reactive diamines in acid media. The intrinsic acid catalysis of the imidization reaction was shown to take place also in polycyclization of PAA in concentrated solutions in amic solvents. It is found that the dependence of relative imidization rate (% conv./min) vs. AA/N‐MP ratio for model low molecular and oligomeric amic acids (AA) in N‐MP at 140–150°C possesses a sharp maximum near the molar ratio 1:1, the imidization rate at the point of the maximum being an order of magnitude higher than that for diluted solutions. A scheme is proposed which includes the opportunity of two reaction channels to occur: A usual one (I) and a catalytic one (II). In diluted solutions and in solid phase experiments with easy evacuation of volatile products, the role of catalytic channel II is low. To the contrary, in high concentrated solutions or in solid phase experiments under the conditions exluding volatile products evacuation, the catalytic channel becomes the key one. It is proposed that the catalytic reaction proceeds via the common acid catalysis mechanism, the solvent and water playing the role of co‐catalysts, probably through the mechanism of ionic dissociation of AA or hydrogen‐ bound complex AA‐solvent. It is shown that the water released in the course of solid phase imidization of phtalamic acid at 140°C under the conditions where vaporization is impossible causes a sharp autocatalytic effect after initial 20%‐conversion period to obtain entirely imidizied product.
Controlled polymerization of cyclic esters. structure of initiators and of active species related to the selectivity of initiation and propagation
Authors: Penczek Stanislaw , Duda Andrzej , Libiszowski Jan 
Published: March 2011

AbstractThis paper reviews mostly the already published work of our own, complemented with some new data and related to the control (i.e. selectivity) in the anionic and covalent (pseudoanionic) polymerization of cyclic esters. Ionic and covalent growing species are briefly compared in terms of their susceptibility to undergo side reactions. Then, structures of covalent initiators (mostly multivalent metal alkoxides) are discussed from the view point of their behavior in initiation and formation of active species. R2AlOR', (RO)3Al, and other metal alkoxides are discussed.
Chemical modification of polymeric hydrocarbons
Authors: Braun Dietrich , Hellmann Goetz P. 
Published: March 2011

AbstractAlthough polymeric hydrocarbons (PCH) carry no functions, they can be modified in many ways. Unsaturated PCH undergo addition reactions as hydrogenation, halogenation, epoxidation and thiol addition. Saturated PCH can be substituted with various functions, notably halogen and chlorosulfonyl groups. All PCH can be modified, by a grafting mechanism, with functional monomers as maleic anhydride. Some modified PCH play a major role in multiphase systems as blends, rubber‐modified thermoplastics and thermoplastic elastomers. Attractive grafting procedures involve in‐situ grafting in PCH/monomer solutions and during reactive blending processes.
Challenges in polypropylene by chemical modification
Authors: Rätzsch Manfred , Bucka Hartmut , Hesse Achim , Reichelt Norbert , Borsig E. 
Published: March 2011

AbstractRadical reactions of i‐PP are a well known technical process for the chemical degradation to increase the flowability of the i‐PP melt. By decreasing the temperature and increasing the life time of the PP‐radicals, a process to synthesize long chain branched i‐PP, was developed. The long chain branched‐i‐PP allows to introduce the i‐PP in processing technologies as blow moulding film technology or foaming technology. The mechanism will be discussed.The radical grafting of Polypropylene (PP) becomes more important for the developing of PP‐alloys with extended properties. Methylmethacrylate and styrene were polymerized and grafted in PP at low temperatures in solid state. Grafting and polymerizing in solid state means solving the monomers in the PP‐powder directly from the reactor without contacting with oxygen (air). The reaction is started by the thermal decomposition of a peroxide. The reactivity of the primary radicals from the peroxide and the transfer reactions of the polymer radical of the PMMA or PS influences the amount of the grafted polymer. The solubility of the monomers and the peroxide in the amorphous i‐PP‐phase was measured. The grafting yield and the dispersity of the second polymer depends on the solubility and dispersity of peroxide and monomers in the PP‐powder particles.
Modification of propylene‐ethylene copolymers by reactive extrusion
Authors: Dionisi Rodolfo A. , Failla Marcelo D. , Villar Marcelo A. , Quinzani Lidia M. , Vallés Enrique M. 
Published: March 2011

AbstractThe rheological properties of commercial propylene‐ethylene copolymers were modified by reactive extrusion. A dialkyl peroxide was used as initiator of the controlled degradation reaction of the starting polymers. The experiments were carried out in a twin screw extruder at different peroxide concentrations, temperatures, and screw speeds. Gel permeation chromatography was used to estimate the molecular weight distribution of the original and modified copolymers. It has been observed that the estimated molecular weight of the copolymers tends to decrease with the increase in peroxide concentration at all extrusion conditions studied. The linear viscoelastic properties of all the polymers were evaluated at different temperatures and frequencies in a rotational rheometer. Both the viscous and the elastic properties decrease with augmenting peroxide concentration. The Theological behavior of the materials is strongly affected by the global ethylene content of the copolymers. The scanning electron microscopy study did not reveal a significant difference between the morphology of the unmodified and the modified blends for a given composition of the original copolymers. In all the cases the microstructure is composed of a finely dispersed phase of ethylene‐propylene copolymer within a continuous polypropylene phase.
The effect of crosslinking on mechanical properties of ldpe filled with organic fillers
Authors: Chodak Ivan , Nogellova Zuzana , Kokta Bohuslav V. 
Published: March 2011

AbstractMechanical properties of low density polyethylene filled with various organic fillers were investigated. Different effect of different fillers on the properties was observed and the effect of crosslinking of these materials is also different. Fine anisotropic fillers behave similarly as inorganic fillers. The effect of crosslinking is the highest for composites containing large particulate fillers like beech wood flour. The effects are discussed in terms of mechanical behaviour and crosslinking degree determined from extraction or equilibrium swelling data. A formation of covalent bonds between the filler surface and polymeric matrix is proposed as a result of crosslinking.
Behaviour of chlorosulfonated polyethylene under gamma irradiation
Authors: Ivan G. , Giurginca Maria , Zaharescu Traian 
Published: March 2011

AbstractThe behaviour of chlorosulfonated polyethylene on gamma irradiation was investigated over the range of total absorbed dose of 5 to 550 kGy. The structural modifications were followed by infrared spectroscopy and some main kinetic characteristics of the process were assessed. Determinations of gel content and evaluation of changes in sulphur and chlorine content were correlated with the evolved amounts of hydrochloric acid and with changes in unsaturation of polymers.
Synthetic resins as designable supports for metal‐based chemistry: The issue of their nanomorphology and molecular accessibility
Authors: Corain Benedetto , D'Archivio Angelo A. , Galantini Luciano , Lora Silvano , Panatta Alberto , Tettamanti Enzo 
Published: March 2011

AbstractMacromolecular cross‐linked ligands containing pyridyl pendant groups are characterized by a combination of inverse steric exclusion chromatography, ESR and NMR spectrometries in water and methanol. On the basis of the relevant results, methanol is seen to be clearly the best swelling agent and it is chosen as medium for CuII coordination.
Metal ion effects in ionic copolymers
Authors: Eisenberg Adi , Bartels Carl 
Published: March 2011

AbstractThis paper presents a discussion of four areas in which the interaction between organic polymers and metal species is of importance. The first section discusses the effect of metal ions in random ionomers in bulk, where the presence of ions strongly influence the mechanical properties. The next topic covers the influence of metal ions on aqueous solutions of block copolymers, and describes the morphogenic effects seen in such systems. The third section deals with the use of metal ions in non‐aqueous solutions of block copolymers leading to the formation of microreactors with a high degree of size control. Finally, the attachment of organometallic species to the corona of block copolymer micelles in non‐aqueous solution is discussed in terms of the effect of the metal on the micelle dimensions.
Macrocyclic metal complexes as ladder polymers
Authors: Hanack Michael , Stihler Patrick 
Published: March 2011

AbstractMacrocyclic bis‐dienes and diendienophile were prepared in Diels‐Alder reactions starting from the bis‐dienophilic (hemiporphyrazinato)nickel complex 1. Compound 1 was reacted either with the tetraene 2 or with tetra‐phenylcyclopentadienone (4). By combination of macrocyclic bis‐dienes and bis‐dienophiles, ladder‐type oligomers (e.g. 9 or 10) were synthesized. The described oligomers are precursors for the corresponding conjugated oligomers, which are of interest as organic conductors. The preparation of the corresponding phthalocyanine compounds e.g. 13–16 and a method for obtaining the wanted “D2h” phthalocyanine 19 without using tedious methods are reported.
Unique behaviors of polymers having metalloporphyrin as their side chains
Authors: Kamachi Mikiharu 
Published: March 2011

AbstractSeveral kinds of polymers having tetraphenylporphyrin (TPP) or some metallotetraphenylporphyrin (AgTPP, CuTPP, VOTPP or ZnTPP) moieties as their side chains have been prepared by the radical polymerization of the corresponding vinyl monomers. Visible spectra of these polymers show the clear hypochromism in the Soret bands of the tetraphenylporphyrin moieties as compared with those of the corresponding monomers. Polymer effects were clearly observed in the magnetic behaviors and the oxygen adsorption of paramagnetic metalloporphyrin moieties. In addition, polymer effects on photophysical and photochemical behaviors of ZnTPP were found in the amphiphilic polymers covalently tethered with small amounts of ZnTPP and hydrophobic substituents above a critical content, which form hydrophobic domains due to aggregation of the hydrophobic groups in aqueous solution.
Metal‐catalyzed organosulfur cathodes for rechargeable lithium batteries
Authors: Oyama Noboru , Pope John M. , Tatsuma Tetsu , Hatozaki Osamu , Matsumoto Futoshi , Chi Qijin , Paulson Scott C. , Iwaku Masahiro 
Published: March 2011

AbstractExtensive studies were carried out to apply composite materials composed of polyaniline (PAn) and 2,5‐dimercapto‐1,3,4‐thiadiazole (DMcT) to develop cathode materials which exhibit high energy densities. Previous results have established that composites of PAn and DMcT which are coated onto copper substrates exhibit greatly enhanced charge and discharge performance. It is shown that composite materials composed of DMcT, PAn, and Cu ion have the ability to be reversibly charged and discharged at ca. 260 A h per kg‐cathode (ca. 830 W h per kg‐cathode) for more than 80 cycles. These two results are explored in general in this contribution via investigation of the electron transfer reactions between the components using UV/Vis and investigation of the copper substrate/DMcT chemistry using electrochemical quartz crystal microbalance and phase modulated interferometric microscopy.
Enhanced carrier‐transfer in multi‐layered organic thin film: Application to electrochromism and electroluminescence
Authors: Toshima Naoki , Tominaga Tsuyoshi 
Published: March 2011

AbstractMulti‐layered organic thin films were prepared by stepwise vapor deposition of planar molecules with delocalized π‐electrons on indium tin oxide (ITO) glass or KCl crystalline surface. The order of the deposition of π‐planar molecules with different redox potential can control enhancement or inhibition of the hole or electron transfer according to the concept of “sequential potential field”, or a potential cascade by the organization of redox components. This concept is here applied to electrochromic or electroluminescent devices composed of multi‐layered organic thin films.
An overview on the development of macromolecule‐metal complexes and brief sketch on their recent trends
Authors: Tsuchida Eishun 
Published: March 2011

AbstractIn early 1970s, there was growing tendency that the macromolecule‐metal complexes should have been understood as a molecular science among many international scientists. Y. Y. Jiang, Academia Scinica, firstly proposed an international symposium on this field and the first congress (MMC‐1) was held in 1985. From the 4th one, this series has been under the auspices of IUPAC and we have reached MMC‐7. The current interests in this field are, for example, photoinduced electron transfer, outer‐sphere process, chemical reactions in subnano‐geometrical space, multi‐electron transfer reaction. They are all linked to the high performances of advanced materials. The role of macromolecules in macromolecule‐metal complexes are summarized and recent topics of this area are described.
Development and some aspects of the present situation of macromolecule‐metal complexes
Authors: Wöhrle Dieter , Suvorova Olga 
Published: March 2011

AbstractMacromolecule metal complexes (MMCs) — the combination between a macromolecule, a metal chelate/complex/ion or cluster — are dominating factors for different functions in living systems, and are becoming more and more important in different sciences and applications as artifical synthesized systems.
Tandem transition metal catalyzed isomerization and cationic polymerization
Authors: Crivello James V. , Rajaraman Surésh K. 
Published: March 2011

AbstractA wide variety of mono‐, di‐ and multifunctional allyl ethers and related compounds are readily polymerized using a newly discovered polymerization reaction which has been termed: a transition metal‐catalyzed tandem isomerization and cationic polymerization. Employing dicobalt octacarbonyl in combination with organosilanes, the polymerization of these monomers takes place rapidly to give high molecular weight polymers.