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Polymeric Chains (polymeric + chain)
Selected AbstractsCharacterization of "Cd10S4(SPh)12", the Thermal Decomposition Product of (NMe4)4[Cd10S4(SPh)16]: Synthesis of a Neutral Cd54 Sulfide Cluster and of a Polymeric Chain of Thiolate-Bridged Cd17 Sulfide ClustersEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 21 2010Maria Bendova Abstract Contrary to claims in the literature that a cluster of the composition of "Cd10S4(SPh)12" was formed by thermal treatment of (NMe4)4[Cd10S4(SPh)16], experimental evidence was gathered that the core structure of the cluster is not exclusively retained and other CdS species are also formed. When "Cd10S4(SPh)12" was treated with PhSH/NEt3 only a part of the material was converted into (NHEt3)4[Cd10S4(SPh)16]. From solutions of "Cd10S4(SPh)12" in strongly coordinating solvents the new neutral CdS clusters Cd54S28(SPh)52Lx (L = pyridine, DMSO or DMF) and [Cd17S4(SPh)26py], were crystallized. The latter forms polymeric chains of phenylthiolate-bridged Cd17 units. [source] ChemInform Abstract: A New Polymeric Chain Constructed from Isopolyanions and Lanthanide Cations: Synthesis, Crystal Structure, and Properties of (NH4)5 [Ln(NO3)2(H2O)3] [H2W12O40]×nH2O (Ln: Ce, Pr, Nd, Gd, Dy, Ho).CHEMINFORM, Issue 46 2008Dongmei Shi Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] From 1D Polymeric Chain to Two-fold Parallel Interpenetration of (4,4) Net: Synthesis and Characterization of Two New Copper(II) Complexes Derived from Highly Polydentate Aminopolycarboxylate LigandCHINESE JOURNAL OF CHEMISTRY, Issue 7 2008Ya-Pan WU Abstract Two new copper(II) polymers, {[Cu2(egta)(bpe)(H2O)2]·H2O}n (1) and {[Cu2(egta)(bipy)(H2O)2]·5H2O}n(2), [H4egta=3,12-bis(carboxymethyl)-6,9-dioxa-3,12-diazatetradecanedioic acid, bpe=1,2-bis(4-pyridyl)ethane, bipy4,4,-bipyridyl] have been synthesized and structurally characterized by single-crystal X-ray diffraction, elemental analysis, IR spectra and TG analysis. The structure determination reveals that both 1 and 2 crystallize in a monoclinic system, space group P21/c. Complex 1 exhibits a two-fold parallel interpenetration of (4,4) net framework consisting of 1D zigzag chains interlocked together through hydrogen bonding interaction. However, the meso-helix chains of 2 are packed to form 2D supramolecular structures. Interestingly, in 2, the host frameworks encapsulate a unique pentamer water cluster and are further connected into 1D tapes by water-water hydrogen bonding interaction. Magnetic measurements reveal that there is a weak ferromagnetic interaction between the adjacent Cu(II) ions in 1. [source] New Type of Polymeric Chain Constructed by Exo-bidentate Binaphthol DerivativeCHINESE JOURNAL OF CHEMISTRY, Issue 10 2005Ya-Qiong Gong Abstract The self-assembly of a racemic exo-bidentate ligand 2,2,-bis(4-pyridylmethyloxy)-1,1,-binaphthyl, namely Rac -L, with cadmium(II) salt gave rise to a new one-dimensional polymer, which has been characterized by single crystal X-ray diffraction analysis. The polymer crystallizes in a triclinic space group P -1 with unit cell parameters: a=0.6976(1) nm, b=1.30160(14) nm, c=1.71146(17) nm,,=105.141(3) °,,=94.263(5)°,,=100.405(4)°, V=1.4633(2) nm3, Z=2, C32H29CdCl2N2O4.5, M=696.88, Dc=1.584 g/cm3, F(000) =708, ,(Mo K,) =0.972 mm,1. The final R and wR are 0.0498 and 0.1282 for 5079 observed reflections with I,,(I). [source] Structural Diversity in Organotin Compounds Derived from Bulky Monoaryl Phosphates: Dimeric, Tetrameric, and Polymeric Tin Phosphate ComplexesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2008Ramaswamy Murugavel Abstract Monoaryl phosphates with a bulky aryl substituent have been used to synthesize new organotin clusters and polymers. The equimolar reaction between 2,6-diisopropylphenylphosphate (dipp-H2) and Me2SnCl2 in ethanol at 25 °C leads to the formation of [Me2Sn(,3 -dipp)]n (1), while the reaction of 2,6-dimethylphenylphosphate (dmpp-H2) with Me2SnCl2 in either a 1:1 or 2:1 molar ratio proceeds to produce exclusively [Me2Sn(,-dmpp-H)2]n·nH2O (2). Compounds 1 and 2 are 1D polymers with different architectures. In compound 1, the tin atom is five-coordinate (trigonal bipyramidal). Each dipp ligand bridges three different tin atoms to form an infinite ladder-chain structure. In 2, each six-coordinate (octahedral) tin atom is surrounded by four phosphate oxygen atoms originating from four different bridging dmpp-H ligands, thus forming a spirocyclic coordination polymeric chain. The use of nBu2SnO as the diorganotin source in its reaction with dipp-H2 leads to the isolation of dimeric [nBu2Sn(,-dipp-H)(dipp-H)]2 (4), which contains a central Sn2O4P2 unit. There are two chemically different half molecules of 4 in the asymmetric part of the unit cell and hence it actually exists as a 1:1 mixture of [nBu2Sn(,-dipp-H)(dipp-H)]2 and [nBu2Sn(,-dipp)(dipp-H2)]2 in the solid state. The reaction of the monoorgano tin precursor nBuSn(O)(OH)·xH2O with dipp-H2 takes place in acetone at room temperature to yield the tetrameric cluster 5, which has different structures in the solution and in the solid state. 31P NMR spectroscopy clearly suggests that 5 has the formula [nBu4Sn4(,-O)2(,-dipp-H)8] in solution. The single-crystal X-ray diffraction studies in the solid state, however, reveal that compound 5 exists as [nBu4Sn4(,-OH)2(,-dipp-H)6(,-dipp)2]. The use of compounds 1,4 as possible precursors for the preparation of ceramic tin phosphate materials has been investigated. The thermolysis of 1 at 500 °C leads to the formation of quantitative amounts of Sn2P2O7, while the thermolysis of 2, 3, and 4 under similar conditions results in the formation of SnP2O7. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] XAS, ESR and Potentiometric Studies of Three Dinuclear N,N, -para -Xylylenebis(tetraazamacrocycle)copper(II) Complexes , X-ray Crystal Structure of [N,N,- p -Xylylenebis(cyclen)]copper(II)EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 10 2003Mathieu Soibinet Abstract Dicopper complexes with N,N, - p -xylylenebis(cyclam or cyclen) and with the heteroditopic N,N, - p -xylylenebis(cyclam-cyclen) were synthesized. An X-ray study of the N,N, - p -xylylenebis(cyclen)dicopper complex showed that the copper(II) ion is five-coordinate with an H2O molecule in apical position. With this ligand, a polymeric chain was also obtained in the presence of KSCN. The terminal donor atoms of the bridging NCS, anion are coordinated in apical position to the square-pyramidal copper(II) ion. Two alternating kinds of Cu2L4+ moieties are present in the chain, the first with two N4S chromophores and the second with two N5 chromophores. EXAFS and XANES results are in agreement with a five-coordinate copper ion in the cyclen unit and a six-coordinate copper ion in the cyclam unit. Thermodynamic constants were determined by potentiometry. The existence of dinuclear Cu2L4+ species (ligand/metal ratio < 1) and mononuclear CuLHn(2+n)+ species (ligand/metal ratio > 1) were confirmed by an ESR study at variable pH. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Red-Emitting Polyfluorenes Grafted with Quinoline-Based Iridium Complex: "Simple Polymeric Chain, Unexpected High Efficiency"ADVANCED FUNCTIONAL MATERIALS, Issue 1 2010Zhihua Ma Abstract A series of red-light emitting electrophosphorescent polyfluorenes (PFs) with varying content of a quinoline-based iridium complex, (PPQ)2Ir(acac) (bis(2,4-diphenylquinolyl-N,C2,) iridium(acetylacetonate)), in the side chain are synthesized by Suzuki polycondensation. Because of the efficient Förster energy transfer from the PF main chain to (PPQ)2Ir(acac) and direct charge trapping on the complex, the electroluminescent emission from PF is nearly completely quenched, even though the amount of iridium complex incorporated into the polymers is as low as 1,mol %. Based on a single-layer device configuration, a luminous efficiency of up to 5.0,cd A,1 with a luminance of 2000,cd m,2 and Commission Internationale de L'Eclairage coordinates of (0.63, 0.35) (x, y) is realized, which is far superior to that of previously reported red-light emitting PFs containing benzothiazole- and isoquinoline-based iridium complexes. This result is beyond expectations, especially when considering that the simple polymeric chain involved has no additional charge-transporting moieties. Noticeably, the device efficiency remains as high as 4.2,cd A,1 with a luminance of 4000,cd m,2 even at current densities of 100,mA cm,2. Further optimization of the device configuration by incorporating an additional electron-injection layer leads to improved efficiencies of 8.3 and 7.5,cd A,1 at luminances of 100 and 1000,cd m,2, respectively. This state-of-the-art performance indicates that covalently attaching quinoline-based iridium complexes to a PF backbone is a simple and effective strategy to develop high-efficiency red-light emitting electrophosphorescent polymers. [source] Syntheses and crystal structures of triorganotin (IV) derivatives with 2,2,-bipyridine-4,4,-dicarboxylic acidHETEROATOM CHEMISTRY, Issue 1 2009Ru-Fen Zhang Four organotin complexes with 2,2,-bipyridine-4,4,-dicarboxylic acid, H2dcbp: (Ph3n)2(dcbp) 1, [(PhCH2)3n]2(dcbp) , 2CH3OH 2, [(Me3Sn)2(dcbp)]n3, [(Bu3Sn)2(dcbp)]n4 have been synthesized. The complexes 1,4 were characterized by elemental, IR, 1H, 13C, 119n NMR, and X-ray crystallographic analyses. Crystal structures show that complex 1 is a monomer with one ligand coordinated to two triorganotin moieties, and a 1D infinite polymeric chain generates via intermolecular CH,,,N hydrogen bond; complex 2 is also a monomer and forms a 2D network by intermolecular O,H,,,O weak interaction; both of complexes 3 and 4 form 2D network structures where 2,2,-bipyridine-4,4,-dicarboxylate acts as a tetradentate ligand coordinated to trimethyltin and tri-n-butyltin ions, respectively. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:19,28, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20506 [source] Self-assembly of supramolecular polymers into tunable helical structuresJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 6 2008Ho-Joong Kim Abstract There is growing interest in the design of synthetic molecules that are able to self-assemble into a polymeric chain with compact helical conformations, which is analogous to the folded state of natural proteins. Herein, we highlight supramolecular approach to the formation of helical architectures and their conformational changes driven by external stimuli. Helical organization in synthetic self-assembling systems can be achieved by the various types of noncovalent interactions, which include hydrogen bonding, solvophobic effects, and metal-ligand interactions. Since the external environment can have a large influence on the strength and configuration of noncovalent interactions between the individual components, stimulus-induced alterations in the intramolecular noncovalent interactions can result in dynamic conformational change of the supramolecular helical structure thus, driving significant changes in the properties of the materials. Therefore, these supramolecular helices hold great promise as stimuli-responsive materials. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1925,1935, 2008 [source] Long-range effects of chirality in aromatic poly(isocyanide)sJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 10 2006David B. Amabilino Abstract The preparation of optically active atropoisomeric polymers which present chiral backbones, thanks to induction during their synthesis from stereogenic centers, located far away from the skeleton is possible, thanks principally to semirigid conformations of the promesogenic spacers between them. The result is that chiral "information" can be passed as far as 21 Å from the asymmetric center to the carbon atom that forms the polymeric chain in poly(isocyanide)s. The sense of chiral induction in these conformationally rigid polymers parallels the helical sense of the cholesteric phases, as well as to the helical senses of chiral smectic C phases, induced by the monomers in nematic and smectic C phases, respectively. All these phenomena obey the odd,even rules proposed for chiral sense changes in these liquid crystalline phases. Noncovalent interactions play an important part in the induction process, in which steric arguments can be used to justify the inductions observed. The methodology can be used to prepare macromolecules, which display switching behavior upon thermal or electrochemical stimulus. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3161,3174, 2006 [source] Water-Soluble Polymeric Thioxanthone Photoinitiator Containing Glucamine as CoinitiatorMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 15 2008Xuesong Jiang Abstract A novel kind of water-soluble polymeric photoinitiator was synthesized by introducing thioxanthone moieties and glucamine into the polymeric chain, as well as low-molecular weight model compounds. The photochemical and photophysical properties of these photoinitiators were studied. PTX-GA possesses a similar UV-vis absorption, weaker fluorescence emission and a shorter lifetime of the TX triplet state (,) as compared to TX-MGA and TX-PMAC/MDEA. ESR showed that in TX-PMAC/MDEA the smallest number of radicals is generated. Photopolymerization of arylamide and methylene bisacryamide initiated by these photoinitiators shows that PTX-GA is more effective than TX-MGA and TX-PMAC/MDEA. [source] A synchrotron radiation study of the one-dimensional complex of sodium with (1S)- N -carboxylato-1-(9-deazaadenin-9-yl)-1,4-dideoxy-1,4-imino- d -ribitol, a member of the 'immucillin' familyACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2010Graeme J. Gainsford The sodium salt of [immucillin-A,CO2H], (Imm-A), namely catena -poly[[[triaquadisodium(I)](,-aqua)[,-(1S)- N -carboxylato-1-(9-deazaadenin-9-yl)-1,4-dideoxy-1,4-imino- d -ribitol][triaquadisodium(I)][,-(1S)- N -carboxylato-1-(9-deazaadenin-9-yl)-1,4-dideoxy-1,4-imino- d -ribitol]] tetrahydrate], {[Na2(C12H13N4O6)2(H2O)7]·4H2O}n, (I), forms a polymeric chain via Na+,O interactions involving the carboxylate and keto O atoms of two independent Imm-A molecules. Extensive N,O,H...O hydrogen bonding utilizing all water H atoms, including four waters of crystallization, provides crystal packing. The structural definition of this novel compound was made possible through the use of synchrotron radiation utilizing a minute fragment (volume ,2.4 × 10,5,mm,3) on a beamline optimized for protein data collection. A summary of intra-ring conformations for immucillin structures indicates considerable flexibility while retaining similar intra-ring orientations. [source] Synthesis, structure and biological activity of triorganotin 1H -tetrazolyl-1-acetates: cyclic hexamer and linkage coordination polymersAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 1 2010Yun-Fu Xie Abstract Reaction of 1H -tetrazolyl-1-acetic acid (CHN4CH2CO2H) with (R3Sn)2O or R3SnOH yields triorganotin 1H -tetrazolyl-1-acetates [CHN4CH2CO2SnR3, R = Ph (1), p -tolyl (2), cyclohexyl (3), n -Bu (4) and Et (5)]. 1H -tetrazolyl-1-acetates in these triorganotin derivatives display remarkably different coordination modes, depending on the properties of the organic substituents bonded to the tin atoms. Complex 1 displays a rare cyclohexameric structure by the assembly of the SnN coordination bond, while complex 2 forms a linkage coordination polymer through the intermolecular Sn···N interactions. The structure of complex 3 is similar to that of complex 2, but the intermolecular Sn···N interactions are weaker in the former. However, in complex 4, the tetrazolyl nitrogen atoms do not coordinate to the tin atoms. This complex forms a polymeric chain by the unsymmetric bridging carboxylate group. All these complexes exhibit good antifungal activities in vitro against Alternaria solani, Cercospora arachidicola, Gibberella zeae, Physalospora piricola and Botrytis cinerea. The corresponding EC50 values of these complexes were tested. Copyright © 2009 John Wiley & Sons, Ltd. [source] catena -Poly[[silver(I)-,-hexane-1,6-diamine-,2N:N,] cinnamate dihydrate]ACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2004Zhong-Lu You The title compound, {[Ag(C6H16N2)](C9H7O2)·2H2O}n, has been synthesized and characterized by elemental analysis and single-crystal X-ray diffraction. The Ag atom is coordinated in a linear configuration by two N atoms from two hexane-1,6-diamine ligands, giving a zigzag polymeric chain with an [,Ag,N,C,C,C,C,C,C,N,]n backbone running parallel to the c axis. In the crystal packing, adjacent chains interact with the anions via the lattice water molecules, thus forming layers parallel to the bc plane. [source] Redox Active Two-Component Films of Palladium and Covalently Linked Zinc Porphyrin,Fullerene DyadELECTROANALYSIS, Issue 9 2006Marta Plonska Abstract Redox active films have been generated electrochemically by the reduction of dyads consisting of fullerene C60 covalently linked to zinc meso -tetraphenyloporphyrin, ZnPC60, and palladium acetate. The films are believed to consist of a polymeric network formed via covalent bonds between the palladium atoms and the fullerene moieties. In these films, the zinc porphyrin moiety is covalently linked to the polymeric chains through the pyrrolidine ring of the fullerene. The ZnPC60/Pt films are electrochemically active in both positive and negative potential excursions. At positive potentials, two oxidation steps for the zinc porphyrin are observed. In the negative potential range, electron transfer processes involving the zinc porphyrin and the fullerene entities are observed. Film formation is also accompanied by palladium deposition on the electrode surface. The presence of a metallic phase in the film influences its morphology, structure and electrochemical properties. [source] A CuIINiII Complex with Ethylenediamine: Crystal Structure and Ferromagnetic Behaviour of an Aqua-Bridged Heterometallic Chain Containing Ambidentate Ni(OAc)42, BlocksEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 22 2010Oksana V. Nesterova Abstract A one-pot reaction of copper powder and nickel and ammonium acetates in a CH3OH solution of ethylenediamine (en) yields a unique 1D aqua-bridged polymer [Cu(en)2(,2 -H2O)2Ni(OAc)4]n·4nH2O (1) with an ambidentate Ni(OAc)42, fragment that has not been previously characterized. The basic structural motif of 1 contains a previously unreported heterometallic M(,2 -H2O)M, aqua-bridge chain with alternating metal atoms. A complex system of N/O,H···O hydrogen bonds strengthens the polymeric chains and links them into a supramolecular three-dimensional network. Variable-temperature magnetic susceptibility measurements of 1 revealed a weak ferromagnetic coupling (J = 1.1 cm,1) between the paramagnetic copper(II) and nickel(II) ions, which is transmitted through the oxygen bridges. [source] Dye-Doped Polyhedral Oligomeric Silsesquioxane (POSS)-Modified Polymeric Matrices for Highly Efficient and Photostable Solid-State LasersADVANCED FUNCTIONAL MATERIALS, Issue 20 2009Roberto Sastre Abstract Here, the design, synthesis, and characterization of laser nanomaterials based on dye-doped methyl methacrylate (MMA) crosslinked with octa(propyl-methacrylate) polyhedral oligomeric silsesquioxane (8MMAPOSS) is reported in relation to their composition and structure. The influence of the silicon content on the laser action of the dye pyrromethene 567 (PM567) is analyzed in a systematic way by increasing the weight proportion of POSS from 1 to 50%. The influence of the inorganic network structure is studied by replacing the 8MMAPOSS comonomer by both the monofunctionalized heptaisobutyl-methacryl-POSS (1MMAPOSS), which defines the nanostructured linear network with the POSS cages appearing as pendant groups of the polymeric chains, and also by a new 8-hydrogenated POSS incorporated as additive to the polymeric matrices. The new materials exhibit enhanced thermal, optical, and mechanical properties with respect to the pure organic polymers. The organization of the molecular units in these nanomaterials is studied through a structural analysis by solid-state NMR. The domain size of the dispersed phase assures a homogeneous distribution of POSS into the polymer, thus, a continuous phase corresponding to the organic matrix incorporates these nanometer-sized POSS crosslinkers at a molecular level, in agreement with the transparency of the samples. The silicon,oxygen core framework has to be covalently bonded into the polymer backbone instead of being a simple additive and both the silica content and crosslinked degree exhibit a critical influence on the laser action. [source] Synthesis of biodegradable copolymers with low-toxicity zirconium compounds.JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2006Abstract The results of the copolymerization of glycolide with cyclic trimethylene carbonate and 2,2-dimethyltrimethylene carbonate are described. The copolymerization was conducted in the presence of low-toxicity zirconium(IV) acetylacetonate as an initiator. With this kind of initiator, the composition of the comonomer units in the copolymer chains was assumed to be obtained with high efficiency. Despite significant differences in the comonomer reactivity, in copolymers containing comparable amounts of glycolidyl and carbonate sequences, highly randomized chain structures were observed. This effect resulted from strong intermolecular transesterification that proceeded during the studied copolymerization and caused glycolidyl microblock randomization. The assignment of the spectral NMR lines to appropriate comonomer sequences of polymeric chains was performed in the region of methylene protons of glycolidyl units in 1H NMR spectra of the copolymers and in the carbonyl region of carbon spectra. The equations were formulated for a detailed characterization of the obtained copolymer chains, the average lengths of the blocks, and the transesterification and randomization coefficients. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 98,114, 2006 [source] Raman spectroscopy of conducting poly (methyl methacrylate)/polyaniline dodecylbenzenesulfonate blendsJOURNAL OF RAMAN SPECTROSCOPY, Issue 2 2010Abdul Shakoor Abstract Polyaniline soluble in organic solvents was prepared using dodecylbenzenesulphonic acid (DBSA) as functional dopant. The solubility parameter was calculated and the most suitable solvent chloroform was checked for the solubility and the most compatible polymer PMMA was selected for blending. Miscibility was maximized with 1% by weight of hydroquinone. Blending of doped polyaniline with dodecylbenzenesulphonic acid (PAni.DBSA) in poly (methyl methacrylate) (PMMA) was explained by a change in the conformation of the polymeric chains leading to an increase in the conductivity. The electrical conductivity increased as the weight percent of PAni.DBSA increased, showing a percolation threshold as low as 3.0% by weight and the highest conductivity was achieved at 20% by wt of PAni.DBSA. Scanning electron micrographs showed lowest level of phase separation. Raman spectroscopy is used to characterize the blending process of two polymers aiming to understand the transformations in different types of charged segments. Raman results give complementary data about the blending process showing that together with the structural change of the polymeric chains, there is also a chemical transformation of these polymers. Analysis of Raman spectra was done investigating the relative intensities of the bands at 574 cm,1 and 607 cm,1. A relationship between conductivity and Raman was also proposed. Copyright © 2009 John Wiley & Sons, Ltd. [source] Use of N -(N,-arylamino)maleimides to improve the thermal properties of poly(vinyl chloride) through chemical modification and graft copolymerizationJOURNAL OF VINYL & ADDITIVE TECHNOLOGY, Issue 4 2008Abir S. Abdel-Naby The reaction of poly(vinyl chloride) (PVC) with N -(N,-arylamino)maleimide derivatives was studied. The thermal stability of the modified polymer was improved markedly when compared with that of the unmodified polymer. The stability improvement was attributed to the replacement of the labile chlorine atoms by more stable organic groups. The modified polymer also showed a lower extent of discoloration when compared with that of unmodified PVC. In order to introduce a polymeric stabilizer into PVC, the dienophilic monomer was chemically grafted onto the polymeric chains. The mechanism of the chemical modification as well as that of the graft copolymerization are discussed. J. VINYL ADDIT. TECHNOL., 2008. © 2008 Society of Plastics Engineers. [source] Effects of ozone exposure on the structural, mechanical and barrier properties of select plastic packaging filmsPACKAGING TECHNOLOGY AND SCIENCE, Issue 6 2002Banu F. Ozen Abstract The effects of ozone (O3) gas exposure at various concentrations and treatment times on structural, mechanical and barrier properties of polyethylene and polyamide films were investigated. Changes in the structure of the films were monitored using an FT-IR spectrometer. The results showed that O3 treatment affected polyethylene and polyamide films differently. While O3 treatment caused formation of oxygen-containing functional groups and degradation of polymeric chains in polyethylene films, O3 treatment of polyamide films significantly increased the ,C,N, stretch observed at 1125,cm,1 in the FT-IR spectra. The changes in the mechanical properties of polyethylene films depended on the O3 treatment conditions (temperature and O3 concentration were the most significant), but an increase in tensile strength of polyamide films was observed regardless of the treatment conditions. Permeability to O2 for both types of films decreased with increasing O3 treatment time. Copyright © 2003 John Wiley & Sons, Ltd. [source] A review on interface modification and characterization of natural fiber reinforced plastic compositesPOLYMER ENGINEERING & SCIENCE, Issue 9 2001Jayamol George An Important aspect with respect to optimal mechanical performance of fiber reinforced composites in general and durability in particular is the optimization of the interfacial bond between fiber and polymer matrix. The quality of the fiber-matrix interface is significant for the application of natural fibers as reinforcement for plastics. Since the fibers and matrices are chemically different, strong adhesion at their interfaces is needed for an effective transfer of stress and bond distribution throughout an Interface. A good compatibilization between cellulose fibers and non-polar matrices is achieved from polymeric chains that will favor entanglements and interdiffiusion with the matrix. This article gives a critical review on the physical and chemical treatment methods that improve the fiber-matrix adhesion and their characterization methods. [source] Ultraviolet-induced crosslinking of poly(vinyl alcohol) evaluated by principal component analysis of FTIR spectraPOLYMER INTERNATIONAL, Issue 10 2001R Miranda, Teresa M Abstract The crosslinking of poly(vinyl alcohol) (PVA) films under ultraviolet irradiation for between 1 and 4,h was studied in air at 25,°C in the presence of sodium benzoate by Fourier-transform infrared spectroscopy (FTIR) using the attenuated total reflectance technique (ATR). Principal component analysis (PCA) is a mathematical procedure that allows treatment of the entire infrared spectrum and is very appropriate for analysing the chemical modifications initiated by sodium benzoate which occur in PVA upon UV irradiation. By PCA it was possible to clarify the mechanism of crosslinking of PVA. From this FTIR,PCA study, it is suggested that a free radical arising from the photolysis of sensitizer would abstract a tertiary hydrogen atom from the polymer chain to yield a polymeric radical. This radical reacts with OH groups, leading to the formation of ether bonds between the polymeric chains and hence to crosslinking and insolubilization of the PVA. © 2001 Society of Chemical Industry [source] Organic,inorganic hybrid membranes prepared from the sol,gel process of poly(butyleneadipate- co -terephthalate) and TiO2POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 8 2009Chien-Hong Lin Abstract Organic,inorganic hybrids based on poly(butyleneadipate- co -terephthalate)/titanium dioxide (PBAT/TiO2) hybrid membranes were prepared via a sol,gel process. The PBAT/TiO2 hybrid membranes were prepared for various PBAT/TiO2 ratios. The resulting hybrids were characterized with a morphological structure, hydrophilicity, biodegradability, and thermal properties. The results showed that macrovoids underwent a transition into a sponge-like membrane structure with the addition of TiO2. After sol,gel transition, a strong interaction between the inorganic network and polymeric chains led to an increase in glass transition temperature (Tg), thermal degrading temperature, and hydrophilicity, and hence a higher biodegradability. According to X-ray diffraction measurements of the crystal structure of the hybrid, the presence of TiO2 did not change the crystal structure of PBAT. TiO2 networks are uniformly dispersed into the PBAT matrix and no aggregation of TiO2 networks in the hybrid membranes was observed through the small angle X-ray scattering measurements. Thus, the sol,gel process of PBAT and TiO2 can be used to prepare a hybrid with higher application temperature and faster biodegradation rate. Copyright © 2008 John Wiley & Sons, Ltd. [source] Quasi-three-dimensional network of molecular interactions and electronic structure of a new organic semiconductor, ET(NCS)0.77ACTA CRYSTALLOGRAPHICA SECTION B, Issue 1 2002Olga N. Kazheva The radical cation salt ET(NCS)0.77 [bis(ethylenedithio)tetrathiafulvalene thiocyanate (1/0.77)] has been prepared for the first time by electrocrystallization and its crystal and electronic structure at 110,K was investigated. The unit-cell dimensions are orthorhombic, a = 6.638,(1), b = 8.309,(2), c = 28.776,(6),Å, V = 1587.1,(6),Å3, space group Pbcm, Z = 4. The compound has a layered structure. The ET radical cations of the conducting cationic layer build stacks. In the anionic layer the thiocyanate groups form polymeric chains where they are oriented in a `head-to-tail' mode. The structure has short intermolecular contacts of the cation,cation, anion,anion and cation,anion types, which leads to the formation of a three-dimensional structure of intermolecular interactions. This phenomenon is very rare in molecular conductors. Tight binding band structure calculations suggest, however, that the interlayer interactions through the anions are weak and that the incomplete occupation of the anion sites is the reason for the activated conductivity of the salt. [source] Copper(II) chloride and bromide complexes with 2-methyl-2H -tetrazol-5-amine: an X-ray powder diffraction studyACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2010Ludmila S. Ivashkevich The complex catena -poly[[dibromidocopper(II)]-bis(,-2-methyl-2H -tetrazol-5-amine)-,2N4:N5;,2N5:N4], [CuBr2(C2H5N5)2]n, (I), and the isotypic chloride complex catena -poly[[dichloridocopper(II)]-bis(,-2-methyl-2H -tetrazol-5-amine)-,2N4:N5;,2N5:N4], [CuCl2(C2H5N5)2]n, (II), were investigated by X-ray powder diffraction at room temperature. The crystal structure of (I) was solved by direct methods, while the Rietveld refinement of (II) started from the atomic coordinates of (I). In both structures, the Cu atoms lie on inversion centres, adopting a distorted octahedral coordination of two halogen atoms, two tetrazole N atoms and two 5-amine group N atoms. Rather long Cu,Namine bonds allow consideration of the amine group as semi-coordinated. The compounds are one-dimensional coordination polymers, formed as a result of 2-methyl-2H -tetrazol-5-amine ligands bridging via a tetrazole N atom and the amine N atom. In the polymeric chains, adjacent Cu atoms are connected by two such bridges. [source] Structures of 1-hydrophenanthroimidazoles: building blocks in the synthesis of expanded-ring bis(imidazoles)ACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2009Robert T. Stibrany The structures of 1H -phenanthro[9,10- d]imidazole, C15H10N2, (I), and 3,6-dibromo-1H -phenanthro[9,10- d]imidazole hemihydrate, C15H8Br2N2·0.5H2O, (II), contain hydrogen-bonded polymeric chains linked by columns of ,,, stacked essentially planar phenanthroimidazole monomers. In the structure of (I), the asymmetric unit consists of two independent molecules, denoted (Ia) and (Ib), of 1H -phenanthro[9,10- d]imidazole. Alternating molecules of (Ia) and (Ib), canted by 79.07,(3)°, form hydrogen-bonded zigzag polymer chains along the a -cell direction. The chains are linked by ,,, stacking of molecules of (Ia) and (Ib) along the b -cell direction. In the structure of (II), the asymmetric unit consists of two independent molecules of 3,6-dibromo-1H -phenanthro[9,10- d]imidazole, denoted (IIa) and (IIb), along with a molecule of water. Alternating molecules of (IIa), (IIb) and water form hydrogen-bonded polymer chains along the [110] direction. The donor,acceptor distances in these N(imine)...H,O(water)...H,N(amine) hydrogen bonds are the shortest thus far reported for imidazole amine and imine hydrogen-bond interactions with water. Centrosymmetrically related molecules of (IIa) and (IIb) alternate in columns along the a -cell direction and are canted by 48.27,(3)°. The present study provides the first examples of structurally characterized 1H -phenanthroimidazoles. [source] The coordination polymers poly[,-4,4,-bipyridyl-di-,-formato-copper(II)] and catena -poly[[[diaqua(1-benzofuran-2,3-dicarboxylato)copper(II)]-,-1,2-di-4-pyridylethane] dihydrate]ACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2009Rajesh Koner The title compounds, [Cu(CHO2)2(C10H8N2)]n, (I), and {[Cu(C10H4O5)(C12H12N2)(H2O)2]·2H2O}n, (II), are composed of one-dimensional linear coordination polymers involving copper(II) ions and bidentate bipyridyl species. In (I), the polymeric chains are located on twofold rotation axes at (x, x, 0) and are arranged in layered zones centered at z = 0, , ½ and parallel to the ab plane of the tetragonal crystal. Weak coordination of the formate anions of one layer to the copper centers of neighboring layers imparts a three-dimensional connectivity to this structure. In (II), the polymeric chains propagate parallel to the a axis of the crystal. Noncoordinated water molecules link the chains through O,H...O hydrogen bonding in directions perpendicular to c, imparting to the entire structure three-dimensional connectivity. The metal ions adopt distorted octahedral and square-based pyramidal environments in (I) and (II), respectively. This study indicates that, under the given conditions, extended coordination involves CuII centers associating with the bipyridyl ligands rather than with the competing benzofurandicarboxylate entities. [source] Influence of solvent on the structures of two one-dimensional cobalt(II) coordination polymers with tetrachloroterephthalateACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2009Yong-Qin Fang The title cobalt coordination polymers, catena -poly[[[aquatripyridinecobalt(II)]-,-tetrachloroterephthalato] pyridine solvate], {[Co(C8Cl4O4)(C5H5N)3(H2O)]·C5H5N}n, (I), and catena -poly[[[diaquadipyridinecobalt(II)]-,-tetrachloroterephthalato] 1,4-dioxane trihydrate], {[Co(C8Cl4O4)(C5H5N)2(H2O)2]·C4H8O2·3H2O}n, (II), have been prepared with tetrachloroterephthalic acid (H2BDC-Cl4) under different solvent media. Both complexes form infinite cobalt(II),tetrachloroterephthalate polymeric chains. In (I), two independent CoII ions are six-coordinated through N3O3 donor sets in slightly distorted octahedral geometries provided by two carboxylate and three pyridine ligands, and one water molecule. The structure of (II) contains two independent CoII atoms, each lying on a twofold axis, which adopt a tetragonally distorted N2O4 octahedral geometry via two carboxylate groups, two pyridine ligands and two water molecules. The different stoichiometry of coordinated and solvent guest molecules leads to different two-dimensional supramolecular networks, with (I) utilizing C,H..., and weak ,,, interactions and (II) utilizing mainly conventional hydrogen bonding. [source] Manganese(II) and cobalt(II) complexes of 1,4-bis(diphenylphosphinoyl)butaneACTA CRYSTALLOGRAPHICA SECTION C, Issue 1 2009Anthony M. J. Lees The title complexes, catena -poly[[[diaquadiethanolmanganese(II)]-,-1,4-bis(diphenylphosphinoyl)butane-,2O:O,] dinitrate 1,4-bis(diphenylphosphinoyl)butane solvate], {[Mn(C2H6O)2(C28H28O2P2)(H2O)2](NO3)2·C28H28O2P2}n, (I), and catena -poly[[[diaquadiethanolcobalt(II)]-,-1,4-bis(diphenylphosphinoyl)butane-,2O:O,] dinitrate 1,4-bis(diphenylphosphinoyl)butane solvate], {[Co(C2H6O)2(C28H28O2P2)(H2O)2](NO3)2·C28H28O2P2}n, (II), are isostructural and centrosymmetric, with the MII ions at centres of inversion. The coordination geometry is octahedral, with each metal ion coordinated by two trans ethanol molecules, two trans water molecules and two bridging 1,4-bis(diphenylphosphinoyl)butane ligands which link the coordination centres to form one-dimensional polymeric chains. Parallel chains are linked by hydrogen bonds to uncoordinated 1,4-bis(diphenylphosphinoyl)butane molecules, which are bisected by a centre of inversion. Further hydrogen bonds, weak C,H...O interactions to nitrate anions, and weak C,H..., interactions serve to stabilize the structure. This study reports a development of the coordination chemistry of bis(diphenylphosphinoyl)alkanes, with the first reported structures of complexes of the first-row transition metals with 1,4-bis(diphenylphosphinoyl)butane. [source] | ||||||||||||||||||||||||||||