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Organic Polymers (organic + polymer)

Distribution by Scientific Domains

Polymers and Materials Science	52%
Chemistry	44%

Distribution within Polymers and Materials Science

General & Introductory Materials Science	57%
Polymer Science & Technology General	21%

Selected Abstracts

Emerging N-Type Redox-Active Radical Polymer for a Totally Organic Polymer-Based Rechargeable Battery

ADVANCED MATERIALS, Issue 16 2009
Takeo Suga
A n-type and redox-active radical polymer bearing galvinoxyl radicals, poly(galvinoxylstyrene), is utilized as an anode-active material, which enabled, for the first time, the fabrication of a totally organic polymer- based rechargeable battery in conjunction with p-type redox-active radical polymer. This battery was characterized by its remarkably high power rate capability. [source]

Formation of Nanostructures in Multi Component Systems Based on Organic Polymer and Coordination Metal Compound

MACROMOLECULAR SYMPOSIA, Issue 1 2006
Nataly Kozak
Abstract Structuring of polyurethane (PU) networks is analyzed under influence of transition metal coordination compounds: mono-ionic ,-diketonates and polyheteronuclear metal-organic complexes. Formed in situ nanostructures both organic and inorganic were found in organic polymer modified with coordination metal compound. Influence of coordination junction point spatial symmetry and content of metal ion in modifier on structure and dielectric characteristics of modified PUs is analyzed using X-ray, EPR, SEM and transmission optical microscopy, DRS and DSC methods. [source]

Current-Free Deposition of Prussian Blue with Organic Polymers: Towards Improved Stability and Mass Production of the Advanced Hydrogen Peroxide Transducer

ELECTROANALYSIS, Issue 3-5 2009
Anastasiya
Abstract We report on a novel approach for open-circuit (current-free) deposition of Prussian blue. Synthesis of Prussian blue is carried out by reduction of ferric ferricyanide with organic molecules, which are known to form polymers upon oxidation. The proposed interfacial deposition is a result of the synthesis in the presence of electrode support due to preconcentration of precursors at the interface. The resulting modified electrodes displayed the dramatically improved operational stability in hydrogen peroxide continuous monitoring with no loss of either electrochemical or analytical performance characteristics compared to electrodes with electrochemically deposited Prussian blue. The shown possibility to deposit stable films with regular structure in the absence of any external voltage could open new horizons for sensor science. [source]

Cover Picture: Hierarchically Organized Superstructure Emerging from the Exquisite Association of Inorganic Crystals, Organic Polymers, and Dyes: A Model Approach Towards Suprabiomineral Materials (Adv. Funct.

ADVANCED FUNCTIONAL MATERIALS, Issue 9 2005
Mater.
Abstract Suprabiomineral materials possessing hierarchically organized superstructures are investigated by Imai and Oaki on p.,1407. Inorganic crystals, organic polymers, and functional dyes have assembled via a simple biomimetic route into a superstructure that contains six different tiers, from the macroscale to the nanoscale. The hierarchy originates from the strong interaction between crystals and polymers and the diffusion-controlled conditions. The versatile role of the polymer is found to be essential for the construction of a superstructure. This approach promises to generate novel types of functional materials with controllable structures and properties. We report a novel hierarchically organized superstructure emerging from an exquisite association of inorganic crystals, organic polymers, and dyes. The resultant K2SO4/poly(acrylic acid) composite includes five different tiers from the nanoscopic to the macroscopic. An additional new tier leading to functionality is formed by the incorporation of organic dyes that are organized in a nanospace. The emergent superstructure and properties are designed through changes in polymer concentration. The multiple roles of the polymer realize the generation of the architecture at each size scale. This model approach should be widely applicable to other systems, allowing for the preparation of innovative materials by an appropriate combination of crystals, polymers, and functional molecules. [source]

Solvent-Resistant PDMS Microfluidic Devices with Hybrid Inorganic/Organic Polymer Coatings

ADVANCED FUNCTIONAL MATERIALS, Issue 23 2009
Bo-Yeol Kim
Abstract This study presents a method for the fabrication of solvent-resistant poly(dimethylsiloxane) (PDMS) microfluidic devices by coating the microfluidic channel with a hybrid inorganic/organic polymer (HR4). This modification dramatically increases the resistance of PDMS microfluidic channels to various solvents, because it leads to a significant reduction in the rate of solvent absorption and consequent swelling. The compatibility of modified PDMS with a wide range of solvents is investigated by evaluating the swelling ratio measured through weight changes in a standard block. The HR4-modified PDMS microfluidic device can be applied to the formation of water-in-oil (W/O) and oil-in-water (O/W) emulsions. The generation of organic solvent droplets with high monodispersity in the microfluidic device without swelling problems is demonstrated. The advantage of this proposed method is that it can be used to rapidly fabricate microfluidic devices using the bulk properties of PDMS, while also increasing their resistance to various organic solvents. This high compatibility with a variety of solvents of HR4-modified PDMS can expand the application of microfluidic systems to many research fields. [source]

Rarely Decorated Rutile Frameworks Built from Triangular Organic Spacers and Distorted Octahedral Co3 Building Blocks

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 24 2007
Feng Luo
Abstract Under mild temperatures, the self-assembly of CoCl2 and H3BTC in a solution of dmso generates a guest-free metal,organic polymer, namely Co3(BTC)2(,1 -dmso)2(,2 -dmso)2(1: dmso = dimethylsulfoxide, H3BTC = 1,3,5-benzenetricarboxylic acid). In 1, the CoII ions show the six-coordinate octahedral geometry completed by the BTC3, ions and the dmso oxygen atoms; remarkably, the coordinated dmso ligands not only act as terminal ligands to complete the octahedral geometry of the CoII ions, but also play an important role in bridging CoII ions together to give the Co3 secondary building units (SBUs). From a topological viewpoint, this novel polymer is classified to be the decorated (3,6)-connected rutile net with the (4.62)2(42.610.83) topology, where BTC3, ligands and Co3 SBUs are viewed to be the 3- and 6-connected nodes, respectively. In addition, the magnetic properties of 1 are explored by using a linear trinuclear cobalt mode, thusleading to g = 2.41, J = ,34.92 cm,1, TIP = 340,×,10,6 cm3,mol,1,, = ,6 K (a , parameter was included to take into account intertrinuclear interactions).(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

A Two-Dimensional, Hydrogen-Bond-Cross-Linked Molybdenum(VI) Network Polymer with Catalytic Activity

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2007
Yi Luan
Abstract The new hybrid inorganic,organic polymer [MoO2Cl2(H2O)2]·(H2dipy-pra)Cl2 (1), where dipy-pra = 1,3-bis(4-pyridyl)propane, has been synthesized and crystallographically characterized. MoO2Cl2(H2O)2 and the [H2dipy-pra]2+ cation are cross-linked by Mo,H2O···Cl and H2dipy-pra···Cl hydrogen bonds to form a two-dimensional layer structure. Complex 1 is an efficient catalyst, with H2O2 as the oxygen-source oxidant and NaHCO3 as the cocatalyst, in the epoxidation of olefinic compounds under ambient conditions.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

Emerging N-Type Redox-Active Radical Polymer for a Totally Organic Polymer-Based Rechargeable Battery

Photoinduced Formation of Wrinkled Microstructures with Long-Range Order in Thin Oxide Films,

ADVANCED MATERIALS, Issue 24 2007
M. Takahashi
Thin oxide films with long-range ordered microstructures were fabricated by a wrinkling process initiated by photopolymerization. The faster polymerization of the film surface generates a buckling effect to create patterns in the films. The removal of the organic polymer by thermal treatment leaves titania microstructures having long-range order. This method of producing micropatterned structures can find several applications in photonics. [source]

Hybrids of poly(ethylene oxide- b -amide-6) and ZrO2 sol,gel: Preparation, characterization, and application in processes of membranes separation

ADVANCES IN POLYMER TECHNOLOGY, Issue 1 2002
Rita Aparecida Zoppi
Abstract Hybrids consisting of poly(ethylene oxide- b -amide-6), PEBAXTM, and zirconium oxide were prepared from hydrolysis and condensation of zirconium tetraisopropoxide in solution containing the dissolved organic polymer. These hybrids were characterized by thermogravimetric analysis, differential scanning calorimetry, infrared spectroscopy, and electron microscopy. Results show that the incorporation of the inorganic phase seems to promote the degradation of the organic polymer. Composite membranes consisting of a porous support of poly(vinylidene fluoride), PVDF, and a filter layer of PEBAX/ZrO2 were prepared and characterized by electron microscopy. Permeation tests of water or aqueous solutions containing poly(ethylene glycol) of different molar masses were carried out to determine the permeation rate and the membrane cutoff respectively. To determine the phosphate retention, permeation tests using a KH2PO4 aqueous solution were carried out. Independent of composition of the filter layer, values of phosphate retention were nearly equivalent to 80%. © 2002 John Wiley & Sons, Inc. Adv Polym Techn 21: 2,16, 2002; DOI 10.1002/adv.10011 [source]

Transparent Anatase Nanocomposite Films by the Sol,Gel Process at Low Temperatures

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2000
Atsunori Matsuda
We have successfully prepared transparent anatase nanocomposite films on various types of substrates, including organic polymers, using the sol,gel method at temperatures <100°C under ambient pressure. This novel process is based on the findings that (i) anatase nanocrystals are uniquely formed in sol,gel-derived SiO2,TiO2 films that have been subjected to a hot-water treatment, and (ii) the addition of an organic polymer such as poly(ethylene glycol) in the films accelerates the formation of anatase nanocrystals. The film coating on the substrates is a promising candidate for use as a photocatalyst to decompose environmental pollutants and harmful microorganisms. [source]

Formation of Nanostructures in Multi Component Systems Based on Organic Polymer and Coordination Metal Compound

Light emission from different ZnO junctions and nanostructures

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 5 2009
M. Willander
Abstract We will discuss our experimental results for optical spectra produced by hole-injection from different p-type organic and inorganic materials into n-type ZnO nanowires. The influence of different growth techniques and conditions on the nanowires and their emission spectral characteristics will then be analyzed and discussed. The latest findings on the mixture of the green emission band responsible for visible light emission from ZnO and the blue light emission from the organic polymer will be presented. Different high brightness light emitting diodes (HB-LEDs) from our grown ZnO nanowires are demonstrated. The p-type multi layer organic structures contain PEDOT:PSS as hole injectors combined with a hole transporting layer, and in some structures, a final top electron blocking/hole barrier stepping layer is placed. The purpose of this layer is to adjust the hole and electron emission from the corresponding junction side to optimize the LED performance. Structural scanning electron microscopy (SEM), electrical (I ,V characteristics), photoluminescence (PL) and electroluminescence (EL) characteristics of these devices are displayed. Theoretically, we study the superfluidity of a two-dimensional system of excitonic polaritons in an optical microcavity with an embedded quantum well. Using the effective low-energy action for thermodynamic phase fluctuations, we obtain an expression for the analogue of the superfluid density in the system in terms of the "current,current" correlation function. The Kosterlits,Thouless transition temperature to the superfluid state as a function of the controlling parameters is calculated. Two methods are considered for producing traps for a polariton system in an optical microcavity. The behaviour of a two-component Bose condensate of photons and excitons is analyzed theoretically for both types of the trap. The Bose condensate is described by the coupled system of equations of the Gross,Pitaevskii type. The approximate wave functions and the spatial profiles of coupled photon and exciton condensates are obtained. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Synthesis and applications of novel fluoroalkyl end-capped cooligomers containing diphenylacetylene segments: a new approach to the surface arrangement of diphenylacetylene segments on the traditional organic polymer

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 3 2010
Masaki Mugisawa
Abstract Fluoroalkyl end-capped cooligomers containing diphenylacetylene segments [RF -(DPMA)x -(Co-M)y - RF] were prepared by reaction of fluoroalkanoyl peroxide with 4-(phenylethynyl)phenyl methacrylate (DPMA) and radical polymerizable comonomers such as N,N -dimethylacrylamide (DMAA) and acryloylmorpholine (ACMO) under very mild conditions. Fluorinated cooligomers containing diphenylacetylene segments thus obtained exhibited a good solubility in a variety of organic solvents. These fluorinated cooligomers were also applied to the surface modification of traditional organic polymers such as poly(methyl methacrylate) (PMMA) to exhibit not only a good surface active property imparted by fluorine but also a fluorescent characteristic related to diphenylacetylene segments on their surface. In addition, these fluorinated cooligomers could form the nanometer size-controlled fluorinated molecular aggregates in chloroform. Interestingly, some benzenes and biphenyl (BP) derivatives could interact with these fluorinated oligomeric aggregates as guest molecules, and in particular 2-chloro-5-nitrobenzotrifluoride (CNB) was most effective for enhancing the fluorescent intensity of these guest molecules. Copyright © 2009 John Wiley & Sons, Ltd. [source]

An Efficient Hybrid, Nanostructured, Epoxidation Catalyst: Titanium Silsesquioxane,Polystyrene Copolymer Supported on SBA-15

CHEMISTRY - A EUROPEAN JOURNAL, Issue 4 2007
Lei Zhang
Abstract A novel interfacial hybrid epoxidation catalyst was designed with a new immobilization method for homogeneous catalysts by coating an inorganic support with an organic polymer film containing active sites. The titanium silsesquioxane (TiPOSS) complex, which contains a single-site titanium active center, was immobilized successfully by in-situ copolymerization on a mesoporous SBA-15-supported polystyrene polymer. The resulting hybrid materials exhibit attractive textural properties (highly ordered mesostructure, large specific surface area (>380,m2,g,1) and pore volume (,0.46,cm3,g,1)), and high activity in the epoxidation of alkenes. In the epoxidation of cyclooctene with tert -butyl hydrogen peroxide (TBHP), the hybrid catalysts have rate constants comparable with that of their homogeneous counterpart, and can be recycled at least seven times. They can also catalyze the epoxidation of cyclooctene with aqueous H2O2 as the oxidant. In two-phase reaction media, the catalysts show much higher activity than their homogeneous counterpart due to the hydrophobic environment around the active centers. They behave as interfacial catalysts due to their multifunctionality, that is, the hydrophobicity of polystyrene and the polyhedral oligomeric silsesquioxanes (POSS), and the hydrophilicity of the silica and the mesoporous structure. Combination of the immobilization of homogeneous catalysts on two conventional supports, inorganic solid and organic polymer, is demonstrated to achieve novel heterogeneous catalytic ensembles with the merits of attractive textural properties, tunable surface properties, and optimized environments around the active sites. [source]

A factorially-designed study of physicochemical reactive dye colour removal from simulated cotton textile processing wastewaters

COLORATION TECHNOLOGY, Issue 5 2002
G Carvalho
The process performance of coagulation to remove reactive dyes from dyehouse effluent is affected by multiple factors, which can be best examined in factorially-designed experiments. A preliminary jar-test procedure was used to select coagulants and the optimal pH and coagulant dosage ranges. An inorganic salt (ferrous sulphate) and an organic polymer (DEC 50) were selected for further studies. Factorially-designed jar-test experiments were performed with different compositions of a synthetic cotton processing wastewater to determine which factors most affected colour removal and highlight interactions between them. Some additives, such as an oxidative desizing agent and a peroxide stabiliser, favoured colour removal within specific concentration ranges. The presence of sizing agents and surfactants reduced process efficiency. Increasing concentrations of ferrous sulphate could counteract this, but would result in higher sludge disposal costs. [source]

Dielectric Properties of a Printed Sol,Gel Matrix Composite,

ADVANCED ENGINEERING MATERIALS, Issue 5 2010
Tobias Lehnert
Low temperature processable materials with high dielectric constants are required for application on flexible organic substrates, for example, in printed electronics. To date, mainly organic polymers with embedded functional particles have been investigated for this purpose. For the first time, we present a printable dielectric composite material composed of ferroelectric high permittivity particles (BaTiO3) bonded by a mainly inorganic sol,gel derived network. The exemplary optimization of the properties by varying the sol,gel precursor illustrates the potential of sol,gel chemistry for printable functional materials. An operational gravure printed capacitor including printed silver electrodes is presented. The measured dielectric constants are among the highest reported in literature for low temperature cured films with moderate dissipation factors. Besides these promising dielectric properties, this composite film shows a ferroelectric response. [source]

Dye-Doped Polyhedral Oligomeric Silsesquioxane (POSS)-Modified Polymeric Matrices for Highly Efficient and Photostable Solid-State Lasers

ADVANCED FUNCTIONAL MATERIALS, Issue 20 2009
Roberto 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]

Phase Segregation in Thin Films of Conjugated Polyrotaxane, Poly(ethylene oxide) Blends: A Scanning Force Microscopy Study,

ADVANCED FUNCTIONAL MATERIALS, Issue 6 2007
L. Sardone
Abstract Scanning force microscopy (SFM) is used to study the surface morphology of spin-coated thin films of the ion-transport polymer poly(ethylene oxide) (PEO) blended with either cyclodextrin (CD)-threaded conjugated polyrotaxanes based on poly(4,4,-diphenylene-vinylene) (PDV), ,-CD,PDV, or their uninsulated PDV analogues. Both the polyrotaxanes and their blends with PEO are of interest as active materials in light-emitting devices. The SFM analysis of the blended films supported on mica and on indium tin oxide (ITO) reveals in both cases a morphology that reflects the substrate topography on the (sub-)micrometer scale and is characterized by an absence of the surface structure that is usually associated with phase segregation. This observation confirms a good miscibility of the two hydrophilic components, when deposited by using spin-coating, as suggested by the luminescence data on devices and thin films. Clear evidence of phase segregation is instead found when blending PEO with a new organic-soluble conjugated polymer such as a silylated poly(fluorene)- alt -poly(para -phenylene) based polyrotaxane (THS,,-CD,PF,PPP). The results obtained are relevant to the understanding of the factors influencing the interfacial and the intermolecular interactions with a view to optimizing the performance of light-emitting diodes, and light-emitting electrochemical cells based on supramolecularly engineered organic polymers. [source]

Siloxane Copolymers for Nanoimprint Lithography,

ADVANCED FUNCTIONAL MATERIALS, Issue 1 2007
P. Choi
Abstract Presented here is the novel use of thermoplastic siloxane copolymers as nanoimprint lithography (NIL) resists for 60,nm features. Two of the most critical steps of NIL are mold release and pattern transfer through dry etching. These require that the NIL resist have low surface energy and excellent dry-etching resistance. Homopolymers traditionally used in NIL, such as polystyrene (PS) or poly(methyl methacrylate) (PMMA), generally cannot satisfy all these requirements as they exhibit polymer fracture and delamination during mold release and have poor etch resistance. A number of siloxane copolymers have been investigated for use as NIL resists, including poly(dimethylsiloxane)- block -polystyrene (PDMS- b -PS), poly(dimethylsiloxane)- graft -poly(methyl acrylate)- co -poly(isobornyl acrylate) (PDMS- g -PMA- co -PIA), and PDMS- g -PMMA. The presence of PDMS imparts the materials with many properties that are favorable for NIL, including low surface energy for easy mold release and high silicon content for chemical-etch resistance,in particular, extremely low etch rates (comparable to PDMS) in oxygen plasma, to which organic polymers are quite susceptible. These properties give improved NIL results. [source]

Cover Picture: Hierarchically Organized Superstructure Emerging from the Exquisite Association of Inorganic Crystals, Organic Polymers, and Dyes: A Model Approach Towards Suprabiomineral Materials (Adv. Funct.

Density functional crystal orbital study of cyano-substituted poly(para -phenylene-vinylene) and poly(quinoxaline-vinylene)

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 8 2006
F. Bartha
Abstract We have calculated the optical and electronic properties of several conjugated organic polymers: poly(p -phenylene-vinylene) (PPV) and its derivatives. Cyano substitutions on the phenylene ring: poly(2,5-dicyano- p -phenylene-vinylene) (2,5-DCN-PPV) and on the vinylene linkage: poly(p -phenylene-7(,8)-(di)cyano-vinylene) are considered. In addition, poly(quinoxaline-vinylene) (PQV) is studied. The infinite isolated quasi-1D chains are treated with periodic boundary conditions, using atomic basis sets. In a comparative study of PPV, some issues regarding the selection of the functionals and basis sets are discussed and excitation energies derived from time-dependent and from ordinary methods are compared. It is concluded that for these polymers the calculations are informative at the B3LYP/6-31G** density functional theory (DFT) level. The absolute values might change with improved methods, but the similarity of the polymers suggests that the relative characterization is adequate. Band structures are communicated along with characteristics of the highest occupied and the lowest unoccupied crystal orbitals (HOCO and LUCO). Electron affinities, ionization potentials, valence and conduction bandwidths, and effective masses at the bandgap are given. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [source]

The Immobilization of Rhodium-4-(diphenylphosphino)-2- (diphenylphosphinomethyl)-pyrrolidine (Rh-PPM) Complexes: A Systematic Study

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 12-13 2006
Benoît Pugin
Abstract A modular toolbox for the immobilization of homogeneous catalysts to various supports is described. It consists of functionalized chiral diphosphines and three different linkers based on isocyanate chemistry and it is used to attach the 4-(diphenylphosphino)-2-(diphenylphosphinomethyl)-pyrrolidine (PPM) ligand to a large variety of soluble, swellable and non-swellable solid organic polymers and to silica gels. As model reaction the hydrogenation of acetamidocinnamic acid derivatives, catalyzed with high enantioselectivity was chosen. Besides information on the usefulness of a particular type of support for synthetic applications, the experiments were also designed to address the question how parameters such as solubility, swellability, cage or pore size and solvent affect the rate and enantioselectivity of an immobilized catalyst. Rhodium complexes of ligands attached to soluble polymers and inorganic supports achieved ees up to 95,% and turnover frequencies between 700 and 1400,h,1, very close to the values of the homogeneous Rh catalyst (ee 95,%, TOF 1320,h,1). Insoluble or strongly cross-linked organic polymers led to catalysts with lower enantioselectivity and activity. PPM ligands attached to water soluble dendrimer fragments allowed hydrogenation in water solution with ees up to 94,%, albeit with much lower activity compared to reactions in methanol with the homogeneous catalyst. [source]

Transparent Anatase Nanocomposite Films by the Sol,Gel Process at Low Temperatures

Fire and flame retardants for PVC

JOURNAL OF VINYL & ADDITIVE TECHNOLOGY, Issue 3 2003
A. William Coaker
The flammability performance of PVC plays a significant role in its selection for many applications. Its relatively high chlorine content (56.8%) makes it more resistant to ignition and burning than most organic polymers. In the case of flexible PVC, the plasticizers that contribute flexibility in most instances detract from its resistance to fire. To meet specifications such as oxygen index, heat release, smoke evolution, or extent of burning in cable tests, flame-retardant (FR) and smoke-suppressant (SS) additives are often incorporated. Synergistic combinations of FR and SS additives help PVC formulations meet many stringent FR specifications cost effectively. [source]

Synthesis and Study of CdS Nanoparticle-Doped Poly(1,4-dihexyloxybenzene)

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 4 2008
Gouri Sankar Paul
Abstract A simple, economical and high yielding method to prepare poly(1,4-dihexyloxybenzene), an alkylated derivative of poly(para -phenylene) (PPP), is reported. We further prepared a composite of poly(1,4-dihexyloxybenzene) and CdS nanoparticles and studied their structural, optical, stability and transport properties. It was observed that the conductivity of poly(1,4-dihexyloxybenzene) increased by several orders of magnitude when doped with CdS nanoparticles. Similarly, CdS nanoparticle-doped PPP showed higher thermal stability, when compared to the neat polymer. As these composites could be processed in the same way as organic polymers, they would find applications in many low-cost optoelectronic devices. [source]

Synthesis and Properties of Novel Cross-Linked Fluoroalkyl End-Capped Oligomeric Nanoparticles Containing Adamantane Units

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 6 2007
Masaki Mugisawa
Abstract Fluoroalkyl end-capped cooligomers that contain both oxime-blocked isocyanato and hydroxyadamantyl segments are prepared by the cooligomerization of fluoroalkanoyl peroxide with the corresponding monomers under mild conditions. This fluorinated cooligomer affords new cross-linked fluoroalkyl end-capped cooligomeric nanoparticles that contain adamantane segments by the deprotecting reaction of oxime-blocked isocyanato segments in cooligomers in excellent to moderate isolated yield. A variety of cross-linked fluoroalkyl end-capped cooligomeric nanoparticles that contain adamantane segments are also prepared by similar deprotecting reactions with this fluorinated cooligomer in the presence of adamantane-1,5-diol. Furthermore, we have prepared cross-linked fluoroalkyl end-capped cooligomers that contain oxime-blocked isocyanato segments by the use of 2-hydroxyethyl acrylate and poly(ethylene glycol)-containing methacrylate monomer as comonomers, respectively. However, the deprotecting reactions of the oxime-blocked isocyanato segments in the cooligomers do not afford the expected nanoparticles, and these cross-linked cooligomers are found to show a gelling characteristic. The thermal stability of these cross-linked fluorinated cooligomeric nanoparticles that contain adamantane segments increases significantly compared to that of the parent fluorinated cooligomer. More interestingly, the thermal stability of these cross-linked fluorinated nanoparticles is almost the same as that of the fluoroalkyl end-capped acrylic acid oligomer/SiO2 nanocomposites (content of SiO2 in composites: 70%). In addition, these cross-linked fluorinated nanoparticles have been applied to the surface modification of traditional organic polymers such as poly(methyl methacrylate) to exhibit a good oleophobicity imparted by fluorine on their surface. [source]

Synthesis and applications of novel fluoroalkyl end-capped cooligomers containing diphenylacetylene segments: a new approach to the surface arrangement of diphenylacetylene segments on the traditional organic polymer

Further uses of the heat of oxidation in chemical hazard assessment

PROCESS SAFETY PROGRESS, Issue 1 2003
Laurence G. Britton
Flammability: The "net heat of oxidation" technique described in an earlier publication is extended to predicting the lower flammable limits, lower limit flame temperatures, and limiting oxygen concentrations of chlorinated organic fuels having H:Cl ratios greater than unity. A new Rule is derived for predicting the effect of initial temperature on the lower flammable limits and limiting oxygen concentrations of organic fuels. It is suggested that this Rule be used in preference to the modified "Burgess-Wheeler" Rule. The effect of initial pressure is discussed. Instability: Net heats of oxidation (kcal/mol oxygen) for a series of disparate fuel groups are compared with ",HD," the maximum heat of decomposition (cal/g) calculated using CHETAH methodology. Given the reasonable assumption that CHETAH's "maximum heat of decomposition" cannot exceed the net heat of combustion ",HC," examination is made as to whether the ratio of these parameters (each expressed in units of kcal/mol), coined the "Reaction Heat Ratio" (RH), provides a useful new indicator for instability assessment. Of these parameters, the net heat of oxidation (,HC/S) is the best indicator to help assign NFPA Instability Ratings. However, ,HC/S cannot generally be used to assign ratings for organo-peroxides. Also, its performance as an indicator for hazardous polymerization depends on the ,HC/S difference between the reacting monomer and the polymer product, so it should become increasingly unreliable as the monomer ,HC/S approaches -100 kcal/mol oxygen. The ranking method tacitly assumes organic polymers to have a constant heat of oxidation of about -100 kcal/mol oxygen. Errors in this assumption must invalidate the ranking approach where ,HC/S differences are small. Finally, separate "cut-offs" must be used at each NFPA Instability Rating for organo-nitrates versus other organics containing combinations of CHON atoms. Additional materials need to be examined to extend this preliminary analysis. The net heat of oxidation would be a useful additional output parameter of the CHETAH program, if only for its application in flammability assessment. No conclusions are drawn regarding the usefulness of net heat of oxidation or RH in conducting CHETAH hazard assessments, since this procedure requires consideration of several variables. However, the analysis may be helpful to the ASTM E 27.07 subcommittee responsible for developing the program. For example, the -,HD , 700 cal/g cut-off used to assign a "high" CHETAH hazard rating typically corresponds to organic materials rated NFPA 1, the second to lowest hazard rating. [source]

Mass spectrometry in the characterization of ambers.

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 5 2008

Amber is a fossil resin constituted of organic polymers derived through complex maturation processes of the original plant resin. A classification of eight samples of amber of different geological age (Miocene to Triassic) and geographical origin is here proposed using direct mass spectrometric techniques, i.e. laser desorption ionization (LDI), atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI), in order to obtain a fingerprint related to the amber origin. Differences and similarities were detected among the spectra with the four methods, showing quite complex spectra, full of ionic species in the mass range investigated (up to m/z 2000). The evaluation required statistical analysis involving multivariate techniques. Cluster analysis or principal component analysis (PCA) generally did not show a clear clustering with respect to the age of samples, except for the APPI method, which allowed a satisfying clustering. Using the total ion current (TIC) obtained by the different analytical approaches on equal quantities of the different amber samples and plotted against the age, the only significant correlation appeared to be that involving APPI. To validate the method, four amber samples from Cretaceous of Spain were analyzed. Also in this case a significant correlation with age was found only with APPI data. PCA obtained with TIC values from all the MS methods showed a fair grouping of samples, according to their age. Three main clusters could be detected, belonging to younger, intermediate and older fossil resins, respectively. This MS analysis on crude amber, either solid or extract, followed by appropriate multivariate statistical evaluation, can provide useful information on amber age. The best results are those obtained by APPI, indicating that the quantity of amber soluble components that can be photoionized decreases with increasing age, in agreement with the formation of highly stable, insoluble polymers. Copyright © 2008 John Wiley & Sons, Ltd. [source]