bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Halides on the Luminescence of Oxide/Anthracene/Polymer Nanocomposites
Authors: Szabó Dorothée V. , Reuter Heike , Schlabach Sabine , Lellig Christoph , Vollath Dieter 
Published: April 2011

ABSTRACTNanocomposites made of an oxide core of a wide band gap insulator, a lumophore monolayer of anthracene and an outer protecting layer of PMMA are studied regarding their luminescence properties and the influence of halides stemming either from the precursor used for synthesis or from the lumophore itself. Halide-free nanocomposites exhibit luminescence spectra resembling to that of anthracene with some significant differences concerning the intensity ratio and an additional peak at 420 nm. Nanocomposites made from chlorides show excimer-like spectra with broad maxima. In microanalysis residual chlorine can be detected. Chlorine-free oxide kernels, coated with 9, 10 dichloroanthracene exhibit luminescence spectra resembling to a superposition of the pure lumophores 9 chloro- and 9, 10 dichloroanthracene. It can be shown that the origin of the halide strongly influences, but does not quench the luminescence spectra of the powders. Suspensions of the chlorine containing nanocomposites in ethanol exhibit modified anthracene like spectra. This is a strong indication for dechlorination by proton-transfer in ethanol. Suspensions of the same material in water lead to spectra showing a superposition of exci-mer spectrum and modified anthracene spectrum. Here a partial dechlorination occurs.
Self-assembled oligonucleotide semiconductor conjugated to GaN nanostructures for biophotonic applications
Authors: Neogi A. , Li J. , Sarkar A. , Neogi P. B. , Gorman B. , Golding T. , Morkoc H. 
Published: April 2011

ABSTRACTWe investigate the optical properties of a new class of wide-bandgap semiconductor based biomaterial system. We have synthesized a guanosine derivative with a strong dipole moment, which self-assemble in ∼ 50 –100 nm confined pits to form a ribbon like semiconductor structure (SAGC). SAGC were successfully self-assembled on GaN/AlN QD matrix and the luminescence from GaN QDs can be resonantly transferred to the SAGC molecules resulting in a significant enhancement in emission from the guanine molecules. We also propose the design of ultraviolet-visible photonic bandgap structures based on hybrid SAGC-GaN photonic crystal.
Supernatant Controlled Synthesis of Monodispersed Zinc Sulfide Spheres and Multimers
Authors: Song Yanning , Liddell Chekesha M. 
Published: April 2011

ABSTRACTUniform zinc sulfide spheres and multimers ranging in size from ∼ 90 nm to 1.0 micron were produced in large quantities by adding varying amount of supernatant in a secondary nucleation process. The particle morphology was investigated using scanning and transmission electron microscopy. Smaller particles exhibited increased surface roughness in the nitrate system. Characterization by x-ray and electron diffraction showed that the particles were built up from nanocrystallites. The relationship between the particle size, porosity, and refractive index was studied by modeling UV-Vis spectra using the Mie scattering method. Monodispersed zinc sulfide spheres and multimers in the size range from 100 nm to 600 nm can be used as high refractive index building blocks for photonic crystals with band gaps covering the entire visible spectrum as well as portions of the near-IR and UV regions.
Photoluminescence-structure relationships in ormosils for integrated optical devices
Authors: Sá Ferreira Rute , Molina Celso , Dahmouche Karim , Ribeiro Sidney , Gonçalves Rogéria R. , Bermudez Verónica de Zea , Carlos Luís Dias 
Published: April 2011

ABSTRACTPlanar waveguides with low losses in the infrared (from 0.6–1.1 dB/cm) were prepared with sol-gel derived poly(oxyethylene)/siloxane hybrid doped with zirconium(IV) n-propoxide (ZPO) and methacryloxypropyltrimethoxysilane (MAPTMS). The doped nanohybrids were characterized by small angle X-ray scattering, 29Si nuclear magnetic resonance and photoluminescence spectroscopy and compared with the undoped hybrid material. The results indicate an effective interaction between the zirconium particles and the siliceous nanodomains.
Hierarchical Porous Silicas for Chromatographic Applications Obtained by Pseudomorphic Synthesis
Authors: Galarneau Anne , Iapichella Julien , Petitto Carolina , Renzo Francesco Di , Fajula François 
Published: April 2011

ABSTRACTPseudomorphic transformation of pre-shaped silica beads into MCM-41 and MCM-48 is introduced as a new versatile procedure to independently control and finely tune the textural characteristics of advanced high-performance chromatographic supports at nano- and micrometer scale. The reaction takes place in the intergranular porosity of the parent silica-gel particle which acts as a nanoreactor. Because the resulting hybrid mesophase is metastable in its synthesis medium, the kinetics of each of the elementary steps – diffusion of hydroxide and surfactant, dissolution of parent silica, self-assembly, condensation of the new silica network-must be precisely controlled. In the paper examples are given of the preparation of discrete homodisperse spherical particles of MCM-41 and MCM-48, with pore sizes in the range 4 to 9 nm, form different silica sources.
Study of Relationship between Morphology and Mechanical Properties of SiO2-Polyacrylate Hybrid Nanocomposite
Authors: Kao Yi-Hsiao , Su Wei-Fang , Lin K. C. 
Published: April 2011

ABSTRACTThe atomic force microscopic technique is utilized to study the spatial distribution of silica nanoparticles embedded in poly(tetraethylene glycol diacrylate) matrix. The cast samples of these hybrid materials show distinct mechanical property change as the weight ratio (SiO2/polyacrylate) reaches 40%. The morphological observation from spin-coated films on silicon substrates shows pronounced nanoparticle network formation correlated to the elasticity transition. The percolating particles reduce the local strain field, i.e. inhibit the deformation of the stratum, and cause the dramatic increase in the Young's modulus. Our experimental result is consistent with recent theoretical prediction [1].
Structure of Nanocomposite films of CdS nanoparticles in a polymer matrix
Authors: Luccio Tiziana Di , Nickel Bert , Antolini Francesco , Pentimalli Marzia , Tapfer Leander 
Published: April 2011

ABSTRACTA thiolate precursor was dispersed in a polymer solution and a precursor/polymer film was obtained by casting. Thermal annealing of the precursor/polymer film leads to the formation of a nanocomposite of nanometer-sized CdS dispersed in the polymer (thermolytic process). Different polymers were used as matrix material; in particular we employed a cyclo-olefin copolymer for its good optical properties and extremely low water absorption. After annealing with a temperature between 230 and 250°C in vacuum (pressure of about 6×10−3 mbar) the CdS nanoparticles are found to be crystalline with a diameter of about 2nm in size. The nanoparticle size can be increased up to 15nm by annealing at higher temperatures (300°C). The details of the structural properties of the nanocomposite films have been investigated by small and wide angle x-ray scattering (SAXS and WAXS, respectively). A simple dependence of the nanoparticle dimensions on the annealing temperature was found. Furthermore, SAXS measurements indicate that the separation between the nanoparticles compares with their diameter.
Octadecylphosphonic Acid Self-Assembled Monolayers as Lubricant Coatings Stable in Alkaline Media
Authors: Soullier J. , Tordjeman P. , Mutin P. H. 
Published: April 2011

ABSTRACTThe formation of octadecylphosphonic acid self-assembled monolayers (SAMs) on titanium deposited by cathodic sputtering on planar substrates has been studied by water contact angle measurements and Atomic Force Microscopy (AFM). Dense monolayers were obtained after one week of reaction. Tribological experiments indicated that these monolayers had good lubricating properties, which were maintained after immersion in a 1 M NaOH solution at 65 °C for up to 100 min. The stability in alkaline media of octadecylphosphonic acid SAMs on titanium was ascribed to the high chemical stability of Ti-O-P interfacial bonds.
Er3+-doped Polyether/siloxane Hybrid Materials for Optoelectronics
Authors: Nunes S. C. , de Zea Bermudez V. , Sá Ferreira R. A. , Carlos L. D. , Morales E. , Marques P. V. S. 
Published: April 2011

ABSTRACTThe sol-gel method was employed to obtain poly(oxyethylene) (POE)/siloxane hybrids (di-ureasils) doped with erbium triflate (Er(CF3SO3)3). The host hybrid matrix employed is composed of a siliceous framework to which short POE chains are covalently bonded through urea linkages (-NH(C(=O)NH-). Xerogels with ∞ > n ≥ 5 (where n, salt composition, is the molar ratio of OCH2CH2 moieties per Er ion) were analyzed. Samples with n ≥ 20 are amorphous. Those with n > 20 are thermally stable up to about 325 °C. In the di-ureasils proposed, the Er ions are active at room temperature (RT). Concentration effects on the quenching of the 1.53 mm emission intensity (excited at 488 nm) are negligible.
“Abrasion Resistant Coatings with Ultraviolet Absorption, via sol-gel dipping method.“
Authors: Arfsten Naiming , Alvarez Manuel A. 
Published: April 2011

ABSTRACTMulti-cpoxy functional - glycidyl ether is used as a cross-linking epoxy compound between modified 22'44'-tetrahydroxybenzophenone and silicone molecules. The adduct reaction products, as effective abrasion resistant coatings and yet reactive in the sol gel process, are formulated into the colloidal based polysiloxane resin as an essential part of the solution for dip coating sheets. Such coatings incorporate ultraviolet radiation selection or absorbing compounds with superb chemical stability and mechanical strength for coatings on substrates such as glass. The hardness of these coatings was measured at 6H following ASTM (D-3363) film hardness by pencil test. The resulting coatings were exposed to ultraviolet (UV-A) radiation during a time greater than 600 hours. The exposed samples still maintain excellent absorption in the UV range.
Two-Dimensional Crystalline Lattice Templating: A New Method for the Preparation of Polymer-Covered Metal and Alloyed Metal Nanorods by a Redox Process.
Authors: Pavel Alexandru C. , Romanovicz Dwight K. , Yacaman Miguel J. , McDevitt John T. 
Published: April 2011

ABSTRACTWe demonstrate in this paper that two-dimensional (2-D) layered ceramics, materials that are highly anisotropic in terms of structure and properties can be used to induce the formation of polymer-covered metal nanorods. The procedure took advantage of the intrinsic planar, layered ordering of the metal cations suitable to be reduced and can be further used to engineer one-dimensional (1-D) metal alloy nanostructures by appropriate doping of the initial layered ceramic lattice with suitable cationic species. The procedure involved the formation in an intermediate step of a polymer-layered ceramic nanocomposite, highly porous to the diffusion of the reducing agent. Two structurally similar layered bismuthates, Bi2Sr2CaCu2O8+δand Bi6Sr2CaO12were used as the precursor layered ceramics and the redox-active metal cations were Cu2+and Bi3+.
Monolithic O/I-Hybrids with Hierarchically Ordered Meso- and Macropores
Authors: Nakanishi Kazuki , Kobayashi Yuki , Amatani Tomohiko , Hirao Kazuyuki , Kodaira Tetsuya 
Published: April 2011

ABSTRACTOrganic-Inorganic hybrid gels with hierarchical well-defined macropores and supramolecularly templated mesopores with long-range orders have been synthesized in the systems of bridged poly(silsesquioxane) systems. Nonionic surfactants such as poly(ethyleneglycol)-poly(propyleneglycol)- poly(ethyleneglycol) triblock copolymers, EOPOEOs, were found to be effective both in inducing the phase separation to give macroporous morphology and in templating the mesopores with narrow size distribution. The number of methylene units in the bridge, changed from 1 to 6 in the present experiments, affected both the phase separation tendency and template strength. In the system containing 1, 2-bis(trimethoxysilyl)ethane, 2D-hexagonal arrangement of mesopores have been prepared in the gel skeleton comprising the well-defined continuous macroporous network with an aid of micelle-stabilizing agent.
Sol-Gel Silica Particles for Controlled Release Applications
Authors: Barbé Christophe , Calleja Sandrine , Kong Linggen , Drabarek Elizabeth , Bush Alexandra , Sizgek Erden , Finnie Kim 
Published: April 2011

ABSTRACTUsing sol-gel technology combined with water-in-oil (W/O) emulsions, we have developed an innovative method for producing ceramic particles with independent control over the release rate and particle size. The average particle size can be varied from 10 nm to 100 μm and is controlled by the emulsion chemistry. The release rate can be independently varied from mg/hours to mg/month, and is controlled by the internal microstructure of the particles and the initial sol-gel chemistry.
Surface-modified Zirconium Oxide Clusters and their Use as Components for Inorganic-Organic Hybrid Materials
Authors: Gao Yu , Dragan Denise Silvia , Jupa Myhedin , Kogler Franz René , Puchberger Michael , Schubert Ulrich 
Published: April 2011

ABSTRACTPre-formed transition metal oxide clusters with methacrylate ligands were polymerized in the presence of organic co-monomers to form inorganic-organic hybrid polymers. The number of polymerizable ligands and thus the crosslinking density of the hybrid polymers can be varied for a given cluster type by partially exchanging the methacrylate ligands for non-reactive ones. The properties of the hybrid polymers can also be varied by adjusting the conditions of the polymerization reaction, especially by a pre-polymerization procedure. It is shown that the thermal stability of polystyrene crosslinked by Zr6O4(OH)4(OMc)12 is thus greatly improved.
Synthesis and Characterization of Imide-Oligosiloxanes Hybrid Nanocompisite (Imide HYBRIMER) by Reaction of Nano Amine Modified Oligosiloxane and Dianhydride
Authors: Lee Tae-Ho , Kim Jeong Hwan , Ko Ji Hoon , Bae Byeong-Soo 
Published: April 2011

ABSTRACTImide-oligosiloxanes hybrid nanocomposites (Imide HYBRIMER) were synthesized and their unique structure and thermal and mechanical properties were investigated. Imide HYBRIMER was made by reaction with nano-sized amine oligosiloxane (AO) and dianhydride, where oligosiloxane moieties were cross-linked by imide bonds to form three-dimensional nanocomposite. The AO were prepared from condensation reaction with aminopropyltirmethoxysilane (APTS) and diphenylsilanediol (DPSD) under base catalysts without water and solvents. The preparation of imide HYBRIMER was completed through the thermal imidization of amic acids, which were formed by reaction with amines groups in the AO and two different kinds of dianhydrides. The imide HYBRIMER were stable up to 400°C and thermal expansion coefficients measured by thermo-mechanical analysis (TMA) were varied from 33 to 80 ppm/°C. Higher thermal stabilities and mechanical strengths could be obtained by incorporating siloxane moieties in hybrid nanocomposites. The imide HYBRIMER, which has three dimensional network, could induce very low birefringence about 0.003, which was lower than that of linear typed polyimides.
Iron Oxide – Doped Mesostructured Silica Films
Authors: Supplit Ralf , Hüsing Nicola , Fritscher Christina , Jakubiak Patrycja , Kessler Vadim G. , Seisenbaeva Gulaim A. , Bernstorff Sigrid 
Published: April 2011

ABSTRACTPoly(ethylene oxide)—poly(propylene oxide)—poly(ethylene oxide) (PEO-PPO-PEO) was reacted with iron ethoxide in a molar ratio of 1:2. This modified surfactant was used as a template for the synthesis of mesostructured, nanocomposite iron oxide-silica films and powders. Grazing incidence (GI)-SAXS measurements of the films showed that depending on the concentration of the surfactant wormhole-like, 2d-centered rectangular, orthorhombic and lamellar nanocomposite structures were formed. Interestingly, the mesoscopic ordering of the orthorhombic and 2d-centered rectangular pore structure is retained even after calcination at 1000 °C for one hour. The influence of heat treatment on the mesostructure was investigated by GI-SAXS, TEM and N2-sorption measurements.
LDH-DNA Nanohybrids: a complete biophysical characterization
Authors: Leroux Fabrice , Belkacen Málha Ben , Guyot Ghislain , Taviot-Guého Christine , Léone Philippe , Cario Laurent , Desigaux Léa , Pitard Bruno 
Published: April 2011

ABSTRACTRecently, LDH have been considered as a new kind of gene delivery system [1, 2]. In this work, we report the formation of magnesium-gallium LDH-DNA nanohybrids using the coprecipitation method. This “self assembly” approach enabled the incorporation of long DNA fragments up to 6000–8000 bp. X-ray diffraction analyses indicate a parallel orientation of DNA double helix in the interlamellar space with respect to the hydroxide sheets. The Mg/Ga molar ratio within the hydroxide layers appears to be determined by DNA macromolecules which may interact with charged complexes that form during cation hydrolysis. The presence of DNA macromolecules also inhibits the crystal growth: hydrodynamic diameter measurements revealed homogeneous populations of particles with a mean diameter ranging from 90 to 150 nm, compatible with cell penetration through endocytosis. Concerning the charge surface of this new DNA delivery system, ζ-potential measurements indicate negative values ranging from –20 to - 40 mV which suggest incomplete DNA intercalation. Yet, this small negative surface might be suitable for protecting DNA from extra-cellular degradations without preventing cell penetration.
Layered Tungsten Oxide-Based Hybrid Materials Incorporating Transition Metal Ions
Authors: Ingham Bridget , Chong S. V. , Tallon Jeff L. 
Published: April 2011

ABSTRACTLayered organic-inorganic hybrid materials based on tungsten oxide as the inorganic framework have been synthesised to include transition metal ions. The resulting materials have been characterised using a number of techniques. X-ray diffraction shows an interlayer expansion with increasing alkyl length. Infrared vibrational spectra of manganese tungstate compounds indicate the organic amine molecules are neutrally charged, and the inorganic framework is unaltered as one varies the organic intercalate. The magnetic behaviour of the materials has also been explored using a SQUID magnetometer. In the manganese tungstate hybrids an antiferromagnetic (AF) transition is observed, which decreases in temperature as the inorganic interlayer spacing is increased. A nickel tungstate hybrid sample, on the other hand, displays a ferromagnetic transition, which we attribute to a canted AF phase below 15 K. In all cases studied, the behaviour can be mapped to an effective moment (Peff) per transition metal ion, which agrees well with theoretical and literature values for other transition metal oxides.
Intercalation of n-alkylamines in the vapor phase into vanadium pentoxide xerogel dispersed into silica matrix
Authors: Figueiredo Mariza A. , Oliveira Herenilton P. 
Published: April 2011

ABSTRACTIn this work, we report a new intercalation reaction: three different n-alkylamines (n-butylamine, n-hexylamine and n-octylamine), in vapor phase, were intercalated into non-dispersed vanadium pentoxide xerogel and into this lamellar material homogeneously dispersed in Si–O–Si network (obtained by polycondensation of the silicon alkoxide) interpenetrated with V–O–V and V–OH–V polymeric chains. The reaction with non-dispersed xerogel leads to increase of interlamelar distance for low time of reaction (up to 2 hours) and after 24 hours we observed a new phase. In contrast, for the reaction with xerogel dispersed in silica, it was observed only the increase of the basal distance retaining the original bi-dimensional structure (00l diffractions lines were observed); suggesting that the silica matrix stabilizes the vanadium pentoxide structure as the result of a mutual “solubility” due to cross-linking and entanglement of both components. In addition, for this reaction it was observed a selective amine intercalation. The reactions were monitored using powder X-ray diffraction, Fourier-transform infrared and electronic spectroscopy, electron paramagnetic resonance and scanning electron microscopy.
Control of the Morphology of the Layered-Silicate Epoxy Nanocomposite
Authors: Chen Chenggang , Tolle Tia Benson 
Published: April 2011

ABSTRACTPolymer layered-silicate nanocomposites have attracted great attention due to their unique nanostructure and properties. The property of the nanocomposite is determined by the morphology of the nanocomposite. The typical morphologies of the nanocomposite are the intercalated and exfoliated nanostructures. In this study, the layered-silicate epoxy nanocomposite with different morphology can be controlled and achieved. The different morphology could include the intercalated nanostructure with the 15 Å increase of the interplanar spacing, the intercalated one with ∼150 Å increase of the gallery and fully exfoliated nanostructure.
The Structure of a Molybdenum Disulfide Intercalation Compound
Authors: Brüning Ralf , Bulmer Kristopher , Bissessur Rabin , Haines Robert I. , Varma Pravin , Emeneau Stephen 
Published: April 2011

ABSTRACTThe X-ray powder diffraction spectrum of MoS2 with intercalated 5, 5, 7, 12, 12, 14-hexamethyl-1, 4, 8, 11-tetraazacyclotetradecane-1-acetic acid shows well-defined peaks as well as broad scattering. The X-ray scattering of this compound was simulated by generating model particles and calculating their X-ray scattering by evaluating the Debye sum. The match between the measured and simulated spectra was improved by trial-and-error. Matching the peak widths shows that the particles contain a total of about 6600 MoS2 units in about eight layers. The layers are oriented in the same direction (not turbostratic). However, they are translated randomly in the plane perpendicular to the stacking direction. In contrast to prior work on intercalation compounds, which considered various types of periodic reconstruction within the MoS2 layer, we obtain the best match with a non-periodic reconstruction in addition to a periodic superlattice. It involves dimer and trimer groupings of the molybdenum atoms with a random choice of centers. The intercalated tetraazamacrocycles form a two-dimensional glass. The effects of the key model assumptions on the calculated spectrum are demonstrated.
Effects of Surface Modification of Mg(OH)2 with Polysiloxane Oil and Silica Additive on the Flame Retardancy and Mechanical Properties of LDPE-Mg(OH)2 Composites
Authors: Kodama K. , Hyodo T. , Shimizu Y. , Egashira M. 
Published: April 2011

ABSTRACTComposites of low density polyethylene (LDPE) and 40 wt% Mg(OH)2 modified with several kinds of polysiloxane oils were prepared in order to evaluate the effect of the surface modification of Mg(OH)2 on the mechanical properties and oxygen index of the composites. A composite containing Mg(OH)2 modified with methylhydrogen polysiloxane oil showed an oxygen index of 23.8% O2 and an elongation of 425%. These values were superior to other composites containing Mg(OH)2 modified with other kinds of polysiloxane oils. The oxygen index could be enhanced up to 24.8% by co-addition of 5 wt% fumed silica as another flame retardant to the composite of LDPE and 35 wt% Mg(OH)2 (modified with methylhydrogen polysiloxane oil), while fixing the total amount of the flame retardants at 40 wt%.
Responsive Polymer/Clay Aerogel Composites
Authors: Bandi Suneel , Schiraldi David A. 
Published: April 2011

AbstractClay aerogels are a relatively unexplored form of matter that are only now being investigated for use in the reinforcement of organic polymers. We have recently demonstrated an efficient process for producing these aerogels; we now report our preliminary work describing the preparation and properties of polymer/clay aerogel composites, including temperature-responsive materials.