Home About us Contact
|
Home About us Contact | ||
|
|
||
TEM Images (tem + image)
Selected AbstractsHRTEM Study of Precipitates in Mg-Zn-Y Alloys as Cast and after Extrusion,ADVANCED ENGINEERING MATERIALS, Issue 7 2005J. Rao Three kinds of precipitates were newly found, which are Mg3Zn3Y2, MgZn and MgZn2, in Mg-Zn-Y alloys both as-cast and after extrusion due to the composition concentration of Zn and Y on nanometer scale. This figure shows the high-resolution TEM image of MgZn precipitate in Mg substrate with the crystallographic parameters labeled in details. The boundary between MgZn precipitate and Mg substrate is very clear, no second phases were observed. [source] Recrystallization and Texture in a Ferritic Stainless Steel: an EBSD Study,ADVANCED ENGINEERING MATERIALS, Issue 8 2003C.W. Sinclair The recrystallization behavior of laboratory-processed AISI409 ferritic stainless steel sheet has been studied with a focus on texture inhomogeneity and "sluggish" recrystallization kinetics, mainly using EBSD in the scanning electron microscope. Pronounced texture gradients were observed in some grain orientations (see Figure for a TEM image of the , versus ,-grain border region) and correlated to the deformation-induced substructure. The strong pinning of some boundaries has been linked not only to textural effects, but also to the precipitation of fine titanium carbonitrides. [source] Shape Memory Materials: Identification of Quaternary Shape Memory Alloys with Near-Zero Thermal Hysteresis and Unprecedented Functional Stability (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 12 2010Mater. On page 1917, R. Zarnetta et al. report that for the reversible martensitic transformation in shape memory alloys the compatibility at the austenite/martensite interface is directly related to the width of the thermal hysteresis and to the functional stability. A "perfect" compatibility results in the growth of twinless martensite (blue) within the austenite (red), as shown in the TEM image for a Ti50Ni39Pd11 shape memory alloy (image provided courtesy of R. Delville). [source] Block Copolymer Nanostructures: Nanoscopic Morphologies in Block Copolymer Nanorods as Templates for Atomic-Layer Deposition of Semiconductors (Adv. Mater.ADVANCED MATERIALS, Issue 27 200927/2009) The frontispiece shows a TEM image of block copolymer nanorods exhibiting nanoscopic domain structures visualized by selective staining. The insets represent the methodology for producing semiconductor nanostructures reported by Yong Wang, Martin Steinhart, and co-workers on p. 2763. The first panel shows block copolymer nanorods, the second, the nanorods after conversion of the nanoscopic domain structure into a mesopore structure, and the third, the complex 1D semiconductor nanostructures obtained by ALD using the mesopores as templates. [source] A Facile Route to ZnS,Polymer Nanocomposite Optical Materials with High Nanophase Content via ,-Ray Irradiation Initiated Bulk Polymerization,ADVANCED MATERIALS, Issue 9 2006C. Lü Transparent ZnS/polymer bulk nanocomposites with high particle contents are prepared via ,-ray irradiation initiated polymerization. This strategy involves the design and tailoring of the surface of the nanoparticles and choice of the monomer as well as the selection of the polymerization route. The figure shows a TEM image of a bulk nanocomposite containing mercaptoethanol-capped ZnS with a particle content of 20,wt,%. [source] Cover Picture: Enhancement of Radiative Recombination in Silicon via Phonon Localization and Selection-Rule Breaking (Adv. Mater.ADVANCED MATERIALS, Issue 7 20067/2006) Abstract The cover shows a low-magnification TEM image of a periodically nanopatterned all-silicon structure exhibiting enhanced light emission at room temperature. The microstructure was studied using high-resolution TEM, allowing direct observation of high densities of structural defects in the nanopatterned silicon surface layer, which are held responsible for the phonon-localization effect leading to enhanced radiative recombination, as reported on p.,841 by Xu and co-workers. [source] Chemo-Enzymatic Synthesis of Raffinose-Branched Polyelectrolytes and Self-Assembly Application in Microcapsules,MACROMOLECULAR BIOSCIENCE, Issue 1 2006Qi Wu Abstract Summary: A novel biocompatible polyelectrolyte poly(vinyl raffinose- co -acrylic acid) (PRCA) containing a raffinose branch was prepared via redox polymerization using Fe2+/K2S2O8/H2O2 starting from enzymatically-synthesized monomer: 1- O -vinyldecanedioyl raffinose. Copolymers with different monomer feed ratios were prepared and characterized with IR, NMR, and GPC. PRCA can be alternated with polycation to form microcapsules on a crystals template by electrostatic layer-by-layer technique. The multilayers of PRCA/poly(methacryloyloxyethyl dimethylbenzyl ammonium chloride) (PMBA) on quartz slides and PRCA/poly(dimethyldiallyl ammonium chloride) (PDDA) on acyclovir crystals template were fabricated and characterized with UV-Vis spectra, the microelectrophoretic measurement, and TEM. Hollow capsules can be formed after the removal of acyclovir crystals template in a buffer solution. The nano-capsule-carrying galactose residue is a potential targeting drug-controlled delivery systems. Synthesis of PRCA and TEM image of a hollow (PRCA/PDDA)10 capsule. [source] Structure and Properties of CdS/Regenerated Cellulose NanocompositesMACROMOLECULAR MATERIALS & ENGINEERING, Issue 10 2005Dong Ruan Abstract Summary: Novel inorganic-organic hybrid materials composed of cadmium sulfide (CdS) semiconducting nanocrystals and regenerated cellulose (RC) were prepared by using in situ synthesizing method. Cellulose was dissolved in a 6 wt.-% NaOH/4 wt.-% urea/thiourea aqueous solution at low temperature followed by addition of cadmium chloride (CdCl2), resulting that the CdS nanocrystals were successfully grown in situ in the cellulose solution. Nanocomposite films containing homogeneous CdS nanoparticles were obtained by casting the resulting solution. Their structure and optical properties were characterized by X-ray photoelectron spectroscopy, wide-angle X-ray diffraction, thermogravimetry analysis, dynamic mechanical analysis, atomic force microscopy, transmittance electronic microscope, UV-vis spectroscopy, and photoluminescence spectroscopy. The experimental results confirmed that the CdS nanocrystalline existed in the composite films, and cellulose matrix provided a confined medium for CdS particle growth in uniform size. The CdS/RC composites showed narrow emission in photoluminescence spectra, and their optical absorbance in the UV range was higher than that of the cellulose film without CdS. This work provided a simple method to prepare cellulose functional materials in NaOH/urea aqueous solution. Photoluminescence of CdS/RC nanocomposites and TEM image of CdS nanocrystals dispersed in RC matrix. [source] Synthesis of PEDOT Nanoparticles and Vesicles by Dispersion Polymerization in Alcoholic MediaMACROMOLECULAR RAPID COMMUNICATIONS, Issue 17 2006Muhammad Mumtaz Abstract Summary: The synthesis of PEDOT nanoparticles and vesicles by dispersion polymerization in a methanol/water mixture (3/2, v/v) is reported, using either ammonium persulfate or iron(III) p -toluenesulfonate as oxidants and , -EDOT-PEO as a reactive stabilizer. The influence of the oxidant as well as the , -EDOT-PEO molar mass and concentration on the core-shell particle morphology and conductivity properties have been investigated. PEDOT particles with conductivities up to 1.5,×,10,2 S,·,cm,1 have been obtained in high yield. TEM image of PEDOT vesicles prepared using PEO-based stabilizers of 25,000 g,·,mol,1 in water/methanol mixture (2:3 v/v) at room temperature using ammonium persulfate as an oxidant. [source] Electrostatic Forces Induce Poly(vinyl alcohol)-Protected Copper Nanoparticles to Form Copper/Poly(vinyl alcohol) Nanocables via ElectrospinningMACROMOLECULAR RAPID COMMUNICATIONS, Issue 2 2006Zhenyu Li Abstract Summary: Copper/poly(vinyl alcohol) (PVA) nanocables have been successfully obtained by electrospinning a PVA-protected copper nanoparticle solution. The molar ratio of copper ions to PVA (in terms of VA repeating units) plays an important role in the formation of copper/PVA nanocables. The average diameter of the copper cores and PVA shells is about 100 and 400 nm, respectively. The structures of the copper/PVA nanocables are characterized by transmission electron microscopy (TEM) and their formation is confirmed by scanning electron microscopy (SEM). TEM image of a copper/PVA nanocable. [source] Facile Fabrication of Functional Polypyrrole Nanotubes via a Reactive Self-Degraded TemplateMACROMOLECULAR RAPID COMMUNICATIONS, Issue 21 2005Xiaoming Yang Abstract Summary: Polypyrrole nanotubes with high electric conductivity and azo function have been fabricated in high yield via an in-situ polymerization. During the process fibrillar complex of FeCl3 and methyl orange (MO), acting as a reactive self-degraded template, directed the growth of polypyrrole on its surface and promoted the assembly into hollow nanotubular structures. TEM image of uncompleted PPy nanotubes synthesized in MO solutions after reaction for 40 min. [source] Construction of Polycation-Based Non-Viral DNA Nanoparticles and Polyanion Multilayers via Layer-by-Layer Self-Assembly,MACROMOLECULAR RAPID COMMUNICATIONS, Issue 20 2005Kefeng Ren Abstract Summary: The multilayers of polycation-based non-viral DNA nanoparticles and biodegradable poly(L -glutamic acid) (PGA) were constructed by a layer-by-layer (LbL) technique. Poly(ethyleneimine) (PEI) was used to condense DNA to develop non-viral DNA nanoparticles. AFM, UV-visible spectrometry, and TEM measurements revealed that the PEI-DNA nanoparticles were successfully incorporated into the multilayers. The well-structured, easily processed multilayers with the non-viral DNA nanoparticles may provide a novel approach to precisely control the delivery of DNA, which may have great potential for gene therapy applications in tissue engineering, medical implants, etc. A TEM image of the cross section of a (PGA/PEI-DNA nanoparticle)20 multilayer. [source] Supramolecular Assembly of Gold Nanoparticles Mediated by Polypseudorotaxane with Thiolated , -Cyclodextrin,MACROMOLECULAR RAPID COMMUNICATIONS, Issue 5 2005Yu Liu Abstract Summary: A water-soluble gold nanoparticle aggregate 2 was prepared by chloroauric acid and a polypseudorotaxane 1 of mono-6-thio- , -cyclodextrin with poly(propylene glycol) bis(2-aminopropyl ether) (,,,2,000) in the presence of sodium borohydride in N,N -dimethylformamide (DMF) solution. The investigative results indicated that the gold nanoparticle aggregate 2 might act as an efficient DNA-cleavage reagent. A typical TEM image of gold nanoparticle aggregate 2. [source] A Novel Approach to the Preparation of Nanoblends of Poly(2,6-dimethyl-1,4-phenylene oxide)/Polyamide 6MACROMOLECULAR RAPID COMMUNICATIONS, Issue 2 2005Yali Ji Abstract Summary: A novel approach of in situ polymerization and in situ compatibilization was adopted to prepare poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) and polyamide 6 (PA6) nanoblends. Anionic ring-opening polymerization of , -caprolactam was carried out in the presence of PPO, the chain of which bore p -methoxyphenylpropionate (MPAA), acting as macroactivator to initiate PA6 chain growth from the PPO chain and form a graft copolymer of PPO and PA6 and pure PA6 simultaneously. The nanostructured PA6 dispersed phase in the PPO matrix could be achieved. A TEM image of poly(2,6-dimethyl-1,4-phenylene oxide)/polyamide 6 nanoparticles obtained from in situ polymerization and in situ compatibilization. [source] Silk Sericin Retards the Crystallization of Silk FibroinMACROMOLECULAR RAPID COMMUNICATIONS, Issue 20 2004Ki Hoon Lee Abstract Summary: The thermal and structural analysis of silk fibroin (SF) and silk sericin (SS) blend films reveals that the crystallization of SF is retarded in the presence of SS. Although a phase separation was observed, there might be a strong interaction at the boundary of the SF and SS through intermolecular hydrogen bonding, which restricts the conformational transition of SF. TEM image of the cross-section of the SF/SS blend (75:25) film (magnification: ×15,000). [source] Encapsulation and Sustained Release of Curcumin using Superparamagnetic Silica ReservoirsCHEMISTRY - A EUROPEAN JOURNAL, Issue 23 2009Fun Chin Abstract For controlled release and targeted delivery of curcumin in an aqueous medium a method of encapsulating curcumin and magnetic nanoparticles inside porous silica matrix has been developed. Curcumin and superparamagnetic nanoparticles are loaded inside porous silica in a single process. The graphic shows the TEM image of microtomed sample of Fe3O4 particles surrounded by a silica matrix. [source] Kinetic and DFT Studies on the Photoinduced Desorption of Sulfur from Gold Nanoparticles Loaded on Titanium DioxideCHEMPHYSCHEM, Issue 12 2005Tomokazu Kiyonaga Cleaning poisoned gold catalysts: Kinetic analysis of the photoinduced desorption of sulfur from gold nanoparticles loaded on TiO2 particles in water revealed that the rate constant increases with increasing pH. Photoelectrochemical measurements and DFT calculations led to the conclusion that this reaction results from an upward shift in the Fermi energy of gold nanoparticles by irradiation. The picture shows a high-resolution TEM image of an Au nanoparticle on TiO2. [source] Silica Supported Submicron SiO2@Y2SiO5:Eu3+ and SiO2@Y2SiO5:Ce3+/Tb3+ Spherical Particles with a Core,Shell Structure: Sol,Gel Synthesis and CharacterizationEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2006Cuikun Lin Abstract X1 -Y2SiO5:Eu3+ and X1 -Y2SiO5:Ce3+ and/or Tb3+ phosphor layers have been coated on nonaggregated, monodisperse, submicron spherical SiO2 particles by a sol,gel process, followed by surface reaction at high temperature (1000 °C), to give core/shell structured SiO2@Y2SiO5:Eu3+ and SiO2@Y2SiO5:Ce3+/Tb3+ particles. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), TEM, photoluminescence (PL), low voltage cathodoluminescence (CL), and time-resolved PL spectra and lifetimes are used to characterize these materials. The XRD results indicate that X1 -Y2SiO5 layers have been successfully coated on the surface of SiO2 particles, as further verified by the FESEM and TEM images. The PL and CL studies suggest that SiO2@Y2SiO5:Eu3+, SiO2@Y2SiO5:Tb3+ (or Ce3+/Tb3+), and SiO2@Y2SiO5:Ce3+ core/shell particles exhibit red (Eu3+, 613 nm: 5D0,7F2), green (Tb3+, 542 nm: 5D4,7F5), or blue (Ce3+, 450 nm: 5d-4f) luminescence, respectively. PL excitation, emission, and time-resolved spectra demonstrate that there is an energy transfer from Ce3+ to Tb3+ in the SiO2@Y2SiO5:Ce3+,Tb3+ core/shell particles. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Catalyst-Free Synthesis and Characterization of Metastable Boron Carbide NanowiresADVANCED FUNCTIONAL MATERIALS, Issue 24 2009Aruna Velamakanni Abstract Catalyst-free growth of boron carbide nanowires is achieved by pyrolysis of diborane and methane at 650,750,°C and around 500 mTorr in a quartz tube furnace. Electron-diffraction analysis using a novel diffraction-scanning transmission electron microscopy (D-STEM) technique indicates that the crystalline nanowires are single-crystal orthorhombic boron carbide. TEM images show that the nanowires are covered by a 1,3,nm thick amorphous layer of carbon. Elemental analysis by electron energy loss spectroscopy (EELS) shows only boron and carbon while energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) show the presence of oxygen as well as boron and carbon. [source] The Effect of Thermal Treatment on the Morphology and Charge Carrier Dynamics in a Polythiophene,Fullerene Bulk Heterojunction,ADVANCED FUNCTIONAL MATERIALS, Issue 8 2005J. Savenije Abstract The influence of various thermal treatment steps on the morphology and the photoconductive properties of a non-contacted, 50,nm thick blend (50:50,wt.-%) of [6,6]-phenyl C61 -butyric acid methyl ester (PCBM) and poly(3-hexyl thiophene) (P3HT) spin-coated from chloroform has been studied using transmission electron microscopy (TEM) and the electrodeless time-resolved microwave conductivity technique. After annealing the film for 5,min at 80,°C, TEM images show the formation of crystalline fibrils of P3HT due to a more ordered packing of the polymer chains. The thermal treatment results in a large increase of the photoconductivity, due to an enhancement of the hole mobility in these crystalline P3HT domains from 0.0056,cm2,V,1,s,,1 for the non-annealed sample to 0.044,cm2,V,1,s,,1 for the sample annealed at 80,°C. In contrast, the temporal shape of the photoconductivity, with typical decay half-times, ,1/2, of 1,,s for the lowest excitation intensities, is unaffected by the temperature treatment. Further annealing of the sample at 130,°C results in the formation of three different substructures within the heterojunction: a PCBM:P3HT blend with PCBM-rich clusters, a region depleted of PCBM, and large PCBM single crystals. Only a minor increase in the amplitude, but a tenfold rise of the decay time of the photoconductivity, is observed. This is explained by the formation of PCBM-rich clusters and large PCBM single crystals, resulting in an increased diffusional escape probability for mobile charge carriers and hence reduced recombination. [source] Effect of the origin of ZnO nanoparticles dispersed in polyimide films on their photoluminescence and thermal stabilityJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2008Anongnat Somwangthanaroj Abstract Polyimide (PI) films containing dispersed ZnO nanoparticles were prepared from both zinc nitrate hexahydrate (designated as Zn(NO3)2/PI) and ZnO nanoparticles, 2-nm average primary size (ZnO/PI). This work shows how the origin of ZnO affects both the photoluminescence and thermal decomposition of the film. The presence of ZnO derived from Zn(NO3)2·6H2O was confirmed by X-ray diffraction technique. The fluorescent intensities from Zn(NO3)2/PI and ZnO/PI were much higher than that from pure PI films. When the ZnO concentration exceeded a certain saturation level, the emission intensity decreased due to the undesirable aggregation of ZnO. At the same concentration, ZnO/PI exhibited higher emission intensity than Zn(NO3)2/PI. All samples prepared under nitrogen emitted higher intensity than their counterparts prepared under argon. The ZnO/PI film was thermally more stable than the Zn(NO3)2/PI one. From TEM images of 117.6 mol% ZnO/PI films, the ZnO aggregates, whose average size was 17,90 nm, were well distributed throughout the film but poorly dispersed in nanometer range. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Morphology and mechanical and viscoelastic properties of rubbery epoxy/organoclay montmorillonite nanocompositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2007Amar Boukerrou Abstract The morphology and mechanical and viscoelastic properties of rubbery epoxy/organoclay montmorillonite (MMT) nanocomposites were investigated with wide-angle X-ray scattering (WAXS), transmission electron microscopy (TEM), tensile testing, and dynamic mechanical thermal analysis. An ultrasonicator was used to apply external shearing forces to disperse the silicate clay layers in the epoxy matrix. The first step of the nanocomposite preparation consisted of swelling MMT in a curing agent, that is, an aliphatic diamine based on a polyoxypropylene backbone with a low viscosity for better diffusion into the intragalleries. Then, the epoxy prepolymer was added to the mixture. Better dispersion and intercalation of the nanoclay in the matrix were expected. The organic modification of MMT with octadecylammonium ions led to an increase in the initial d -spacing (the [d001] peak) from 14.4 to 28.5 Å, as determined by WAXS; this indicated the occurrence of an intercalation. The addition of 5 phr MMTC18 (MMT after the modification) to the epoxy matrix resulted in a finer dispersion, as evidenced by the disappearance of the diffraction peak in the WAXS pattern and TEM images. The mechanical and viscoelastic properties were improved for both MMT and MMTC18 nanocomposites, but they were more pronounced for the modified ones. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 103: 3547,3552, 2007 [source] Synthesis of multiwalled carbon nanotubes on Al2O3 supported Ni catalysts in a fluidized-bedAICHE JOURNAL, Issue 1 2010Jun Liu Abstract Multiwalled carbon nanotubes (MWNTs) were synthesized on Al2O3 supported Ni catalysts from C2H2 and C2H4 feedstocks in a fluidized bed. The influence of the ratio of superficial gas velocity to the minimum fluidization velocity (U/Umf), feedstock type, the ratio of carbon in the total quantity of gas fed to the reactor, reaction temperature, the ratio of hydrogen to carbon in the feed gas, and nickel loading were all investigated. Significantly, the pressure drop across the fluidized-bed increased as the reaction time increased for all experiments, due to the deposition of MWNTs on the catalyst particles. This resulted in substantial changes to the depth and structure of the fluidized bed as the reaction proceeded, significantly altering the bed hydrodynamics. TEM images of the bed materials showed that MWNTs, metal catalysts, and alumina supports were predominant in the product mixture, with some coiled carbon nanotubes as a by-product. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Synthesis of hollow crosslinked miktoarm polymer using miniemulsion as templatesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 6 2009De'an Xiong Abstract Hollow crosslinked polymers (HCPs) were synthesized using arm first method via atom transfer radical polymerization. The polymerization process was performed in miniemulsion system, in which the macroinitiator, PEG-Br, was in the water phase, whereas the vinyl-monomer, 4-vinylpyridine (4VP), and the crosslinker, DVB, were in the butanone phase. TEM images and light scattering characterization showed that the resultant polymer contained a hollow space, and the volume of the hollow space could be adjusted by changing the ratio of water to butanone. Also, hollow crosslinked Miktoarm polymers (HCMPs) were synthesized through this method when two different macroinitiators, PEG-Br and PNIPAM-Br, were used to coinitiate the polymerization of the vinyl-monomer, 4VP and DVB. The 1H NMR spectra showed that the hollow polymers contained both PEG arms and PNIPAM arms. The hollow morphologies of the resultant Miktoarm polymers were the same as the HCPs. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1651,1660, 2009 [source] Construction of diads and triads copolymer systems containing perylene, porphyrin, and/or fullerene blocksJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 20 2006Ning Wang Abstract A series of conjugated copolymers containing perylene, porphyrin, and/or fullerene units on the main chain have been synthesized. The structures and photophysical properties of polymers were characterized by FTIR, NMR, UV,vis, and fluorescence spectroscopy, gel permeation chromatography, and cyclic voltammetry. The photoinduced charge transfer properties of the films were also measured by a three-electrode cell technique. A rapid, steady, and reproducible cathodic photocurrent response for each polymer was produced when the film was irradiated by a white light. The SEM and TEM images displayed the aggregation superstructures of the polymers. In chloroform, polySPeZnP2F could form a large quantity of spherical nanoparticles. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5863,5874, 2006 [source] Functionalized multi-walled carbon nanotubes with poly(N -(2-hydroxypropyl)methacrylamide) by RAFT polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 8 2006Chun-Yan Hong Abstract In this study, we grafted water-soluble biocompatible polymer, poly(N -(2-hydroxypropyl)methacrylamide) (PHPMA), onto the surface of multi-walled carbon nanotubes (MWNTs). The reversible addition-fragmentation chain transfer (RAFT) agents, dithioesters, were successfully immobilized onto the surface of MWNTs first, PHPMA chains were then subsequently grafted onto MWNTs via RAFT polymerization by using dithioesters immobilized on MWNTs as RAFT agent. FTIR, XPS, 1H NMR, Raman and TGA were used to characterize the resulting products and to determine the content of water-soluble PHPMA chains in the product. The MWNTs grafted with PHPMA chains have good solubility in distilled water, PBS buffer, and methanol. TEM images of the samples provide direct evidence for the formation of a nanostructure that MWNTs coated with polymer layer. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2419,2427, 2006 [source] Fabrication of NiO Nanoparticle-Coated Lead Zirconate Titanate Powders by the Heterogeneous Precipitation MethodJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2003Ping-Hua Xiang NiO nanoparticle-coated lead zirconate titanate (PZT) powders are successfully fabricated by the heterogeneous precipitation method using PZT, Ni(NO3)2·6H2O, and NH4HCO3 as the starting materials. The amorphous NiCO3·2Ni(OH)2·2H2O are uniformly coated on the surface of PZT particles. XRD analysis and the selected-area diffraction (SAD) pattern indicate that the amorphous coating layer is crystallized to NiO after being calcined at 400°C for 2 h. TEM images show that the NiO particles of ,8 nm are spherical and weakly agglomerated. The thickness of the nanocrystalline NiO coating layer on the surface of PZT particle is ,30 nm. [source] Laser-induced atomic assembling of periodic layered nanostructures of silver nanoparticles in fluoro-polymer film matrixLASER PHYSICS LETTERS, Issue 5 2010V.N. Bagratashvili Abstract Fluorinated acrylic polymer (FAP) films have been impregnated with silver precursor (Ag(hfac)COD) by supercritical fluid technique and next irradiated with laser (, = 532 nm). Laser-chemically reduced Ag atoms have been assembled into massifs of Ag nanoparticles (3,8 nm) in FAP/Ag(hfac)COD films matrix in the form of periodic layered nanostructures (horizontal to film surface) with unexpectedly short period (90,180 nm). The wavelet analysis of TEM images reveals the existence of even shorter-period structures in such films. Photolysis with non-coherent light or pyrolysis of FAP/Ag(hfac)COD film results in formation of Ag nanoparticles massifs but free of any periodic nanoparticle assemblies. Our interpretation of the observed effect of laser formation of short-period nano-sized Ag nanoparticle assemblies is based on self-enhanced interference process in the course of modification of optical properties of film. (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Microphase-Separated Poly(vinylpyridine) Block Copolymer Prepared with a Novel Bifunctional InitiatorMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 7 2009Masami Shoji Abstract A vinylpyridine block copolymer was prepared by stepwise controlled/living radical polymerization with a novel bifunctional initiator, 4-(2-bromopropanoyloxy)- N -(p -methylbenzyloxy)-2,2,6,6-tetramethylpiperidine. The initiator was synthesized in a facile manner using commercially available p -xylene and 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (4-hydroxy TEMPO). Through stepwise atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) and nitroxide-mediated radical polymerization (NMRP) of 4-vinylpyridine (4VP), the PMMA- b- P4VP copolymer was prepared with a wide range of the copolymer compositions. Microphase-separation was demonstrated in cross sectional TEM images of self-standing block copolymer membranes. [source] N -Isopropylacrylamide/2-Hydroxyethyl Methacrylate Star Diblock Copolymers: Synthesis and Thermoresponsive BehaviorMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 24 2006Zhiqiang Cao Abstract Summary: Tri-arm star diblock copolymers, poly(2-hydroxyethyl methacrylate)- block -poly(N -isopropylacrylamide) [P(HEMA- b -NIPAAm)] with PHEMA and PNIPAAm as separate inner and outer blocks were synthesized via a two-step ATRP at room temperature. The formation, molecular weight and distribution of polymers were examined, and the kinetics of the reaction was monitored. The PDI of PHEMA was shown to be lower, indicating well-controlled polymerization of trifunctional macro-initiator and resultant star copolymers. The thermoresponsive behavior of diblock copolymer aqueous solution were studied by DSC, phase diagrams, temperature-variable 1H NMR, TEM and DLS. The results revealed that introducing a higher ratio of HEMA into copolymers could facilitate the formation of micelles and the occurrence of phase transition at lower temperatures. TEM images showed that I-(HEMA40 -NIPAAm320)3 solutions developed into core-shell micelles with diameters of approximately 100 nm. I-(HEMA40 -NIPAAm320)3 was used as a representative example to elucidate the mechanism underlying temperature-induced phase transition of copolymer solution. In this study we proposed a three-stage transition process: (1) separately dispersed micelles state at ,17,22,°C; (2) aggregation and fusion of micelles at ,22,29,°C; (3) sol-gel transition of PNIPAAm segments at ,29,35,°C, and serious syneresis of shell layers. Molecular architecture of Poly(HEMA- b -NIPAAm). [source] | |||||||||||||||||||||||||||||||