We have evidenced the high sensitivity of infrared-induced second harmonic generation (IR-ISHG) to the structural changes occurred in amorphous hydrogenated silicon films (a-Si: H) prepared by RF-glow discharge technique at different substrate temperatures and doping types. In every case, a maximal signal of the IR-induced SHG is achieved at temperature of about 110 K and pump-probe delaying time about 22–39 ps. It indicates a marked effect of doped subsystems in the observed nonlinear optical effects. A substantial effect of doping is established from a drastic change of the IR-induced SHG behavior presenting an anomaly at about 400 MW/<mml:math id="E1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msup><mml:mrow><mml:mtext>cm</mml:mtext></mml:mrow><mml:mn>2</mml:mn></mml:msup></mml:mrow></mml:math> for a pumping power with wavelength 1.54 <mml:math id="E2" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>μ</mml:mi></mml:math>m. A minimum of the SHG is observed in that case for standard nondoped films. Note here that the doping type does not affect the behavior of the second-order nonlinear optical susceptibility. The thermo annealing leads to a slight decrease of the effective second-order susceptibilities. Larger changes are observed with doped samples for the pump-probe delaying time from about 39 till 24 ps.

J. Ebothé

K. J. Plucinski

K. Nouneh

P. Roca i Cabarrocas

I. V. Kityk

Nonlinear Optical Study of Nano-Sized Effects in a-Si: H Thin Films Deposited by RF-Glow Discharge

Novel polyimide-silica nanocomposites with interphase chemical bonding have been prepared using the sol-gel process. The morphology, thermal and mechanical properties were studied as a function of silica content and compared with the similar composites having no interphase interaction. The polyimide precursors, polyamic acids (PAAs) with or without pendant hydroxyl groups were prepared from the reaction of pyromellitic dianhydride with a mixture of oxydianiline and 1,3 phenylenediamine or 2,4-diminophenol in dimethylacetamide. The PAA with pendant hydroxyl groups was reacted with isocyanatopropyltriethoxysilane to produce alkoxy groups on the chain. The reinforcement of PAA matrices with or without alkoxy groups on the chain was carried out by mixing appropriate amount of tetraethoxysilane (TEOS) and carrying out its hydrolysis and condensation in a sol-gel process. Thin hybrid films were imidized by successive heating up to 300<mml:math id="E1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mtext>C</mml:mtext><mml:mo>∘</mml:mo></mml:mrow></mml:math>. The presence of alkoxy groups on the polymer chain and their cocondensation with TEOS developed the silica network which was interconnected chemically with the polyimide matrix. SEM studies show a drastic decrease in the silica particle size in the chemically bonded system. Higher thermal stability and mechanical strength, improved transparency, and low values of thermal coefficient of expansion were observed in case of chemically bonded composites.

A. Al Arbash

Z. Ahmad

F. Al-Sagheer

A. A. M. Ali

Microstructure and Thermomechanical Properties of Polyimide-Silica Nanocomposites

Both process and mechanical of silicon substrate chemical mechanical polishing (CMP) are studied in detail, and the effects of experiments designed indicate that nano-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mrow><mml:mtext>SiO</mml:mtext></mml:mrow><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math> grinding particles seem to be acted as catalyzer besides the grinding action during the CMP process. This is different from the traditional function. As a result, in the condition of low pH, the nano-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mrow><mml:mtext>SiO</mml:mtext></mml:mrow><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math> slurry can be recycled. In the meanwhile, the removal rate can gain stability and pH value does not change obviously.

Liu  Yuling

Wang  Juan

Sun  Ming

Liu  Chenglin

Study on the Effect of Nano-SiO2 in ULSI Silicon Substrate Chemical Mechanical Polishing Process

Polystyrene (PS) chains with molecular weights comprised between 8000 and 64000 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mtext>g</mml:mtext><mml:msup><mml:mrow><mml:mo>&#x22C5;</mml:mo><mml:mtext>mol</mml:mtext></mml:mrow><mml:mrow><mml:mo>-1</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math> and narrow polydispersities were grown from the surface of silica nanoparticles (Aerosil A200 fumed silica and St&#246;ber silica, resp.) through nitroxide-mediated polymerization (NMP). Alkoxyamine initiators based on N-tert-butyl-1-diethylphosphono-2,2-dimethylpropyl nitroxide (DEPN) and carrying a terminal functional group have been synthesized in situ and grafted to the silica surface. The resulting grafted alkoxyamines have been employed to initiate the growth of polystyrene chains from the inorganic surface. The maximum grafting density of the surface-tethered PS chains was estimated and seemed to be limited by initiator confinement at the interface. Then, the PS-grafted St&#246;ber silica nanoparticles were entrapped inside latex particles via miniemulsion polymerization. Transmission electron microscopy indicated the successful formation of silica-polystyrene core-shell particles.

B&#233;rang&#232;re  Bailly

Anne-Carole  Donnenwirth

Christ&#232;le  Bartholome

Emmanuel  Beyou

Elodie  Bourgeat-Lami

Silica-Polystyrene Nanocomposite Particles Synthesized by Nitroxide-Mediated Polymerization and Their Encapsulation through Miniemulsion Polymerization

Nanocomposite gel coat system is prepared using unsaturated polyester resin with aerosil powder, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mrow><mml:mtext>CaCO</mml:mtext></mml:mrow><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math>, and organoclay. The influence of organoclay addition on mechanical and water barrier properties of gel coat system is studied for different amount (1, 2, and 3 wt <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>&#x0025;</mml:mi></mml:math>) of organoclay. The nanolevel incorporation of organoclay improves the mechanical and water barrier properties of nanocomposite gel coat system. The nanocomposite gel coat system exhibits 55<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>&#x0025;</mml:mi></mml:math> improvement in tensile modulus and 25<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>&#x0025;</mml:mi></mml:math> improvement in flexural modulus. There is a 30<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>&#x0025;</mml:mi></mml:math> improvement in impact property of nanocomposite gel coat system. The dynamic mechanical analysis shows a slight increase in glass transition temperature for nanocomposite gel coat system.

P.  Jawahar

M.  Balasubramanian

Preparation and Properties of Polyester-Based Nanocomposite Gel Coat System

This article analyzed and studied the concentration mechanism of metal impurities of ULSI multilayered wiring CMP in the special-purpose nanometer <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mrow><mml:mtext>SiO</mml:mtext></mml:mrow><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math> grinding compound in the substrate chip surface and the process of purification with chelating agent; we also obtained the remarkable effect and the effective application in the microelectron component preparation.

Li  Weiwei

Zhang  Xihui

Liu  Changyu

Control Effect of Nanometer SiO2 Hydrosol on Alloy Impurity in CMP Process of ULSI

Vacuum-assisted resin transfer molding (VARTM) process was used to fabricate the nanocomposites through integrating carbon nanofiber paper into traditional glass fiber reinforced composites. The carbon nanofiber paper had a porous structure with highly entangled carbon nanofibers and short glass fibers. In this study, the carbon nanofiber paper was employed as an interlayer and surface layer of composite laminates to enhance the damping properties. Experiments conducted using the nanocomposite beam indicated up to 200–700% increase of the damping ratios at higher frequencies. The scanning electron microscopy (SEM) characterization of the carbon nanofiber paper and the nanocomposites was also conducted to investigate the impregnation of carbon nanofiber paper by the resin during the VARTM process and the mechanics of damping augmentation. The study showed a complete penetration of the resin through the carbon nanofiber paper. The connectivities between carbon nanofibers and short glass fibers within the carbon nanofiber paper were responsible for the significant energy dissipation in the nanocomposites during the damping tests.

Jihua Gou

Scott O'Braint

Haichang Gu

Gangbing Song

Damping Augmentation of Nanocomposites Using Carbon Nanofiber Paper

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Journal of Nanomaterials publishes research on nanoscale and nanostructured materials with an emphasis on synthesis, processing, characterization, and the applications of nanomaterials.

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Chief Editor Stefano Bellucci is Professor of Theoretical Physics at the National Institute for Nuclear Physics in Frascati, Italy. His research interests include&nbsp;nanoscience and nanotechnology, nanocarbon-based composites, and the biomedical applications of nanomaterials.

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Journal of Nanomaterials

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Journal of Nanomaterials

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Articles

Nonlinear Optical Study of Nano-Sized Effects in a-Si: H Thin Films Deposited by RF-Glow Discharge

Microstructure and Thermomechanical Properties of Polyimide-Silica Nanocomposites

Study on the Effect of Nano-SiO₂ in ULSI Silicon Substrate Chemical Mechanical Polishing Process

Silica-Polystyrene Nanocomposite Particles Synthesized by Nitroxide-Mediated Polymerization and Their Encapsulation through Miniemulsion Polymerization

Preparation and Properties of Polyester-Based Nanocomposite Gel Coat System

Control Effect of Nanometer SiO₂ Hydrosol on Alloy Impurity in CMP Process of ULSI

Damping Augmentation of Nanocomposites Using Carbon Nanofiber Paper