Matrix-Assisted Formation of Metal Nanoparticles in Organosilica Sol-Gels

2002 ◽  
Vol 726 ◽  
Author(s):  
Sandie H. Cheung ◽  
Bakul C. Dave
Keyword(s):  
Metal Nanoparticles ◽  
Chemical Reduction ◽  
Sol Gel ◽  
Synthesis Method ◽  
Porous Silica ◽  
Ambient Conditions ◽  
Transmission Electron ◽  
Organically Modified ◽  
Structural Template

AbstractThe use of organosilica sol-gels for controlled in-situ formation of metal nanoparticles is investigated. The use of an organically-modified alkoxysilane precursor provides chemically interacting nanopores for the sequestration and binding of metal ions followed by chemical reduction to form metal nanoparticles. The sol-gel matrix acts as a structural template to enable growth of the metal nanoparticles within its porous silica framework, and prevents clustering to form precipitate. Furthermore, simple redox chemistry is used to convert pre-formed copper nanoparticles in the sol-gel matrix into silver and gold nanoparticles. A particularly important aspect of this synthesis method is that all the reaction chemistry is performed under ambient conditions. The particles are characterized by high resolution transmission electron microscopy for their sizes and size distribution. The elemental composition of the particles is determined by energy dispersive X-ray analysis.

In Situ Synthesis and Tribological Behavior of Copper Nanopieces in Liquid Paraffin as Additive in Mobil 1 5W- 30 Lubricating Oil

2013 ◽  
Vol 669 ◽  
pp. 349-354
Author(s):  
Xi Feng Zhang ◽  
Ke Wei Li ◽  
Ying Zhou ◽  
Xiao Nong Cheng
Keyword(s):  
Tribological Behavior ◽  
Average Length ◽  
Chemical Reduction ◽  
Liquid Paraffin ◽  
Synthesis Method ◽  
Lubricating Oil ◽  
X Ray Diffraction ◽  
Average Width ◽  
Transmission Electron

To synthesize morphology- controlled nano- copper with excellent lubrication properties as lubricant’s additive, chemical reduction synthesis method was used coalescing in situ via liquid paraffin as resolvent and modification with polyethylene glycol (PEG-2000). The as- prepared Cu nanopieces with 35.59 nm average length and 21.03 nm average width were characterized by X-ray diffraction (XRD), and transmission electron microscopy (TEM). The tribological behavior of Mobil 1 5W-30 lubricating oil with nano- Cu were measured by ball- on- disk UMT- Ⅱ tribometer and analyzed by SEM and EDS. It is found that the tribological performance of Mobil 1 5W- 30 with nano- Cu is improved, and the optimization addition is 0.4% (Cu wt) with the lowest friction coefficient.

Bioencapsulation in Sol-Gel Glasses

1998 ◽  
Vol 519 ◽  
Author(s):  
L. Bergogne ◽  
S. Fennouh ◽  
J. Livage ◽  
C. Roux
Keyword(s):  
Sol Gel ◽  
Porous Silica ◽  
Silica Matrix ◽  
Whole Cells ◽  
The Past ◽  
Wide Range ◽  
Activity Of Enzymes ◽  
Gel Glasses ◽  
Micro Organisms

AbstractBioencapsulation in sol-gel materials has been widely studied during the past decade. Trapped species appear to retain their bioactivity in the porous silica matrix. Small analytes can diffuse through the pores allowing bioreactions to be performed in-situ, inside the sol-gel glass. A wide range of biomolecules and micro-organisms have been encapsulated. The catalytic activity of enzymes is used for the realization of biosensors or bioreactors. Antibody-antigen recognition has been shown to be feasible within sol-gel matrices. Trapped antibodies bind specifically the corresponding haptens and can be used for the detection of traces of chemicals. Even whole cells are now encapsulated without any alteration of their cellular organization. They can be used for the production of chemicals or as antigens for immunoassays.

Eu3+/Tb3+ Co-Doped Cerium Oxide Transparent Nanocomposite for Color-Tunable Emission

NANO ◽  
2018 ◽  
Vol 13 (10) ◽  
pp. 1850119
Author(s):  
Xiaoyan Li ◽  
Yunlong Yu ◽  
Xiangfeng Guan ◽  
Peihui Luo ◽  
Linqin Jiang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thermal Stability ◽  
Transmission Electron Microscopy ◽  
Sol Gel ◽  
Homogeneous Precipitation ◽  
Transmission Electron ◽  
Color Tunable ◽  
Co Doped ◽  
Tunable Emission

Eu[Formula: see text]/Tb[Formula: see text] co-doped nanocomposite containing CeO2 nanocrystals was successfully prepared by an in situ sol–gel polymerization approach. High-resolution transmission electron microscopy demonstrated the homogeneous precipitation of CeO2 nanocrystals among the polymethylmethacrylate (PMMA) matrix. The thermal stability and UV-shielding capability of the obtained nanocomposite were improved with increase of CeO2 content. The tuning of the emissive color from green and yellow to red can be easily achieved by varying the dopant species and concentration. These results suggested that the obtained nanocomposite could be potentially applicable in transparent solid-state luminescent devices.

scholarly journals Polypropylene Nanocomposites Obtained byIn SituPolymerization Using Metallocene Catalyst: Influence of the Nanoparticles on the Final Polymer Morphology

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Paula Zapata ◽  
Raúl Quijada
Keyword(s):  
Catalytic System ◽  
Sol Gel ◽  
Metallocene Catalyst ◽  
Particle Morphology ◽  
Polymer Particle ◽  
Silica Nanospheres ◽  
Sem Images ◽  
Transmission Electron ◽  
Polypropylene Nanocomposites

Polypropylene nanocomposites containing silica nanospheres based on the sol-gel methods were produced viain situpolymerization using a rac-Et(Ind)2ZrCl2/methylaluminoxane (MAO) system. Two different routes were used depending on the interaction between the silica nanoparticles with the catalytic system. In route 1 the nanoparticles were added together with the catalytic system (rac-Et(Ind)2ZrCl2)/(MAO) directly into the reactor, and in route 2 the metallocene rac-Et(Ind)2ZrCl2was supported on silica nanospheres pretreated with (MAO). SEM images show that when the nanospheres were added by both routes, they were replicated in the final polymer particle morphology; this phenomenon was more pronounced for PP obtained by route 2. The polypropylene (PP) nanocomposites obtained by both routes had a slightly higher percent crystallinities and crystallinity temperatures than pure PP. Transmission electron microscopy (TEM) images show that the nanospheres were well dispersed into the polypropylene matrix, particularly in the nanocomposites obtained by the support system (route 2).

Silica and Silane Coupling Agent for in Situ Reinforcement of Acrylonitrile-Butadiene Rubber

1999 ◽  
Vol 72 (1) ◽  
pp. 119-129 ◽  
Author(s):  
K. Murakami ◽  
S. Osanai ◽  
M. Shigekuni ◽  
S. Iio ◽  
H. Tanahashi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Sol Gel ◽  
Silica Particles ◽  
Butadiene Rubber ◽  
Acrylonitrile Butadiene Rubber ◽  
In Situ Silica ◽  
Transmission Electron ◽  
Dispersion Agent ◽  
The Relationship

Abstract In situ silica reinforcement for the acrylonitrile-butadiene rubber (NBR) vulcanizates, which were premixed with a conventional silica (VN-3) and γ-mercaptopropyltrimethoxysilane (γ-MPS), was achieved by the sol-gel reaction of tetraethoxysilane (TEOS) using ethylenediamine. It was observed that the reinforcement efficiency tended to increase with the increase of mechanically premixed conventional silica. From the observations of transmission electron microscopy and scanning electron microscopy, the simultaneous use of VN-3 and γ-MPS was found to promote the formation of large silica particles and clusters with a relatively good dispersion by the sol-gel reaction of TEOS in the NBR vulcanizate. The results of hysteresis measurements supported this promotion. It was considered to be due to the surface modification of VN-3 by the sol-gel reaction of TEOS and the presence of γ-MPS which worked as a dispersion agent for silica particles. The relationship between the mechanical properties and the morphology of the in situ silica filled vulcanizates is discussed.

Phase Transformations in Sol-Gel PZT Thin Films

2000 ◽  
Vol 623 ◽  
Author(s):  
D.P. Eakin ◽  
M.G. Norton ◽  
D.F. Bahr
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Room Temperature ◽  
Structural Changes ◽  
Sol Gel ◽  
Ex Situ ◽  
Ambient Conditions ◽  
Crystalline Films ◽  
In Situ Heating

AbstractThin films of PZT were deposited onto platinized and bare single crystal NaCl using spin coating and sol-gel precursors. These films were then analyzed using in situ heating in a transmission electron microscope. The results of in situ heating are compared with those of an ex situ heat treatment in a standard furnace, mimicking the heat treatment given to entire wafers of these materials for use in MEMS and ferroelectric applications. Films are shown to transform from amorphous to nanocrystalline over the course of days when held at room temperature. While chemical variations are found between films crystallized in ambient conditions and films crystallized in the vacuum conditions of the microscope, the resulting crystal structures appear to be insensitive to these differences. Significant changes in crystal structure are found at 500°C, primarily the change from largely amorphous to the beginnings of clearly crystalline films. Crystallization does occur over the course of weeks at room temperature in these films. Structural changes are more modest in these films when heated in the TEM then those observed on actual wafers. The presence of Pt significantly influences both the resulting structure and morphology in both in situ and ex situ heated films. Without Pt present, the films appear to form small, 10 nm grains consisting of both cubic and tetragonal phases, whereas in the case of the Pt larger, 100 nm grains of a tetragonal phase are formed.

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