Particle Growth and Development During the In-Situ Precipitation of Silica in a Polymeric Matrix

1990 ◽  
Vol 180 ◽  
Author(s):  
Ping Xu ◽  
Shuhong Wang ◽  
James E. Mark
Keyword(s):  
Sol Gel ◽  
Particle Growth ◽  
Isolation Technique ◽  
Additional Information ◽  
Elastomeric Matrix ◽  
Transmission Electron ◽  
Elastomeric Materials ◽  
Equilibrium Amount ◽  
Hydrolysis Of

ABSTRACTThe hydrolysis of tetraethoxysilane much used in the sol-gel approach to ceramics can be studied in a matrix isolation technique in which the silica thus formed precipitates within a polymeric material. This technique was applied here in the in-situ precipitation of silica particles in an elastomeric matrix of poly(dimethylsiloxane). Transmission electron microscopy and mechanical property measurements were carried out as a function of time over a period of 60 days. The equilibrium amount of silica precipitated was obtained relatively quickly, after approximately one day, but reorganization of the particles continued for several days thereafter. This “aging” process resulted in particles that are better defined and more uniform in size, but their ability to reinforce the elastomeric materials was only marginally increased. Scattering techniques are also being used to obtain additional information on this interesting process.

Performance of Polishing Slurries containing Silica Particles grown by Sol-Gel Method

2000 ◽  
Vol 613 ◽  
Author(s):  
Sun Hyuk Bae ◽  
Jae-Hyun So ◽  
Seung-Man Yang ◽  
Do Hyun Kim
Keyword(s):  
Fumed Silica ◽  
Sol Gel ◽  
Particle Growth ◽  
Silica Particles ◽  
Gel Method ◽  
Sol Gel Method ◽  
Irregular Shapes ◽  
Wafer Polishing ◽  
Transmission Electron ◽  
Silica Slurry

ABSTRACTSilica slurry used as abrasives in wafer polishing process is made by dispersing silica particles in an alkali solution. Since commercially available colloidal or fumed silica particles need some modifications to be directly used as abrasive slurry due to their small sizes, irregular shapes or broad size distribution, we have prepared silica abrasives by particle growth of fumed silica or colloidal silica as seeds by sol-gel method. Silica slurries prepared by this step-wise growth from commercial seeds were tested using one-armed polisher for the comparison with commercial slurries and showed the performance comparable to commercial slurries. Microstructures of polishing slurries were investigated using transmission electron microscopy and ARES rheometer. From the result, stability of the slurry was found to be more important than the primary particle sizes for the polishing performance.

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 Encapsulated CdS Tabular Nanocomposites via a Template Directed Agglomeration Mechanism

2008 ◽  
Vol 8 (11) ◽  
pp. 5878-5886 ◽  
Author(s):  
Jun Wang ◽  
Stephen J. Sollenberger ◽  
Ying Yuan ◽  
Timothy J. Yosenick ◽  
James H. Adair
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Coating Layer ◽  
Layer Growth ◽  
Cds Nanoparticles ◽  
Atomic Force ◽  
Transmission Electron ◽  
Potential Applications ◽  
Hydrolysis Of

Silica coated CdS tabular nanocomposites were synthesized through precipitation of CdS nanoparticles in octylamine/water bilayer system followed by in situ hydrolysis of tetraethoxylsilicate (TEOS) precursor. Face diameter of the nanoplatelets was in the range of 50∼250 nm with a variable thickness (3 to 25 nm) dictated by octylamine content or R ratio ([water]/[octylamine]). A uniform SiO2 outer shell of about 15 nm was observed regardless of the size of the high aspect ratio CdS nanoplatelets, which appeared to be agglomerated primarily owing to the confined bilayer template. Morphology and microstructure of the CdS/SiO2 tabular nanocomposites were characterized using atomic force microscope (AFM) and high resolution transmission electron microscope (HRTEM). A noticeable enhancement in absorbance for the UV-vis spectra was observed due to the SiO2 coating layer. Growth mechanism of nanocomposite platelets and potential applications associated with this anisotropic nanocomposite are discussed.

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.

Synthesis and Characterization of Organic/Inorganic Interpenetrating Polymer Networks

1995 ◽  
Vol 385 ◽  
Author(s):  
Barry J. Bauer ◽  
Catheryn L. Jackson ◽  
Da-Wei Liu
Keyword(s):  
Sol Gel ◽  
Polymer Networks ◽  
Interpenetrating Polymer Networks ◽  
X Ray ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Pure Phases ◽  
Hydrolysis Of ◽  
Polymerization Conditions

ABSTRACTInterpenetrating polymer networks have been synthesized by performing sol-gel chemistry and conventional organic polymerizations in mixtures of the monomers. The organic polymers were acrylates, and the inorganic phase was SiO2 formed by hydrolysis of orthosilicates. Polymerizations were conducted at a variety of relative rates, and the chemistry was designed to allow different amounts of grafting between the components. The morphology was characterized by transmission electron microscopy and small angle neutron and x-ray scattering. Wide variations in morphology were observed depending on the polymerization conditions, ranging from grossly phase separated to dendritic to finely divided structures (at a 100Å size scale). The phases ranged from mixtures of the two components to relatively pure phases. The interface between the phases ranged from very narrow to relatively broad.

Precipitation of Silica-Titania Mixed-Oxide Fillers into Poly(Dimethylsiloxane) Networks

1994 ◽  
Vol 67 (5) ◽  
pp. 806-819 ◽  
Author(s):  
Jianye Wen ◽  
James E. Mark
Keyword(s):  
Mixed Oxides ◽  
Sol Gel ◽  
Particle Sizes ◽  
High Modulus ◽  
Good Adhesion ◽  
Host Matrix ◽  
In Situ Silica ◽  
Elastomeric Matrix ◽  
Swelling Equilibrium

Abstract Previous studies have demonstrated techniques by which model elastomers prepared by end linking poly(dimethylsiloxane) (PDMS) chains can be reinforced by the in-situ precipitation of silica from a base-catalyzed sol-gel conversion of tetraethoxysilane (TEOS). The present investigation extends this technique to silica-titania mixed oxides through the sol-gel conversion of mixtures of TEOS and titanium n-butoxide. The elastomeric networks reinforced by this novel mixed filler were found to have very good mechanical properties, and swelling equilibrium measurements indicate that there is good adhesion between the SiO2-TiO2 filler and the elastomeric matrix. Compared with networks containing silica alone, the networks containing silica-titania mixed oxides had somewhat better combinations of high modulus and good extensibility. The particle size was typically several hundred A˚ in diameter but was found to be inversely dependent on the crosslink density of the PDMS network. Thus, larger particle sizes can be obtained at lower crosslink densities (which give larger network mesh sizes). The distribution of particle sizes is relatively narrow, and there is very little particle aggregation. The presence of in-situ silica-titania mixed oxides can also increase the onset temperature for degradation of the PDMS host matrix.

scholarly journals Titanium Dioxide Nanofibers and Microparticles Containing Nickel Nanoparticles

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Faheem A. Sheikh ◽  
Javier Macossay ◽  
Muzafar A. Kanjwal ◽  
Abdalla Abdal-hay ◽  
Mudasir A. Tantry ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Production Systems ◽  
Sol Gel ◽  
Titanium Isopropoxide ◽  
Electrospinning Process ◽  
Internal Morphology ◽  
Hydrolysis Of ◽  
Potential Use ◽  
Sem Analyses

The present study reports on the introduction of various nanocatalysts containing nickel (Ni) nanoparticles (NPs) embedded within TiO2 nanofibers and TiO2 microparticles. Typically, a sol-gel consisting of titanium isopropoxide and Ni NPs was prepared to produce TiO2 nanofibers by the electrospinning process. Similarly, TiO2 microparticles containing Ni were prepared using a sol-gel syntheses process. The resultant structures were studied by SEM analyses, which confirmed well-obtained nanofibers and microparticles. Further, the XRD results demonstrated the crystalline feature of both TiO2 and Ni in the obtained composites. Internal morphology of prepared nanofibers and microparticles containing Ni NPs was characterized by TEM, which demonstrated characteristic structures with good dispersion of Ni NPs. In addition, the prepared structures were studied as a model for hydrogen production applications. The catalytic activity of the prepared materials was studied by in situ hydrolysis of NaBH4, which indicated that the nanofibers containing Ni NPs can lead to produce higher amounts of hydrogen when compared to other microparticles, also reported in this paper. Overall, these results confirm the potential use of these materials in hydrogen production systems.

In situ TEM crystallization of sol-gel derived BaTiO3 thin films

1994 ◽  
Vol 52 ◽  
pp. 588-589
Author(s):  
Martha L. Mecartney ◽  
M. C. Gust ◽  
N. D. Evans
Keyword(s):  
Thin Films ◽  
Sol Gel ◽  
In Situ Tem ◽  
Lattice Match ◽  
Gel Layer ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Good Lattice ◽  
Thick Layers

BaTiO3 thin films made by the sol-gel process require a crystallization heat treatment to transform the amorphous gel into a crystalline material. This work used a Ba-Ti methoxypropoxide precursor in a 0.25M solution of methoxypropanol which was spin coated as 5 (each -600 nm thick) layers on (100) Si (FIG. 1). The {100} planes of perovskite BaTiO3 have a good lattice match with {110} Si; d110 of Si = 0.38 nm, and d100 of BaTiO3 = 0.4 nm. Consequently, it should be possible to grow heteroepitaxial films of (100) BaTiO3 on (100) Si. Such samples pyrolized at 350.C and then annealed in a conventional furnace at 750°C for one hour, however, did not crystallize heteroepitaxially with the substrate. Rather, crystallization occurred by a nucleation and growth process from within the gel. Furthermore, the gel layer at the Si/BaTiO3 interface remained amorphous. In-situ hot stage experiments were conducted in a transmission electron microscope (TEM) to determine the nucleation and crystallization behavior.

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