Synthesis of TEOS-Based Silica Spherical Particles by Sol-Gel Process

2013 ◽  
Vol 773 ◽  
pp. 606-610
Author(s):  
Jing Li ◽  
Hong Qi Zhang ◽  
Wei Xue
Keyword(s):  
Sol Gel ◽  
Silica Particles ◽  
Electron Cloud ◽  
Polymerization Rate ◽  
Spherical Particles ◽  
Condensation Polymerization ◽  
Spherical Silica ◽  
Sol Gel Process ◽  
Spherical Silica Particles

Spherical silica particles, with mean sizes about 1.2 μm, were prepared through TEOS sol-gel process catalyzed by ammonia. The silica particles have a smooth surface and a small specific surface area, 3.4 m2/g. The sol-gel process was monitored by React IRTMusing an in-situ technique. Based on the measurements, mechanism of TEOS hydrolyzation and succedent condensation polymerization was inferred. With the adding of ammonia, OH-anion attacks Si atomic nucleus directly and makes it showing negative electricity. Therefore the electron cloud shifts to the OR group on the other side. This weakens the Si-O bond and results in the removal of the OR group. Furthermore, silanol, generated from TEOS hydrolyzation, attracts Si-OR or other Si-OH around; thereby resulting rapid dehydration or dealcohol between molecular. So the condensation polymerization rate is elevated, and Si-O-Si bond comes into being. Lastly, cross-linking reaction among Si-O-Si bonds forms the particle.

Preparation of Spherical Silica with Controllable Size

2018 ◽  
Vol 281 ◽  
pp. 65-70
Author(s):  
Shu Lin Wang ◽  
Zhao Wang ◽  
Bing Hao Li ◽  
Man Xu
Keyword(s):  
Particle Size ◽  
Silica Particle ◽  
Sol Gel ◽  
Silica Particles ◽  
Spherical Particles ◽  
Alkali Content ◽  
Spherical Silica ◽  
Hydrolysis Temperature ◽  
Spherical Silica Particles ◽  
Size And Morphology

The spherical silica particles were prepared by sol-gel method with TEOS as precursor, ethanol as solvent in the presence of ammonia. The effects of reaction temperature and the amount of ammonia and TEOS on the size and morphology of silica particles were investigated. The hydrolysis temperature , alkali and TEOS content does not affect the morphology of silica, the silica particles were spherical; With the increase of hydrolysis temperature, particle size of silica showed first increased and then decreased, when the hydrolysis temperature is 30 °C, the silica particle size up to 0.6 μm, when the hydrolysis temperature is 60 °C, the silica particle size is 0.15 μm; With the increase of the content of alkali, silica particle size showed first increased and then decreased, when the alkali content is 20 ml, the silica particle size up to 0.6 μm and when the alkali content is 10 ml, the silica particle size is 0.2 μm; With the increase of TEOS dosage, the amount of spherical silica increased and the particle size of silica spherical particles first increased and then decreased.

Synthesis of spherical silica particles by sol-gel method and application

2008 ◽  
Vol 19 (8) ◽  
pp. 977-983 ◽  
Author(s):  
Kiyomi Fuchigami ◽  
Yoshinari Taguchi ◽  
Masato Tanaka
Keyword(s):  
Sol Gel ◽  
Silica Particles ◽  
Gel Method ◽  
Sol Gel Method ◽  
Spherical Silica ◽  
Spherical Silica Particles

Template-Free Synthesis of Ellipsoidal Silica Nanoparticles

2012 ◽  
Vol 1386 ◽  
Author(s):  
Henan Zhang ◽  
Daniel L. Akins
Keyword(s):  
Surface Tension ◽  
Self Assembly ◽  
Sol Gel ◽  
The Self ◽  
Micellar System ◽  
Synthesis Conditions ◽  
Spherical Silica ◽  
Sol Gel Process ◽  
Spherical Silica Particles ◽  
Template Free

ABSTRACTFor a sol-gel process occurring in a water/oil (w/o) system, the self-assembly of silica nuclei can be controlled by close control of synthesis conditions. We have synthesized ellipsoidal or spherical silica particles by a template-free scheme that involves controlling surface tension on silica nuclei through via use of different volume ratios of a w/o micellar system.

Fabrication of teardrop-shaped silica particles in polyelectrolyte diluted solution through in situ sol–gel process

2011 ◽  
Vol 58 (3) ◽  
pp. 651-655 ◽  
Author(s):  
LinYong Song ◽  
ChunLei Lin ◽  
Lan Wang ◽  
HaiLin Sheng ◽  
YiFeng Zhou ◽  
...  
Keyword(s):  
Sol Gel ◽  
Silica Particles ◽  
Sol Gel Process ◽  
Diluted Solution

Study on the Sol-Gel Process of TEOS by React-IR

2011 ◽  
Vol 110-116 ◽  
pp. 1401-1405 ◽  
Author(s):  
Hua Hua Zhou ◽  
Wei Xue ◽  
Fang Li ◽  
Yan Fei Qin
Keyword(s):  
Sol Gel ◽  
Porous Silica ◽  
Polymerization Rate ◽  
Condensation Polymerization ◽  
Acid Base ◽  
Nucleophilic Reaction ◽  
Sol Gel Process ◽  
Acidic Conditions ◽  
Adsorption Desorption ◽  
Meso Scale

Porous silica was prepared through TEOS sol-gel process catalyzed by acid-base joint catalyst, and the process was monitored by React IRTM. Based on the measurements, mechanism of TEOS hydrolyzation and succedent condensation polymerization was inferred. Under acidic conditions, H+ attacks –OR group of TEOS firstly, then the electronegative Cl- can attack Si4+ and make TEOS be hydrolyzed. When basic catalyst was added, the reaction will be accelerated. The promotion effect of base is attributed to the direct nucleophilic reaction mechanism and the smaller size of OH-, which can attack Si more easily. Thirdly, silanol, generated from TEOS hydrolyzation, attract Si-OR or other Si-OH around; thereby resulting rapid dehydration or de-alcohol reaction. So the condensation polymerization rate is elevated, and Si-O-Si bond comes into being. Lastly, cross-linking reaction among Si-O-Si bonds forms the particle like conglomeration. The porous silica was characterized by SEM and N2 adsorption-desorption technique. It was shown that the silica had large specific surface area, 818.5 m2/g, and relatively narrow distribution of pore size in meso-scale. Futhermore, the mesopores were nonuniform in shape and arrangement.

Effect of Sodium Chloride on the Sol-Gel Synthesized Silica Colloidal Particles

2011 ◽  
Vol 181-182 ◽  
pp. 417-421 ◽  
Author(s):  
Yun Gao Cai ◽  
Qing Lan Ma ◽  
Yuan Ming Huang
Keyword(s):  
Sodium Chloride ◽  
Colloidal Particles ◽  
Size Range ◽  
Sol Gel ◽  
Silica Particles ◽  
Tetraethyl Orthosilicate ◽  
Silica Spheres ◽  
Spherical Silica ◽  
Spherical Silica Particles ◽  
Wide Size Distribution

The effect of sodium chloride on the sol-gel synthesized silica colloidal particles has been investigated. The silica colloidal particles in the size range of 420-800 nm were synthesized from the hydrolysis and condensation of tetraethyl orthosilicate by varying the amount of sodium chloride from 15 to 30 mg while keeping the tetraethyl orthosilicate (20 ml), ethanol (125 ml), ammonia (6 ml) and distilled water (18 ml) fixed. Scanning electron microscopy (SEM) was employed to analyze the morphology of the synthesized silica particles. Our results demonstrated that: (1) sticky and spongy silica spheroids were resulted if the amount of sodium chloride was less than 15 mg; (2) spherical silica particles were resulted with good monodispersity when the amount of sodium chloride was in the range of 22-24 mg; and (3) silica spheres were obtained but with a wide size distribution when the amount of sodium chloride was more than 26 mg.

scholarly journals Preparation of Gd Complex-Immobilized Silica Particles and Their Application to MRI

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Yoshio Kobayashi ◽  
Hikaru Morimoto ◽  
Tomohiko Nakagawa ◽  
Yohsuke Kubota ◽  
Kohsuke Gonda ◽  
...  
Keyword(s):  
Ethylenediaminetetraacetic Acid ◽  
Sol Gel ◽  
Silica Particles ◽  
Disodium Salt ◽  
Colloid Solution ◽  
Amino Groups ◽  
Spherical Silica ◽  
Spherical Silica Particles ◽  
Average Size ◽  
Ethylenediaminetetraacetic Acid Disodium Salt

A preparation method for Gd-ethylenediaminetetraacetic acid disodium salt dihydrate (ETDA) complex-immobilized silica particles (Gd-EDTA/SiO2) is proposed. Preparation of spherical silica particles was performed by a sol-gel method at 35°C using 0.2 M tetraethylorthosilicate, 25 M H2O, and 0.01 M NaOH in ethanol, which produced silica particles with an average size of  nm. Immobilization of Gd-EDTA on the silica particles was conducted at 35°C by introducing amino groups on the silica particles with (3-aminopropyl)trimethoxysilane at pH 3 (NH2/SiO2) and then making Gd-EDTA act on the NH2/SiO2 particles at pH 5. The as-prepared Gd-EDTA/SiO2 particle colloid solution was concentrated up to a Gd concentration of 0.347 mM by centrifugation. The sphere structure of Gd-EDTA/SiO2 particles was undamaged, and the colloid solution was still colloidally stable, even after the concentrating process. The concentrated Gd-EDTA/SiO2 colloid solution revealed good MRI properties. A relaxivity value for T1-weighted imaging was as high as 5.15 mM−1 s−1, that was comparable to that for a commercial Gd complex contrast agent.

In Situ Production of Spherical Silica Particles Containing Self-Organized Mesopores

Nano Letters ◽  
2001 ◽  
Vol 1 (5) ◽  
pp. 231-234 ◽  
Author(s):  
Ferry Iskandar ◽  
Mikrajuddin ◽  
Kikuo Okuyama
Keyword(s):  
Silica Particles ◽  
Self Organized ◽  
Spherical Silica ◽  
Spherical Silica Particles ◽  
In Situ Production
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