Fabrication of Glass Micro- and Nanospheres from Liquid Precursors Using Droplet Generation and Sol-Gel Processing

1994 ◽  
Vol 372 ◽  
Author(s):  
Kyekyoon Kim
Keyword(s):  
Sol Gel ◽  
Droplet Generation ◽  
Silica Spheres ◽  
Generation Process ◽  
Hollow Silica ◽  
Nanometer Range ◽  
Glass Spheres ◽  
Liquid Precursors ◽  
Controlled Porosity ◽  
Gel Processing

AbstractTwo novel methods particularly suitable for continuously fabricating uniform glass spheres are described, one suitable for spheres micrometers to millimeters in diameter and the other for spheres of diameters in the submicron range, down to tens of nanometers. Both methods start from liquid precursors and combine droplet generation which is effected by a nozzle with sol-gel processing. One difference is that in the latter method, which is termed the charged liquid cluster beam (CLCB) technique, one employs flow-limited field-injection electrostatic spraying to further reduce the size of the drops to the nanometer range in the droplet generation process. Using the two methods, uniform hollow silica aerogel spheres, micrometer to millimeter in diameter, of controlled porosity and silica spheres with diameters in the nanometer range were produced. By utilizing the appropriate liquid precursors, the present methods can fabricate spheres composed of a variety of materials, including glass. Due to its ability to fabricate nanodrops, the CLCB technique is suited to fabricating nanoparticles as well as thin films of controlled stoichiometry and chemical composition.

Hollow Silica Spheres of Controlled Size and Porosity by Sol-Gel Processing

1991 ◽  
Vol 74 (8) ◽  
pp. 1987-1992 ◽  
Author(s):  
Kyekyoon (Kevin) Kim ◽  
Kam Yong Jang ◽  
Ravindra S. Upadhye
Keyword(s):  
Sol Gel ◽  
Silica Spheres ◽  
Hollow Silica ◽  
Hollow Silica Spheres ◽  
Gel Processing

Sol–gel synthesis, microstructure and adsorption properties of hollow silica spheres

2011 ◽  
Vol 65 (12) ◽  
pp. 1811-1814 ◽  
Author(s):  
Haitao Fan ◽  
Zhibin Lei ◽  
Jia Hong Pan ◽  
X.S. Zhao
Keyword(s):  
Sol Gel ◽  
Adsorption Properties ◽  
Silica Spheres ◽  
Hollow Silica ◽  
Hollow Silica Spheres ◽  
Sol Gel Synthesis

Sol-Gel Strategies for Controlled Porosity Ceramic Materials: Thin Film and Bulk

1994 ◽  
Vol 368 ◽  
Author(s):  
C. Jeffrey Brinker ◽  
Rakesh Sehgal ◽  
Narayan K. Raman ◽  
Sai S. Prakash ◽  
Laurent Delatire
Keyword(s):  
Thin Film ◽  
Sol Gel ◽  
Ceramic Materials ◽  
Particle Packing ◽  
Membrane Reactors ◽  
Organic Templates ◽  
Controlled Porosity ◽  
Processing Techniques ◽  
Catalytic Membrane Reactors ◽  
Gel Processing

ABSTRACTUsing sol-gel processing techniques it is possible to vary the condensation pathway over wide ranges to form primary species ranging in structure from oligomers to polymers to particles. The porosity of the corresponding dry gels depends on the size and structure of the primary species, the organization of these structures, often by aggregation, to form a gel, and the collapse of the gel by drying. This paper reviews these ideas in the context of forming thin film or bulk specimens. Several strategies are introduced to control porosity on length scales of interest for catalysis and catalytic membrane reactors: 1) aggregation of fractals; 2) management of capillary pressure; 3) surface derivatization; 4) relative rates of condensation and evaporation; 5) the use of organic templates and 6) sintering. These strategies are contrasted with the more traditional particle packing approach to preparing controlled porosity materials.

Influence of silanization on voltammetry at electrodes modified with silica films of controlled porosity formed by electrochemically initiated sol-gel processing

2011 ◽  
Vol 15 (11-12) ◽  
pp. 2409-2417 ◽  
Author(s):  
James A. Cox ◽  
Kamila M. Wiaderek ◽  
B. Layla Mehdi ◽  
Benjamin P. Gudorf ◽  
David Ranganathan ◽  
...  
Keyword(s):  
Sol Gel ◽  
Silica Films ◽  
Controlled Porosity ◽  
Gel Processing

Physical-Chemistry Parameters of SiO2 Monoliths Processed Via Sol - Gel

1991 ◽  
Vol 248 ◽  
Author(s):  
A. M. Elias ◽  
M. E. Elias ◽  
M. M Nunes
Keyword(s):  
Optical Properties ◽  
Sol Gel ◽  
Ph Effects ◽  
Chemical Additives ◽  
Liquid Precursors ◽  
Rate Of Hydrolysis ◽  
Ph Range ◽  
Time Required ◽  
Fiber Preforms ◽  
Gel Processing

AbstractHigh quality glasses may be prepared from liquid precursors, via sol - geL Starting materials and variable control determine the final characteristics of silica monoliths for optical fiber preforms, prepared via sol - gel, as we have found in previous studies. The rate of hydrolysis. and condensation reactions, as wcU as the time required for densification of a gel, is dependent on water/alkoxide ratio, pH and the presence of drying control chemical additives. The physical and optical properties of the preforms are also determined by the specific conditions of the sol - gel processing.In this study we present an additional analysis of pH effects on the kdnetics, before and during the material syneresis. The effect of CO2 as a contaminant, is also considered. Samples are prepared from hydrolysis of tetrametoxysane in methanol - water mixtures, in the presence of a - picoline. At 20°C, the initial values of pH range between 8 and 6 and show an exponential decrease as the hydrolytic polymensation proceeds, tending to acidic or more acidic values. These steps also are followed by TEM and SEM and are correlated with the sort of aggregates formed in the material along the percolation process. Optical properties of the preforms are interpreted in terms of the clusters formed from those aggregates.Details on instrumental monitoring of [H+] along the alcogelation process are discussed.

Preparation of Silica Hollow Spheres Used as Filler for Paper

2012 ◽  
Vol 200 ◽  
pp. 339-342 ◽  
Author(s):  
Wen Juan Gu ◽  
Ying Li ◽  
Xiao Hui Zhang
Keyword(s):  
Formation Mechanism ◽  
Shell Thickness ◽  
Sol Gel ◽  
Hollow Spheres ◽  
Hollow Structure ◽  
Silica Spheres ◽  
Hollow Silica ◽  
Calcination Process ◽  
Gel Method ◽  
Hollow Silica Spheres

Silica of hollow structure exhibits a number of special characteristic. In this paper, a new way to prepare hollow silica spheres which can be used as filler for paper was reported. In this approach, when silica shells were coated on polyvinylacetate (PVAc) template particles by the sol-gel method, the PVAc cores would be dissolved synchronously, forming hollow spheres. Neither additional dissolution nor a calcination process was needed to remove the PVAc cores. The morphology of the hollow silica spheres was also characterized by TEM. It was shown that the hollow silica spheres with 130-400nm in diameter and 15-35nm in the shell thickness could be synthesized. The possible formation mechanism was also brought forward. The possibility and potential advantages in usage as filler for paper were analyzed theoretically. We confer that this filler can improve the printability of the paper, and reduce its density compared with traditional fillers.

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