1993 Volume 18 Issue 4 Pages 196-206
Properties and applications of porous glass materials prepared by phase separation are reviewed. New porous glass, SPG (Shirasu porous glass) from SiO2-Al2O3-B2O3-CaO glass and conventional Vycor type from SiO2-B2O3-Na2O glass are more representative materials from the point of applications among several types of porous glass.
Pore size range were largely extented from 4-40nm of Vycor type to 4-20, μm by the development of SPG. Both types have the narrowest pore size distribution among all kinds of porous materials. The microstructure of porous glass with cylindrical and interconnected countless pores are very uniformly controlled through each element. The porous glass membranes are resistant to high temperature, acids, organic solvents and microbes. Surface treatment by chemical reagents is possible to change surface properties. The mechanical strength is enough for applications to membrane technology. SPG is superior to alumina and zirconia having the same level of porosity especially in compressive strength.
The porous glass can be prepared into shapes of tubes, flat sheets or powder.
Membrane emulsification is a new technology to produce single emulsion (Oil in Water, W/O) with uniformly controlled particle size and also to produce double emulsion (O/W/O, W/O/W) with high yield. A large scale application was achieved already with the membrane emulsification using SPG.
Membrane separation, bubbling element for efficiently dissolving gas into liquid, carrier for HPLC analysis and DNA synthesis are also newly developed applications for the porous glass materials.
