Methods for manufacture of aerogels
Embodiments of the present invention describe a method for producing gel beads comprising: depositing catalyzed sol droplets comprising a gel precursor into a moving dispensing medium, said medium being immiscible with the sol, and allowing gelation of the sol to occur in the moving dispensing medium thereby producing gel beads. This system utilizes a horizontally flowing dispensing medium where the catalyzed sol droplet is fully formed before deposited therein.
1 . A method for producing gel beads comprising:
depositing catalyzed sol droplets comprising a gel precursor into a dispensing medium, said dispensing medium being immiscible with the sol, and
allowing gelation of the sol to occur in the moving dispensing medium thereby producing gel beads.
2 . The method of claim 1 wherein the sol droplet is deposited in a horizontally flowing dispensing medium.
3 . The method of claim 2 wherein the sol droplets are continuously or intermittently deposited in the medium.
4 . The method of claim 2 wherein the density of the medium is greater than the density of the sol droplet.
5 . The method of claim 2 wherein the density of the medium is between about 0.85 g/cm 3 and about 1.1 g/cm 3 preferably between about 0.9 g/cm 3 and about
6 . The method of claim 2 wherein the beads comprise an inorganic compound.
7 . The method of claim 6 , wherein the inorganic compound comprises a material selected from the group consisting of zirconia, yttria, hafnia, alumina, titania, ceria, and silica, magnesium oxide, calcium oxide, magnesium fluoride, calcium fluoride, and combinations thereof
8 . The method of claim 2 wherein the beads comprise an organic-inorganic compound.
9 . The method of claim 8 , wherein the inorganic-organic compound comprises a material selected from any combination of group 1 with group 2 wherein group 1 comprises zirconia, yttria, hafnia, alumina, titania, ceria, and silica, magnesium oxide, calcium oxide, magnesium fluoride and calcium fluoride and group 2 comprises polyacrylates, polyolefins (including thermoplastics and rubber materials), polystyrenes, polyacrylonitriles, polyurethanes, polyimides, polyfurfural alcohol, phenol furfuryl alcohol, melamine formaldehydes, resorcinol formaldehydes, cresol formaldehyde, phenol formaldehyde, polyvinyl alcohol dialdehyde, polycyanurates, polyacrylamides, various epoxies, agar, and agarose, and combinations thereof.
10 . The method claim 2 , wherein the sol droplets dispensed into the flowing liquid medium in through a nozzle.
11 . The method of claim 2 , wherein a stream of air or oil is in contact with the sol droplet prior to deposition thereof.
12 . The method of claim 15 wherein the stream of air or oil causes the sol droplet to form into a plurality of smaller droplets.
13 . The process of claim 2 , wherein the medium flows horizontally and moves the beads away from the sol droplet depositing zone.
14 . The process of claim 2 , wherein the medium is immiscible with the sol thereby resulting in a spherical shape of the resulting gel beads.
15 . The process of claim 2 , wherein the liquid medium is a polyorganosiloxane.
16 . The process of claim 2 , wherein the gelation is induced by dissipation of a sufficient amount of energy into a cross-sectional area of the sol droplets.
17 . The process of claim 16 , wherein the energy source is electromagnetic in origin, such as infrared, x-ray, microwave, gamma ray and the like.
18 . The process of claim 16 , wherein the energy source is a particle beam, such as an electron beam, beta particle, or alpha particle radiation source.
19 . The method of claim 2 wherein the beads are spherical and have a diameter between about 10 micrometers to about 100 micrometers.
20 . The method of claim 2 wherein the beads are spherical and have a diameter above about 100 micrometers.