Microsphere synthesis via ultrasonic spray pyrolysis
An apparatus, methods, and systems for forming microspheres comprises a furnace and an ultrasonic nozzle. The furnace has a channel and is operable to generate heat in the channel. The ultrasonic nozzle is configured to receive precursor solution and spray precursor droplets into the channel so that the heat in the channel causes the precursor droplets to form the microspheres.
1 . A method of forming microspheres, the method comprising:
pumping a precursor solution through an ultrasonic nozzle thereby forming a spray comprising droplets of the precursor solution, the ultrasonic nozzle being positioned above a furnace;
introducing the droplets of the precursor solution downwardly into the furnace via an opening positioned near a top of the furnace and below the ultrasonic nozzle; and
heating the droplets of the precursor solution in the furnace to form the microspheres.
2 . The method of claim 1 , wherein the precursor solution comprises at least one curable polymer dissolved in a solvent.
3 . The method of claim 2 , wherein the heating the droplets evaporates the solvent and cures the at least one curable polymer, thereby forming the microspheres.
4 . The method of claim 1 , wherein the precursor solution further comprises an additional polymer.
5 . The method of claim 4 , wherein the curable polymer comprises a silicone material, wherein the additional polymer comprises polyethylene glycol, and wherein the solvent comprises a hydrocarbon solvent.
6 . The method of claim 5 , wherein the solvent is selected from the group consisting of toluene, xylene, ligroin, mineral spirits, and chlorinated hydrocarbons.
7 . The method of claim 1 , wherein the precursor solution has a total polymer concentration of greater than 100 mg/mL.
8 . The method of claim 1 , wherein the droplets are introduced into the channel without introducing a carrier gas into the channel.
9 . The method of claim 1 , further comprising concurrently introducing a carrier gas along with the droplets into the channel.
10 . The method of claim 9 , wherein the ultrasonic nozzle is installed within a conduit positioned above the furnace, the conduit comprising a side opening through which the ultrasonic nozzle is horizontally installed and a top opening positioned above the side opening, and wherein the carrier gas is introduced into the conduit downwardly through the top opening, and wherein the droplets and carrier gas are directed through an opening near the top of the furnace into the channel of the furnace.
11 . The method of claim 1 , wherein the microspheres have an average particle size (D50) of at least about 30 micrometers.
12 . The method of claim 1 , wherein the microspheres comprise are core-and-shell microspheres.
13 . The method of claim 1 , wherein the ultrasonic nozzle is aimed downward toward the furnace such that the ultrasonic nozzle sprays the droplets of the precursor solution downward into the furnace.
14 . The method of claim 1 , wherein the ultrasonic nozzle is aimed horizontally, the introducing step including spraying the droplets of the precursor solution into a downward flowing carrier gas.
15 . The method of claim 1 , further comprising a step of collecting the microspheres in a collection vessel positioned below the furnace.
16 . The method of claim 15 , wherein the collecting step includes receiving the microspheres in a solvent within the collection vessel, the method further comprising a step of separating the microspheres from the solvent via a centrifuge.
17 . A method of forming microspheres, the method comprising:
pumping a precursor solution through an ultrasonic nozzle thereby forming a spray comprising droplets of the precursor solution;
introducing the droplets of the precursor solution downwardly into a channel of a furnace;
concurrently introducing a carrier gas along with the droplets of the precursor solution into the channel; and
heating the droplets of the precursor solution in the furnace to form the microspheres,
wherein the ultrasonic nozzle is installed within a conduit positioned above the furnace, the conduit comprising a side opening through which the ultrasonic nozzle is horizontally installed and a top opening positioned above the side opening, and wherein the carrier gas is introduced into the conduit downwardly through the top opening, and wherein the droplets and carrier gas are directed through an opening near a top of the furnace into the channel of the furnace.
18 . The method of claim 17 , further comprising a step of collecting the microspheres in a collection vessel positioned below the furnace.
19 . The method of claim 18 , wherein the collecting step includes receiving the microspheres in a solvent within the collection vessel, the method further comprising a step of separating the microspheres from the solvent via a centrifuge.
20 . A method of forming microspheres, the method comprising:
pumping a precursor solution through an ultrasonic nozzle thereby forming a spray comprising droplets of the precursor solution;
introducing the droplets of the precursor solution downwardly into a furnace;
heating the droplets of the precursor solution in the furnace to form the microspheres; and
collecting the microspheres in a collection vessel positioned below the furnace.
21 . The method of claim 20 , wherein the collecting step includes receiving the microspheres in a solvent within the collection vessel, the method further comprising a step of separating the microspheres from the solvent via a centrifuge.