Method of 3D printing a cellular solid
A method of printing a cellular solid by direct bubble writing comprises introducing an ink formulation comprising a polymerizable monomer and a gas into a nozzle, which includes a core flow channel radially surrounded by an outer flow channel. The ink formulation is directed into the outer flow channel and the gas is directed into the core flow channel. The ink formulation and the gas are ejected out of the nozzle as a stream of bubbles, where each bubble includes a core comprising the gas and a liquid shell overlying the core that comprises the ink formulation. After ejection, the polymerizable monomer is polymerized to form a solid polymeric shell from the liquid shell, and the bubbles are deposited on a substrate moving relative to the nozzle. Thus, a polymeric cellular solid having a predetermined geometry is printed.
1. A method of printing a cellular solid on a substrate, the method comprising:
introducing an ink formulation and a gas into a nozzle comprising a core flow channel radially surrounded by an outer flow channel, the ink formulation being directed into the outer flow channel and the gas being directed into the core flow channel;
ejecting the ink formulation and the gas out of the nozzle as a stream of bubbles, each bubble including a core comprising the gas and a liquid shell overlying the core and comprising the ink formulation;
after ejection, solidifying the liquid shell to form a solid shell within one second after deposition of the bubbles on the substrate; and
moving the substrate and the nozzle relative to one another according to a predetermined geometry, thereby printing a solid three-dimensional cellular structure having said predetermined geometry.
2. The method of claim 1 , wherein each of the solid shells comprises a metal, ceramic, semiconductor, and/or polymer.
3. The method of claim 1 , wherein solidifying comprises freezing, evaporating, curing, crosslinking, and/or polymerizing.
4. The method of claim 1 , wherein the stream of bubbles is a monodisperse stream of bubbles.
5. The method of claim 1 , wherein the ink formulation further comprises a nanoparticle precursor.
6. The method of claim 5 , wherein the nanoparticle precursor comprises a metal salt, and wherein, during solidification of the liquid shell, the metal salt is reduced to form metal nanoparticles dispersed in the solid shell.
7. The method of claim 1 , wherein the gas is selected from the group consisting of: air, oxygen, nitrogen, helium and argon.
8. The method of claim 1 , wherein the gas is directed into the nozzle at a pressure in a range from 1 kPa to 10 kPa.
9. The method of claim 1 , wherein a flow rate of the ink formulation is in a range from 3 ml/min to 15 ml/min.
10. The method of claim 1 , wherein the cellular solid comprises a closed cell microarchitecture.
11. The method of claim 1 , wherein the cellular solid comprises an open cell microarchitecture.
12. The method of claim 1 , wherein cells of the cellular solid have a nominal size in a range from 0.01 mm to 10 mm.
13. The method of claim 1 , wherein the nozzle moves relative to the substrate at a translation speed in a range from 1 mm/s to 300 mm/s.
14. The method of claim 1 , wherein the cellular solid is configured for pressure sensing, sound control, heat exchange, catalysis, and/or mechanical energy absorption.
15. A method of printing a cellular solid on a substrate, the method comprising:
introducing an ink formulation comprising a flowable polymer precursor and a gas into a nozzle comprising a core flow channel radially surrounded by an outer flow channel, the ink formulation being directed into the outer flow channel and the gas being directed into the core flow channel;
ejecting the ink formulation and the gas out of the nozzle as a stream of bubbles, each bubble including a core comprising the gas and a liquid shell overlying the core comprising the ink formulation;
after ejection, curing the flowable polymer precursor prior to one second after deposition of the bubbles on the substrate to form a solid polymeric shell from the liquid shell, the bubbles thereby being solidified; and
depositing the bubbles on the substrate, while moving the nozzle and the substrate relative to one another according to a predetermined geometry, thereby printing a solid cellular structure having said predetermined geometry.
16. The method of claim 15 , wherein curing the flowable polymer precursor comprises exposing the bubbles to light, heat or a chemical curing agent.
17. The method of claim 15 , wherein the flowable polymer precursor comprises a polymerizable monomer.
18. The method of claim 17 , wherein the polymerizable monomer is a photopolymerizable monomer, and wherein the polymerizing comprises exposing the bubbles to ultraviolet (UV) light.
19. The method of claim 15 , wherein the ink formulation includes a nanoparticle precursor.
20. The method of claim 19 , wherein the nanoparticle precursor comprises a metal salt, and wherein, during curing of the liquid shell, the metal salt is reduced to form metal nanoparticles dispersed in the solid shell.
21. The method of claim 15 , wherein the stream of bubbles is a monodisperse stream of bubbles.
22. The method of claim 15 , wherein the gas is selected from the group consisting of: air, oxygen, nitrogen, helium and argon.
23. The method of claim 15 , wherein the gas is directed into the nozzle at a pressure in a range from 1 kPa to 10 kPa.
24. The method of claim 15 , wherein a flow rate of the ink formulation is in a range from 3 ml/min to 15 ml/min.
25. The method of claim 15 , wherein the cellular structure comprises a closed cell microarchitecture.
26. The method of claim 15 , wherein the cellular structure comprises an open cell microarchitecture.
27. The method of claim 15 , wherein pores of the cellular structure have a nominal size in a range from 0.3 mm to 0.7 mm.
28. The method of claim 15 , wherein the nozzle is moved relative to the substrate at a translation speed in a range from 1 mm/s to 300 mm/s.
29. The method of claim 15 , wherein the cellular solid is configured for pressure sensing, sound control, heat exchange, catalysis, and/or mechanical energy absorption.
30. The method of claim 15 , wherein the cellular solid comprises locally controlled gradients in pore size, interconnectivity, and/or material composition.