Three-dimensional printed porous silicone matrix using leachable porogen
The silicone-based ink for additive manufacturing includes a siloxane macromer, and a porogen mixture comprising a water-soluble porogen and a surfactant. The product of additive manufacturing with a silicone-based ink includes a three-dimensional printed structure including a plurality of continuous filaments arranged in a predefined pattern and a plurality of inter-filament pores defined by the predefined pattern of the continuous filaments. In addition, each continuous filament of the three-dimensional printed structure includes a silicone matrix having an open cell structure with a plurality of intra-filament pores, and the intra-filament pores form continuous channels through the silicone matrix.
1. A method of forming a three-dimensional structure comprising a porous silicone matrix, the method comprising:
forming the three-dimensional structure using a siloxane mixture, the siloxane mixture comprising a siloxane macromer and a porogen mixture comprising glycerol and polyvinyl pyrrolidone;
curing the formed three-dimensional structure to at least a predefined crosslink density to form a silicone matrix; and
leaching the porogen mixture from the silicone matrix to result in a plurality of pores forming interconnected channels through the silicone matrix of the three-dimensional structure.
2. The method as recited in claim 1 , wherein forming the three-dimensional structure includes extruding a continuous filament of the siloxane mixture through a nozzle to form a printed three-dimensional structure having a plurality of continuous filaments arranged in a predefined pattern.
3. The method as recited in claim 1 , wherein the forming the three-dimensional structure includes forming a structure selected from the group consisting of: a mold, a cast, and a template.
4. The method as recited in claim 1 , wherein the siloxane mixture includes a curing agent and a crosslinking agent.
5. The method as recited in claim 4 , wherein the siloxane mixture includes an effective amount of an inhibitor for controlling a rate of curing by the curing agent.
6. The method as recited in claim 1 , wherein a concentration of the siloxane macromer is in a range of about 25 weight % to about 70 weight % of a total weight of the siloxane mixture.
7. The method as recited in claim 1 , wherein a concentration of the glycerol is in a range of about 35 weight % to about 50 weight % of a total weight of the siloxane mixture.
8. The method as recited in claim 1 , wherein a concentration of the glycerol is in a range of greater than 0 weight % to about 25 weight % of a total weight of the siloxane mixture.
9. The method as recited in claim 1 , wherein leaching the porogen mixture comprises soaking the three-dimensional structure having the silicone matrix in an aqueous solution to dissolve the porogen mixture.
10. The method as recited in claim 1 , further comprising, heating the three-dimensional structure having the silicone matrix for setting the silicone matrix.
11. The method as recited in claim 1 , wherein the porogen mixture further comprises particles selected from the group consisting of: urea particles, sugar particles, polyethylene glycol, and a combination thereof.
12. The method as recited in claim 1 , wherein the porous silicone matrix has an open cell structure.
13. The method as recited in claim 1 , wherein the predefined crosslink density is selected according to a formulation of the siloxane mixture.
14. A product formed by the method of claim 1 , the product comprising:
a three-dimensional printed structure comprising the silicone matrix having the predefined crosslink density, wherein the three-dimensional structure comprises:
a plurality of continuous filaments arranged in a predefined pattern, the continuous filaments each comprising a silicone matrix having an open cell structure with a plurality of intra-filament pores, wherein the intra-filament pores form continuous channels through the silicone matrix; and
a plurality of inter-filament pores, wherein the inter-filament pores are defined by the predefined pattern of the continuous filaments.
15. The product as recited in claim 14 , wherein the silicone matrix includes vinyl terminated siloxane polymers.
16. The product as recited in claim 14 , wherein the continuous filaments have an average diameter greater than about 100 microns.
17. The product as recited in claim 14 , wherein the inter-filament pores are interconnected from a surface of the three-dimensional printed structure to a surface on an opposite side of the three-dimensional printed structure.
18. The method as recited in claim 1 , wherein the siloxane mixture includes an additive for achieving the predefined crosslink density.
19. The method as recited in claim 18 , wherein the additive is configured to cause reduction in an effective crosslink density of the silicone matrix.
20. The method as recited in claim 19 , wherein the additive comprises a hydride terminated chain extension additive.
21. The method as recited in claim 18 , wherein the additive is configured to cause an increase in an effective crosslink density of the silicone matrix.
22. The method as recited in claim 21 , wherein the additive comprises a vinyl-containing additive.