Method of forming porous three-dimensional (3D) article

1. A method of forming a porous three-dimensional (3D) article with an apparatus having a nozzle, said method comprising:

I) printing a first composition on a substrate with the nozzle of the apparatus to form at least one first filament comprising the first composition;

wherein the substrate and the nozzle are spaced a distance from one another and at least one of the substrate and the nozzle is moved at a speed relative to the other during step I);

II) selectively controlling the distance and/or the speed such that the at least one first filament coils on the substrate to give a first layer on the substrate, the first layer comprising a coiled filament, wherein the coiled filament has a width and a period length;

optionally, repeating steps I) and II) with independently selected composition(s) for any additional layer(s); and

III) exposing the layer(s) to a solidification condition;

wherein the porous three-dimensional (3D) article defines a plurality of voids; and

wherein selectively controlling the speed and/or distance in step II) comprises:

first plotting coiling patterns, distance, and speed to give a regime diagram; and

determining a steady coiling zone in the regime diagram such that formation of the coiled filament comprises predictable coiling.

2. The method of claim 1 , further comprising:

IV) printing a second composition with the nozzle of the apparatus to form at least one second filament comprising the second composition on the first layer;

wherein the first layer and the nozzle are spaced a distance from one another and at least one of the substrate and the nozzle is moved at a speed relative to the other during step IV);

V) selectively controlling the distance and/or the speed such that the at least one second filament coils on the first layer to give a second layer on the first layer, the second layer comprising a second coiled filament, wherein the second coiled filament has a width and a period length.

3. The method of claim 2 , wherein: (i) the plurality of voids are defined by at least the first and second filaments; (ii) the first and second filaments are the same and continuous with one another; (iii) at least the first and second filaments include the plurality of voids; (iv) the first and/or second filaments are hollow; or (v) any combination of (i) to (iv).

4. The method of claim 1 , further comprising determining a desired width and/or desired period length of the coiled filament, wherein the distance and/or the speed are selectively controlled in step II) such that the width of the coiled filament is the desired width and/or the period length of the coiled filament is the desired period length.

5. The method of claim 4 , further comprising first plotting for the nozzle and the first composition speed as a function of distance when printing the first composition with the nozzle for establishing parameters to selectively control the distance and/or the speed in II).

6. The method of claim 1 , wherein: (i) the plurality of voids are open-celled; (ii) the plurality of voids are closed-celled; or (iii) a combination of (i) and (ii).

7. The method of claim 1 , wherein step III) is carried out prior to repeating steps I) and II) with independently selected compositions.

8. The method of claim 1 , wherein the solidification condition is selected from: (i) exposure to moisture; (ii) exposure to heat; (iii) exposure to irradiation; (iv) reduced ambient temperature; (v) exposure to solvent; (vi) exposure to mechanical vibration; any combination of (i) to (vi).

9. The method of claim 1 , wherein the first composition comprises a silicone composition selected from: (a) hydrosilylation-curable silicone compositions; (b) condensation-curable silicone compositions; (c) free-radical-curable silicone compositions; and (d) ring opening reaction-curable silicone compositions.

10. The method according to claim 1 , wherein the apparatus comprises a 3D printer selected from a fused filament fabrication printer, a fused deposition modeling printer, a direct ink deposition printer, a selective laser sintering printer, a selective laser melting printer, a stereolithography printer, a powder bed (binder jet) printer, a material jet printer, a direct metal laser sintering printer, an electron beam melting printer, a laminated object manufacturing deposition printer, a directed energy deposition printer, a laser powder forming printer, a polyjet printer, an ink-jetting printer, a material jetting printer, and a syringe extrusion printer.

11. A porous three-dimensional (3D) article formed in accordance with the method of claim 1 .