Polymer composites for fused filament fabrication and methods of making the same
Disclosed are compositions of a fused filament fabrication (FFF) composite filament having embedded functional materials in a thermoplastic matrix. Methods of making the composite filaments are also disclosed. In one example, a FFF composite filament incorporates a MOF, in an amount greater than 10% by mass, dispersed in a matrix polymer. One example of a method of synthesizing FFF composite filaments involves mixing a suspension that has a MOF with a matrix polymer solution to yield a polymer-MOF mixture. The mixture is cast and dried into a solid composite material, which is formed a FFF composite filament having the MOF in an amount greater than 10% by mass.
1. A method of synthesizing a FFF composite filament, the method comprising:
mixing a sacrificial polymer solution in a sacrificial polymer solvent in a suspension that comprises a MOF with a matrix polymer solution that comprises a matrix polymer in a matrix polymer solvent to yield a polymer-MOF mixture and wherein the sacrificial polymer solution and the matrix polymer solution are at least partially miscible with one another;
casting and drying the polymer-MOF mixture into a solid composite material;
forming the solid composite material into a FFF composite filament comprising the MOF in an amount greater than 10% by mass and
selectively removing the sacrificial polymer from the FFF composite filament or from an item printed from the FFF composite filament.
2. The method of claim 1 , wherein said removing comprises dissolving the sacrificial polymer with a sacrificial polymer removal solvent in which the solubility of the sacrificial polymer is greater than the solubility of the matrix polymer.
3. The method of claim 1 , wherein the sacrificial polymer comprises a fluoropolymer.
4. The method of claim 1 , wherein the solid composite material comprises greater than 10% sacrificial polymer by mass.
5. The method of claim 1 , further comprising:
replacing at least a portion of residual solvent that remains in pores of the FFF composite filament, or an item printed from the FFF composite filament, with an exchange solvent having a boiling temperature that is less than that of the residual solvent; and
evaporating the exchange solvent from the pores and activating chemical functionality of the MOF.
6. The method of claim 5 , wherein after said evaporating, the FFF composite filament, or an item printed from the FFF composite filament, has a surface area greater than or equal to 250 m 2 /g.
7. The method of claim 1 , wherein the FFF composite filament comprises the MOF in an amount greater than 25% by mass.
8. The method of claim 1 , wherein the FFF composite filament comprises the matrix polymer in an amount greater than 15% by mass.
9. The method of claim 1 , wherein the matrix polymer comprises polylactic acid, thermoplastic polyurethane, acrylonitrile butadiene styrene, nylon 12, nylon 66, polyvinylidene difluoride, polycarbonate, or a combination thereof.
10. The method of claim 1 , wherein the MOF comprises ZIF-08, UiO-66, MIL-101(Cr), FeBTC, or a combination thereof.
11. The method of claim 1 , wherein the FFF composite filament has a surface area greater than or equal to 2.5 m 2 /g.
12. The method of claim 1 , wherein said forming comprises providing the solid composite material to an extruder and pressing the material through a die to yield the FFF composite filament.