Three-dimensional freeze extrusion for the manufacture of homogeneous and graded rods and tubes
In an aspect, the present disclosure pertains to a method of making a material. Generally, the method includes one or more of the following steps of: (1) placing a mixture having one or more components in a container; and (2) extruding the mixture out of at least one opening of at least one nozzle. In an additional aspect, the present disclosure pertains to a material. In some embodiments, the material includes one or more components. In some embodiments, the one or more components are in the form of a multi-layered structure.
1 . A method of making a material, the method comprising:
applying a temperature gradient to a mixture comprising a plurality of layers, each layer independently composed of one or more different components creating a compositional gradient in an at least one nozzle or syringe, independently extruding a same mixture or a compositionally different mixture out of the at least one nozzle or syringe under conditions to apply the same temperature gradient or a different temperature gradient, together the extruding and temperature gradient conditions result in freeze-casting the mixture from each of the at least one nozzle or syringe to produce an extruded material having a nozzle or syringe formed compositional gradient, and a property gradient selected from at least one of a mechanical property gradient, a physical property gradient, a structural gradient, or combinations thereof; and
controlling the same or a different temperature gradient of the mixture before and during the extruding, and optionally after, through the at least one nozzle or syringe, for spatially directing an ordered crystal formation in the extruded material, wherein the extruded material is a plurality of graded layers.
2 . The method of claim 1 , further comprising placing the mixture in a container having a first end for receiving the mixture, and the at least one nozzle or syringe on a second end of the container.
3 . The method of claim 1 , wherein the mixture is in the form of a solution, a colloid, a gel, a slurry, a suspension, a particle suspension, an emulsion, a slush, or combinations thereof.
4 . The method claim 1 , wherein the plurality of different components are selected from water, solvents, polymers, ceramics, metals, composites, particles, solid beads, hollow beads, platelets, flakes, fibers, fibrils, whiskers, tubes, hydrogels, capsules, hydrogel capsules, carbohydrates, monosaccharides, disaccharides and polysaccharides, lipids, peptides, proteins, blood, cells, biological factors, hormones, growth factors, viral vectors, antibacterial agents, stains, magnetic materials, piezoelectric materials, semiconductors, electrically conductive materials, thermally conductive materials, solutions thereof, colloids thereof, gels thereof, slurries thereof, ice particles thereof, ice crystals thereof, solidified mixture thereof, and combinations thereof.
5 . The method of claim 1 , wherein the freezing comprises directional freezing of the mixture through the temperature gradient in the mixture, wherein the temperature gradient is concentric with respect to the direction of the extruding.
6 . The method of claim 1 , wherein the freezing occurs within the at least one nozzle or syringe.
7 . The method of claim 1 , wherein the freezing occurs during the extruding, while the mixture exits the at least one nozzle or syringe, and after the mixture exits the at least one nozzle or syringe.
8 . The method of claim 1 , wherein the freezing occurs by exposure of the mixture to a cooling source.
9 . The method of claim 1 , wherein a cooling source does not contact the mixture or a component of the at least one nozzle or syringe, or a container.
10 . The method of claim 1 , wherein a cooling source directly contacts the at least one nozzle or syringe, or a container.
11 . The method of claim 1 , wherein a cooling source comprises a plurality of cooling units positioned at different regions around the at least one nozzle or syringe, or a container, to create the temperature gradient in the mixture.
12 . The method of claim 2 , wherein the at least one nozzle or syringe has a shorter length and a narrower diameter than the container.
13 . The method of claim 1 , wherein the property gradient is a longitudinal gradient with respect to the direction of the extruding and a radial gradient with respect to the direction of the extruding, or a radial gradient with respect to the direction of the extruding.
14 . The method of claim 1 , further comprising applying the temperature gradient to the mixture as the mixture exits the extruder to a surface.
15 . The method of claim 1 , further comprising removing solvent from the extruded material.
16 . The method of claim 15 , wherein the solvent is removed by subliming.
17 . The method of claim 16 , wherein the subliming forms a hollow cavity within the extruded material and the hollow cavity comprises a non-uniform diameter.
18 . The method of claim 17 , wherein the hollow cavity comprises a graded diameter, and wherein the graded diameter becomes narrower from a first end of the extruded material to a second end of the extruded material.
19 . The method of claim 1 , wherein the method is performed continuously, and wherein the mixture is continuously extruded for a certain amount of time.
20 . The method of claim 1 , wherein the ordered crystal formation of the extruded material creates and controls a porosity of the extruded material.
21 . The method of claim 1 , wherein the extruded material has a closed cell wall structure or an open cell wall structure.