Nanoclay Particles Form an Internal Scaffolding to Maintain the Integrity of 3D Structures During Printing
This nanoclay colloid combines with hydrogel ink as a self-supporting internal scaffolding material, providing 3D-printed hydrogel precursor structures with the mechanical strength to maintain integrity without the need for rapid solidification or a support bath. To date, the structural integrity of 3D-printed hydrogel structure models depends on two prevailing methodologies during printing: support-bath-enabled fabrication and rapid solidification. In support-bath-enabled fabrication, 3D structures print within a bath containing various supportive materials or substances, called a support bath. This is feasible for some materials and structures, but removing the bath material afterwards is not always possible. In rapid solidification, effective stimuli quickly cause the structures to solidify as they print. However, this constrains material selection and achievable geometries.
As an alternative to these two modes of maintaining structural integrity during printing, researchers at the University of Florida have developed a nanoclay colloid that integrates into the hydrogel ink; the mechanical strength of the colloid allows the structure to maintain its shape in air during deposition. Once the entire structure is printed, researchers gel or crosslink the hydrogel precursor component of the ink to stabilize the final hydrogel structure.
3D printing of self-supported hydrogels free from the constraints of rapid solidification, gelation, curing, or support baths
- Removes the need for structures to change phase (i.e. undergo solidification, curing or gelation) during printing to preserve structural integrity, eliminating constraints on materials and geometry, as well as problems such as nozzle clogging due to short stand-off distance
- Provides internal mechanical support for shape and structure, allowing for 3D printing of hydrogel structures without any kind of external support
Laponite nanoclay is made up of nanoscale platelets/discs. When dispersed in water, these platelets adopt a stable “house-of-cards” arrangement as the aqueous Laponite suspension equilibrates, resulting in a transparent colloidal suspension. Because of this arrangement, the colloid behaves as a solid up to a certain physical stress level. Above that level, the arrangement breaks down and the colloid behaves as a liquid. This allows its extrusion as a liquid from the 3D printer, and then its return to a stable arrangement to retain the printed shape. The hydrogel ink formulations containing the nanoclay colloid retain these flow properties and so maintain their structural integrity during printing. A stimuli applied to crosslink or gel the hydrogel component of the ink stabilizes the structures for handling.