Nanoclay Support Bath for Liquid Build Material Extrusion 3D Printing Without Rapid Phase Change

Nanoclay Bath Supports Printed Structures During Fabrication, Allowing for Liquid Phase Build Material Printing

This nanoclay support bath stabilizes 3D-printed liquid build material (including hydrogel) structures during fabrication, eliminating the need for the structure to undergo a rapid phase change (usually solidification, but sometimes curing or gelation). The traditional approach for liquid build material 3D printing to maintain structural integrity is solidification-while-printing, wherein each layer completely solidifies prior to the deposition of a subsequent layer. This approach poses several problems, such as clogging of the extrusion nozzle depositing the hydrogel, difficulty in printing support structures as they undergo phase change, and weaker interfacial strength between two sequential layers of a structure. To resolve these issues, researchers at the University of Florida have developed a support bath that uses a nanoclay colloid. The stable nanostructure of the colloid behaves like liquid when accepting the deposition of the structure by the extrusion nozzle, and then behaves like a gel to support the structure until it solidifies, enabling truly freeform fabrication of intricate structures. The colloid, unlike other support materials, is insensitive to most stimuli that solidify, or cure, liquid build material structures and is easy to remove in order to harvest the printed object after phase change.

Application

3D printing of various liquid build materials, including hydrogels, free from the constraints and problems of rapid solidification, gelation, or curing

Advantages

• Liquid build material structures deposited in the colloid need not change phase (i.e. undergo solidification, curing, or gelation) while printing for the sake of structural integrity, eliminating constraints on materials and geometry, as well as problems such as nozzle clogging due to short stand-off distance
• Increases freedom in the liquid build material extrusion process, enabling more efficient production of freeform 3D printed structures

Technology

Laponite nanoclay is made up of nanoscale platelets/discs. When dispersed in water, these platelets adopt a stable "house-of-cards" arrangement as an 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. In the support bath, the extrusion nozzle exerts enough pressure on the nearby sections of the nanoclay to make it behave like a liquid and accept the deposition of liquid build materials via the nozzle. Once the nozzle has moved on, the nanoclay returns to its gel-like solid state, supporting the deposited structure.