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Three-dimensional printing (3DP) of functional materials is increasingly important for advanced applications requiring objects with complex or custom geometries or prints with gradients or zones with different properties. A common 3DP technique is direct ink writing (DIW), in which printable inks are comprised of a fluid matrix filled with solid particles, the latter of which can serve a dual purpose of rheology modifiers to enable extrusion and functional fillers for performance-related properties. Although the relationship between filler loading and viscosity has been described for many polymeric systems, a thorough description of the rheological properties of three-dimensional (3D) printable composites is needed to expedite the creation of new materials. In this manuscript, the relationship between filler loading and printability is studied using model paraffin/photopolymer composite inks containing between 0 and 73 vol. % paraffin microbeads. The liquid photopolymer resin is a Newtonian fluid, and incorporating paraffin microbeads increases the ink viscosity and imparts shear-thinning behavior, viscoelasticity, and thixotropy, as established by parallel plate rheometry experiments. Using Einstein and Batchelor's work on colloidal suspension rheology, models were developed to describe the thixotropic behavior of inks, having good agreement with experimental results. Each of these properties contributes to the printability of highly filled ([Formula: see text]43 vol. % paraffin) paraffin/photopolymer composite inks. Through this work, the ability to quantify the ideal rheological properties of a DIW ink and to selectively control and predict its rheological performance will facilitate the development of 3D printed materials with tunable functionalities, thus, advancing 3DP technology beyond current capabilities.
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Multimaterial Multinozzle Adaptive 3D Printing of Soft Materials
Abstract Direct ink writing is a facile method that enables biological, structural, and functional materials to be printed in three dimensions (3D). To date, this extrusion‐based method has primarily been used to soft materials in a layer‐wise manner on planar substrates. However, many emerging applications would benefit from the ability to conformally print materials of varying composition on substrates with arbitrary topography. Here, a high throughput platform based on multimaterial multinozzle adaptive 3D printing (MMA‐3DP) that provides independent control of nozzle height and seamless switching between inks is reported. To demonstrate the MMA‐3DP platform, conformally pattern viscoelastic inks composed of triblock copolymer, gelatin, and photopolymerizable polyacrylate materials onto complex substrates of varying topography, including those with surface defects that mimic skin abrasions or deep gouges. This platform opens new avenues for rapidly patterning soft materials for structural, functional, and biomedical applications.
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- Award ID(s):
- 1922321
- PAR ID:
- 10445418
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials Technologies
- Volume:
- 7
- Issue:
- 8
- ISSN:
- 2365-709X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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