Colloidal inks for directed asssembly of 3-D periodic structures
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Abstract
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| Colloidal assembly of mesoscale periodic structures requires control over, and, hence, a fundamental understanding of interparticle forces, phase behavior, and structure evolution during fabrication. Such structures have been fabricated via directed assembly of colloidal inks. Concentrated colloidal gels with tailored viscoelastic properties were designed to form self-supporting features. The inks were deposited in a layer-by-layer sequence to directly write the desired 3-D pattern. Periodic structures with spanning features that vary between ~ 100 mm and 1 mm were assembled. Rheological measurements were carried out to characterize the flow behavior and elastic properties of concentrated inks of varying gel strength. Deflection measurements of spanning elements were used to probe the relationship between gel strength, deposition speed, and shear rate profiles in the nozzle. These observations revealed that the ink adopted a rigid (gel) core-fluid shell architecture during assembly, which simultaneously facilitated bonding and shape retention of the deposited elements. |
