• Jelitto, Hans

Abstract

In order to translate the exceptional properties of colloidal nanoparticles to macroscale geometries, assembly techniques must bridge a 10⁶‐fold range of length. Moreover, for successfully attaining a final mechanically robust nanocomposite macroscale material, some of the intrinsic nanoparticles’ properties have to be maintained while minimizing the density of strength‐limiting defects. However, the assembly of nanoscale building blocks into macroscopic dimensions, and their effective macroscale properties, are inherently affected by the precision of conditions required for assembly and emergent flaws including point defects, dislocations, grain boundaries, and cracks. In this manuscript, we use a direct‐write self‐assembly technique to construct free‐standing, millimeter‐scale columns comprising spherical iron oxide nanoparticles (15 nm diameter) surface‐functionalized with oleic acid, which self‐assemble into FCC‐supercrystals in minutes during the direct writing process. Subsequent crosslinking of the oleic acid molecules results in nanocomposites with maximum strength of 110 MPa and elastic modulus up to 58 GPa. These mechanical properties are interpreted according to the flaw size distribution and are as high as newly‐engineered platelet‐based nanocomposites. Our findings indicate a broad potential to create mechanically robust, multifunctional 3D structures by combining additive manufacturing with colloidal assembly. This article is protected by copyright. All rights reserved.

Topics

• nanoparticle
• nanocomposite
• density
• impedance spectroscopy
• surface
• grain
• crack
• strength
• dislocation
• iron
• ceramic
• additive manufacturing
• point defect