Three-Dimensional Printing of Flow-inspired Anisotropic Patterns with Liquid Crystalline Polymers.

Anisotropic materials formed by living organisms possess remarkable mechanical properties due to their intricate microstructure and directional freedom. In contrast, human-made materials face challenges in achieving similar levels of directionality due to material constraints and manufacturability. To overcome these limitations, we present an approach using 3D printing of self-assembling thermotropic liquid crystal polymers (LCP). The remarkably high stiffness of the LCP is granted by the alignment of nematic domains within the polymer during extrusion. The Young's modulus ranging from 3 GPa to 40 GPa was found to be strongly influenced by the directionality of the nematic flow. By determining a relationship between stiffness, nozzle diameter and line width, we identify a suitable design space where shaping and mechanical performance can be combined. We demonstrate the ability to print LCPs with on-the-fly width changes to accommodate arbitrary spatially varying directions. This enables us to manufacture exquisite patterns inspired by fluid dynamics with steep curvature variations. The versatility of LCPs combined with this approach allows to 3D-print functional objects with gradients of stiffness and curvatures, offering potential applications in lightweight functional structures embedding crack-mitigation strategies. This method also opens avenues for studying and replicating intricate patterns observed in nature, such as wood or turbulent flow using extrusion 3D printing. This article is protected by copyright. All rights reserved.