Nanostructure and anisotropy of 3D printed lyotropic liquid crystals studied by scattering and birefringence imaging
Journal article, 2021

Extrusion-based 3D printing of hexagonal and lamellar lyotropic liquid crystals is a powerful technique to produce hierarchical materials with well-defined anisotropic structure. Tailoring the properties of 3D printed objects requires a precise control of the nanostructure; however, a sufficiently high degree of anisotropy is often not achieved. In this study, scanning small angle X-ray scattering was performed in situ at the exit of the needle during 3D printing. We study the induced anisotropy and nanostructure in hexagonal and lamellar lyotropic liquid crystals. Mapping of extruded filaments during printing revealed that narrower nozzle diameters (370 μm) resulted in less anisotropic structures with a wider distribution of orientation angles across the cross section, while larger nozzle diameters (550 μm) resulted in more anisotropic structures with an overall higher degree of orientation. The wall shear rate is higher for the narrower nozzle, which produces wall slip, resulting in a highly anisotropic shell, and a less aligned filament core. Further examination of the filaments revealed phase transitions due to solvent evaporation. The time scales were of 10 – 20 min of exposure to atmospheric conditions. Simultaneously, a loss in the macroscopic anisotropy of the hexagonal self-assembled structure was observed. These processes occur during and after extrusion-based 3D printing of liquid crystals and limit the fine control of the final structure. The variability of structures achieved for our different systems highlights the importance of structural characterization during and after extrusion to guarantee high anisotropy and well-defined structures.

Lyotropic liquid crystals

Scanning SAXS

3D printing

Self-assembly

Birefringence

Author

Adrian Rodriguez Palomo

Chalmers, Physics, Materials Physics

Viviane Lutz-Bueno

Paul Scherrer Institut

Manuel Guizar-Sicairos

Roland Kádár

Chalmers, Industrial and Materials Science, Engineering Materials

Martin Andersson

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Martin Andersson Group

Marianne Liebi

Chalmers, Physics, Materials Physics

Additive Manufacturing

2214-8604 (eISSN)

Vol. 47 102289

Subject Categories

Physical Chemistry

Other Materials Engineering

Condensed Matter Physics

Areas of Advance

Materials Science

DOI

10.1016/j.addma.2021.102289

More information

Latest update

10/12/2021