3D Imaging of directional multi-scale cellulose nanostructures through multi-directional dark-field neutron tomography

TL;DR

This paper demonstrates a non-destructive, multi-directional dark-field neutron tomography technique to visualize the 3D nanoarchitecture of cellulose nanostructures in biomaterials, overcoming limitations of traditional imaging methods.

Contribution

It introduces a novel neutron imaging approach for multiscale, 3D visualization of nanocellulose structures, preserving sample integrity and enabling detailed orientation analysis.

Findings

Visualized 3D anisotropic orientation of nanofibrils

Characterized degree of alignment across length scales

Demonstrated non-destructive imaging of large-volume samples

Abstract

Hierarchical biomaterials embody nature's intricate design principles, offering advanced functionalities through the complex, multi-level organization of their molecular and nanosized building blocks. However, the comprehensive characterization of their 3D structure remains a challenge, particularly due to radiation damage caused by conventional X-ray- and electron-based imaging techniques, as well as due to the length scale limitations of scattering-based investigation methods. Here, we present a study utilizing multi-directional dark-field neutron imaging in tomographic mode to visualize the 3D nanoarchitecture of nanocellulose solid foams, a class of sustainable materials possessing complex and highly tunable hierarchical structures. By exploiting the unique properties of neutrons as a probe, this non-destructive method circumvents the inherent limitations of damage-inducing ionizing radiation, preserving the structural and chemical integrity of the biomaterials, and allowing for truly multiscale characterization of the spatial orientation and distribution of cellulose nano fibrils within large-volume samples. In particular, the study showcases the 3-dimensional anisotropic orientation and degree of alignment of nanofibrils with different crystallinity, across various length scales, from nanometers to centimeters. This approach offers a valuable and generally applicable tool for multi-scale characterisation of biobased materials where complex nanoscale arrangements inform macroscopic properties.