Exploring water at the heart of bio-based materials, using synchrotron radiation
At the end of March, a team from the Pomacle Chair of Biotechnology conducted several hours of experiments at the SOLEIL Synchrotron on the Saclay plateau. Their objective: to better understand the behavior of bio-based materials, such as wood, in the presence of water.
Why use a synchrotron to study these materials?
Bio-based composite materials, made from wood or plant fibers, are generating significant interest in numerous sectors, including sustainable packaging, construction, and biomedical applications. Because these materials are sensitive to humidity, optimizing their properties and performance for these applications requires a thorough understanding of their behavior in the presence of water, particularly their microstructure and even nanostructure, and especially their evolution under real-world conditions. While characterizing static samples can be done in the laboratory, studying them during dynamic processes, such as when wood absorbs water, requires advanced experimental equipment like synchrotron radiation sources.
Pictured here: part of the team from the Chair of Biotechnology at Pomacle, involved in the project during the experiment on the SOLEIL PSICHÉ line
Ultra-high resolution 4D imaging
To visualize the interior of a material in 3D, tomography is now commonly used: it consists of reconstructing the sample in 3D from a multitude of 2D projections. In materials science, unlike medical imaging, it is the sample that rotates within the X-ray beam. In a laboratory tomograph, this takes a considerable amount of time (several hours at high resolution). A synchrotron, at an experimental station called a beamline, produces an extremely bright beam of X-rays, which drastically reduces the scanning time.
This exceptional brilliance of X-rays, along with other qualities (coherence, energy selection, nearly parallel beam), makes it possible to obtain images with very high spatial resolution (from a few microns to tens of nanometers) in just a few minutes, and therefore to perform real-time experiments to monitor dynamic phenomena. This is known as 4D imaging (3D + time).
The expertise of the biotechnology chair to observe water at the heart of materials
How does bound water migrate and diffuse within the pores of wood? How does the microstructure of composite materials designed and optimized for biomedical applications (e.g., matrices for bone regeneration) evolve during rehydration?
To answer these questions, a custom-designed imbibition device was developed by the biotechnology chair teams. This device, already tested in a previous synchrotron experiment (SOLEIL's Anatomix beamline) a year ago, allows for controlled exposure of the sample to water, while simultaneously monitoring the imbibition dynamics using X-ray nanotomography coupled with X-ray diffraction measurements. The aim of this experiment on the PSICHÉ beamline is therefore to track the imbibition of liquid water within the pore morphology of the samples, in conjunction with the evolution of their crystallinity.
The preparation of the samples - wood (poplar, spruce, oak…) and starch-based composites - also benefited from the know-how of the LGPM, both for their shaping (adapted geometries, water jet and laser cutting) and for their upstream design, in particular for the optimized (functionalized) composite materials for medical applications.
What results can be expected from this research?
This research provides a better understanding of how water interacts with bio-based materials, from fundamental mechanisms to their behavior under real-world conditions, in order to improve their design and performance, and to enrich multi-scale models by integrating these phenomena and their dynamics. This will allow for the development of new processes to obtain ideal pore morphologies and sizes for various applications.
These results contribute to the development of more environmentally friendly solutions, while paving the way for innovative applications, particularly in the field of health.
Scientists involved: Patrick Perré (project leader), Aya Zoghlami, Brahim Mazian, Franco Otaola, Hajar Naciri, Kaiky Amaro, Pedro Augusto, Sylvain Foret, Thomás Vianna, and Yuri Ferreira da Silva
