BlackWOOD project aims at developing renewable superblack materials for advanced light management. In the project, we use a simple combination of controlled delignification and carbonization to produce wood materials with light reflection below 0.4%, reaching superblack levels. Our process is guided by computational methods thus allowing a by-design approach to control the wood microstructure after carbonization. This enables new applications of wood in laser beam management, optical sensors, and many others.
BlackWOOD framework for materials development is versatile as far its process parameters, including wood species, delignification route and carbonization temperature. Varying these factors, and others, we can produce many different materials. Moreover, removed lignin can be circularized into carbon particles for the preparation of black pigments.
Main results
We have demonstrated wood-based materials with ultralow reflectance in the visible range.
We have developed a processing framework that combines controlled delignification with controlled carbonization and thus can manipulate the wood microstructure to a great extent inducing the growth of carbon nanopyramids directly from wood.
These manipulations allowed the lowest reflectance ever reported for biobased materials, 0.36%.
In subsequent effort we were able to reconfigure wood by manipulating lignin content and allocation in wood using NaClO2, which enabled the growth of carbon microneedles that are light absorptive and electrically conductive.
This allowed the expansion of light absorption ability from UV-Vis to IR and microwave region, in a single material.
We showed that the lignin removed during delignification can be circularized into valued materials. Lignin is made into particles and carbonized to yield high-performance black pigments.
Combining this lignin-based black pigments with nanocellulose led to the development of versatile black(er) inks that can be used for many technologies, from ink writing to 3D printing.
Publications and exhibitions
Zhao, B., Shi, X., Khakalo, S., Meng, Y., Miettinen, A., Turpeinen, T., Mi, S., Sun, Z., Khakalo, A., Rojas, O.J. & Dufau Mattos, B. (2023). Wood-based superblack. Nature Communications, 14, 7875. https://doi.org/10.1038/s41467-023-43594-4
Dufau Mattos, B., Jäntti, N., Khakalo, S., Zhu, Y., Miettinen, A., Parkkonen, J., Khakalo, A., Rojas, O., & Ago, M. (2023). Black Bioinks from Superstructured Carbonized Lignin Particles. Advanced Functional Materials, [2304867]. https://doi.org/10.1002/adfm.202304867
Helsinki Design Week 2023, Designs for Cooler Planet: (In)visible, Unlikely materials. https://www.aalto.fi/en/events/unlikely-materials