Lignin and cellulose ink enable 3D printed wood

Wood is typically shaped through subtractive manufacturing techniques, but the process often generates substantial wood waste, leading to material inefficiency and increased production costs.

Now researchers in materials science and nanoengineering at Rice University, Texas, have developed an additive-free, water-based ink made of lignin and cellulose, which are the fundamental building blocks of wood. The ink can be used to produce architecturally intricate wood structures via direct ink writing.

The work has been published in Science Advances.

In a statement, Muhammad Rahman, an assistant research professor of materials science and nanoengineering at Rice, said: “The ability to create a wood structure directly from its own natural components sets the stage for a more eco-friendly and innovative future.”

“Unlike previous attempts, this method exclusively uses nanoscale wood components for 3D printing, marking a significant advancement in the field,” said Pulickel Ajayan, the Benjamin M. and Mary Greenwood Anderson Professor in Engineering and professor and chair of materials science and nanoengineering.

The university’s research focused on optimising the composition of the ink by adjusting the ratio of lignin, cellulose nanofibres and nanocrystals while maintaining the natural lignin-cellulose balance, according to M.S.H Thakur and Chen Shi, lead co-authors on the study.

Although lignin is one of the most abundant biopolymers on Earth, it is the least-valued product in industries, said Amit Naskar, a project collaborator and senior research and development staff at Oak Ridge National Laboratory.

Post-printing, and after heat treatment, comprehensive analyses were conducted to assess the surface and internal structures of the 3D printed wood, comparing it to natural wood counterparts. The team found that the 3D printed wood exhibited close similarities to natural wood in texture, scent and strength.

Mechanical tests were performed to evaluate compressive and bending strengths, revealing results that surpassed those of natural balsa wood.