The way in which wood grows is controlled by its genetic code, which gives it unique properties in terms of porosity, toughness, and torsional strength. But wood has limitations when it comes to processing. Unlike metals and plastics, it cannot be melted and easily reshaped, and instead must be sawed, planed, or curved. Processes that involve conversion — to make products such as paper, cards, and textiles — destroy the underlying ultrastructure, or architecture, of the wood cells.
A technology was developed that allows wood to be, in effect, grown into exactly the shape desired for the final product through the use of 3D printing. By previously converting wood pulp into a nanocellulose gel, an ink was created that could be 3D-printed. The process interprets and digitizes wood’s genetic code, so that it can instruct a 3D printer.
The arrangement of the cellulose nanofibrils can be precisely controlled during the printing process to actually replicate the desirable ultrastructure of wood. Being able to manage the orientation and shape means that the useful properties of natural wood can be captured. Products that are already forest-based can now be 3D-printed in a much shorter time.
Hemicellulose, a natural component of plant cells, was added to the nanocellulose gel. The hemicellulose acts as a glue, giving the cellulose sufficient strength to be useful in a similar manner to the natural process of lignification, through which cell walls are built.
Honeycomb structures were printed with chambers in between the printed walls; solid particles were then encapsulated inside those chambers. Cellulose has excellent oxygen barrier properties, meaning this could be a promising method for creating airtight packaging for food or pharmaceuticals.
Prototypes also were developed for healthcare products and clothing.