For centuries, cellulose has formed the basis of the world’s most abundantly printed-on material: paper. According to a new research at MIT, it may also become an abundant material to print with — potentially providing a renewable, biodegradable alternative to the polymers currently used in 3-D printing materials.
Using cellulose as a material for additive manufacturing is not a new idea, and many researchers have attempted this but faced major obstacles. When heated, cellulose thermally decomposes before it becomes flowable, partly because of the hydrogen bonds that exist between the cellulose molecules. The intermolecular bonding also makes high-concentration cellulose solutions too viscous to easily extrude.
Instead, the MIT team chose to work with cellulose acetate — a material that is easily made from cellulose and is already widely produced and readily available. Essentially, the number of hydrogen bonds in this material has been reduced by the acetate groups. Cellulose acetate can be dissolved in acetone and extruded through a nozzle. As the acetone quickly evaporates, the cellulose acetate solidifies in place. A subsequent optional treatment replaces the acetate groups and increases the strength of the printed parts.
To demonstrate the chemical versatility of the production process, a small amount of antimicrobial dye was added to the cellulose acetate ink, and they 3-D-printed a pair of surgical tweezers with antimicrobial functionality.