“Cellulose is the most abundant organic polymer in the world,” says MIT postdoc Sebastian Pattinson, lead author of the study, published recently in Advanced Materials Technologies. “And because it’s so inexpensive, it’s biorenewable, biodegradable, and also very chemically versatile, it’s used in a lot of products. Cellulose and its derivatives are used in pharmaceuticals, medical devices, as food additives, building materials, clothing—all sorts of different areas. And a lot of these kinds of products would benefit from the kind of customization that additive manufacturing [3-D printing] enables.”
For these reasons, cellulose has long been a target material for additive manufacturing. However, previous efforts struggled with cellulose’s thermal decomposition before it becomes “flowable.” Also, high concentrations of cellulose were too viscous to extrude.
Pattinson and coauthor A. John Hart, associate professor of mechanical engineering, solved these problems by using cellulose acetate dissolved in acetone at room temperature. Once “printed,” the acetone evaporates, and the cellulose acetate solidifies in place. An optional treatment can be applied afterwards to improve the 3-D printed parts’ strength.
“After we 3-D print, we restore the hydrogen bonding network through a sodium hydroxide treatment,” Pattinson says. “We find that the strength and toughness of the parts we get … are greater than many commonly used materials” for 3-D printing, including acrylonitrile butadiene styrene and polylactic acid.
Antimicrobial dyes can also be added, opening up applications for custom-made tools and remote medical settings.