The Singapore University of Technology and Design (SUTD) has been at the forefront of some pretty innovative research in additive manufacturing. Just last week, a team of researchers from the university announced the co-development of a family of UV curable hydrogels which can stretch up to 1300%—no small feat. Even more recently, a separate study has come out of SUTD about using 3D printing to create large-scale cellulose structures. The research marks an important step ahead for the development of ecological, fully sustainable manufacturing materials.
Cellulose, an organic compound found in the cell walls of plants, is not only one of the most plentiful organic compounds in the world but is also one of the most abundant industrial by-products. For this reason, cellulose has been highly sought after by researchers seeking to adapt the compound for fabrication methods such as 3D printing.
Despite many efforts, however, researchers have consistently encountered problems that have limited the capacity for cellulose to be built into 3D structures, including using derivatives with polluting effects, having to pair the natural material with plastics, high production costs and lack of scalability.
Fortunately, researchers from SUTD have developed a novel method for not just 3D printing sustainable structures from cellulose but creating large-scale objects.
To achieve this, the researchers first turned away from the most commonly known cellulose found in the cell walls of green plants and instead drew inspiration from oomycetes, fungus-like microorganisms whose cell walls are also composed of cellulose. In reproducing oomycetes cell walls, the SUTD researchers introduced small amounts of chitin—the primary element in the cell walls of fungi and arthropods’ exoskeletons—in between cellulose fibers.
The combination of the two natural compounds resulted in a fungal-like adhesive material (FLAM) which is strong, lightweight, inexpensive and can be molded or processed using other techniques. Importantly, FLAM is also completely sustainable because it does not integrate any synthetic plastics or organic solvents and is fully biodegradable in natural conditions (meaning that it does not require a composting facility to biodegrade).
Other notable benefits of the cellulose-based material include its scalability and its versatility: it can reportedly be reproduced anywhere as it does not necessitate specialized facilities. With a cost comparable to commodity plastics, FLAM is also cheap, costing roughly ten times less than standard 3D printing filaments such as PLA and ABS.
To use the material for creating large-scale structures, the SUTD team also developed a special additive manufacturing method, which it believes will be a game-changer when used with the material.
“We believe this first large-scale additive manufacturing process with the most ubiquitous biological polymers on earth will be the catalyst for the transition to environmentally benign and circular manufacturing models, where materials are produced, used, and degraded in closed regional systems,” explained SUTD Assistant Prof Javier Gomez Fernandez, who co-led the research.
“This reproduction and manufacturing with the material composition found in the oomycete wall, namely unmodified cellulose, small amounts of chitosan—the second most abundant organic molecule on earth—and low concentrated acetic acid, is probably one of the most successful technological achievements in the field of bioinspired materials.” Interestingly, Fernandez was also part of the Wyss Institute team responsible for Shrilk Biodegradable Plastic, a fully degradable bioplastic made with chitosan.
Co-lead SUTD Assistant Prof Stylianos Dritsas added: “We believe the results reported here represent a turning point for global manufacturing with broader impact on multiple areas ranging from material science, environmental engineering, automation and the economy. So far we have been focusing on fundamental technology development, and little time has been invested in specific target applications. We are now at the stage of seeking industrial collaborators to bring this technology from the laboratory to the world.”
Across all manufacturing industries, the need for sustainable, ecologically sound materials and processes is becoming more and more crucial as our Earth faces a volatile pollution crisis. By introducing a method for using unmodified compostable polymers that do not necessitate expansive natural resources such as forests, the SUTD team is hoping to put forward a viable and environmentally friendly alternative. SUTD’s research was recently published in Scientific Reports.
It is worth noting that the SUTD team is not alone in its efforts to produce sustainable materials for large-scale 3D printed structures. Researchers from MIT’s Mediated Matter Lab—led by architect Neri Oxman—recently presented their Water-based Digital Fabrication Platform which uses a robotic extrusion system and a biodegradable composite material made from chitosan (a derivative of chitin) to produce large-scale, recyclable structures.