3D printed nanocellulose scaled up for green architectural applications

For the first time, a hydrogel material composed of nanocellulose and algae was tested as an alternative, more environmentally friendly architectural material. The study, carried out by Chalmers University of Technology in Sweden and the Wallenberg Wood Science Center, shows how the abundant sustainable material can be 3D printed into a wide range of architectural components, using significantly less energy than conventional conventional construction methods.

The research is presented in a paper titled “Robotically 3D-printed architectural membranes from room temperature-dried cellulose nanofibril-alginate hydrogel” published in the journal Materials and design.

The construction industry today consumes 50% of the world’s fossil resources, generates 40% of the world’s waste and is responsible for 39% of global carbon dioxide emissions. There is a growing body of research into biomaterials and their applications, in order to move towards a greener future, in line with, for example, the European Green Deal.

Nanocellulose is not a new biomaterial and its properties as a hydrogel are known in the field of biomedicine, where it can be 3D printed in scaffolds for tissue and cell growth, due to its biocompatibility and its humidity. But it has never been dried or used as an architectural material before.

“For the first time, we explored an architectural application of nanocellulose hydrogel. Specifically, we provided the missing knowledge so far on its design-related characteristics and presented, using our samples and prototypes, the possibility of tuning these characteristics through personalized solutions. digital design and robotic 3D printing”, says Malgorzata Zboinska, lead author of the study from Chalmers University of Technology.

The team used nanocellulose fibers and water, with the addition of an algae-based material called alginate. Alginate allowed researchers to produce a 3D printable material because the alginate adds additional flexibility to the material when it dries.

Cellulose is considered the most abundant environmentally friendly alternative to plastic, as it is one of the byproducts of the world’s largest industries. “The nanocellulose used in this study can come from forestry, agriculture, paper mills and straw residue from agriculture. It is a very abundant material in this sense,” explains Zboinska.

3D printing and nanocellulose: a resource-saving technique

The architecture industry today is surrounded by access to digital technologies that enable the use of a wider range of new techniques, but there is a lack of knowledge about how these techniques can be applied.

According to the European Green Deal, from 2030, buildings in Europe must be more resource efficient, and this can be achieved through increased reuse and recycling of materials, such as nanocellulose, a recycled by-product of industry. As buildings need to become more circular, cutting-edge digital techniques are being highlighted as important levers to achieve these goals.

“3D printing is a very resource-efficient technique. It allows us to manufacture products without other elements such as dies and molding forms, which means less waste. It is also very energy efficient. The system “The robotic 3D printing we use doesn’t use heat, just air pressure. This saves a lot of energy since we only work at room temperature,” explains Zboinska.

The energy-efficient process relies on the shear thinning properties of the nanocellulose hydrogel. When you apply pressure it liquefies, allowing it to be 3D printed, but when you remove the pressure it retains its shape. This allows researchers to work without the energy-intensive processes common in the construction industry.

Zboinska and his team designed many different toolpaths to use in the robotic 3D printing process to see how the nanocellulose hydrogel would behave when dried in different shapes and patterns. These dried shapes could then be used as a basis for designing a wide range of free-standing architectural components, such as lightweight room dividers, blinds and wall panel systems. They could also serve as a basis for cladding existing building elements, such as tiles to clad walls, acoustic elements to dampen sound, and be combined with other materials to clad frame walls.

The future of greener building materials

“Traditional building materials are designed to last hundreds of years. Usually they have predictable behaviors and consistent properties. We have concrete, glass and all kinds of hard materials that last and we know how they will age with time. Unlike this, bio-based materials contain organic matter, designed from the start to biodegrade and return to nature.

“We therefore need to gain completely new knowledge about how we might apply them in architecture and how we might adopt their shorter life cycles and heterogeneous behavior patterns, more closely resembling those found in nature rather than in an artificial and fully controlled environment. Design researchers and architects are now intensively looking for ways to design products made from these materials that are both functional and aesthetic,” explains Zboinska.

This study provides the first steps to demonstrate the potential for scaling room-temperature-dried, 3D-printed nanocellulose membrane constructs, as well as a new understanding of the relationship between designing material deposition pathways via 3D printing and dimensions, textures, and geometric effects in the final constructions.

This knowledge provides a necessary springboard that will allow Zboinska and his team to develop, through further research, applications of nanocellulose in architectural products that must meet specific functional and aesthetic requirements of users.

“The still poorly understood properties of new biosourced materials encourage architectural researchers to establish alternative approaches to design these new products, not only in terms of functional qualities, but also acceptance by users. The aesthetics of biosourced materials are an important part of that.

“If we want to offer these biosourced materials to society and people, we also have to work on design. This becomes a very strong element for the acceptance of these materials. If people do not accept them, we will not achieve the objectives of a circular economy and a sustainable built environment.