Category Archives: forestry

‘SWEET’ (smart, wearable, and eco-friendly electronic textiles)

I always appreciate a good acronym and this one is pretty good. (From my perspective, a good acronym is memorable and doesn’t involve tortured terminology such as CRISPR-Cas9, which stands for clustered regularly interspaced short palindromic repeats-CRISPR-associated protein 9).

On to ‘SWEET’ and a January 2, 2025 news item on ScienceDaily announcing a new UK study on wearable e-textiles,

A research team led by the University of Southampton and UWE Bristol [University of the West of England Bristol] has shown wearable electronic textiles (e-textiles) can be both sustainable and biodegradable.

A new study, which also involved the universities of Exeter, Cambridge, Leeds and Bath, describes and tests a new sustainable approach for fully inkjet-printed, eco-friendly e-textiles named ‘Smart, Wearable, and Eco-friendly Electronic Textiles’, or ‘SWEET’.

A January 2, 2025 University of Southampton press release (also on EurekAlert), which originated the news item, describes e-textiles and how this latest work represents a step forward in making them environmentally friendly,

E-textiles are those with embedded electrical components, such as sensors, batteries or lights. They might be used in fashion, for performance sportwear, or for medical purposes as garments that monitor people’s vital signs.

Such textiles need to be durable, safe to wear and comfortable, but also, in an industry which is increasingly concerned with clothing waste, they need to be kind to the environment when no longer required.

Professor Nazmul Karim at the University of Southampton’s Winchester School of Art, who led the study, explains: “Integrating electrical components into conventional textiles complicates the recycling of the material because it often contains metals, such as silver, that don’t easily biodegrade. Our potential ecofriendly approach for selecting sustainable materials and manufacturing overcomes this, enabling the fabric to decompose when it is disposed of.”

The team’s design has three layers, a sensing layer, a layer to interface with the sensors and a base fabric. It uses a textile called Tencel for the base, which is made from renewable wood and is biodegradable. The active electronics in the design are made from graphene, along with a polymer called PEDOT: PSS. These conductive materials are precision inkjet-printed onto the fabric.

The researchers tested samples of the material for continuous monitoring of human physiology using five volunteers. Swatches of the fabric, connected to monitoring equipment, were attached to gloves worn by the participants. Results confirmed the material can effectively and reliably measure both heart rate and temperature at the industry standard level.

Dr Shaila Afroj, an Associate Professor of Sustainable Materials from the University of Exeter and a co-author of the study, highlighted the importance of this performance: “Achieving reliable, industry-standard monitoring with eco-friendly materials is a significant milestone. It demonstrates that sustainability doesn’t have to come at the cost of functionality, especially in critical applications like healthcare.”

The project team then buried the e-textiles in soil to measure its biodegradable properties. After four months, the fabric had lost 48 percent of its weight and 98 percent of its strength, suggesting relatively rapid and also effective decomposition. Furthermore, a life cycle assessment revealed the graphene-based electrodes had up to 40 times less impact on the environment than standard electrodes.

Marzia Dulal from UWE Bristol, a Commonwealth PhD Scholar and the first author of the study, highlighted the environmental impact: “Our life cycle analysis shows that graphene-based e-textiles have a fraction of the environmental footprint compared to traditional electronics. This makes them a more responsible choice for industries looking to reduce their ecological impact.”

The ink-jet printing process is also a more sustainable approach for e-textile fabrications, depositing exact numbers of functional materials on textiles as needed, with almost no material waste and less use of water and energy than conventional screen printing.

Professor Karim concludes: “ Amid rising pollution from landfill sites, our study helps to address a lack of research in the area of biodegradation of e-textiles. These materials will become increasingly more important in our lives, particularly in the area of healthcare, so it’s really important we consider how to make them more eco-friendly, both in their manufacturing and disposal.”

The researchers hope they can now move forward with designing wearable garments made from SWEET for potential use in the healthcare sector, particularly in the area of early detection and prevention of heart-related diseases that 640 million people (source: BHF [British Heart Foundation]) suffer from worldwide.

Here’s a link to and a citation for the paper,

Sustainable, Wearable, and Eco-Friendly Electronic Textiles by Marzia Dulal, Harsh Rajesh Mansukhlal Modha, Jingqi Liu, Md Rashedul Islam, Chris Carr, Tawfique Hasan, Robin Michael Statham Thorn, Shaila Afroj, Nazmul Karim. Energy & Enviornmental Materials DOI: https://doi.org/10.1002/eem2.12854 First published: 18 December 2024

This paper is open access.

Cellulose nanofibers for sustainable hydrophobic paper

A November 5, 2024 news item on phys.org announces research with cellulose nanofibers (CNFx)

A recent study has aimed to create hydrophobic paper by exploiting the mechanical properties and water resistance of cellulose nanofibers, and so produce a sustainable, high-performance material suitable for packaging and biomedical devices. This involved a supramolecular approach, i.e., combining short chains of proteins (peptide sequences) that do not chemically modify the cellulose nanofibers. Sustainable hydrophobic paper may one day replace petroleum-related products.

An August 11, 2024 Politecnico di Milano (Polytechnic University of Milan) press release, also on EurekAlert but published November 5, 2024), which originated the news item, provides more information, Note: Links have been removed,

The aim was to create hydrophobic paper by exploiting the mechanical properties and water resistance of cellulose nanofibres, and so produce a sustainable, high-performance material suitable for packaging and biomedical devices. This involved a supramolecular approach, i.e. combining short chains of proteins (peptide sequences) that do not chemically modify the cellulose nanofibres. Sustainable hydrophobic paper may one day replace petroleum-related products.

The study is entitled: Nanocellulose-short peptide self-assembly for improved mechanical strength and barrier performance, and has just featured on the cover of the Journal of Materials Chemistry B. The work was carried out by researchers from the “Giulio Natta” Department of Chemistry, Materials and Chemical Engineering at the Politecnico di Milano, in collaboration with Aalto University, the VTT-Technical Research Centre in Finland and the SCITEC Institute of the CNR.

Cellulose nanofibres (CNFs) are natural fibres derived from cellulose – a renewable and biodegradable source – and are well known for their strength and versatility. In the study, the researchers from the SupraBioNanoLab (https://www.suprabionano.eu/) of the “Giulio Natta” Department of the Politecnico di Milano showed how it is possible to greatly improve the properties of cellulose nanofibres without chemically modifying them, instead adding small proteins known as peptides.

Our supramolecular approach involved adding small sequences of peptides, which bind onto the nanofibres and so improve their mechanical performance and water-resistance. Elisa Marelli, co-author of the study, explained the methodology:“The results of the study showed that even minimal quantities of peptides (less than 0.1%) can significantly increase the mechanical properties of the hybrid materials produced, giving them greater resistance to stress.”

Finally, the researchers assessed the impact of adding fluorine atoms in the peptide sequences. This made it possible to create a structured hydrophobic film on the material, providing even greater water resistance while still preserving its biocompatible and sustainable characteristics.

As Pierangelo Metrangolo, co-author of the study, pointed out: “This advance opens up new opportunities for creating biomaterials that can compete with petroleum-derived materials in terms of performance, achieving the same quality and efficiency while reducing environmental impact. These hybrid materials are very suitable for sustainable packaging, where resistance to moisture is vital, and also for use in biomedical devices, thanks to their biocompatibility.

Here’s a link to and a citation for the paper,

Nanocellulose-short peptide self-assembly for improved mechanical strength and barrier performance by Alessandro Marchetti, Elisa Marelli, Greta Bergamaschi, Panu Lahtinen, Arja Paananen, Markus Linder, Claudia Pigliacelli and Pierangelo Metrangolo.. J. Mater. Chem. B, 2024,12, 9229-9237 DOI: 10.1039/D4TB01359J First published online: 19 Aug 2024

This paper is open access.

Super-black wood from the University of British Columbia (UBC)

The researchers have developed prototype watches and jewelry using the new super-black wood. Photo credit: UBC Forestry/Ally Penders

Generally stories about very black materials will mention carbon nanotubes but not this time. A July 30, 2024 University of British Columbia (UBC) news release (also on EurekAlert and received via email) announces the discovery of a technique for making super-black wood,

Thanks to an accidental discovery, researchers at the University of British Columbia have created a new super-black material that absorbs almost all light, opening potential applications in fine jewelry, solar cells and precision optical devices. 

Professor Philip Evans and PhD student Kenny Cheng were experimenting with high-energy plasma to make wood more water-repellent. However, when they applied the technique to the cut ends of wood cells, the surfaces turned extremely black. 

Measurements by Texas A&M University’s department of physics and astronomy confirmed that the material reflected less than one per cent of visible light, absorbing almost all the light that struck it. 

Instead of discarding this accidental finding, the team decided to shift their focus to designing super-black materials, contributing a new approach to the search for the darkest materials on Earth.

“Ultra-black or super-black material can absorb more than 99 per cent of the light that strikes it – significantly more so than normal black paint, which absorbs about 97.5 per cent of light,” explained Dr. Evans, a professor in the faculty of forestry and BC Leadership Chair in Advanced Forest Products Manufacturing Technology.

Super-black materials are increasingly sought after in astronomy, where ultra-black coatings on devices help reduce stray light and improve image clarity. Super-black coatings can enhance the efficiency of solar cells. They are also used in making art pieces and luxury consumer items like watches.

The researchers have developed prototype commercial products using their super-black wood, initially focusing on watches and jewelry, with plans to explore other commercial applications in the future.

Wonder wood

The team named and trademarked their discovery Nxylon (niks-uh-lon), after Nyx, the Greek goddess of the night, and xylon, the Greek word for wood. 

Most surprisingly, Nxylon remains black even when coated with an alloy, such as the gold coating applied to the wood to make it electrically conductive enough to be viewed and studied using an electron microscope. This is because Nxylon’s structure inherently prevents light from escaping rather than depending on black pigments.

The UBC team have demonstrated that Nxylon can replace expensive and rare black woods like ebony and rosewood for watch faces, and it can be used in jewelry to replace the black gemstone onyx.

“Nxylon’s composition combines the benefits of natural materials with unique structural features, making it lightweight, stiff and easy to cut into intricate shapes,” said Dr. Evans.

Made from basswood, a tree widely found in North America and valued for hand carving, boxes, shutters and musical instruments, Nxylon can also use other types of wood such as European lime wood.

Breathing new life into forestry

Dr. Evans and his colleagues plan to launch a startup, Nxylon Corporation of Canada, to scale up applications of Nxylon in collaboration with jewellers, artists and tech product designers. They also plan to develop a commercial-scale plasma reactor to produce larger super-black wood samples suitable for non-reflective ceiling and wall tiles. 

“Nxylon can be made from sustainable and renewable materials widely found in North America and Europe, leading to new applications for wood. The wood industry in B.C. is often seen as a sunset industry focused on commodity products—our research demonstrates its great untapped potential,” said Dr. Evans.

Other researchers who contributed to this work include Vickie Ma, Dengcheng Feng and Sara Xu (all from UBC’s faculty of forestry); Luke Schmidt (Texas A&M); and Mick Turner (The Australian National University).

Here’s a link to and a citation for the paper (and hat’s off to the writers for an accessible introduction),

Super-Black Material Created by Plasma Etching Wood by Kenneth J. Cheng, Dengcheng Feng, Luke M. Schmidt, Michael Turner, Philip D. Evans. Advanced Sustainable Systems DOI: https://doi.org/10.1002/adsu.202400184 First published: 16 June 2024

This paper is open access.

I can’t resist; this is such a good introduction, keeping in mind it’s written for an academic journal, from Super-Black Material Created by Plasma Etching Wood.

Super-black materials have very low reflectivity due to structural absorption of light.[1] They are attracting considerable scientific and industrial attention because of their important applications in many fields: astronomy,[2, 3] photovoltaics,[4, 5] and optical science,[6] among others. In these applications, super-black materials minimize unwanted reflection of light enabling devices to operate more accurately or efficiently.[6] In other fields, for example art and design, the attraction of super-black materials lies in their ability to create bizarre visual effects because of huge contrast between black and adjacent colored objects or surfaces.[7] This artistic application of super-black materials is analogous to the juxtaposition of super-black and brightly colored courtship display patches in birds and peacock spiders.[8, 9] In birds, super-black patches have been defined as those having less than 2% directional reflectance at normal incidence.[8] Reflectance values of super-black patches in 32 bird species ranged from 0.045 to 1.97% with an average of 0.94% (300–700 nm).[8] Other studies have associated super-blackness with reflectance values of 1%[10] or 0.5%.[3] Far lower reflectance values have been achieved with materials containing aligned carbon nanotubes (CNT), for example a low-density CNT array (0.045%),[11] the coating Vantablack (0.035%)[7] and a CNT-metal foil (0.005%).[12] The current holder of the “record” for a low reflectivity material (<0.0002%) is an ion-track micro-textured polymer with anti-backscatter matrix.[13]

The low reflectivity of materials such as Vantablack is due to the high absorption of light by graphene and the ability of vertical arrays of CNT to lower surface reflection.[6, 7] In the case of a low-density CNT array, its low reflectivity was ascribed to its random surface profile and presence of a loose network of entangled nanotubes, in addition to vertically oriented nanotubes.[11] Other structures can also be used to reduce reflectivity of synthetic materials including nanopores, and microcavities.[6] Even more diverse structures are found in natural super-black materials, including complex barbule microstructures in birds,[1] cuticular micro-lens arrays in peacock spiders,[9] and polydisperse honeycomb configurations in the wings of butterflies.[14] The structural features of butterfly wings have been used as biomimetic models to create super-black polymer films.[4, 10] This biomimetic route to creating super-black materials has the advantages that “the films are thinner than known alternatives and can be fabricated at lower temperatures via plasma-enhanced chemical vapor deposition, instead of being grown from CNT.”[4, 14]

Biomimicry of nature’s structural material par excellence, wood, is being used to create lightweight stiff and tough composites,[15, 16] but wood is not a model for the creation of super-black materials because even the darkest woods such as ebony (Diospyros spp.) or African blackwood (Dalbergia melanoxylon Guill. & Perr.) lack structural features that reduce reflectivity. Nevertheless, there is interest in using wood in applications where blackness is advantageous such as solar steam generation and desalination of water,[17-20] because wood is widely available, inexpensive, sustainable and can be fabricated into panels and objects. In these applications, wood is carbonized and retains its porous microstructure creating a black material with reflectivity of 3%.[18] The creation of additional porosity by micro-drilling the wood prior to carbonization further reduced reflectivity to 2%.[18] We serendipitously created a super-black wood during undirected investigations into the use of plasma etching to “machine” novel microstructures at basswood (Tilia americana L.) surfaces. We called this material Nxylon, a neologism created from Nyx (Greek goddess of the night) and xylon (Greek for wood materials). One of us published the reflectivity data for Nxylon in 2020.[21] Here we report on the structural features responsible for the super-blackness of Nxylon, describe how it is made and discuss its possible practical uses. During the preparation of this manuscript, we became aware of a novel approach to creating super-black wood involving high temperature carbonization of delignified balsa wood (Ochroma pyramidale (Cav. ex Lam.) Urb.).[22] This material is produced using “mature processing technologies” and can be used to create solid wood products with complex geometries. The surface plasma process we describe is liquid free, generates little waste and is more suited for the creation of super-black veneer which can be used on a small scale to manufacture luxury consumer products. Therein lies the novelty and significance of our work.

The most comprehensive piece I’ve published on the topic of the ‘really, really black’ is in a December 4, 2019 posting, “More of the ‘blackest black’.” At that point, some new work on creating the blackest black (up to 99.99% and 99.995% light absorption, respectively) had come from the US National Institute of Standards and Technology (NIST) and the Massachusetts Institute of Technology (MIT). I also included the latest about an artistic feud over Vantablack (mentioned in the paper’s introduction) and its 99.8% light absorption and provided a link back to my earliest stories on Vantablack.

Aerogels that are 3D printed from nanocellulose

The one on the far right looks a bit like a frog (to me),

Caption: Complexity and lightness: Empa researchers have developed a 3D printing process for biodegradable cellulose aerogel. Credit: Empa

An April 4, 2024 Swiss Federal Laboratories for Materials Science and Technology (EMPA) press release (also on EurekAlert) describes some interesting possibilities for nanocellulose,

At first glance, biodegradable materials, inks for 3D printing and aerogels don’t seem to have much in common. All three have great potential for the future, however: “green” materials do not pollute the environment, 3D printing can produce complex structures without waste, and ultra-light aerogels are excellent heat insulators. Empa researchers have now succeeded in combining all these advantages in a single material. And their cellulose-based, 3D-printable aerogel can do even more.

The miracle material was created under the leadership of Deeptanshu Sivaraman, Wim Malfait and Shanyu Zhao from Empa’s Building Energy Materials and Components laboratory, in collaboration with the Cellulose & Wood Materials and Advanced Analytical Technologies laboratories as well as the Center for X-ray Analytics. Together with other researchers, Zhao and Malfait had already developed a process for printing silica aerogels in 2020. No trivial task: Silica aerogels are foam-like materials, highly open porous and brittle. Before the Empa development, shaping them into complex forms had been pretty much impossible. “It was the logical next step to apply our printing technology to mechanically more robust bio-based aerogels,” says Zhao.

The researchers chose the most common biopolymer on Earth as their starting material: cellulose. Various nanoparticles can be obtained from this plant-based material using simple processing steps. Doctoral student Deeptanshu Sivaraman used two types of such nanoparticles – cellulose nanocrystals and cellulose nanofibers – to produce the “ink” for printing the bio-aerogel.

Over 80 percent water

The flow characteristics of the ink are crucial in 3D printing: Tt must be viscous enough in order to hold a three-dimensional shape before solidification. At the same time, however, it should liquefy under pressure so that it can flow through the nozzle. With the combination of nanocrystals and nanofibers, Sivaraman succeeded in doing just that: The long nanofibers give the ink a high viscosity, while the rather short crystals ensure that it has shear thinning effect so that it flows more easily during extrusion.

In total, the ink contains around twelve percent cellulose – and 88 percent water. “We were able to achieve the required properties with cellulose alone, without any additives or fillers,” says Sivaraman. This is not only good news for the biodegradability of the final aerogel products, but also for its heat-insulating properties. To turn the ink into an aerogel after printing, the researchers replace the pore solvent water first with ethanol and then with air, all while maintaining shape fidelity. “The less solid matter the ink contains, the more porous the resulting aerogel,” explains Zhao.

This high porosity and the small size of the pores make all aerogels extremely effective heat insulators. However, the researchers have identified a unique property in the printed cellulose aerogel: It is anisotropic. This means its strength and thermal conductivity are direction-dependent. “The anisotropy is partly due to the orientation of the nanocellulose fibers and partly due to the printing process itself,” says Malfait. This allows the researchers to control in which axis the printed aerogel piece should be particularly stable or particularly insulating. Such precisely crafted insulating components could be used in microelectronics, where heat should only be conducted in a certain direction.

A lot of potential applications in medicine

Although the original research project, which was funded by the Swiss National Science Foundation (SNSF), was primarily interested in thermal insulation, the researchers quickly saw another area of application for their printable bio-aerogel: medicine. As it consists of pure cellulose, the new aerogel is biocompatible with living tissues and cells. Its porous structure is able to absorb drugs and then release them into the body over a long period of time. And 3D printing offers the possibility of producing precise shapes that could, for instance, serve as scaffolds for cell growth or as implants.

A particular advantage is that the printed aerogel can be rehydrated and re-dried several times after the initial drying process without losing its shape or porous structure. In practical applications, this would make the material easier to handle: It could be stored and transported in dry form and only be soaked in water shortly before use. When dry, it is not only light and convenient to handle, but also less susceptible to bacteria – and does not have to be elaborately protected from drying out. “If you want to add active ingredients to the aerogel, this can be done in the final rehydration step immediately before use,” says Sivaraman. “Then you don’t run the risk of the medication losing its effectiveness over time or if it is stored incorrectly.”

The researchers are also working on drug delivery from aerogels in a follow-up project – with less focus on 3D printing for now. Shanyu Zhao is collaborating with researchers from Germany and Spain on aerogels made from other biopolymers, such as alginate and chitosan, derived from algae and chitin respectively. Meanwhile, Wim Malfait wants to further improve the thermal insulation of cellulose aerogels. And Deeptanshu Sivaraman has completed his doctorate and has since joined the Empa spin-off Siloxene AG, which creates new hybrid molecules based on silicon.

Fascinating work and here’s a link to and a citation for the paper,

Additive Manufacturing of Nanocellulose Aerogels with Structure-Oriented Thermal, Mechanical, and Biological Properties by Deeptanshu Sivaraman, Yannick Nagel, Gilberto Siqueira, Parth Chansoria, Jonathan Avaro, Antonia Neels, Gustav Nyström, Zhaoxia Sun, Jing Wang, Zhengyuan Pan, Ana Iglesias-Mejuto, Inés Ardao, Carlos A. García-González, Mengmeng Li, Tingting Wu, Marco Lattuada, Wim J. Malfait, Shanyu Zhao. Advanced Science DOI: https://doi.org/10.1002/advs.202307921 First published: 13 March 2024

This paper is open access.

You can find Siloxene AG here.

Pulp and paper waste for scrubbing carbon from emissions

This first news release is a little short but the next one is one of the shortest I can recall seeing. First, a February 1, 2024 Canadian Light Source (CLS) news release by Victoria Martinez,

Researchers at McGill University have come up with an innovative approach to improve the energy efficiency of carbon conversion, using waste material from pulp and paper production. The technique they’ve pioneered using the Canadian Light Source at the University of Saskatchewan not only reduces the energy required to convert carbon into useful products, but also reduces overall waste in the environment.

“This is a new field,” says Roger Lin, a graduate student in chemical engineering “We are one of the first groups to combine biomass recycling or utilization with CO2 capture.” The research team, from McGill’s Electrocatalysis Lab, published their findings in the journal RSC [Royal Society of Chemistry] Sustainability.

Capturing carbon emissions is one of the most exciting emerging tools to fight climate change. The biggest challenge is figuring out what to do with the carbon once the emissions have been removed, especially since capturing CO2 can be expensive. The next hurdle is that transforming CO2 into useful products takes energy. Researchers want to make the conversion process as efficient and profitable as possible.

“For these reactions, it really matters that we target energy efficiency,” says Amirhossein Farzi, a PhD student in chemical engineering at McGill. “The highest burden on the profitability of these reactions and these processes is usually how energy efficient they are.”

Farzi, Lin, and their research team focused their efforts on changing out one of the most energy-intensive parts of the carbon conversion process.

Because the approach is so new, there are many questions to answer about how to get the purest outputs and best efficiency. The team used CLS beamlines to observe chemical reactions in real-time, mimicking industrial processes as closely as possible.

The researchers hope to expand the range of products that can be made with CO2, and help develop a truly green technology.

“If we use a renewable energy source like hydro, wind, or solar …then in the end, we have really a carbon negative process,” says Lin.

Then, there was a March 27, 2024 McGill University news release (also on EurekAlert but published April 8, 2024), which is more succinct,

Researchers at McGill University have come up with an innovative approach to improve the energy efficiency of carbon conversion, using waste material from pulp and paper production. The technique they’ve pioneered using the Canadian Light Source at the University of Saskatchewan not only reduces the energy required to convert carbon into useful products, but also reduces overall waste in the environment.

“We are one of the first groups to combine biomass recycling or utilization with CO2 capture,” said Ali Seifitokaldani, Assistant Professor in the Department of Chemical Engineering and Canada Research Chair (Tier II) in Electrocatalysis for Renewable Energy Production and Conversion. The research team, from McGill’s Electrocatalysis Lab, published their findings in the journal RSC Sustainability.

Capturing carbon emissions is one of the most exciting emerging tools to fight climate change. The biggest challenge is figuring out what to do with the carbon once the emissions have been removed, especially since capturing CO2 can be expensive. The next hurdle is that transforming CO2 into useful products takes energy. Researchers want to make the conversion process as efficient and profitable as possible.

Here’s a link to and a citation for the paper,

Efficient integration of carbon dioxide reduction and 5-hydroxymethylfurfural oxidation at high current density by Roger Lin, Haoyan Yang, Hanyu Zheng, Mahdi Salehi, Amirhossein Farzi, Poojan Patel, Xiao Wang, Jiaxun Guo, Kefang Liu, Zhengyuan Gao, Xiaojia Li, Ali Seifitokaldani. RSC Sustainability, 2024; 2 (2): 445 DOI: 10.1039/D3SU00379E First published online: 13 Dec 2023

This paper is open access.

H/t April 8, 2024 news item on ScienceDaily

3D printed nanocellulose for green architectural applications

It’s not happening next week but it is a promising step forward if you’re looking for nancellulose applications. From a February 7, 2024 news item on Nanowerk, Note: A link has been removed,

For the first time, a hydrogel material made of nanocellulose and algae has been tested as an alternative, greener architectural material. The study, from 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 array of architectural components, using much less energy than conventional construction methods.

Caption: 3D printed nanocellulose upscaled for green architectural applications. Credit: Chalmers University of Technology | Emma Fry

A February 6, 2024 Chalmers University of Technology press release (also on EurekAlert but published February 7, 2024), which originated the news item,

The construction industry today consumes 50 percent of the world’s fossil resources, generates 40 percent of global waste and causes 39 percent of global carbon dioxide emissions. There is a growing line of research into biomaterials and their applications, in order to transition to 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 within the field of biomedicine, where it can be 3D printed into scaffolds for tissue and cell growth, due to its biocompatibility and wetness. But it has never been dried and used as an architectural material before.

“For the first time we have explored an architectural application of nanocellulose hydrogel. Specifically, we provided the so far missing knowledge on its design-related features, and showcased, with the help of our samples and prototypes, the tuneability of these features through custom digital design and robotic 3D printing,” says Malgorzata Zboinska, lead author of the study from Chalmers University of Technology.

The team used nanocellulose fibres and water, with the addition of an algae-based material called alginate. The alginate allowed the researchers to produce a 3D printable material, since the alginate added an extra flexibility to the material when it dried.

Cellulose is coined as the most abundant eco-friendly alternative to plastic, as it is one of the byproducts of the world’s largest industries. “The nanocellulose used in this study can be acquired from forestry, agriculture, paper mills and straw residues from agriculture. It is a very abundant material in that sense,” says Malgorzata Zboinska.

3D printing and nanocellulose/ A resource efficient technique

The architectural industry is today surrounded by access to digital technologies which allows for a wider range of new techniques to be used, but there is a gap in the knowledge of how these techniques can be applied. According to the European Green Deal, as of 2030, buildings in Europe must be more resource-efficient, and this can be achieved through elevated reuse and recycling of materials, such as with nanocellulose, an upcycled, byproduct from industry. At the same time as buildings are to become more circular, cutting-edge digital techniques are highlighted as important leverages for achieving these goals.

“3D printing is a very resource efficient technique. It allows us to make products without other things such as dies and casting forms, so there is less waste material. It is also very energy efficient. The robotic 3D printing system we employ does not use heat, just air pressure. This saves a lot of energy as we are only working at room temperature,” says Malgorzata Zboinska.

The energy efficient process relies on the shear thinning properties of the nanocellulose hydrogel. When you apply pressure it liquifies allowing it to be 3D printed, but when you take away the pressure it maintains its shape. This allows the researchers to work without the energy intensive processes that are commonplace in the construction industry.

Malgorzata Zboinska and her team designed many different toolpaths to be used in the robotic 3D printing process to see how the nanocellulose hydrogel would behave when it dried in different shapes and patterns. These dried shapes could then be applied as a basis to design a wide array of architectural standalone components, such as lightweight room dividers, blinds, and wall panel systems. They could also form the basis for coatings of existing building components, such as tiles to clad walls, acoustic elements for damping sound, and combined with other materials to clad skeleton walls.

The future of greener building materials

“Traditional building materials are designed to last for hundreds of years. Usually, they have predictable behaviours and homogenous properties. We have concrete, glass and all kinds of hard materials that endure and we know how they will age over time. Contrary to this, biobased materials contain organic matter, that is from the outset designed to biodegrade and cycle back into nature. We, therefore, need to acquire completely new knowledge on how we could apply them in architecture, and how we could embrace their shorter life cycle loops and heterogenous behaviour patterns, resembling more those found in nature rather than in an artificial and fully controlled environment. Design researchers and architects are now intensely searching for ways of designing products made from these materials, both for function and for aesthetics,” says Malgorzata Zboinska.

This study provides the first steps to demonstrate the upscaling potentials of ambient-dried, 3D-printed nanocellulose membrane constructs, as well as a new understanding of the relationship between the design of the material’s deposition pathways via 3D printing, and the dimensional, textural, and geometric effects in the final constructs. This knowledge is a necessary stepping stone that will allow Malgorzata Zboinska and her team to develop, through further research, applications of nanocellulose in architectural products that need to meet specific functional and aesthetic user requirements.  

“The yet not fully known properties of novel biobased materials prompt architectural researchers to establish alternative approaches to designing these new products, not only in terms of the functional qualities, but also the acceptance from the users. The aesthetics of biobased materials are an important part of this. If we are to propose these biobased materials to society and people, we need to work with the design as well. This becomes a very strong element for the acceptance of these materials. If people do not accept them, we will not reach the goals of a circular economy and sustainable built environment”.

More about the research:

The research is presented in a paper: “Robotically 3D printed architectural membranes from ambient dried cellulose nanofibril-alginate hydrogel”, published in the journal Materials and Design.

The researchers involved in the study are Malgorzata A. Zboinska, Sanna Sämfors and Paul Gatenholm. The researchers were active at Chalmers University of Technology and the Wallenberg Wood Science Center, both in Sweden, at the time of the study.

This work was supported by Adlerbertska Research Foundation and Chalmers University of Technology’s Area of Advance Materials Science. The Knut and Alice Wallenberg Foundation is gratefully acknowledged for funding the Wallenberg Wood Science Center. The authors would also like to recognise the contribution of Karl Åhlund, who assisted in the robotic extrusion system development.

Fact box – previous research:

Printing with nanocellulose was first developed at Chalmers University of Technology within the Wallenberg Wood Science Center in 2015. This is the first time this technology is being scaled up towards applications in buildings.

Here’s a link to and a citation for the paper,

Robotically 3D printed architectural membranes from ambient dried cellulose nanofibril-alginate hydrogel by Malgorzata A. Zboinska, Sanna Sämfors, Paul Gatenholm. Materials & Design Volume 236, December 2023, 112472 DOI: https://doi.org/10.1016/j.matdes.2023.112472

This paper appears to be open access.

For the curious, here’s The European Green Deal.

Mending a broken heart with hydrogels and cellulose nanocrystals (CNC)

Courtesy: University of Waterloo

This February 12, 2024 news item on ScienceDaily highlights work from the University of Waterloo,

You can mend a broken heart this valentine’s day now that researchers invented a new hydrogel that can be used to heal damaged heart tissue and improve cancer treatments.

University of Waterloo chemical engineering researcher Dr. Elisabeth Prince teamed up with researchers from the University of Toronto and Duke University to design the synthetic material made using cellulose nanocrystals [CNC], which are derived from wood pulp.

A February 12, 2024 University of Waterloo news release (also on EurekAlert), which originated the news item, fills in some details,

The material is engineered to replicate the fibrous nanostructures and properties of human tissues, thereby recreating its unique biomechanical properties.

“Cancer is a diverse disease and two patients with the same type of cancer will often respond to the same treatment in very different ways,” Prince said. “Tumour organoids are essentially a miniaturized version of an individual patient’s tumour that can be used for drug testing, which could allow researchers to develop personalized therapies for a specific patient.”

As director of the Prince Polymer Materials Lab, Prince designs synthetic biomimetic hydrogels for biomedical applications. The hydrogels have a nanofibrous architecture with large pores for nutrient and waste transport, which affect mechanical properties and cell interaction. 

Prince, a professor in Waterloo’s Department of Chemical Engineering, utilized these human-tissue mimetic hydrogels to promote the growth of small-scale tumour replicas derived from donated tumour tissue. 

She aims to test the effectiveness of cancer treatments on the mini-tumour organoids before administering the treatment to patients, potentially allowing for personalized cancer therapies. This research was conducted alongside Professor David Cescon at the Princess Margaret Cancer Center.

Prince’s research group at Waterloo is developing similar biomimetic hydrogels to be injectable for drug delivery and regenerative medical applications as Waterloo researchers continue to lead health innovation in Canada.

Her research aims to use injected filamentous hydrogel material to regrow heart tissue damaged after a heart attack. She used nanofibers as a scaffolding for the regrowth and healing of damaged heart tissue. 

“We are building on the work that I started during my PhD to design human-tissue mimetic hydrogels that can be injected into the human body to deliver therapeutics and repair the damage caused to the heart when a patient suffers a heart attack,” Prince said.

Prince’s research is unique as most gels currently used in tissue engineering or 3D cell culture don’t possess this nanofibrous architecture. Prince’s group uses nanoparticles and polymers as building blocks for materials and develops chemistry for nanostructures that accurately mimic human tissues.

The next step in Prince’s research is to use conductive nanoparticles to make electrically conductive nanofibrous gels that can be used to heal heart and skeletal muscle tissue.

Here’s a link to and a citation for the paper,

Nanocolloidal hydrogel mimics the structure and nonlinear mechanical properties of biological fibrous networks by Elisabeth Prince, Sofia Morozova, Zhengkun Chen, and Eugenia Kumacheva. Proceedings of the National Academy of Sciences (PNAS) December 13, 2023 120 (51) e2220755120 DOI: https://doi.org/10.1073/pnas.2220755120

This paper is behind a paywall.

Nanocellulose and food waste, an Australian perspective

A trio of Australian academics (Alan Labas, Benjamin Matthew Long, and Dylan Liu, all from Federation University Australia) have written a September 26, 2023 essay about nanocellulose derived from food waste for The Conversation, Note: Links have been removed,

Food waste is a global problem with approximately 1.3 billion tonnes of food wasted each year throughout the food lifecycle – from the farm to food manufacturers and households.

Across the food supply chain, Australians waste around 7.6 million tonnes of food each year. This costs our economy approximately A$36.6 billion annually.

In a recent study published in Bioresource Technology Reports, we have found a way to use food waste for making a versatile material known as nanocellulose. In particular, we used acid whey – a significant dairy production waste material that it usually difficult to dispose of.

For those who may not be familiar with nanocellulose, a lot of research was done here in Canada with a focus on using forest and agricultural waste products to produce nanocellulose. (See the CelluForce and Blue Goose Biorefineries websites for more about nanocellulose production, which in both their cases results in a specific material known as cellulose nanocrystals [CNC].) There’s more about the different kinds of nanocellulose later in this post.

The September 26, 2023 essay offers a good description of nanocellulose,

Nanocellulose is a biopolymer, which means it’s a naturally produced long chain of sugars. It has remarkable properties – bacterial nanocellulose is strong, chemically stable and biocompatible, meaning it’s not harmful to human cells. This makes it a highly marketable product with applications in packaging, wound treatments, drug delivery or food production.

Then, there’s this about the production process, from the September 26, 2023 essay, Note: A link has been removed,

The traditional approach for making nanocellulose can be expensive, uses large amounts of energy and takes a long time. Some types of nanocellulose production [emphasis mine] also use a chemical process that produces unwanted waste byproducts.

By contrast, our new approach uses just food waste and a symbiotic culture of bacteria and yeasts (SCOBY) – something you may be familiar with as a kombucha starter. Our process is low cost, consumes little energy and produces no waste.

… Lovers of home-brewed kombucha may actually be familiar with the raw nanocellulose material – it forms as a floating off-white structure called a pellicle. Some people already use this kombucha by-product as vegan leather.) A similar pellicle formed on our acid whey mixture.

I’m not sure if the “types of nanocellulose production” the writers are referring to are different types of nanocellose materials or different types of nanocellulose extraction.

A little more about nanocellulose

The Nanocellulose Wikipedia entry highlights the different materials that can be derived from nanocellulose, Note: Links have been removed,

Nanocellulose is a term referring to nano-structured cellulose. This may be either cellulose nanocrystal (CNC or NCC [nanocellulose crystal]), cellulose nanofibers (CNF) also called nanofibrillated cellulose (NFC), or bacterial nanocellulose, which refers to nano-structured cellulose produced by bacteria.

CNF is a material composed of nanosized cellulose fibrils with a high aspect ratio (length to width ratio). Typical fibril widths are 5–20 nanometers with a wide range of lengths, typically several micrometers. It is pseudo-plastic and exhibits thixotropy, the property of certain gels or fluids that are thick (viscous) under normal conditions, but become less viscous when shaken or agitated. When the shearing forces are removed the gel regains much of its original state. The fibrils are isolated from any cellulose containing source including wood-based fibers (pulp fibers) through high-pressure, high temperature and high velocity impact homogenization, grinding or microfluidization (see manufacture below).[1][2][3]

Nanocellulose can also be obtained from native fibers by an acid hydrolysis, giving rise to highly crystalline and rigid nanoparticles which are shorter (100s to 1000 nanometers) than the cellulose nanofibrils (CNF) obtained through homogenization, microfluiodization or grinding routes. The resulting material is known as cellulose nanocrystal (CNC).[4]

Nanochitin is similar in its nanostructure to nanocellulose.

Interestingly, Canadian development efforts are not mentioned in the essay until the very end, where we are lost in a plethora of other mentions, Note 1: Links have been removed; Note 2: All emphases mine,

A lthough wood-driven nanocellulose was first produced in 1983 by Herrick[7] and Turbak,[6] its commercial production postponed till 2010, mainly due to the high production energy consumption and high production cost. Innventia AB (Sweden) established the first nanocellulose pilot production plant 2010.[109] Companies and research institutes actively producing micro and nano fibrillated cellulose include: American Process (US), Borregaard (Norway), CelluComp (UK), Chuetsu Pulp and Paper (Japan), CTP/FCBA (France), Daicel (Japan), Dai-ichi Kyogo (Japan), Empa (Switzerland), FiberLean Technologies (UK), InoFib (France), Nano Novin Polymer Co. (Iran), Nippon Paper (Japan), Norske Skog (Norway), Oji Paper (Japan), RISE (Sweden), SAPPI (Netherlands), Seiko PMC (Japan), Stora Enso (Finland), Sugino Machine (Japan), Suzano (Brazil), Tianjin Haojia Cellulose Co. Ltd (China), University of Maine (US), UPM (Finland), US Forest Products Lab (US), VTT (Finland), and Weidmann Fiber Technology (Switzerland).[110] Companies and research institutes actively producing cellulose nanocrystals include: Alberta Innovates (Canada), American Process (US), Blue Goose Biorefineries (Canada), CelluForce (Canada), FPInnovations (Canada), Hangzhou Yeuha Technology Co. (China), Melodea (Israel/Sweden), Sweetwater Energy (US), Tianjin Haojia Cellulose Co. Ltd (China), and US Forest Products Lab (US).[110] Companies and research institutes actively producing cellulose filaments include: Kruger (Canada), Performance BioFilaments (Canada), and Tianjin Haojia Cellulose Co. Ltd (China).[110] Cellucomp (Scotland) produces Curran, a root-vegetable based nanocellulose.[111]

This leaves me with a couple of questions: Is my understanding of the nanocellulose story insular or Is the Wikipedia entry a little US-centric? It’s entirely possible the answer to both questions could be yes.

Why so much interest in nanocellulose? Money

From the September 26, 2023 essay, Note: A link has been removed,

Demand for nanocellulose is growing worldwide. The global market was valued at US$0.4 billion in 2022 (A$0.6bn) and is expected to grow to US$2 billion by 2030 (A$3.1bn). Bacterial nanocellulose produced from food waste can help to satisfy this demand.

This growth is in part due to how we can use nanocellulose instead of petroleum-based and other non-renewable materials in things like packaging. Among its desirable properties, nanocellulose is also fully biodegradable.

If you have time, do read the September 26, 2023 essay in its entirety.

H/t to September 27, 2023 news item on phys.org

Photonic cellulose nanocrystals (CNC) for flexible sweat sensor

It turns out there’s also a hydrogel aspect to this story about a flexible sweat sensor. As for cellulose nanocrystals (CNC), Canada played a leading role in the development of this nanomaterial and I have a bit more about the Canadian CNC scene later in this posting following the link and citation for the research paper. On to the research,

Highly elastic hydrogels constructed by heat-induced hydrogen bond remodeling can switch between wet and dry states (Image by ZHANG Fusheng and LI Qiongya)

A May 8, 2023 news item on phys.org features this work from the Dalian Institute of Chemical Physics of the Chinese Academy Sciences,

Cellulose nanocrystal (CNC), an emerging bio-based material, has been widely applied in fields such as electronics, bioplastics and energy. However, the functional failure of such materials in wet or liquid environments inevitably impairs their development in biomedicine, membrane separation, environmental monitoring, and wearable devices.

Now, a research group led by Prof. Qing Guangyan from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences [CAS] reported a sustainable, insoluble, and chiral photonic cellulose nanocrystal patch for calcium ion (Ca2+) sensing in sweat.

A May 4, 2023 Dalian Institute of Chemical Physics of the Chinese Academy Sciences press release (also on EurekAlert but published May 8, 2023), which originated the news item, provides more detail about the work,

The researchers developed a simple and efficient method to fabricate insoluble CNC-based hydrogels. They found that by utilizing intermolecular hydrogen bond reconstruction, thermal dehydration enabled the optimized CNC composite photonic film to form a stable hydrogel network in an aqueous solution. Moreover, they indicated that the hydrogel could be reversibly switched between dry and wet states, which was convenient for specific functionalization.

The introduction of functionalized molecules by adsorption swelling in a liquid environment resulted in a hydrogel with freeze resistance (–20°C), strong adhesion, good biocompatibility, and high sensitivity to Ca2+.

“This work is expected to facilitate the application of sustainable cellulose sensors to monitor other metabolites (i.e., glucose, urea, and vitamins, etc.),” said Prof. QING. “It also lays foundation for digitally controlled hydrogel systems operating in environment monitoring, membrane separation, and wearable devices.”

Here’s a link to and a citation for the paper,

Sustainable, Insoluble, and Photonic Cellulose Nanocrystal Patches for Calcium Ion Sensing in Sweat by Qiongya Li, Chenchen He, Cunli Wang, Yuxiao Huang, Jiaqi Yu, Chunbo Wang, Wei Li, Xin Zhang, Fusheng Zhang, Guangyan Qing. small DOI: https://doi.org/10.1002/smll.202207932 First published online: 13 April 2023

This paper is behind a paywall.

FPInnovations is a Canadian research and development (R&D) not-for profit organization that was instrumental in the development of CNC. (If memory serves, they are a spinoff from the University of British Columbia.) There are two Canadian CNC production facilities (that I know of): CelluForce in Québec and Blue Goose Biorefineries in Saskatchewan. I get more information about research into applications for CNC from other parts of the world while the Canadian scene remains mostly silent.

Enabling a transparent wood battery that stores heat and regulates indoor temperature with lemons and coconuts

i’ve had transparent wood stories here before but this time it was the lemons and coconuts which captured my attention.

Peter Olsén and Céline Montanari, researchers in the Department of Biocomposites at KTH Royal Institute of Technology in Stockholm, say the new wood composite uses components of lemon and coconuts to both heat and cool homes. (Photo: David Callahan) Courtesy: KTH Royal Institute of Technology

From a March 30, 2023 news item on Nanowerk,

A building material that combines coconuts, lemons and modified wood could one day be enough to heat and cool your home. The three renewable sources provide the key components of a wood composite thermal battery, which was developed by researchers at KTH Royal Institute of Technology in Stockholm.

Researchers reported the development in the scientific journal, Small (“Sustainable Thermal Energy Batteries from Fully Bio-Based Transparent Wood”). Peter Olsén, researcher in the Department of Biocomposites at KTH, says the material is capable of storing both heat and cold. If used in housing construction, the researchers say that 100 kilos of the material can save about 2.5 kWh per day in heating or cooling—given an ambient temperature of 24 °C.

KTH researcher Céline Montanari says that besides sunlight, any heat source can charge the battery. “The key is that the temperature fluctuates around the transition temperature, 24 °C, which can of course be tailored depending on the application and location,” she says.

A March 30, 2023 KTH Royal Institute of Technology press release, which originated the news item, describes the roles that lemons and coconuts play,

The process starts with removing lignin from wood, which creates open pores in the wood cells walls, and removes color. Later the wood structure is filled with a citrus-based molecule—limonene acrylate—and coconut based molecule. Limonene acrylate transforms into a bio-based polymer when heated, restoring the wood’s strength and allowing light to permeate. When this happens the coconut molecule are trapped within the material, enabling the storage and release of energy.

“The elegance is that the coconut molecules can transition from a solid-to-liquid which absorbs energy; or from liquid-to-solid which releases energy, in much the same way that water freezes and melts,” Montanari says. But in the transparent wood, that transition happens at a more comfortable 24C

“Through this transition, we can heat or cool our surroundings, whichever is needed,” Olsén says

Olsén says that potential uses include exterior and interior building material for both transparency and energy saving – in exteriors and interiors. The first application of the product would be for interior spaces to regulate temperatures around the 24C mark to cool and to heat. More study is needed to develop it for exterior use.

And it’s not just for homes or buildings. “Why not as a future material in greenhouses?” he says. “When the sun shines, the wood becomes transparent and stores more energy, while at night it becomes cloudy and releases the heat stored during the day. That would help reduce energy consumption for heating and at the same time provide improved growth.”

A close-up look at the material produced in the study. Courtesy: KTH Royal Institute of Technology

Here’s a link to and a citation for the paper,

Sustainable Thermal Energy Batteries from Fully Bio-Based Transparent Wood by Céline Montanari, Hui Chen, Matilda Lidfeldt, Josefin Gunnarsson, Peter Olsén, Lars A. Berglund. Small Online Version of Record before inclusion in an issue 2301262 DOI: https://doi.org/10.1002/smll.202301262 First published online: 27 March 2023

This paper is open access.