Tag Archives: cellulose nanofiber

Nanocellulose film and Kiragami hydrogels

A Kirigami pattern of the hydrogel (top) and the hydrogel swollen from dry state (bottom). (Image: NIMS) [downloaded from https://www.nanowerk.com/nanotechnology-news3/newsid=65005.php]

An April 11, 2024 news item on Nanowerk highlights research that combines kiragami with hydrogel production, Note 1: A link has been removed, Note 2: Kiragami is described in the excerpt after this one,

New options for making finely structured soft, flexible and expandable materials called hydrogels have been developed by researchers at Tokyo University of Agriculture and Technology (TUAT). Their work extends the emerging field of ‘kirigami hydrogels’, in which patterns are cut into a thin film allowing it to later swell into complex hydrogel structures.

An April 12, 2024 Tokyo University of Agriculture and Technology (TUAT) press release, which originated the news item, on JCN Newswire, Note: Distribution of press releases can be spread out over days (sometimes identical press releases are sent out twice, months apart),

Hydrogels have a network of water-attracting (hydrophilic) molecules, allowing their structure to swell substantially when exposed to water that becomes incorporated within the molecular network. Researchers Daisuke Nakagawa and Itsuo Hanasaki worked with an initially dry film composed of nanofibers of cellulose, the natural material that forms much of the structure of plant cell walls.

They used laser processing to cut structures into the film before water was added allowing the film to swell. The particular design of the Kirigami pattern works in such a way that the width increases when stretched in the longitudinal direction, which is called the auxetic property. This auxetic property emerges provided that the thickness grows sufficiently when the original thin film is wet.

“As Kirigami literally means the cut design of papers [emphasis mine], it was originally intended for thin sheet structures. On the other hand, our two-dimensional auxetic mechanism manifests when the thickness of the sheet is sufficient, and this three dimensionality of the hydrogel structure emerges by swelling when it is used. It is convenient to store it in the dry state before use, rather than keeping the same water content level of the hydrogel.” says Hanasaki. “Furthermore, the auxeticity is maintained during the cyclic loading that causes the adaptive deformation of the hydrogel to reach another structural state. It will be important for the design of intelligent materials.”

Potential applications for the adaptive hydrogels include soft components of robotic technologies, allowing them to respond flexibly when interacting with objects they are manipulating, for example. They might also be incorporated into soft switches and sensor components. Hydrogels are also being explored for medical applications, including tissue engineering, wound dressings, drug delivery systems and materials that can adapt flexibly to movement and growth. The advance in kirigami hydrogels achieved by the TUAT team significantly extends the options for future hydrogel applications.

“Keeping the designed characteristics while showing adaptivity to the environmental condition is advantageous for the development of multifunctionality,” Hanasaki concludes

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

Adaptive plasticity of auxetic Kirigami hydrogel fabricated from anisotropic swelling of cellulose nanofiber film by Daisuke Nakagawa & Itsuo Hanasaki. Science and Technology of Advanced Materials Volume 25, 2024 – Issue 1 Article: 2331959 DOI: https://doi.org/10.1080/14686996.2024.2331959 Published online: 02 Apr 2024

This is an open access paper.

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.

Cleaning up disasters with Hokusai’s blue and cellulose nanofibers to clean up contaminated soil and water in Fukushima

The Great Wave off Kanagawa (Under a wave off Kanagawa”), also known as The Great Wave or simply The Wave, by Katsushika Hokusai – Metropolitan Museum of Art, online database: entry 45434, Public Domain, https://commons.wikimedia.org/w/index.php?curid=2798407

I thought it might be a good idea to embed a copy of Hokusai’s Great Wave and the blue these scientists in Japan have used as their inspiration. (By the way, it seems these scientists collaborated with Mildred Dresselhaus who died at the age of 86, a few months after their paper was published. In honour of he and before the latest, here’s my Feb. 23, 2017 posting about the ‘Queen of Carbon’.)

Now onto more current news, from an Oct. 13, 2017 news item on Nanowerk (Note: A link has been removed),

By combining the same Prussian blue pigment used in the works of popular Edo-period artist Hokusai and cellulose nanofiber, a raw material of paper, a University of Tokyo research team succeeded in synthesizing compound nanoparticles, comprising organic and inorganic substances (Scientific Reports, “Cellulose nanofiber backboned Prussian blue nanoparticles as powerful adsorbents for the selective elimination of radioactive cesium”). This new class of organic/inorganic composite nanoparticles is able to selectively adsorb, or collect on the surface, radioactive cesium.

The team subsequently developed sponges from these nanoparticles that proved highly effective in decontaminating the water and soil in Fukushima Prefecture exposed to radioactivity following the nuclear accident there in March 2011.

I think these are the actual sponges not an artist’s impression,

Decontamination sponge spawned from current study
Cellulose nanofiber-Prussian blue compounds are permanently anchored in spongiform chambers (cells) in this decontamination sponge. It can thus be used as a powerful adsorbent for selectively eliminating radioactive cesium. © 2017 Sakata & Mori Laboratory.

An Oct. 13, 2017 University of Tokyo press release, which originated the news item, provides more detail about the sponges and the difficulties of remediating radioactive air and soil,

Removing radioactive materials such as cesium-134 and -137 from contaminated seawater or soil is not an easy job. First of all, a huge amount of similar substances with competing functions has to be removed from the area, an extremely difficult task. Prussian blue (ferric hexacyanoferrate) has a jungle gym-like colloidal structure, and the size of its single cubic orifice, or opening, is a near-perfect match to the size of cesium ions; therefore, it is prescribed as medication for patients exposed to radiation for selectively adsorbing cesium. However, as Prussian blue is highly attracted to water, recovering it becomes highly difficult once it is dissolved into the environment; for this reason, its use in the field for decontamination has been limited.

Taking a hint from the Prussian blue in Hokusai’s woodblock prints not losing their color even when getting wet from rain, the team led by Professor Ichiro Sakata and Project Professor Bunshi Fugetsu at the University of Tokyo’s Nanotechnology Innovation Research Unit at the Policy Alternatives Research Institute, and Project Researcher Adavan Kiliyankil Vipin at the Graduate School of Engineering developed an insoluble nanoparticle obtained from combining cellulose and Prussian blue—Hokusai had in fact formed a chemical bond in his handling of Prussian blue and paper (cellulose).

The scientists created this cellulose-Prussian blue combined nanoparticle by first preparing cellulose nanofibers using a process called TEMPO oxidization and securing ferric ions (III) onto them, then introduced a certain amount of hexacyanoferrate, which adhered to Prussian blue nanoparticles with a diameter ranging from 5–10 nanometers. The nanoparticles obtained in this way were highly resistant to water, and moreover, were capable of adsorbing 139 mg of radioactive cesium ion per gram.

Field studies on soil decontamination in Fukushima have been underway since last year. A highly effective approach has been to sow and allow plant seeds to germinate inside the sponge made from the nanoparticles, then getting the plants’ roots to take up cesium ions from the soil to the sponge. Water can significantly shorten decontamination times compared to soil, which usually requires extracting cesium from it with a solvent.

It has been more than six years since the radioactive fallout from a series of accidents at the Fukushima Daiichi nuclear power plant following the giant earthquake and tsunami in northeastern Japan. Decontamination with the cellulose nanofiber-Prussian blue compound can lead to new solutions for contamination in disaster-stricken areas.

“I was pondering about how Prussian blue immediately gets dissolved in water when I happened upon a Hokusai woodblock print, and how the indigo color remained firmly set in the paper, without bleeding, even after all these years,” reflects Fugetsu. He continues, “That revelation provided a clue for a solution.”

“The amount of research on cesium decontamination increased after the Chernobyl nuclear power plant accident, but a lot of the studies were limited to being academic and insufficient for practical application in Fukushima,” says Vipin. He adds, “Our research offers practical applications and has high potential for decontamination on an industrial scale not only in Fukushima but also in other cesium-contaminated areas.”

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

Cellulose nanofiber backboned Prussian blue nanoparticles as powerful adsorbents for the selective elimination of radioactive cesium by Adavan Kiliyankil Vipin, Bunshi Fugetsu, Ichiro Sakata, Akira Isogai, Morinobu Endo, Mingda Li, & Mildred S. Dresselhaus. Scientific Reports 6, Article number: 37009 (2016) doi:10.1038/srep37009 Published online: 15 November 2016

This is open access.

Nanocellulose from sugarcane?

Iran adds to this blog’s growing catalogue of plant materials from which nanocellulose can be derived. From an April 27, 2014 news item on Nanowerk,

Researchers from University of Tehran utilized sugarcane waste to produce nanocomposite film (“All-cellulose nanocomposite film made from bagasse cellulose nanofibers for food packaging application”).

The product has unique physical and mechanical properties and has many applications in packaging, glue making, medicine and electronic industries.

An April 28, 2014 Iran Nanotechnology Initiative Council (INIC) news release, which originated the news item, describes the advantages of this potential product and the research that led to it,

These nanofibers have simpler, faster and more cost-effective production method in comparison with other production methods. The size of the produced cellulose nanofiber has been reported about 39±13 nm while tension resistant of the nanocomposite produced from the nanofibers has been reported about 140 MPa. The produced nanocomposite has higher strength in comparison with the majority of biodegradable and non-biodegradable films. It seems that the produced nanocomposite can be considered an appropriate option for the elimination of artificial polymers and oil derivatives from packaging materials.

In order to produce the product, cellulose fibers were produced through mechanical milling method after separation and purification of cellulose from sugarcane bagasse, and then nanopapers were produced. Next, full cellulose nanocomposite was produced through partial dissolving method, and its characteristics were evaluated.

Results showed that as the time of partial dissolving increases, the diffusivity of the nanocomposite into vapor decreases due to the increase in glassy part (amorphous) to crystalline part. However, thermal resistant decreases as the time of partial dissolving increases because a decrease is observed in the crystalline part.

In addition, when cellulose microfibers turn into nanofibers, resistance against the tension of the produced films increases. The researchers believe that the reason for the increase is the reduction in fault points (points that lead to the fracture in cellulose fibers), increase in specific area, and integrity of nanofibers. Transparency of samples significantly increases as the size of particles decreases to nanometric scale.

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

All-cellulose nanocomposite film made from bagasse cellulose nanofibers for food packaging application by Moein Ghaderi, Mohammad Mousavi, Hossein Yousefi, & Mohsen Labbafi. Carbohydrate Polymers, vol. 104, issue 1, January 2014, pp. 59-65 http://dx.doi.org/10.1016/j.carbpol.2014.01.013

This paper is behind a paywall.

You say nanocrystalline cellulose, I say cellulose nanocrystals; CelluForce at Japan conference and at UK conference

In reading the Oct. 14, 2012 news release from CelluForce about its presence at conferences in Japan and in the UK, I was interested to note the terminology being used,

CelluForce, the world leader in the commercial development of NanoCrystalline Cellulose (NCC), also referred to as Cellulose Nanocrystals (CNC),[emphases mine] is participating in two  upcoming industry conferences:  the ‘Nanocellulose Summit 2012’ in Kyoto, Japan on October 15, 2012, and ‘Investing in Cellulose 2012’, in London, UK, on November 5, 2012.

All of the materials from Canadian companies and not-for-profits have used the term nanocrystalline cellulose (NCC) exclusively, until now. I gather there’ve been some international discussions regarding terminology and that the term cellulose nanocrystals (CNC) is, at the least, a synonym if not the preferred term.

Here’s more about the conference in Japan (from the CelluForce news release),

The 209th Symposium on Sustainable Humanosphere: Nanocellulose Summit 2012’ welcomes the world’s top scientists and large research project leaders involved with nanocellulose to present on each country’s current status and prospects concerning nanocellulose research and industrialization.

What:                  CelluForce – What do we do?

Who:                    Richard Berry, Vice President and Chief  Technology Officer, CelluForce

When:                 Monday, October 15, 2012, 4 p.m. JST

Where:                 Kyoto Terrsa Venue, Shinmachi Kujo Minami-ku,
Kyoto, Japan (Kyoto Citizen’s Amenity Plaza)

I found out a little more about the conference Dr. Richard Berry will be attending on the Nanocellulose Summit 2012 webpage on the Kyoto University website,

The world’s top scientists and large research project leaders involved with nanocellulose (cellulose nanofiber (CNF) [sic] and cellulose nanocrystal (CNC or NCC) ) brought together. They will talk about each country’s current status and prospects concerning nanocellulose research and industrialization.

You can find more details, including the agenda, on the conference webpage.

Here’s more about the investment-oriented conference taking place in the UK,

In its second edition, ‘Investing in Cellulose 2012’ is a global conference on specialty cellulose, organized by CelCo. The company focuses primarily on the specialty cellulose business including the organization of cellulose training courses as well as advisory and consultancy to the industry.

What:                  Nanocrystalline technologies: Bringing Innovation to the Market

Who:                    Jean Moreau, President and CEO, CelluForce

When:                 Monday, November 5, 2012, 2:30 p.m. BST

Where:                The Royal Horseguards Hotel, 2 Whitehall Court Whitehall, London SW1A 2EJ, United Kingdom

I have found an ‘Investing in Cellulose 2012‘ conference webpage (of sorts) on the CelCo website (Note: I have removed some of the formatting),

Based on the success of 2011 specialty cellulose conference and encouraged by a 92% return intention response we are pleased to announce that Investing in Cellulose -2012 Conference will take place in London on November 5th.

A cocktail will kick off the event the preceding night and close around 18:00 of November 5th.

So please SAVE THE DATE in your calendar and contact us HERE

 We have taken into account your wishes and suggestions for this second year event and some of the changes will include:

  • Antitrust lawyer attending meeting allowing larger participation esp. from USA.
  • New topics to allow ether and viscose market to be better covered. Technology section during the day.
  • Seat in lunch accommodations and air condition.
  • Larger china representation.
  • More downstream value chain participation.

We will share later this year the Agenda but feel free to let us know if there were any particular topics you would like us to cover or you would like to present.

The most I could find out about the UK conference organizer is that  Celco Cellulose Consulting is a Swiss company founded by two partners.