Tag Archives: cellulose

Greener cellulose-based products

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A May 3, 2023 North Carolina State University news release (also on EurekAlert) describes research into making more environmentally friendly products based on cellulose, Note: A link has been removed,

Water isn’t just a universal solvent that remains unaffected by its interactions. New publications from North Carolina State University show that water can change its solubility characteristics depending upon what it interacts with. Specifically, when water interacts with cellulose, it can stack in layered shells to control chemical reactions within, and physical properties of, the material. The work has implications for more sustainable and efficient design of cellulose-based products.

“Cellulose is the world’s most abundant biopolymer, and it’s used in applications that range from bandages to electronics,” says Lucian Lucia, professor of forest biomaterials and chemistry at NC State and corresponding author of a new study in Matter. “But cellulose processing has been mostly done by trial and error, and some of it utilizes incredibly harsh chemicals. To find better ways to process cellulose, we need to understand its most fundamental interactions – for example, with water.”

To do so, he worked with colleague Jim Martin, professor of chemistry at NC State, who studies the fundamental properties of water as a solvent.

“Water has the uncanny ability to change characteristics depending on what it’s with, which gives it wide range of solubility characteristics,” Martin says. Martin is the author of an opinion piece in Matter that is a companion to Lucia’s study.

“We change the nature of water by what we dissolve in it, and by the concentrations of those solutes in water,” Martin says. “Think of the continuum between Kool-Aid and hard candy. You start with sugar. In Kool-Aid the sugar is completely dissolved. As you remove the water, you get taffy, then hard candy, then back to crystalline sugar.”

“We know that water is critical to how cellulose is laid down,” Lucia says. “So in this study we probed how it orients itself and plays a reactive role in mitigating or leveraging chemistry.”

The researchers physically manipulated different types of wood fibers and looked at how water bound to itself and other molecules within the resulting structures. They saw that at lower water contents, the water distribution and resulting molecular interactions between the water and the fibers create bridging structures within the material that cause it to lose flexibility.

In fact, they saw that the water can “hide” itself within the cellulose network, forming strong hydrogen bonds. This bonding in turn dictates the tightness or looseness of the bridging structures.

“The water forms shells around the fibers that can stack, like a nesting Russian doll,” Martin says. “The fewer shells, or layers, the harder the fibers. But when you add more layers, the connection between fibers grows farther away and the material becomes softer.”

The researchers hope to explore the variety of bonds water forms within these structures in future work.

“Studying these interactions at the molecular level paves the way toward manipulating water in cellulose to design better products and processes,” Lucian says. “Understanding what is happening from fundamental principles lets us design approaches that take advantage of water’s properties for everything from drug delivery to designing electronics.”

The research paper, “Computational and experimental insights into the molecular architecture of water-cellulose networks,” and the editorial piece, “Water under the influence of solutes: on the non-innocence of a universal solvent,” both appear in the May 3 edition of Matter. The work was supported in part by the National Science Foundation. Former NC State Ph.D. student Kandoker Samaher Salem is first author of the research paper. Co-authors include former NC State Ph.D. student Nelson Barrios, and current NC State faculty Hasan Jameel and Lokendra Pal.

Here are links and citations for the two papers in the news release with the research paper coming first and the editorial coming second,

Computational and experimental insights into the molecular architecture of water-cellulose networks by Khandoker Samaher Salem, Nelson Barrios, Hasan Jameel, Lokendra Pal, Lucian Lucia. Matter Matter Volume 6, Issue 5, 3 May 2023, Pages 1366-1381 DOI: https://doi.org/10.1016/j.matt.2023.03.021

Water under the influence of solutes: On the non-innocence of a universal solvent by James D. Martin. Matter Volume 6, Issue 5, 3 May 2023, Pages 1316-1319 https://doi.org/10.1016/j.matt.2023.03.020

Both research paper and editorial are behind paywalls.

A fire-retardant coating made of renewable nanocellulose materials

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Firefighters everywhere are likely to appreciate the efforts of researchers at Texas A&M University (US) to a develop a non-toxic fire retardant coating. From a February 12, 2019 news item on Nanowerk (Note: A link has been removed),

Texas A&M University researchers are developing a new kind of flame-retardant coating using renewable, nontoxic materials readily found in nature, which could provide even more effective fire protection for several widely used materials.

Dr. Jaime Grunlan, the Linda & Ralph Schmidt ’68 Professor in the J. Mike Walker ’66 Department of Mechanical Engineering at Texas A&M, led the recently published research that is featured on the cover of a recent issue of the journal Advanced Materials Interfaces (“Super Gas Barrier and Fire Resistance of Nanoplatelet/Nanofibril Multilayer Thin Films”).

Successful development and implementation of the coating could provide better fire protection to materials including upholstered furniture, textiles and insulation.

“These coatings offer the opportunity to reduce the flammability of the polyurethane foam used in a variety of furniture throughout most people’s homes,” Grunlan noted.

A February 8, 2019 Texas A&M University news release (also on EurekAlert) by Steve Kuhlmann, which originated the news item, describes the work being done in collaboration with a Swedish team in more detail,

The project is a result of an ongoing collaboration between Grunlan and a group of researchers at KTH Royal Institute of Technology in Stockholm, Sweden, led by Lars Wagberg. The group, which specializes in utilizing nanocellulose, provided Grunlan with the ingredients he needed to complement his water-based coating procedure.

In nature, both the cellulose – a component of wood and various sea creatures – and clay – a component in soil and rock formations – act as mechanical reinforcements for the structures in which they are found.

“The uniqueness in this current study lies in the use of two naturally occurring nanomaterials, clay nanoplatelets and cellulose nanofibrils,” Grunlan said. “To the best of our knowledge, these ingredients have never been used to make a heat shielding or flame-retardant coating as a multilayer thin film deposited from water.”

Among the benefits gained from using this method include the coating’s ability to create an excellent oxygen barrier to plastic films – commonly used for food packaging – and better fire protection at a lower cost than other, more toxic ingredients traditionally used flame-retardant treatments.

To test the coatings, Grunlan and his colleagues applied the flexible polyurethane foam – often used in furniture cushions – and exposed it to fire using a butane torch to determine the level of protection the compounds provided.

While uncoated polyurethane foam immediately melts when exposed to flame, the foam treated with the researchers’ coating prevented the fire from damaging any further than surface level, leaving the foam underneath undamaged.

“The nanobrick wall structure of the coating reduces the temperature experienced by the underlying foam, which delays combustion,” Grunlan said. “This coating also serves to promote insulating char formation and reduces the release of fumes that feed a fire.”

With the research completed, Grunlan said the next step for the overall flame-retardant project is to transition the methods into industry for implementation and further development. 

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

Super Gas Barrier and Fire Resistance of Nanoplatelet/Nanofibril Multilayer Thin Films by Shuang Qin, Maryam Ghanad Pour, Simone Lazar, Oruç Köklükaya, Joseph Gerringer, Yixuan Song, Lars Wågberg, Jaime C. Grunlan. Advanced Materials Interfaces Volume 6, Issue 2 January 23, 2019 1801424 DOI: https://doi.org/10.1002/admi.201801424 First published online: 16 November 2018

This paper is behind a paywall.

Cellulose and natural nanofibres

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Specifically, the researchers are describing these as cellulose nanofibrils. On the left of the image, the seed look mores like an egg waiting to be fried for breakfast but the image on the right is definitely fibrous-looking,

Through contact with water, the seed of Neopallasia pectinata from the family of composite plants forms a slimy sheath. The white cellulose fibres anchor it to the seed surface. Courtesy: Kiel University (CAU)

A December 18, 2018 news item on Nanowerk describes the research into seeds and cellulose,

The seeds of some plants such as basil, watercress or plantain form a mucous envelope as soon as they come into contact with water. This cover consists of cellulose in particular, which is an important structural component of the primary cell wall of green plants, and swelling pectins, plant polysaccharides.

In order to be able to investigate its physical properties, a research team from the Zoological Institute at Kiel University (CAU) used a special drying method, which gently removes the water from the cellulosic mucous sheath. The team discovered that this method can produce extremely strong nanofibres from natural cellulose. In future, they could be especially interesting for applications in biomedicine.

A December 18, 2018 Kiel University press release, which originated the news item, offers further details about the work,

Thanks to their slippery mucous sheath, seeds can slide through the digestive tract of birds undigested. They are excreted unharmed, and can be dispersed in this way. It is presumed that the mucous layer provides protection. “In order to find out more about the function of the mucilage, we first wanted to study the structure and the physical properties of this seed envelope material,” said Zoology Professor Stanislav N. Gorb, head of the “Functional Morphology and Biomechanics” working group at the CAU. In doing so they discovered that its properties depend on the alignment of the fibres that anchor them to the seed surface

Diverse properties: From slippery to sticky

The pectins in the shell of the seeds can absorb a large quantity of water, and thus form a gel-like capsule around the seed in a few minutes. It is anchored firmly to the surface of the seed by fine cellulose fibres with a diameter of just up to 100 nanometres, similar to the microscopic adhesive elements on the surface of highly-adhesive gecko feet. So in a sense, the fibres form the stabilising backbone of the mucous sheath.

The properties of the mucous change, depending on the water concentration. “The mucous actually makes the seeds very slippery. However, if we reduce the water content, it becomes sticky and begins to stick,” said Stanislav Gorb, summarising a result from previous studies together with Dr Agnieszka Kreitschitz. The adhesive strength is also increased by the forces acting between the individual vertically-arranged nanofibres of the seed and the adhesive surface.

Specially dried

In order to be able to investigate the mucous sheath under a scanning electron microscope, the Kiel research team used a particularly gentle method, so-called critical-point drying (CPD). They dehydrated the mucous sheath of various seeds step-by-step with liquid carbon dioxide – instead of the normal method using ethanol. The advantage of this method is that evaporation of liquid carbon dioxide can be controlled under certain pressure and temperature conditions, without surface tension developing within the sheath. As a result, the research team was able to precisely remove water from the mucous, without drying out the surface of the sheath and thereby destroying the original cell structure. Through the highly-precise drying, the structural arrangement of the individual cellulose fibres remained intact.

Almost as strongly-adhesive as carbon nanotubes

The research team tested the dried cellulose fibres regarding their friction and adhesion properties, and compared them with those of synthetically-produced carbon nanotubes. Due to their outstanding properties, such as their tensile strength, electrical conductivity or their friction, these microscopic structures are interesting for numerous industrial applications of the future.

“Our tests showed that the frictional and adhesive forces of the cellulose fibres are almost as strong as with vertically-arranged carbon nanotubes,” said Dr Clemens Schaber, first author of the study. The structural dimensions of the cellulose nanofibers are similar to the vertically aligned carbon nanotubes. Through the special drying method, they can also vary the adhesive strength in a targeted manner. In Gorb’s working group, the zoologist and biomechanic examines the functioning of biological nanofibres, and the potential to imitate them with technical means. “As a natural raw material, cellulose fibres have distinct advantages over carbon nanotubes, whose health effects have not yet been fully investigated,” continued Schaber. Nanocellulose is primarily found in biodegradable polymer composites, which are used in biomedicine, cosmetics or the food industry.

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

Friction-Active Surfaces Based on Free-Standing Anchored Cellulose Nanofibrils by Clemens F. Schaber, Agnieszka Kreitschitz, and Stanislav N. Gorb. ACS Appl. Mater. Interfaces, 2018, 10 (43), pp 37566–37574 DOI: 10.1021/acsami.8b05972 Publication Date (Web): September 19, 2018

Copyright © 2018 American Chemical Society

This paper is behind a paywall.

New semiconductor material from pigment produced by fungi?

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Chlorociboria Aeruginascens fungus on a tree log. (Image: Oregon State University)

Apparently the pigment derived from the fungi you see in the above picture is used by visual artists and, perhaps soon, will be used by electronics manufacturers. From a June 5, 2018 news item on Nanowerk,

Researchers at Oregon State University are looking at a highly durable organic pigment, used by humans in artwork for hundreds of years, as a promising possibility as a semiconductor material.

Findings suggest it could become a sustainable, low-cost, easily fabricated alternative to silicon in electronic or optoelectronic applications where the high-performance capabilities of silicon aren’t required.

Optoelectronics is technology working with the combined use of light and electronics, such as solar cells, and the pigment being studied is xylindein.

A June 5, 2018 Oregon State University news release by Steve Lundeberg, which originated the news item, expands on the theme,

“Xylindein is pretty, but can it also be useful? How much can we squeeze out of it?” said Oregon State University [OSU] physicist Oksana Ostroverkhova. “It functions as an electronic material but not a great one, but there’s optimism we can make it better.”

Xylindien is secreted by two wood-eating fungi in the Chlorociboria genus. Any wood that’s infected by the fungi is stained a blue-green color, and artisans have prized xylindein-affected wood for centuries.

The pigment is so stable that decorative products made half a millennium ago still exhibit its distinctive hue. It holds up against prolonged exposure to heat, ultraviolet light and electrical stress.

“If we can learn the secret for why those fungi-produced pigments are so stable, we could solve a problem that exists with organic electronics,” Ostroverkhova said. “Also, many organic electronic materials are too expensive to produce, so we’re looking to do something inexpensively in an ecologically friendly way that’s good for the economy.”

With current fabrication techniques, xylindein tends to form non-uniform films with a porous, irregular, “rocky” structure.

“There’s a lot of performance variation,” she said. “You can tinker with it in the lab, but you can’t really make a technologically relevant device out of it on a large scale. But we found a way to make it more easily processed and to get a decent film quality.”

Ostroverkhova and collaborators in OSU’s colleges of Science and Forestry blended xylindein with a transparent, non-conductive polymer, poly(methyl methacrylate), abbreviated to PMMA and sometimes known as acrylic glass. They drop-cast solutions both of pristine xylindein and a xlyindein-PMMA blend onto electrodes on a glass substrate for testing.

They found the non-conducting polymer greatly improved the film structure without a detrimental effect on xylindein’s electrical properties. And the blended films actually showed better photosensitivity.

“Exactly why that happened, and its potential value in solar cells, is something we’ll be investigating in future research,” Ostroverkhova said. “We’ll also look into replacing the polymer with a natural product – something sustainable made from cellulose. We could grow the pigment from the cellulose and be able to make a device that’s all ready to go.

“Xylindein will never beat silicon, but for many applications, it doesn’t need to beat silicon,” she said. “It could work well for depositing onto large, flexible substrates, like for making wearable electronics.”

This research, whose findings were recently published in MRS Advances, represents the first use of a fungus-produced material in a thin-film electrical device.

“And there are a lot more of the materials,” Ostroverkhova said. “This is just first one we’ve explored. It could be the beginning of a whole new class of organic electronic materials.”

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

Fungi-Derived Pigments for Sustainable Organic (Opto)Electronics by Gregory Giesbers, Jonathan Van Schenck, Sarath Vega Gutierrez, Sara Robinson. MRS Advances https://doi.org/10.1557/adv.2018.446 Published online: 21 May 2018

This paper is behind a paywall.

Gamechanging electronics with new ultrafast, flexible, and transparent electronics

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There are two news bits about game-changing electronics, one from the UK and the other from the US.

United Kingdom (UK)

An April 3, 2017 news item on Azonano announces the possibility of a future golden age of electronics courtesy of the University of Exeter,

Engineering experts from the University of Exeter have come up with a breakthrough way to create the smallest, quickest, highest-capacity memories for transparent and flexible applications that could lead to a future golden age of electronics.

A March 31, 2017 University of Exeter press release (also on EurekAlert), which originated the news item, expands on the theme (Note: Links have been removed),

Engineering experts from the University of Exeter have developed innovative new memory using a hybrid of graphene oxide and titanium oxide. Their devices are low cost and eco-friendly to produce, are also perfectly suited for use in flexible electronic devices such as ‘bendable’ mobile phone, computer and television screens, and even ‘intelligent’ clothing.

Crucially, these devices may also have the potential to offer a cheaper and more adaptable alternative to ‘flash memory’, which is currently used in many common devices such as memory cards, graphics cards and USB computer drives.

The research team insist that these innovative new devices have the potential to revolutionise not only how data is stored, but also take flexible electronics to a new age in terms of speed, efficiency and power.

…

Professor David Wright, an Electronic Engineering expert from the University of Exeter and lead author of the paper said: “Using graphene oxide to produce memory devices has been reported before, but they were typically very large, slow, and aimed at the ‘cheap and cheerful’ end of the electronics goods market.

“Our hybrid graphene oxide-titanium oxide memory is, in contrast, just 50 nanometres long and 8 nanometres thick and can be written to and read from in less than five nanoseconds – with one nanometre being one billionth of a metre and one nanosecond a billionth of a second.”

Professor Craciun, a co-author of the work, added: “Being able to improve data storage is the backbone of tomorrow’s knowledge economy, as well as industry on a global scale. Our work offers the opportunity to completely transform graphene-oxide memory technology, and the potential and possibilities it offers.”

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

Multilevel Ultrafast Flexible Nanoscale Nonvolatile Hybrid Graphene Oxide–Titanium Oxide Memories by V. Karthik Nagareddy, Matthew D. Barnes, Federico Zipoli, Khue T. Lai, Arseny M. Alexeev, Monica Felicia Craciun, and C. David Wright. ACS Nano, 2017, 11 (3), pp 3010–3021 DOI: 10.1021/acsnano.6b08668 Publication Date (Web): February 21, 2017

Copyright © 2017 American Chemical Society

This paper appears to be open access.

United States (US)

Researchers from Stanford University have developed flexible, biodegradable electronics.

A newly developed flexible, biodegradable semiconductor developed by Stanford engineers shown on a human hair. (Image credit: Bao lab)

A human hair? That’s amazing and this May 3, 2017 news item on Nanowerk reveals more,

As electronics become increasingly pervasive in our lives – from smart phones to wearable sensors – so too does the ever rising amount of electronic waste they create. A United Nations Environment Program report found that almost 50 million tons of electronic waste were thrown out in 2017–more than 20 percent higher than waste in 2015.

Troubled by this mounting waste, Stanford engineer Zhenan Bao and her team are rethinking electronics. “In my group, we have been trying to mimic the function of human skin to think about how to develop future electronic devices,” Bao said. She described how skin is stretchable, self-healable and also biodegradable – an attractive list of characteristics for electronics. “We have achieved the first two [flexible and self-healing], so the biodegradability was something we wanted to tackle.”

The team created a flexible electronic device that can easily degrade just by adding a weak acid like vinegar. The results were published in the Proceedings of the National Academy of Sciences (“Biocompatible and totally disintegrable semiconducting polymer for ultrathin and ultralightweight transient electronics”).

“This is the first example of a semiconductive polymer that can decompose,” said lead author Ting Lei, a postdoctoral fellow working with Bao.

A May 1, 2017 Stanford University news release by Sarah Derouin, which originated the news item, provides more detail,

In addition to the polymer – essentially a flexible, conductive plastic – the team developed a degradable electronic circuit and a new biodegradable substrate material for mounting the electrical components. This substrate supports the electrical components, flexing and molding to rough and smooth surfaces alike. When the electronic device is no longer needed, the whole thing can biodegrade into nontoxic components.

Biodegradable bits

Bao, a professor of chemical engineering and materials science and engineering, had previously created a stretchable electrode modeled on human skin. That material could bend and twist in a way that could allow it to interface with the skin or brain, but it couldn’t degrade. That limited its application for implantable devices and – important to Bao – contributed to waste.

Flexible, biodegradable semiconductor on an avacado

The flexible semiconductor can adhere to smooth or rough surfaces and biodegrade to nontoxic products. (Image credit: Bao lab)

Bao said that creating a robust material that is both a good electrical conductor and biodegradable was a challenge, considering traditional polymer chemistry. “We have been trying to think how we can achieve both great electronic property but also have the biodegradability,” Bao said.

Eventually, the team found that by tweaking the chemical structure of the flexible material it would break apart under mild stressors. “We came up with an idea of making these molecules using a special type of chemical linkage that can retain the ability for the electron to smoothly transport along the molecule,” Bao said. “But also this chemical bond is sensitive to weak acid – even weaker than pure vinegar.” The result was a material that could carry an electronic signal but break down without requiring extreme measures.

In addition to the biodegradable polymer, the team developed a new type of electrical component and a substrate material that attaches to the entire electronic component. Electronic components are usually made of gold. But for this device, the researchers crafted components from iron. Bao noted that iron is a very environmentally friendly product and is nontoxic to humans.

The researchers created the substrate, which carries the electronic circuit and the polymer, from cellulose. Cellulose is the same substance that makes up paper. But unlike paper, the team altered cellulose fibers so the “paper” is transparent and flexible, while still breaking down easily. The thin film substrate allows the electronics to be worn on the skin or even implanted inside the body.

From implants to plants

The combination of a biodegradable conductive polymer and substrate makes the electronic device useful in a plethora of settings – from wearable electronics to large-scale environmental surveys with sensor dusts.

“We envision these soft patches that are very thin and conformable to the skin that can measure blood pressure, glucose value, sweat content,” Bao said. A person could wear a specifically designed patch for a day or week, then download the data. According to Bao, this short-term use of disposable electronics seems a perfect fit for a degradable, flexible design.

And it’s not just for skin surveys: the biodegradable substrate, polymers and iron electrodes make the entire component compatible with insertion into the human body. The polymer breaks down to product concentrations much lower than the published acceptable levels found in drinking water. Although the polymer was found to be biocompatible, Bao said that more studies would need to be done before implants are a regular occurrence.

Biodegradable electronics have the potential to go far beyond collecting heart disease and glucose data. These components could be used in places where surveys cover large areas in remote locations. Lei described a research scenario where biodegradable electronics are dropped by airplane over a forest to survey the landscape. “It’s a very large area and very hard for people to spread the sensors,” he said. “Also, if you spread the sensors, it’s very hard to gather them back. You don’t want to contaminate the environment so we need something that can be decomposed.” Instead of plastic littering the forest floor, the sensors would biodegrade away.

As the number of electronics increase, biodegradability will become more important. Lei is excited by their advancements and wants to keep improving performance of biodegradable electronics. “We currently have computers and cell phones and we generate millions and billions of cell phones, and it’s hard to decompose,” he said. “We hope we can develop some materials that can be decomposed so there is less waste.”

Other authors on the study include Ming Guan, Jia Liu, Hung-Cheng Lin, Raphael Pfattner, Leo Shaw, Allister McGuire, and Jeffrey Tok of Stanford University; Tsung-Ching Huang of Hewlett Packard Enterprise; and Lei-Lai Shao and Kwang-Ting Cheng of University of California, Santa Barbara.

The research was funded by the Air Force Office for Scientific Research; BASF; Marie Curie Cofund; Beatriu de Pinós fellowship; and the Kodak Graduate Fellowship.

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

Biocompatible and totally disintegrable semiconducting polymer for ultrathin and ultralightweight transient electronics by Ting Lei, Ming Guan, Jia Liu, Hung-Cheng Lin, Raphael Pfattner, Leo Shaw, Allister F. McGuire, Tsung-Ching Huang, Leilai Shao, Kwang-Ting Cheng, Jeffrey B.-H. Tok, and Zhenan Bao. PNAS 2017 doi: 10.1073/pnas.1701478114 published ahead of print May 1, 2017

This paper is behind a paywall.

The mention of cellulose in the second item piqued my interest so I checked to see if they’d used nanocellulose. No, they did not. Microcrystalline cellulose powder was used to constitute a cellulose film but they found a way to render this film at the nanoscale. From the Stanford paper (Note: Links have been removed),

… Moreover, cellulose films have been previously used as biodegradable substrates in electronics (28⇓–30). However, these cellulose films are typically made with thicknesses well over 10 μm and thus cannot be used to fabricate ultrathin electronics with substrate thicknesses below 1–2 μm (7, 18, 19). To the best of our knowledge, there have been no reports on ultrathin (1–2 μm) biodegradable substrates for electronics. Thus, to realize them, we subsequently developed a method described herein to obtain ultrathin (800 nm) cellulose films (Fig. 1B and SI Appendix, Fig. S8). First, microcrystalline cellulose powders were dissolved in LiCl/N,N-dimethylacetamide (DMAc) and reacted with hexamethyldisilazane (HMDS) (31, 32), providing trimethylsilyl-functionalized cellulose (TMSC) (Fig. 1B). To fabricate films or devices, TMSC in chlorobenzene (CB) (70 mg/mL) was spin-coated on a thin dextran sacrificial layer. The TMSC film was measured to be 1.2 μm. After hydrolyzing the film in 95% acetic acid vapor for 2 h, the trimethylsilyl groups were removed, giving a 400-nm-thick cellulose film. The film thickness significantly decreased to one-third of the original film thickness, largely due to the removal of the bulky trimethylsilyl groups. The hydrolyzed cellulose film is insoluble in most organic solvents, for example, toluene, THF, chloroform, CB, and water. Thus, we can sequentially repeat the above steps to obtain an 800-nm-thick film, which is robust enough for further device fabrication and peel-off. By soaking the device in water, the dextran layer is dissolved, starting from the edges of the device to the center. This process ultimately releases the ultrathin substrate and leaves it floating on water surface (Fig. 3A, Inset).

Finally, I don’t have any grand thoughts; it’s just interesting to see different approaches to flexible electronics.

3D printing with cellulose

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The scientists seem quite excited about their work with 3D printing and cellulose. From a March 3, 2017 MIT (Massachusetts Institute of Technology) news release (also on EurekAlert),

For centuries, cellulose has formed the basis of the world’s most abundantly printed-on material: paper. Now, thanks to new research at MIT, it may also become an abundant material to print with — potentially providing a renewable, biodegradable alternative to the polymers currently used in 3-D printing materials.

“Cellulose is the most abundant organic polymer in the world,” says MIT postdoc Sebastian Pattinson, lead author of a paper describing the new system in the journal Advanced Materials Technologies. The paper is co-authored by associate professor of mechanical engineering A. John Hart, the Mitsui Career Development Professor in Contemporary Technology.

Cellulose, Pattinson explains, is “the most important component in giving wood its mechanical properties. 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.”

Meanwhile, 3-D printing technology is rapidly growing. Among other benefits, it “allows you to individually customize each product you make,” Pattinson says.

Using cellulose as a material for additive manufacturing is not a new idea, and many researchers have attempted this but faced major obstacles. When heated, cellulose thermally decomposes before it becomes flowable, partly because of the hydrogen bonds that exist between the cellulose molecules. The intermolecular bonding also makes high-concentration cellulose solutions too viscous to easily extrude.

Instead, the MIT team chose to work with cellulose acetate — a material that is easily made from cellulose and is already widely produced and readily available. Essentially, the number of hydrogen bonds in this material has been reduced by the acetate groups. Cellulose acetate can be dissolved in acetone and extruded through a nozzle. As the acetone quickly evaporates, the cellulose acetate solidifies in place. A subsequent optional treatment replaces the acetate groups and increases the strength of the printed parts.

“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 (ABS) and polylactic acid (PLA).

To demonstrate the chemical versatility of the production process, Pattinson and Hart added an extra dimension to the innovation. By adding a small amount of antimicrobial dye to the cellulose acetate ink, they 3-D-printed a pair of surgical tweezers with antimicrobial functionality.

“We demonstrated that the parts kill bacteria when you shine fluorescent light on them,” Pattinson says. Such custom-made tools “could be useful for remote medical settings where there’s a need for surgical tools but it’s difficult to deliver new tools as they break, or where there’s a need for customized tools. And with the antimicrobial properties, if the sterility of the operating room is not ideal the antimicrobial function could be essential,” he says.

Because most existing extrusion-based 3-D printers rely on heating polymer to make it flow, their production speed is limited by the amount of heat that can be delivered to the polymer without damaging it. This room-temperature cellulose process, which simply relies on evaporation of the acetone to solidify the part, could potentially be faster, Pattinson says. And various methods could speed it up even further, such as laying down thin ribbons of material to maximize surface area, or blowing hot air over it to speed evaporation. A production system would also seek to recover the evaporated acetone to make the process more cost effective and environmentally friendly.

Cellulose acetate is already widely available as a commodity product. In bulk, the material is comparable in price to that of thermoplastics used for injection molding, and it’s much less expensive than the typical filament materials used for 3-D printing, the researchers say. This, combined with the room-temperature conditions of the process and the ability to functionalize cellulose in a variety of ways, could make it commercially attractive.

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

Additive Manufacturing of Cellulosic Materials with Robust Mechanics and Antimicrobial Functionality by Sebastian W. Pattinson and A. John Hart. Advanced Materials Technologies DOI: 10.1002/admt.201600084 Version of Record online: 30 JAN 2017

© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

nano tech 2017 being held in Tokyo from February 15-17, 2017

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I found some news about the Alberta technology scene in the programme for Japan’s nano tech 2017 exhibition and conference to be held Feb. 15 – 17, 2017 in Tokyo. First, here’s more about the show in Japan from a Jan. 17, 2017 nano tech 2017 press release on Business Wire (also on Yahoo News),

The nano tech executive committee (chairman: Tomoji Kawai, Specially Appointed Professor, Osaka University) will be holding “nano tech 2017” – one of the world’s largest nanotechnology exhibitions, now in its 16th year – on February 15, 2017, at the Tokyo Big Sight convention center in Japan. 600 organizations (including over 40 first-time exhibitors) from 23 countries and regions are set to exhibit at the event in 1,000 booths, demonstrating revolutionary and cutting edge core technologies spanning such industries as automotive, aerospace, environment/energy, next-generation sensors, cutting-edge medicine, and more. Including attendees at the concurrently held exhibitions, the total number of visitors to the event is expected to exceed 50,000.

The theme of this year’s nano tech exhibition is “Open Nano Collaboration.” By bringing together organizations working in a wide variety of fields, the business matching event aims to promote joint development through cross-field collaboration.

Special Symposium: “Nanotechnology Contributing to the Super Smart Society”

Each year nano tech holds Special Symposium, in which industry specialists from top organizations from Japan and abroad speak about the issues surrounding the latest trends in nanotech. The themes of this year’s Symposium are Life Nanotechnology, Graphene, AI/IoT, Cellulose Nanofibers, and Materials Informatics.

Notable sessions include:

Life Nanotechnology
“Development of microRNA liquid biopsy for early detection of cancer”
Takahiro Ochiya, National Cancer Center Research Institute Division of Molecular and Cellular Medicine, Chief

AI / IoT
“AI Embedded in the Real World”
Hideki Asoh, AIST Deputy Director, Artificial Intelligence Research Center

Cellulose Nanofibers [emphasis mine]
“The Current Trends and Challenges for Industrialization of Nanocellulose”
Satoshi Hirata, Nanocellulose Forum Secretary-General

Materials Informatics
“Perspective of Materials Research”
Hideo Hosono, Tokyo Institute of Technology Professor

View the full list of sessions:
>> http://nanotech2017.icsbizmatch.jp/Presentation/en/Info/List#main_theater

nano tech 2017 Homepage:
>> http://nanotechexpo.jp/

nano tech 2017, the 16th International Nanotechnology Exhibition & Conference
Date: February 15-17, 2017, 10:00-17:00
Venue: Tokyo Big Sight (East Halls 4-6 & Conference Tower)
Organizer: nano tech Executive Committee, JTB Communication Design

As you may have guessed the Alberta information can be found in the .Cellulose Nanofibers session. From the conference/seminar program page; scroll down about 25% of the way to find the Alberta presentation,

Production and Applications Development of Cellulose Nanocrystals (CNC) at InnoTech Alberta

Behzad (Benji) Ahvazi
InnoTech Alberta Team Lead, Cellulose Nanocrystals (CNC)

[ Abstract ]

The production and use of cellulose nanocrystals (CNC) is an emerging technology that has gained considerable interest from a range of industries that are working towards increased use of “green” biobased materials. The construction of one-of-a-kind CNC pilot plant [emphasis mine] at InnoTech Alberta and production of CNC samples represents a critical step for introducing the cellulosic based biomaterials to industrial markets and provides a platform for the development of novel high value and high volume applications. Major key components including feedstock, acid hydrolysis formulation, purification, and drying processes were optimized significantly to reduce the operation cost. Fully characterized CNC samples were provided to a large number of academic and research laboratories including various industries domestically and internationally for applications development.

[ Profile ]

Dr. Ahvazi completed his Bachelor of Science in Honours program at the Department of Chemistry and Biochemistry and graduated with distinction at Concordia University in Montréal, Québec. His Ph.D. program was completed in 1998 at McGill Pulp and Paper Research Centre in the area of macromolecules with solid background in Lignocellulosic, organic wood chemistry as well as pulping and paper technology. After completing his post-doctoral fellowship, he joined FPInnovations formally [formerly?] known as PAPRICAN as a research scientist (R&D) focusing on a number of confidential chemical pulping and bleaching projects. In 2006, he worked at Tembec as a senior research scientist and as a Leader in Alcohol and Lignin (R&D). In April 2009, he held a position as a Research Officer in both National Bioproducts (NBP1 & NBP2) and Industrial Biomaterials Flagship programs at National Research Council Canada (NRC). During his tenure, he had directed and performed innovative R&D activities within both programs on extraction, modification, and characterization of biomass as well as polymer synthesis and formulation for industrial applications. Currently, he is working at InnoTech Alberta as Team Lead for Biomass Conversion and Processing Technologies.

Canada scene update

InnoTech Alberta was until Nov. 1, 2016 known as Alberta Innovates – Technology Futures. Here’s more about InnoTech Alberta from the Alberta Innovates … home page,

Effective November 1, 2016, Alberta Innovates – Technology Futures is one of four corporations now consolidated into Alberta Innovates and a wholly owned subsidiary called InnoTech Alberta.

You will find all the existing programs, services and information offered by InnoTech Alberta on this website. To access the basic research funding and commercialization programs previously offered by Alberta Innovates – Technology Futures, explore here. For more information on Alberta Innovates, visit the new Alberta Innovates website.

As for InnoTech Alberta’s “one-of-a-kind CNC pilot plant,” I’d like to know more about it’s one-of-a-kind status since there are two other CNC production plants in Canada. (Is the status a consequence of regional chauvinism or a writer unfamiliar with the topic?). Getting back to the topic, the largest company (and I believe the first) with a CNC plant was CelluForce, which started as a joint venture between Domtar and FPInnovations and powered with some very heavy investment from the government of Canada. (See my July 16, 2010 posting about the construction of the plant in Quebec and my June 6, 2011 posting about the newly named CelluForce.) Interestingly, CelluForce will have a booth at nano tech 2017 (according to its Jan. 27, 2017 news release) although the company doesn’t seem to have any presentations on the schedule. The other Canadian company is Blue Goose Biorefineries in Saskatchewan. Here’s more about Blue Goose from the company website’s home page,

Blue Goose Biorefineries Inc. (Blue Goose) is pleased to introduce our R3TM process. R3TM technology incorporates green chemistry to fractionate renewable plant biomass into high value products.

Traditionally, separating lignocellulosic biomass required high temperatures, harsh chemicals, and complicated processes. R3TM breaks this costly compromise to yield high quality cellulose, lignin and hemicellulose products.

The robust and environmentally friendly R3TM technology has numerous applications. Our current product focus is cellulose nanocrystals (CNC). Cellulose nanocrystals are “Mother Nature’s Building Blocks” possessing unique properties. These unique properties encourage the design of innovative products from a safe, inherently renewable, sustainable, and carbon neutral resource.

Blue Goose assists companies and research groups in the development of applications for CNC, by offering CNC for sale without Intellectual Property restrictions. [emphasis mine]

Bravo to Blue Goose! Unfortunately, I was not able to determine if the company will be at nano tech 2017.

One final comment, there was some excitement about CNC a while back where I had more than one person contact me asking for information about how to buy CNC. I wasn’t able to be helpful because there was, apparently, an attempt by producers to control sales and limit CNC access to a select few for competitive advantage. Coincidentally or not, CelluForce developed a stockpile which has persisted for some years as I noted in my Aug. 17, 2016 posting (scroll down about 70% of the way) where the company announced amongst other events that it expected deplete its stockpile by mid-2017.

‘Getting into’ cellulose walls at the University of Cambridge (UK) and University of Melbourne (Australia)

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“Getting into” as used in the headline is slang for exploring a topic in more depth which is what an international team of researchers did when they ‘got into’ cellulose. From a June 9, 2016 news item on phys.org (Note: Links have been removed),

In the search for low emission plant-based fuels, new research may help avoid having to choose between growing crops for food or fuel.

Scientists have identified new steps in the way plants produce cellulose, the component of plant cell walls that provides strength, and forms insoluble fibre in the human diet.

The findings could lead to improved production of cellulose and guide plant breeding for specific uses such as wood products and ethanol fuel, which are sustainable alternatives to fossil fuel-based products.

Published in the journal Nature Communications today, the work was conducted by an international team of scientists, led by the University of Cambridge and the University of Melbourne.

A June 9, 2016 University of Cambridge press release, which originated the news item, provides more detail,

“Our research identified several proteins that are essential in the assembly of the protein machinery that makes cellulose”, said Melbourne’s Prof Staffan Persson.

“We found that these assembly factors control how much cellulose is made, and so plants without them can not produce cellulose very well and the defect substantially impairs plant biomass production. The ultimate aim of this research would be breed plants that have altered activity of these proteins so that cellulose production can be improved for the range of applications that use cellulose including paper, timber and ethanol fuels.”

The newly discovered proteins are located in an intracellular compartment called the Golgi where proteins are sorted and modified.

“If the function of this protein family is abolished the cellulose synthesizing complexes become stuck in the Golgi and have problems reaching the cell surface where they normally are active” said the lead authors of the study, Drs. Yi Zhang (Max-Planck Institute for Molecular Plant Physiology) and Nino Nikolovski (University of Cambridge).

“We therefore named the new proteins STELLO, which is Greek for to set in place, and deliver.”

“The findings are important to understand how plants produce their biomass”, said Professor Paul Dupree from the University of Cambridge’s Department of Biochemistry.

“Greenhouse-gas emissions from cellulosic ethanol, which is derived from the biomass of plants, are estimated to be roughly 85 percent less than from fossil fuel sources. Research to understand cellulose production in plants is therefore an important part of climate change mitigation.”

“In addition, by using cellulosic plant materials we get around the problem of food-versus-fuel scenario that is problematic when using corn as a basis for bioethanol.”

“It is therefore of great importance to find genes and mechanisms that can improve cellulose production in plants so that we can tailor cellulose production for various needs.”

Previous studies by Profs. Persson’s and Dupree’s research groups have, together with other scientists, identified many proteins that are important for cellulose synthesis and for other cell wall polymers.

With the newly presented research they substantially increase our understanding for how the bulk of a plant’s biomass is produced and is therefore of vast importance to industrial applications.

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

Golgi-localized STELLO proteins regulate the assembly and trafficking of cellulose synthase complexes in Arabidopsis by Yi Zhang, Nino Nikolovski, Mathias Sorieul, Tamara Vellosillo, Heather E. McFarlane, Ray Dupree, Christopher Kesten, René Schneider, Carlos Driemeier, Rahul Lathe, Edwin Lampugnani, Xiaolan Yu, Alexander Ivakov, Monika S. Doblin, Jenny C. Mortimer, Steven P. Brown, Staffan Persson, & Paul Dupree. Nature Communications 7,
Article number: 11656 doi:10.1038/ncomms11656 Published  09 June 2016

This paper is open access.

Biodegradable films from cellulose nanofibrils

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A team at Purdue University (Indiana, US) has developed a new process for biodegradable films based on cellulose according to a June 8, 2016 news item on phys.org,

Purdue University researchers have developed tough, flexible, biodegradable films from cellulose, the main component of plant cell walls. The films could be used for products such as food packaging, agricultural groundcovers, bandages and capsules for medicine or bioactive compounds.

Food scientists Srinivas Janaswamy and Qin Xu engineered the cellophane-like material by solubilizing cellulose using zinc chloride, a common inorganic salt, and adding calcium ions to cause the cellulose chains to become tiny fibers known as nanofibrils, greatly increasing the material’s tensile strength. The zinc chloride and calcium ions work together to form a gel network, allowing the researchers to cast the material into a transparent, food-grade film.

A June 7, 2016 Purdue University news release by Natalie van Hoose, which originated the news item, discusses the need for these films and provides a few more technical details about the work (Note: A link has been removed),

“We’re looking for innovative ways to adapt and use cellulose – an inexpensive and widely available material – for a range of food, biomedical and pharmaceutical applications,” said Janaswamy, research assistant professor of food science and principal author of the study. “Though plastics have a wide variety of applications, their detrimental impact on the environment raises a critical need for alternative materials. Cellulose stands out as a viable option, and our process lays a strong foundation for developing new biodegradable plastics.”

Cellulose’s abundance, renewability and ability to biodegrade make it a promising substitute for petroleum-based products. While a variety of products such as paper, cellophane and rayon are made from cellulose, its tightly interlinked structure and insolubility – qualities that give plants strength and protection – make it a challenging material to work with.

Janaswamy and Xu loosened the cellulose network by adding zinc chloride, which helps push cellulose’s closely packed sheets apart, allowing water to penetrate and solubilize it. Adding calcium ions spurs the formation of nanofibrils through strong bonds between the solubilized cellulose sheets. The calcium ions boost the tensile strength of the films by about 250 percent.

The production process preserves the strength and biodegradability of cellulose while rendering it transparent and flexible.

Because the zinc chloride can be recycled to repeat the process, the method offers an environmentally friendly alternative to conventional means of breaking down cellulose, which tend to rely on toxic chemicals and extreme temperatures.

“Products based on this film can have a no-waste lifecycle,” said Xu, research assistant professor of food science and first author of the study. “This process allows us to create a valuable product from natural materials – including low-value or waste materials such as corn stover or wood chips- that can eventually be returned to the Earth.”

The methodology could be adapted to mass-produce cellulose films, the researchers said.

The next step in the project is to find ways of making the cellulose film insoluble to water while maintaining its ability to biodegrade.

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

A facile route to prepare cellulose-based films by Qin Xu, Chen Chen, Katelyn Rosswurm, Tianming Yao, Srinivas Janaswamy. Carbohydrate Polymers Volume 149, 20 September 2016, Pages 274–281 doi:10.1016/j.carbpol.2016.04.114

This paper is behind a paywall.

Inside-out plants show researchers how cellulose forms

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Strictly speaking this story of tricking cellulose into growing on the surface rather than the interior of a cell is not a nanotechnology topic but I imagine that the folks who research nanocellulose materials will find this work of great interest. An Oct. 8, 2015 news item on ScienceDaily describes the research,

Researchers have been able to watch the interior cells of a plant synthesize cellulose for the first time by tricking the cells into growing on the plant’s surface.

“The bulk of the world’s cellulose is produced within the thickened secondary cell walls of tissues hidden inside the plant body,” says University of British Columbia Botany PhD candidate Yoichiro Watanabe, lead author of the paper published this week in Science.

“So we’ve never been able to image the cells in high resolution as they produce this all-important biological material inside living plants.”

An Oct. 8, 2015 University of British Columbia (UBC) news release on EurekAlert, which originated the news item, explains the interest in cellulose,

Cellulose, the structural component of cell walls that enables plants to stay upright, is the most abundant biopolymer on earth. It’s a critical resource for pulp and paper, textiles, building materials, and renewable biofuels.

“In order to be structurally sound, plants have to lay down their secondary cell walls very quickly once the plant has stopped growing, like a layer of concrete with rebar,” says UBC botanist Lacey Samuels, one of the senior authors on the paper.

“Based on our study, it appears plant cells need both a high density of the enzymes that create cellulose, and their rapid movement across the cell surface, to make this happen so quickly.”

This work, the culmination of years of research by four UBC graduate students supervised by UBC Forestry researcher Shawn Mansfield and Samuels, was facilitated by a collaboration with the Nara Institute of Technology in Japan to create the special plant lines, and researchers at the Carnegie Institution for Science at Stanford University to conduct the live cell imaging.

“This is a major step forward in our understanding of how plants synthesize their walls, specifically cellulose,” says Mansfield. “It could have significant implications for the way plants are bred or selected for improved or altered cellulose ultrastructural traits – which could impact industries ranging from cellulose nanocrystals to toiletries to structural building products.”

The researchers used a modified line of Arabidopsis thaliana, a small flowering plant related to cabbage and mustard, to conduct the experiment. The resulting plants look exactly like their non-modified parents, until they are triggered to make secondary cell walls on their exterior.

One of the other partners in this research, Stanford University’s Carnegie Institution of Science published an Oct. 8, 2015 news release on EurekAlert focusing on other aspects of the research (Note: Some of this is repetitive),

Now scientists, including Carnegie’s David Ehrhardt and Heather Cartwright, have exploited a new way to watch the trafficking of the proteins that make cellulose in the formation cell walls in real time. They found that organization of this trafficking by structural proteins called microtubules, combined with the high density and rapid rate of these cellulose producing enzymes explains how thick and high strength secondary walls are built. This basic knowledge helps us understand plants can stand upright, which was essential for the move of plants from the sea to the land, and may useful for engineering plants with improved mechanical properties for to increase yields or to produce novel bio-materials. The research is published in Science.

The live-cell imaging was conducted at Carnegie with colleagues from the University of British Columbia (UBC) using customized high-end instrumentation. For the first time, it directly tracked cellulose production to observe how xylem cells, cells that transport water and some nutrients, make cellulose for their secondary cell walls. Strong walls are based on a high density of enzymes that catalyze the synthesis of cellulose (called cellulose synthase enzymes) and their rapid movement across the xylem cell surface.

Watching xylem cells lay down cellulose in real time has not been possible before, because the vascular tissues of plants are hidden inside the plant body. Lead author Yoichiro Watanabe of UBC applied a system developed by colleagues at the Nara Institute of Science and Technology to trick plants into making xylem cells on their surface. The researchers fluorescently tagged a cellulose synthase enzyme of the experimental plant Arabidopsis to track the activity using high-end microscopes.

“For me, one of the most exciting aspects of this study was being able to observe how the microtubule cytoskeleton was actively directing the synthesis of the new cell walls at the level of individual enzymes. We can guess how a complex cellular process works from static snapshots, which is what we usually have had to work from in biology, but you can’t really understand the process until you can see it in action. ” remarked Carnegie’s David Ehrhardt.

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

Visualization of cellulose synthases in Arabidopsis secondary cell walls by Y. Watanabe, M. J. Meents, L. M. McDonnell, S. Barkwill, A. Sampathkumar, H. N. Cartwright, T. Demura, D. W. Ehrhardt, A.L. Samuels, & S. D. Mansfield. Science 9 October 2015: Vol. 350 no. 6257 pp. 198-203 DOI: 10.1126/science.aac7446

This paper is behind a paywall.

With all of this talk of visualization, it’s only right that the researchers have made an image from their work available,

Caption: An image of artificially-produced cellulose in cells on the surface of a modified Arabidopsis thaliana plant. Credit: University of British Columbia.

Caption: An image of artificially-produced cellulose in cells on the surface of a modified Arabidopsis thaliana plant. Credit: University of British Columbia.