Tag Archives: nanocellulose

Cellulose nanocrystals and a computational approach to new materials

There’s been a lot of research into cellulose nanomaterials as scientists work to develop applications for cellulose nanocrystals (CNC)* and cellulose nanofibrils (CNF). To date, there have been no such breakthroughs or, as they used to say, no such ‘killer apps’. An Oct. 2, 2015 news item on Nanowerk highlights work which made finally lead the way,

Theoretically, nanocellulose could be the next hot supermaterial.

A class of biological materials found within numerous natural systems, most notably trees, cellulose nanocrystals have captured researchers’ attention for their extreme strength, toughness, light weight, and elasticity. The materials are so strong and tough, in fact, that many people think they could replace Kevlar in ballistic vests and combat helmets for military. Unlike their source material (wood), cellulose nanocrystals are transparent, making them exciting candidates for protective eyewear, windows, or displays.

Although there is a lot of excitement around the idea of nanocellulose-based materials, the reality often falls flat.

“It’s difficult to make these theoretical properties materialize in experiments,” said Northwestern Engineering’s Sinan Keten. “Researchers will make composite materials with nanocellulose and find that they fall short of theory.”

Keten, an assistant professor of mechanical, civil, and environmental engineering at Northwestern University’s McCormick School of Engineering, and his team are bringing the world one step closer to a materials-by-design approach toward developing nanocomposites with cellulose. They have developed a novel, multi-scale computational framework that explains why these experiments do not produce the ideal material and proposes solutions for fixing these shortcomings, specifically by modifying the surface chemistry of cellulose nanocrystals to achieve greater hydrogen bonding with polymers.

An Oct. 2, 2015 (McCormick School of Engineering) Northwestern University news release (also on EurekAlert), which originated the news item, provides more context for the research before describing a new technique for better understanding the materials,

Found within the cellular walls of wood, cellulose nanocrystals are an ideal candidate for polymer nanocomposites — materials where a synthetic polymer matrix is embedded with nanoscale filler particles. Nanocomposites are commonly made synthetic fillers, such as silica, clay, or carbon black, and are used in a myriad of applications ranging from tires to biomaterials.

“Cellulose nanocrystals are an attractive alternative because they are naturally bioavailable, renewable, nontoxic, and relatively inexpensive,” Keten said. “And they can be easily extracted from wood pulp byproducts from the paper industry.”

Problems arise, however, when researchers try to combine the nanocellulose filler particles with the polymer matrix. The field has lacked an understanding of how the amount of filler affects the composite’s overall properties as well as the nature of the nanoscale interactions between the matrix and the filler.

Keten’s solution improves this understanding by focusing on the length scales of the materials rather than the nature of the materials themselves. By understanding what factors influence properties on the atomic scale, his computational approach can predict the nanocomposite’s properties as it scales up in size — with a minimal need for experimentation.

“Rather than just producing a material and then testing it to see what its properties are, we instead strategically tune design parameters in order to develop materials with a targeted property in mind,” Sinko said. “When you are equalizing music, you can turn knobs to adjust the bass, treble, etc. to produce a desired sound. In materials-by-design, we similarly can ‘turn the knobs’ of specific parameters to adjust the resulting properties.”

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

Tuning Glass Transition in Polymer Nanocomposites with Functionalized Cellulose Nanocrystals through Nanoconfinement by Xin Qin, Wenjie Xia, Robert Sinko, and Sinan Keten. Nano Lett., Article ASAP
DOI: 10.1021/acs.nanolett.5b02588 Publication Date (Web): September 4, 2015

Copyright © 2015 American Chemical Society

This paper is open access.

*Cellulose nanocrystals (CNC) are also known as nancellulose crystals (NCC).

Cellulose nanocrystals and supercapacitors at McMaster University (Canada)

Photos: Xuan Yang and Kevin Yager.

Photos: Xuan Yang and Kevin Yager. Courtesy McMaster University

I love that featherlike structure holding up a tiny block of something while balanced on what appears to be a series of medallions. What it has to do with supercapacitors (energy storage) and cellulose nanocrystals is a mystery but that’s one of the images you’ll find illustrating an Oct. 7, 2015 news item on Nanotechnology Now featuring research at McMaster University,

McMaster Engineering researchers Emily Cranston and Igor Zhitomirsky are turning trees into energy storage devices capable of powering everything from a smart watch to a hybrid car.

The scientists are using cellulose, an organic compound found in plants, bacteria, algae and trees, to build more efficient and longer-lasting energy storage devices or supercapacitors. This development paves the way toward the production of lightweight, flexible, and high-power electronics, such as wearable devices, portable power supplies and hybrid and electric vehicles.

A Sept. 10, 2015 McMaster University news release, which originated the news item, describes the research in more detail,

Cellulose offers the advantages of high strength and flexibility for many advanced applications; of particular interest are nanocellulose-based materials. The work by Cranston, an assistant chemical engineering professor, and Zhitomirsky, a materials science and engineering professor, demonstrates an improved three-dimensional energy storage device constructed by trapping functional nanoparticles within the walls of a nanocellulose foam.

The foam is made in a simplified and fast one-step process. The type of nanocellulose used is called cellulose nanocrystals and looks like uncooked long-grain rice but with nanometer-dimensions. In these new devices, the ‘rice grains’ have been glued together at random points forming a mesh-like structure with lots of open space, hence the extremely lightweight nature of the material. This can be used to produce more sustainable capacitor devices with higher power density and faster charging abilities compared to rechargeable batteries.

Lightweight and high-power density capacitors are of particular interest for the development of hybrid and electric vehicles. The fast-charging devices allow for significant energy saving, because they can accumulate energy during braking and release it during acceleration.

For anyone interested in a more detailed description of supercapacitors, there’s my favourite one which involves Captain America’s shield along with some serious science in my April 28, 2014 posting.

Getting back to the research at McMaster, here’s a link to and a citation for the paper,

Cellulose Nanocrystal Aerogels as Universal 3D Lightweight Substrates for Supercapacitor Materials by Xuan Yang, Kaiyuan Shi, Igor Zhitomirsky, and Emily D. Cranston. Advanced Materials DOI: 10.1002/adma.201502284View/save citation First published online 2 September 2015

This paper is behind a paywall.

One final bit, cellulose nanocrystals (CNC) are sometimes referred to as nanocrystalline cellulose (NCC).

Carrot-based helmets: a nanocellulose commercialization story

NanoCelluComp, a European Commission-funded project, whose name bears a close resemblance to a Scottish company, CelluComp, ended last year (my March 5, 2014 post). Both, NanoCelluComp and CelluComp, were/are involved in research featuring carrots and nanocellulose.

An Aug. 6, 2015 news item on ScienceDaily describes some Swiss/Scottish research into using carrot nanofibers in helmets,

Crackpot idea or recipe for success? This is a question entrepreneurs often face. Is it worth converting the production process to a new, ecologically better material? Empa [Swiss Federal Laboratories for Materials Science and Technology or Eidgenössische Materialprüfungs- und Forschungsansta] has developed an analysis method that enables companies to simulate possible scenarios — and therefore avoid bad investments. Here’s an example: Nanofibers made of carrot waste from the production of carrot juice, which can be used to reinforce synthetic parts.

All over the world, research is being conducted into biodegradable and recyclable synthetics. However, fiber-reinforced components remain problematic — if glass or carbon fibers are used. Within the scope of an EU research project, the Scottish company Cellucomp Limited has now developed a method to obtain nanofibers from carrot waste. [emphasis mine] These fibers would be both cost-effective and biodegradable. However, is the method, which works in the lab, also marketable on a large scale?

Here’s a composite image illustrating the notion of a carrot-based helmet,

Motorcycle helmets consist of fiber-reinforced synthetic material. Instead of glass fibers, a biological alternative is now also possible: plant fibers from the production of carrot juice. Empa researchers are now able to analyze whether this kind of production makes sense from an ecological and economical perspective – before money is actually invested in production plants.  Photo: 4ever.eu, composite photo: Empa

Motorcycle helmets consist of fiber-reinforced synthetic material. Instead of glass fibers, a biological alternative is now also possible: plant fibers from the production of carrot juice. Empa researchers are now able to analyze whether this kind of production makes sense from an ecological and economical perspective – before money is actually invested in production plants.
Photo: 4ever.eu, composite photo: Empa

An Aug. 6, 2015 Empa press release (also on EurekAlert), which originated the news item, provides more details abut the drive to commercialize this nanocellulose product,

An MPAS (multi-perspective application selection) method developed at Empa helps identify the industrial sectors where new materials might be useful from a technical and economical perspective. At the same time, MPAS also considers the ecological aspect of these new materials. The result for our example: Nanofibers made of carrot waste might be used in the production of motorcycle helmets or side walls for motorhomes in the future.

Three-step analysis

In order to clarify a new material’s market potential, Empa researchers Fabiano Piccinno, Roland Hischier and Claudia Som proceed in three steps for the MPAS method. First of all, the field of possible applications is defined: Which applications come into question based on the technical properties and what categories can they be divided into? Can the new material replace an existing one?

The second step concerns the technical feasibility and market potential: Can the material properties required be achieved with the technical process? Might the product quality vary from one production batch to the next? Can the lab process be upgraded to an industrial scale cost-effectively? Is the material more suited to the low-cost sector or expensive luxury goods? And finally: Does the product meet the legal standards and the customers’ certification needs?

In the third step, the ecological aspect is eventually examined: Is this new material for the products identified really more environmentally friendly – once all the steps from product creation to recycling have been factored in? Which factors particularly need to be considered during production stage to manufacture the material in as environmentally friendly a way as possible?

Industrial production on a five-ton scale – calculated theoretically

The MPAS approach enables individual scenarios for a future production to be calculated with an extremely high degree of accuracy. In the case of the carrot waste nanofibers, for instance, it is crucial whether five tons of fresh carrots or only 209 kilograms of carrot waste (fiber waste from the juicing process) are used as the base material for their production. The issue of whether the solvent is ultimately recycled or burned affects the production costs. And the energy balance depends on how the enzymes that loosen the fibers from the carrots are deactivated. In the lab, this takes place via heat; for production on an industrial level, the use of bleaching agents would be more cost-effective.

Conclusion: six possible applications for “carrot fibers“

For fiber production from carrot waste, the MPAS analysis identified six possible customer segments for the Scottish manufacturer Cellucomp that are worth taking a closer look at: Protective equipment and devices for recreational sport, special vehicles, furniture, luxury consumer goods and industrial manufacturing. The researchers listed the following examples: Motorcycle helmets and surfboards, side walls for motorhomes, dining tables, high-end loudspeaker boxes and product protection mats for marble-working businesses. Similarly detailed analyses can also be conducted for other renewable materials – before a lot of money is actually invested in production plants.

There are other attempts to commercialize nanocellulose (as I understand it, cellulose is one of the most common materials on earth and can be derived from several sources including trees, bananas, pineapples, and more) mentioned in my July 30, 2015 post. I will repeat a question from that post, where are the Canadian research efforts to develop and commercialize nanocellulose? If you have information, please do let me know.

Replacing metal with nanocellulose paper

The quest to find uses for nanocellulose materials has taken a step forward with some work coming from the University of Maryland (US). From a July 24, 2015 news item on Nanowerk,

Researchers at the University of Maryland recently discovered that paper made of cellulose fibers is tougher and stronger the smaller the fibers get … . For a long time, engineers have sought a material that is both strong (resistant to non-recoverable deformation) and tough (tolerant of damage).

“Strength and toughness are often exclusive to each other,” said Teng Li, associate professor of mechanical engineering at UMD. “For example, a stronger material tends to be brittle, like cast iron or diamond.”

A July 23, 2015 University of Maryland news release, which originated the news item, provides details about the thinking which buttresses this research along with some details about the research itself,

The UMD team pursued the development of a strong and tough material by exploring the mechanical properties of cellulose, the most abundant renewable bio-resource on Earth. Researchers made papers with several sizes of cellulose fibers – all too small for the eye to see – ranging in size from about 30 micrometers to 10 nanometers. The paper made of 10-nanometer-thick fibers was 40 times tougher and 130 times stronger than regular notebook paper, which is made of cellulose fibers a thousand times larger.

“These findings could lead to a new class of high performance engineering materials that are both strong and tough, a Holy Grail in materials design,” said Li.

High performance yet lightweight cellulose-based materials might one day replace conventional structural materials (i.e. metals) in applications where weight is important. This could lead, for example, to more energy efficient and “green” vehicles. In addition, team members say, transparent cellulose nanopaper may become feasible as a functional substrate in flexible electronics, resulting in paper electronics, printable solar cells and flexible displays that could radically change many aspects of daily life.

Cellulose fibers can easily form many hydrogen bonds. Once broken, the hydrogen bonds can reform on their own—giving the material a ‘self-healing’ quality. The UMD discovered that the smaller the cellulose fibers, the more hydrogen bonds per square area. This means paper made of very small fibers can both hold together better and re-form more quickly, which is the key for cellulose nanopaper to be both strong and tough.

“It is helpful to know why cellulose nanopaper is both strong and tough, especially when the underlying reason is also applicable to many other materials,” said Liangbing Hu, assistant professor of materials science at UMD.

To confirm, the researchers tried a similar experiment using carbon nanotubes that were similar in size to the cellulose fibers. The carbon nanotubes had much weaker bonds holding them together, so under tension they did not hold together as well. Paper made of carbon nanotubes is weak, though individually nanotubes are arguably the strongest material ever made.

One possible future direction for the research is the improvement of the mechanical performance of carbon nanotube paper.

“Paper made of a network of carbon nanotubes is much weaker than expected,” said Li. “Indeed, it has been a grand challenge to translate the superb properties of carbon nanotubes at nanoscale to macroscale. Our research findings shed light on a viable approach to addressing this challenge and achieving carbon nanotube paper that is both strong and tough.”

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

Anomalous scaling law of strength and toughness of cellulose nanopaper by Hongli Zhu, Shuze Zhu, Zheng Jia, Sepideh Parvinian, Yuanyuan Li, Oeyvind Vaaland, Liangbing Hu, and Teng Li. PNAS (Proceedings of the National Academy of Sciences) July 21, 2015 vol. 112 no. 29 doi: 10.1073/pnas.1502870112

This paper is behind a paywall.

There is a lot of research on applications for nanocellulose, everywhere it seems, except Canada, which at one time was a leader in the business of producing cellulose nanocrystals (CNC).

Here’s a sampling of some of my most recent posts on nanocellulose,

Nanocellulose as a biosensor (July 28, 2015)

Microscopy, Paper and Fibre Research Institute (Norway), and nanocellulose (July 8, 2015)

Nanocellulose markets report released (June 5, 2015; US market research)

New US platform for nanocellulose and occupational health and safety research (June 1, 2015; Note: As you find new applications, you need to concern yourself with occupational health and safety.)

‘Green’, flexible electronics with nanocellulose materials (May 26, 2015; research from China)

Treating municipal wastewater and dirty industry byproducts with nanocellulose-based filters (Dec. 23, 2014; research from Sweden)

Nanocellulose and an intensity of structural colour (June 16, 2014; research about replacing toxic pigments with structural colour from the UK)

I ask again, where are the Canadians? If anybody has an answer, please let me know.

Nanocellulose as a biosensor

While nanocellulose always makes my antennae quiver (for anyone unfamiliar with the phrase, it means something along the lines of ‘attracts my attention’), it’s the collaboration which intrigues me most about this research. From a July 23, 2015 news item on Azonano (Note: A link has been removed),

An international team led by the ICREA Prof Arben Merkoçi has just developed new sensing platforms based on bacterial cellulose nanopaper. These novel platforms are simple, low cost and easy to produce and present outstanding properties that make them ideal for optical (bio)sensing applications. …

ICN2 [Catalan Institute of Nanoscience and Nanotechnology; Spain] researchers are going a step further in the development of simple, low cost and easy to produce biosensors. In an article published in ACS Nano they recently reported various innovative nanopaper-based optical sensing platforms. To achieve this endeavour the corresponding author ICREA Prof Arben Merkoçi, Group Leader at ICN2 and the first author, Dr Eden Morales-Narváez (from ICN2) and Hamed Golmohammadi (visiting researcher at ICN2), established an international collaboration with the Shahid Chamran University (Iran), the Gorgan University of Agricultural Sciences and Natural Resources (Iran) and the Academy of Sciences of the Czech Republic. [emphases mine]

Spain, Iran, and the Czech Republic. That’s an interesting combination of countries.

A July 23, 2015 ICN2 press release, which originated the news item, provides more explanations and detail,

Cellulose is simple, naturally abundant and low cost. However, cellulose fibres ranging at the nanoscale exhibit extraordinary properties such as flexibility, high crystallinity, biodegradability and optical transparency, among others. The nanomaterial can be extracted from plant cellulose pulp or synthetized by non-pathogenic bacteria. Currently, nanocellulose is under active research to develop a myriad of applications including filtration, wound dressing, pollution removal approaches or flexible and transparent electronics, whereas it has been scarcely explored for optical (bio)sensing applications.

The research team led by ICREA Prof Arben Merkoçi seeks to design, fabricate, and test simple, disposable and versatile sensing platforms based on this material. They designed different bacterial cellulose nanopaper based optical sensing platforms. In the article, the authors describe how the material can be tuned to exhibit plasmonic or photoluminescent properties that can be exploited for sensing applications. Specifically, they have prepared two types of plasmonic nanopaper and two types of photoluminescent nanopaper using different optically active nanomaterials.

The researchers took advantage of the optical transparency, porosity, hydrophilicity, and amenability to chemical modification of the material. The bacterial cellulose employed throughout this research was obtained using a bottom-up approach and it is shown that it can be easily turned into useful devices for sensing applications using wax printing or simple punch tools. The scientific team also demonstrates how these novel sensing platforms can be modulated to detect biologically relevant analytes such as cyanide and pathogens among others.

According to the authors, this class of platforms will prove valuable for displaying analytical information in diverse fields such as diagnostics, environmental monitoring and food safety. Moreover, since bacterial cellulose is flexible, lightweight, biocompatible and biodegradable, the proposed composites could be used as wearable optical sensors and could even be integrated into novel theranostic devices. In general, paper-based sensors are known to be simple, portable, disposable, low power-consuming and inexpensive devices that might be exploited in medicine, detection of explosives or hazardous compounds and environmental studies.

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

Nanopaper as an Optical Sensing Platform by Eden Morales-Narváez, Hamed Golmohammadi, Tina Naghdi, Hossein Yousefi, Uliana Kostiv, Daniel Horák, Nahid Pourreza, and Arben Merkoçi.ACS Nano, Article ASAP DOI: 10.1021/acsnano.5b03097 Publication Date (Web): July 2, 2015
Copyright © 2015 American Chemical Society

This paper is behind a paywall.

Microscopy, Paper and Fibre Research Institute (Norway), and nanocellulose

In keeping with a longstanding interest here in nanocellulose (aka, cellulose nanomaterials) the Norwegian Paper and Fibre Research Institute’s (PFI) ??,??, 2015 announcement about new ion milling equipment and a new scanning electron microscope suitable for research into cellulose at the nanoscale caught my eye,

In order to advance the microscopy capabilities of cellulose-based materials and thanks to a grant from the Norwegian Pulp and Paper Research Institute foundation, PFI has invested in a modern ion milling equipment and a new Scanning Electron Microscope (SEM).

Unusually, the entire news release is being stored at Nanowerk as a July 3, 2015 news item (Note: Links have been removed),

“There are several microscopy techniques that can be used for characterizing cellulose materials, but the scanning electron microscope is one of the most preferable ones as the microscope is easy to use, versatile and provides a multi-scale assessment”, explains Gary Chinga-Carrasco, lead scientist at the PFI Biocomposite area.

“However, good microscopy depends to a large extent on an adequate and optimized preparation of the samples”, adds Per Olav Johnsen, senior engineer and microscopy expert at PFI.

“We are always trying to be in front in the development of new characterization methods, facilitating research and giving support to our industrial partners”, says Chinga-Carrasco, who has been active in developing new methods for characterization of paper, biocomposites and nanocellulose and cannot hide his enthusiasm when he talks about PFI’s new equipment. “In the first period after the installation it is important to work with the equipment with several material samples and techniques to really become confident with its use and reveal its potential”.

The team at PFI is now offering new methods for assessing cellulose materials in great detail. They point out that they have various activities and projects where they already see a big potential with the new equipment.

Examples for these efforts are the assessment of porous nanocellulose structures for biomedical applications (for instance in the NanoHeal program) and the assessment of surface modified wood fibres for use in biocomposites (for instance in the FiberComp project).

Also unusual is the lack of detail about the microscope’s and ion milling machine’s technical specifications and capabilities.

The NanoHeal program was last mentioned here in an April 14, 2014 post and first mentioned here in an Aug. 23, 2012 posting.

Final comment, I wonder if Nanowerk is embarking on a new initiative where the company agrees to store news releases for various agencies such as PFI and others who would prefer not to  archive their own materials. Just a thought.

Cellulose Nanofibrillated Fiber Based Transistors from the University of Wisconsin-Madison

There’s a team of researchers at the University of Wisconsin-Madison working to substitute silicon used in computer chips with cellulose derived from wood (my May 27, 2015 posting). Their latest effort, featuring mobile electronics, is described in a July 1, 2015 news item on Azonano,

A report published by the U.S. Environmental Protection Agency in 2012 showed that about 152 million mobile devices are discarded every year, of which only 10 percent is recycled — a legacy of waste that consumes a tremendous amount of natural resources and produces a lot of trash made from expensive and non-biodegradable materials like highly purified silicon.

Now researchers from the University of Wisconsin-Madison have come up with a new solution to alleviate the environmental burden of discarded electronics. They have demonstrated the feasibility of making microwave biodegradable thin-film transistors from a transparent, flexible biodegradable substrate made from inexpensive wood, called cellulose nanofibrillated fiber (CNF). This work opens the door for green, low-cost, portable electronic devices in future.

A June 30, 2015 American Institute of Physics news release by Zhengzheng Zhang, which originated the news item, describes the research in more detail,

“We found that cellulose nanofibrillated fiber based transistors exhibit superior performance as that of conventional silicon-based transistors,” said Zhenqiang Ma, the team leader and a professor of electrical and computer engineering at the UW-Madison. “And the bio-based transistors are so safe that you can put them in the forest, and fungus will quickly degrade them. They become as safe as fertilizer.”

Nowadays, the majority of portable electronics are built on non-renewable, non-biodegradable materials such as silicon wafers, which are highly purified, expensive and rigid substrates, but cellulose nanofibrillated fiber films have the potential to replace silicon wafers as electronic substrates in environmental friendly, low-cost, portable gadgets or devices of the future.

Cellulose nanofibrillated fiber is a sustainable, strong, transparent nanomaterial made from wood. Compared to other polymers like plastics, the wood nanomaterial is biocompatible and has relatively low thermal expansion coefficient, which means the material won’t change shape as the temperature changes. All these superior properties make cellulose nanofibril an outstanding candidate for making portable green electronics.

To create high-performance devices, Ma’s team employed silicon nanomembranes as the active material in the transistor — pieces of ultra-thin films (thinner than a human hair) peeled from the bulk crystal and then transferred and glued onto the cellulose nanofibrill substrate to create a flexible, biodegradable and transparent silicon transistor.To create high-performance devices, Ma’s team employed silicon nanomembranes as the active material in the transistor — pieces of ultra-thin films (thinner than a human hair) peeled from the bulk crystal and then transferred and glued onto the cellulose nanofibrill substrate to create a flexible, biodegradable and transparent silicon transistor.

But to make portable electronics, the biodegradable transistor needed to be able to operate at microwave frequencies, which is the working range of most wireless devices. The researchers thus conducted a series of experiments such as measuring the current-voltage characteristics to study the device’s functional performance, which finally showed the biodegradable transistor has superior microwave-frequency operation capabilities comparable to existing semiconductor transistors.

“Biodegradable electronics provide a new solution for environmental problems brought by consumers’ pursuit of quickly upgraded portable devices,” said Ma. “It can be anticipated that future electronic chips and portable devices will be much greener and cheaper than that of today.”

Next, Ma and colleagues plan to develop more complicated circuit system based on the biodegradable transistors.

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

Microwave flexible transistors on cellulose nanofibrillated fiber substrates by Jung-Hun Seo, Tzu-Hsuan Chang, Jaeseong Lee, Ronald Sabo, Weidong Zhou, Zhiyong Cai, Shaoqin Gong, and Zhenqiang Ma.  Applied Physics Letters, Volume 106, Issue 26 or  Appl. Phys. Lett. 106, 262101 (2015); http://dx.doi.org/10.1063/1.4921077

This is an open access paper.

‘Green’, flexible electronics with nanocellulose materials

Bendable or flexible electronics based on nanocellulose paper present a ‘green’ alternative to other solutions according to a May 20, 2015 American Chemical Society (ACS) news release (also on EurekAlert),

Technology experts have long predicted the coming age of flexible electronics, and researchers have been working on multiple fronts to reach that goal. But many of the advances rely on petroleum-based plastics and toxic materials. Yu-Zhong Wang, Fei Song and colleagues wanted to seek a “greener” way forward.

The researchers developed a thin, clear nanocellulose paper made out of wood flour and infused it with biocompatible quantum dots — tiny, semiconducting crystals — made out of zinc and selenium. The paper glowed at room temperature and could be rolled and unrolled without cracking.

(h’t Nanotechnology Now, May 20, 2015)

There’s no mention in the news release or abstract as to what material (wood, carrot, banana, etc.) was used to derive the nanocellulose. Regardless, here’s a link to and a citation for the paper,

Let It Shine: A Transparent and Photoluminescent Foldable Nanocellulose/Quantum Dot Paper by Juan Xue, Fei Song, Xue-wu Yin, Xiu-li Wang, and Yu-zhong Wang. ACS Appl. Mater. Interfaces, 2015, 7 (19), pp 10076–10079 DOI: 10.1021/acsami.5b02011 Publication Date (Web): May 4, 2015

Copyright © 2015 American Chemical Society

This paper is behind a paywall.

Treating municipal wastewater and dirty industry byproducts with nanocellulose-based filters

Researchers at Sweden’s Luleå University of Technology have created nanocellulose-based filters in collaboration with researchers at the Imperial College of London (ICL) good enough for use as filters according to a Dec. 23, 2014 news item on Nanowerk,

Prototypes of nano-cellulose based filters with high purification capacity towards environmentally hazardous contaminants from industrial effluents e.g. process industries, have been developed by researchers at Luleå University of Technology. The research, conducted in collaboration with Imperial College in the UK has reached a breakthrough with the prototypes and they will now be tested on a few industries in Europe.

“The bio-based filter of nano-cellulose is to be used for the first time in real-life situations and tested within a process industry and in municipal wastewater treatment in Spain. Other industries have also shown interest in this technology and representatives of the mining industry have contacted me and I have even received requests from a large retail chain in the UK,” says Aji Mathew Associate Professor, Division of Materials Science at Luleå University.

A Dec. 22, 2014 Luleå University of Technology press release, which originated the news item, further describes the research,

Researchers have combined a cheap residue from the cellulose industry, with functional nano-cellulose to prepare adsorbent sheets with high filtration capacity. The sheets have since been constructed to different prototypes, called cartridges, to be tested. They have high capacity and can filter out heavy metal ions from industrial waters, dyes residues from the printing industry and nitrates from municipal water. Next year, larger sheets with a layer of nano-cellulose can be produced and formed into cartridges, with higher capacity.

– Each such membrane can be tailored to have different removal capability depending on the kind of pollutant, viz., copper, iron, silver, dyes, nitrates and the like, she says.

Behind the research, which is funded mainly by the EU, is a consortium of research institutes, universities, small businesses and process industries. It is coordinated by Luleå University led by Aji Mathew. She thinks that the next step is to seek more money from the EU to scale up this technology to industrial level.

– Alfa Laval is very interested in this and in the beginning of 2015, I go in with a second application to the EU framework program Horizon 2020 with goals for full-scale demonstrations of this technology, she says.

Two of Aji Mathews graduate student Peng Liu and Zoheb Karim is also deeply involved in research on nano-filters.

– I focus on how these membranes can filter out heavy metals by measuring different materials such as nanocrystals and nano-fibers to determine their capacity to absorb and my colleague focuses on how to produce membranes, says Peng Liu PhD student in the Department of Materials Science and Engineering at Luleå University of Technology.

I have been following the nanocellulose work at Luleå University of Technology for a few years now. The first piece was a Feb. 15, 2012 post titled, The Swedes, sludge, and nanocellulose fibres, and the next was a Sept. 19, 2013 post titled, Nanocellulose and forest residues at Luleå University of Technology (Sweden). It’s nice to mark the progress over time although I am curious as to the source for the nanocellulose, trees, carrots, bananas?

Producing cellulose nanoparticles from waste cotton

This nanocellulose item comes courtesy of Iran, from a July 29, 2014 news item on Nanowerk (Note: A link has been removed),

Researchers from Amir Kabir University of Technology succeeded in the synthesis of cellulose nanoparticles by using two environmentally-friendly processes (“Spherical cellulose nanoparticles preparation from waste cotton using a green method”).

The use of waste cotton fibers for the production of cellulose nanoparticles is among the interesting points in this research.

In addition to biodegradability and the ability to be recovered and re-used, cellulose nanoparticles are light and cheap, and they have very desirable mechanical properties. Therefore, they have high potential to be used in pharmaceutics, foodstuff, cosmetics, paper production and composite manufacturing.

A July 29, 2014 Iran Nanotechnology Initiative Council (INIC) news release, which originated the news item, provides more detail about the research,

Dr. Tayyebeh Fattahi Mei-abadi, one of the researchers, explained about the advantages of this method over the usual methods, and said, “In this project, spherical cellulose nanoparticles were produced from waste cotton fibers through enzyme hydrolysis and ultrasound methods. Acidic hydrolysis is usually used in the majority of the researches on the production of cellulose nanoparticles. This method is not in agreement with environmental issues, and it leaves byproducts. But in this research, enzyme hydrolysis method was used, which enables the production of nanoparticles under mild condition without any environmental damage, and it does not require specific equipment. In addition, ultrasonic process was carried out with low energy in a short period, which makes cost-effective the production of cellulose nanoparticles through this method.”

In the production of the nanoparticles, various parts of cellulose enzyme were attached to cellulose chains, and they started to hydrolyze crystalline and amorphous areas. As hydrolysis goes on, particles with average size of 520 nm are formed. Then, ultrasound energy converts the hydrolyzed fibers into nanoparticles at about 70 nm in size.

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

Spherical cellulose nanoparticles preparation from waste cotton using a green method by Tayebeh Fattahi Meyabadi, Fatemeh Dadashian, Gity Mir Mohamad Sadeghi, and Hamid Ebrahimi Zanjani Asl.Powder Technology Volume 261, July 2014, Pages 232–240 DOI: 10.1016/j.powtec.2014.04.039

This paper is behind a paywall.