Tag Archives: nanocellulose crystals

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).

Synthesizing nerve tissues with 3D printers and cellulose nanocrystals (CNC)

There are lots of stories about bioprinting and tissue engineering here and I think it’s time (again) for one which one has some good, detailed descriptions and, bonus, it features cellulose nanocrystals (CNC) and graphene. From a May 13, 2015 news item on Azonano,

The printer looks like a toaster oven with the front and sides removed. Its metal frame is built up around a stainless steel circle lit by an ultraviolet light. Stainless steel hydraulics and thin black tubes line the back edge, which lead to an inner, topside box made of red plastic.

In front, the metal is etched with the red Bio Bot logo. All together, the gray metal frame is small enough to fit on top of an old-fashioned school desk, but nothing about this 3D printer is old school. In fact, the tissue-printing machine is more like a sci-fi future in the flesh—and it has very real medical applications.

Researchers at Michigan Technological University hope to use this newly acquired 3D bioprinter to make synthesized nerve tissue. The key is developing the right “bioink” or printable tissue. The nanotechnology-inspired material could help regenerate damaged nerves for patients with spinal cord injuries, says Tolou Shokuhfar, an assistant professor of mechanical engineering and biomedical engineering at Michigan Tech.

Shokuhfar directs the In-Situ Nanomedicine and Nanoelectronics Laboratory at Michigan Tech, and she is an adjunct assistant professor in the Bioengineering Department and the College of Dentistry at the University of Illinois at Chicago.

In the bioprinting research, Shokuhfar collaborates with Reza Shahbazian-Yassar, the Richard and Elizabeth Henes Associate Professor in the Department of Mechanical Engineering-Engineering Mechanics at Michigan Tech. Shahbazian-Yassar’s highly interdisciplinary background on cellulose nanocrystals as biomaterials, funded by the National Science Foundation’s (NSF) Biomaterials Program, helped inspire the lab’s new 3D printing research. “Cellulose nanocrystals with extremely good mechanical properties are highly desirable for bioprinting of scaffolds that can be used for live tissues,” says Shahbazian-Yassar. [emphases mine]

A May 11, 2015 Michigan Technological University (MTU) news release by Allison Mills, which originated the news item, explains the ‘why’ of the research,

“We wanted to target a big issue,” Shokuhfar says, explaining that nerve regeneration is a particularly difficult biomedical engineering conundrum. “We are born with all the nerve cells we’ll ever have, and damaged nerves don’t heal very well.”

Other facilities are trying to address this issue as well. Many feature large, room-sized machines that have built-in cell culture hoods, incubators and refrigeration. The precision of this equipment allows them to print full organs. But innovation is more nimble at smaller scales.

“We can pursue nerve regeneration research with a simpler printer set-up,” says Shayan Shafiee, a PhD student working with Shokuhfar. He gestures to the small gray box across the lab bench.

He opens the red box under the top side of the printer’s box. Inside the plastic casing, a large syringe holds a red jelly-like fluid. Shafiee replenishes the needle-tipped printer, pulls up his laptop and, with a hydraulic whoosh, he starts to print a tissue scaffold.

The news release expands on the theme,

At his lab bench in the nanotechnology lab at Michigan Tech, Shafiee holds up a petri dish. Inside is what looks like a red gummy candy, about the size of a half-dollar.

Here’s a video from MTU illustrating the printing process,

Back to the news release, which notes graphene could be instrumental in this research,

“This is based on fractal geometry,” Shafiee explains, pointing out the small crenulations and holes pockmarking the jelly. “These are similar to our vertebrae—the idea is to let a nerve pass through the holes.”

Making the tissue compatible with nerve cells begins long before the printer starts up. Shafiee says the first step is to synthesize a biocompatible polymer that is syrupy—but not too thick—that can be printed. That means Shafiee and Shokuhfar have to create their own materials to print with; there is no Amazon.com or even a specialty shop for bioprinting nerves.

Nerves don’t just need a biocompatible tissue to act as a carrier for the cells. Nerve function is all about electric pulses. This is where Shokuhfar’s nanotechnology research comes in: Last year, she was awarded a CAREER grant from NSF for her work using graphene in biomaterials research. [emphasis mine] “Graphene is a wonder material,” she says. “And it has very good electrical conductivity properties.”

The team is extending the application of this material for nerve cell printing. “Our work always comes back to the question, is it printable or not?” Shafiee says, adding that a successful material—a biocompatible, graphene-bound polymer—may just melt, mush or flat out fail under the pressure of printing. After all, imagine building up a substance more delicate than a soufflé using only the point of a needle. And in the nanotechnology world, a needlepoint is big, even clumsy.

Shafiee and Shokuhfar see these issues as mechanical obstacles that can be overcome.

“It’s like other 3D printers, you need a design to work from,” Shafiee says, adding that he will tweak and hone the methodology for printing nerve cells throughout his dissertation work. He is also hopeful that the material will have use beyond nerve regeneration.

This looks like a news release designed to publicize work funded at MTU by the US National Science Foundation (NSF) which is why there is no mention of published work.

One final comment regarding cellulose nanocrystals (CNC). They have also been called nanocrystalline cellulose (NCC), which you will still see but it seems CNC is emerging as the generic term. NCC has been trademarked by CelluForce, a Canadian company researching and producing CNC (or if you prefer, NCC) from forest products.

SAPPI to locate cellulose nanofibril facility in the Netherlands

SAPPI (formerly South African Pulp and Paper Industries) has announced it will build a nanocellulose facility in the Netherlands. From a March 11, 2015 news item on Nanowerk,

Sappi Limited, a leading global producer of dissolving wood pulp and graphics, speciality and packaging papers, is pleased to announce that it will build a pilot-scale plant for low-cost Cellulose NanoFibrils (nanocellulose) production at the Brightlands Chemelot Campus in Sittard-Geleen in the Netherlands. The pilot plant is expected to be operational within nine months.

A March 11, 2015 SAPPI media release (also on PR Newswire), which originated the news item, provides more detail about SAPPI’s nanocellulose business plans and the proposed pilot plant,

Commenting on the decision, Andrea Rossi, Group Head Technology, Sappi Limited, explained that the pilot plant will help with Sappi’s move into new adjacent business fields based on renewable raw materials. Sappi’s strategy includes seeking growth opportunities by producing innovative performance materials from renewable resources. The raw material for the pilot plant would be supplied from any of Sappi’s Saiccor, Ngodwana and Cloquet dissolving wood pulp plants. The pilot plant is the precursor for Sappi to consider the construction of a commercial CNF plant.

He goes on to say “the pilot plant will test the manufacturing of dry re-dispersible Cellulose NanoFibrils (CNF) using the proprietary technology developed by Sappi and Edinburgh Napier University. The location of the pilot plant at Brightlands Chemelot Campus provides Sappi with easy access to multiple partners with whom Sappi will seek to co-develop products that will incorporate CNF across a large variety of product applications to optimise performance and to create unique characteristics for these products.

The CNF produced by Sappi will have unique morphology, specifically modified for either hydrophobic or hydrophilic applications. Products produced using Sappi’s CNF will be optimally suitable for conversion in lighter and stronger fibre-reinforced composites and plastics, in food and pharmaceutical applications, and in rheology modifiers as well as in barrier and other paper and coating applications.

Speaking on behalf of Brightlands Chemelot Campus, the CEO Bert Kip said “We’re proud that a globally leading company like Sappi has chosen our campus for their new facility. The initiative perfectly fits with our focus area on bio-based materials and our new pilot plant infrastructure.”

In December 2014, Sappi and Edinburgh Napier University announced the results of their 3 year project to find a low cost energy-saving process that would allow Sappi to produce the nanocellulose on a commercially viable basis – and importantly without producing large volumes of chemical waste water associated with existing techniques. At the time, Professor Rob English, who led the research with his Edinburgh Napier colleague, Dr. Rhodri Williams, said “What is significant about our process is the use of unique chemistry, which has allowed us to very easily break down the wood pulp fibers into nanocellulose. There is no expensive chemistry required and, most significantly, the chemicals used can be easily recycled and reused without generating large quantities of waste water.

Math Jennekens, R&D Director at Sappi Europe who is the project coordinator and will oversee the pilot plant, said “We are very excited to be able to move from a bench top environment into real-world production. Our targeted run-rate will be 8 tons per annum. We will produce a dry powder that can be easily redispersed in water. The nanocellulose is unmodified which makes it easier to combine with other materials. The product will be used to build partnerships to test the application of our nanocellulose across the widest range of uses.”

He went on to thank the Government of the Province of Limburg in the Netherlands for their significant support and financial contribution towards the establishment of the pilot plant.

This business with a pilot production plant reminds me of CelluForce which has a cellulose nanocrystal (CNC) or, as it’s also known, nanocellulose crystal (NCC) production plant located in Windsor, Québec. They too announced a production plant which opened to fanfare in January 2012. in my Oct. 3, 2013 post (scroll down about 60% of the way) I noted that production had stopped in August 2013 due to a growing stockpile. As of March 11, 2015, I was not able to find any updates about the stockpile on the CelluForce website. The most recent CelluForce information I’ve been able to find is in a Feb. 19, 2015 posting (scroll down about 40% of the way).