CelluForce is the leading supplier of cellulose nanocrystals for numerous applications in different markets.
What are cellulose nanocrystals?
Cellulose nanocrystals (also called nanocrystalline cellulose) are nanoscale (10-9 m) particles that are derived from cellulose, a natural polymer found in plant cell walls. They are one of a few different types of nanocellulose.
Nanocrystalline cellulose is made by CelluForce through a process called acid hydrolysis, which involves breaking down the more accessible portion of the cellulose to leave the crystalline structures. The acid used during the hydrolysis process generates chemical moieties and charges on the surface of the particles which makes them chemically reactive and customizable for various applications. For example, the sulfuric acid used at CelluForce will generate an acidic cellulose sulfate half-ester group as shown below.
Cellulose nanocrystals are rod-shaped particles with diameters of 2-5 nanometers and lengths of around 100 nanometers that have high surface area, high aspect ratio, and excellent mechanical strength, stiffness, and thermal stability.
Cellulose nanocrystals are biodegradable, renewable, and non-toxic, making them an environmentally friendly alternative to many synthetic and fossil-based materials.
How are cellulose nanocrystals made?
Cellulose nanocrystals produced by CelluForce are extracted through a process called acid hydrolysis, which involves breaking down the cellulose generated by trees into smaller crystalline structures. The process involves the following steps:
- Hydrolysis: Cellulose is treated with sulfuric acid under controlled conditions of temperature and time. The acid digests more accessible portions of the cellulose chains to leave the highly crystalline structures that are cellulose nanocrystals.
- Neutralization and Washing: The resulting cellulose nanocrystals are then neutralized to remove any remaining acid and washed thoroughly to remove any impurities.
- Drying: The cellulose nanocrystals are then dried through a spray-drying process, to produce a powder that can be easily stored, dispersed, and used in various applications.
The cellulose nanocrystal properties, such as their size, shape, and surface chemistry, can be controlled by varying the cellulose source or adjusting the parameters of the production process.
Extracting cellulose nanocrystals from trees
Properties and applications of cellulose nanocrystals
Cellulose nanocrystals can be used as sustainable additives or as films in a multitude of applications because of the key properties they exhibit.
Blocks
Cellulose nanocrystals can act as a physical barrier. Their nanometric size allows them to fill small spaces or form a dense network to block or slow down the passage of liquids, gases and particles through a structure.
In addition, cellulose nanocrystals have surface charges that can attract or repel other particles, depending on their charge. This property can be used to selectively block certain particles or substances while allowing others to pass through.
Example: CelluRods®, when added as a layer in polylactic acid films, greatly improve gas barrier properties*.
*Reference: Chowdhury, R. A., Clarkson, C., & Youngblood, J. P. (2018, 06). 2018 TAPPI International Conference on Nanotechnology for Renewable Materials. Roll-to-roll Fabrication of Transparent Cellulose Nanocrystal (CNC) Coatings with Controlled Anisotropy, 12. Madison, Wisconsin, USA: TAPPI NANO DIVISION.
Emulsifies
Cellulose nanocrystals can emulsify, making colloidal suspensions by forming a stable interface between two immiscible liquids, such as oil and water or water in oil.
The emulsifying properties of cellulose nanocrystals stem from their concentration at the oil-water interface which stabilizes the resulting emulsion. Cellulose nanocrystals have hydrophilic (water-loving) and hydrophobic (water-repelling) crystal facets, which allow them to orient at the oil-water interface to form a stable layer that prevents the droplets from coalescing and the two phases from separating.
Furthermore, CNCs can form a three-dimensional network at the interface, which provides additional stability to the emulsion. The strength of this network depends on various factors, such as the concentration, the pH of the system, and the nature of the oils and emulsifiers used.
Example: CelluRods® can be added as a solid surfactant to stabilize oil-in-water or water-in-oil suspensions*.
*Reference: Miao C, Tayebi M, Hamad, WY. 2018 Investigation of the formation mechanisms in high internal phase Pickering emulsions stabilized by cellulose nanocrystals. Phil. Trans. R. Soc. A 376: 20170039.
Functionalization
Cellulose nanocrystals can be functionalized through various chemical modification methods, allowing their properties to be tailored for specific applications. Cellulose nanocrystals can be modified with chemical groups to improve their interaction with other substances.
Cellulose nanocrystals can be modified with groups that can allow cross-linking. This change can be used to enhance the mechanical properties and stability of composites or coatings.
Cellulose nanocrystals can be functionalized through polymer grafting. The attached polymers allow better compatibility with polymer systems, improving dispersibility and resulting properties of the reinforced polymer.
Overall, functionalizing cellulose nanocrystals expands their range of potential applications.
Lubricates
Cellulose nanocrystals can act as particle lubricants. They work by reducing friction and wear between two surfaces by forming a protective layer on the surface. They can shear under flow and fill in surface irregularities, reducing the contact area between the two surfaces and decreasing friction.
Cellulose nanocrystals can also act as a sacrificial layer, meaning that they wear away more easily than the surfaces they are protecting. This can help to prevent damage to the underlying surfaces and prolong the life of the equipment.
Example: CelluRods® can be added to water to improve mechanical seal performance*.
*Reference: Shariatzadeh, M. J., & Grecov, D. (2018). Cellulose Nanocrystals Suspensions as Water-Based Lubricants for Slurry Pump Gland Seals. International Journal of Aerospace and Mechanical Engineering, Vol:12, No:6.
Optically Active
Cellulose nanocrystals organize in suspension which can cause structures to develop which can interact with light. When these suspensions are dried slowly, helical crystal planes are developed in the resulting solid film which diffract light. This property can be used to create structural colours upon drying because light is reflected differently depending on the orientation of the helix relative to the direction of light polarization.
Strengthens
Cellulose nanocrystals have a high aspect ratio (length to width ratio) and are inherently strong. The elastic moduli for individual particles is in the range of 100-140 GPa, which is comparable to or higher than other high-strength materials like carbon fiber or KevlarTM.
Cellulose nanocrystals can strengthen materials through their ability to form strong bonds with other components and create a network that reinforces the material and increase its strength.
In addition, cellulose nanocrystals can act as nucleating agents which can promote the formation of small crystal nuclei, which can then grow into larger crystals and increase the crystallinity of the material. This increased crystallinity can lead to improved mechanical properties.
Example: CelluRods® can be added to rubber latex to improve mechanical properties of rubber products. *
*Reference: Mekonnen, T., & Ah-Leung, T. (2018). Study of Cellulose NanoCrystals Reinforced Formulated Natural Rubber Composites. University of Waterloo, Department of Chemical Engineering. Montréal, QC: CelluForce.
Suspends
When cellulose nanocrystals are properly dispersed in a liquid, they form ordered structures which imparts liquid crystal properties to the suspension. The liquid crystal is a dynamic network that can limit the motion of other particles and prevent them from settling.
This ability to suspend other particles also allow for a better distribution and dispersion of the suspended particles which in turn allow them to perform better (reduced usage). This ability is maintained even at high temperature when compared to standard polymeric suspension agents.
Example: CelluRods® can be used in electric displays to suspend conductive elements.*
*Reference: CelluForce data
Thermally Stable
Cellulose nanocrystals are known to exhibit high thermal stability due to their crystalline nature and strong intermolecular hydrogen bonding. The thermal stability of cellulose nanocrystals can vary depending on their source and preparation method. In general, they are stable up to temperatures of 250-300°C, without significant degradation, although some changes in their properties, such as discoloration, may occur.
At higher temperatures, cellulose nanocrystals can undergo thermal degradation, which results in a reduction in their crystallinity and loss of some of their mechanical properties.
Thickens
Cellulose nanocrystals have been shown to effectively thicken various materials, including liquids and coatings. Their high surface area, large number of hydroxyl (-OH) groups and electrostatic interactions contribute to the thickening effect of the material.
Cellulose nanocrystals exhibit non-Newtonian fluid behavior where its viscosity decreases as the shear rate increases and the fluid flows more easily.
Example: CelluRods® can be added to oil and gas fluids to maintain viscosity in higher operating temperature ranges*.
* Reference: CelluForce data
Sustainability of cellulose nanocrystals
Cellulose nanocrystals are considered to be a sustainable material. They are derived from cellulose, which is a natural polymer found in plant cell walls, and can be extracted from a variety of sources, including wood pulp, agricultural waste, and other plant-based materials. At CelluForce, we ensure that all our cellulose is obtained from PEFC certified sources and guarantee that our raw material is obtained using responsible forestry practices which protect biodiversity, prevent deforestation, and respect the rights of indigenous people and local communities.
Since cellulose nanocrystals are derived from renewable resources, they can replace synthetic and fossil-based materials that are derived from non-renewable sources.
Cellulose nanocrystals are biodegradable; they can be broken down by natural processes into harmless substances, and do not accumulate in the environment.
Additionally, the production of cellulose nanocrystals generates benign by-products that can be recycled or reused. At CelluForce, we minimize the carbon footprint of our products through an efficient production process which has been optimized over the last 10 years and using renewable energy sources. The carbon footprint of our cellulose nanocrystals is further improved by the fact that the crystals can be used to produce lightweight materials, reducing the overall carbon footprint of the final products they are used for.
The use of cellulose nanocrystals can significantly contribute to a more sustainable and environmentally friendly approach to materials and product development.
Safety of cellulose nanocrystals
Cellulose nanocrystals are generally considered safe for use in various applications. Cellulose nanocrystals are derived from cellulose, which is a natural and biocompatible material that has been used in various applications for many years.
Cellulose nanocrystals are also biodegradable, which means they do not accumulate in the environment or pose a long-term risk to human health or the environment.
An array of in vitro and in vivo test performed by CelluForce, and others have now demonstrated the product safety. Oral, inhalation, and dermal tests have shown that cellulose nanocrystals fall in the least toxic category in the Globally Harmonized System of Classification and Labelling of Chemicals and the material is currently approved for use in cosmetic products.
The handling of our cellulose nanocrystals powder is also facilitated by the agglomeration of nanocrystals in micron-size spheroids.
Regulation
Cellulose nanocrystals are composed of cellulose (CAS 9004-34-6) and registered for use in most jurisdictions.
The regulation of cellulose nanocrystals can vary depending on the specific application and the country where they are being used.
It is important to follow all relevant regulations and guidelines when using cellulose nanocrystals to meet the regulatory requirements in the jurisdiction of use.
Our products’ regulatory datasheets are available on each of our products‘ pages.
Other Frequently Asked Questions
Nanocellulose is a term used to describe all types of nanomaterials derived from cellulose fibers, including cellulose nanocrystals or nanocrystalline cellulose, cellulose nanofibrils and bacterial cellulose. Cellulose nanocrystals and nanofibrils are typically derived from plant-based cellulose through chemical extraction or mechanical fibrillation processes, respectively. Bacterial cellulose is produced by certain bacteria, such as Acetobacter xylinum, through biosynthesis.
The surface modification of cellulose nanocrystals is the process of chemically altering their surface functional groups to enhance their properties and performance or make them more suitable for specific applications. Examples include esterification, etherification, silylation, polymer grafting, amidation, and click chemistry. These processes can improve the compatibility of cellulose nanocrystals with various matrices, increase their functionality, and expand their versatility and range of potential uses.
Cellulose is derived from plant cell walls, including wood, cotton, and other natural fibers. It can also be produced by bacteria, such as Acetobacter, which are used to produce bacterial cellulose nanocrystals. At CelluForce, we primarily use cellulose extracted from wood pulp.
Cellulose nanomaterials have a wide range of potential applications, including as reinforcement in composites, in targeted drug delivery, as performance additives, in tissue engineering, and in paints and coatings. Visit our markets page to discover a wide range of different possible applications.
Cellulose nanocrystals (CNCs) are not present in nature in their isolated form but are derived from naturally occurring cellulose sources. In nature, cellulose exists as long chains of glucose molecules linked by β-1,4-glycosidic bonds. These cellulose chains form microfibrils, which contain both highly ordered crystalline regions and less ordered “amorphous” regions. The crystalline portions of these microfibrils are what eventually become individual cellulose nanocrystals when extracted by acid hydrolysis or other means.
Cellulose nanocrystals (CNCs) are derived from cellulose, which is a naturally biodegradable material. As nanoparticles of cellulose, CNCs retain much of the biodegradability of their parent material. The biodegradability of CNCs makes them attractive for developing environmentally friendly materials.
The biodegradation of cellulose-based materials typically occurs in two steps:
- Breakdown of the cellulose polymer into lower-molecular-mass species such as cellobiose or glucose through abiotic or biotic reactions.
- Bio-assimilation or metabolism of the cellulose polymer fragments by microorganisms and their mineralization.
CNCs are considered suitable for creating biodegradable nanocomposites and foams due to their biodegradability. In biodegradable polymer blends, the addition of CNCs can contribute to the materials being fully biodegradable.
Cellulose nanocrystals are rod-shaped particles with dimensions in the nanoscale (nm) range. Their size can vary depending on the source material and preparation method. The length of cellulose nanocrystals typically ranges from 100 to 250 nm. The width or cross-section of cellulose nanocrystals is usually between 3 and 50 nm.