Nanocellulose is a light solid substance obtained from plant matter which comprises nanosized cellulose fibrils. This new material is a pseudo-plastic and possesses the property of specific kinds of fluids or gels that are generally thick in normal conditions. The lateral dimensions of nanocellulose range from 5 to 20 nm, and the longitudinal dimension ranges from a few 10's of nanometers to several microns.
Nanocellulose is transparent, electrically conductive, and stronger than steel.
Properties of Nanocellulose
The properties of nanocellulose are listed below:
- Stiffer than Kevlar®
- Electrically conductive
- The crystalline form is transparent, and gas impermeable
- It can be produced in large quantities in a cost-effective manner
- It has a very high tensile strength - 8 times that of steel
- It is highly absorbent when used as a basis for aerogels or foams.
- The raw material - cellulose - is the most abundant polymer on earth
Production of Nanocellulose
Nanocellulose is generally produced from wood pulp though it can also be prepared from any cellulosic source material. Nanocellulose is produced using the following steps:
- Remove non-cellulose impurities from the wood pulp using a homogenizer. The high-pressure homogenizers used in the production process helps delaminate the cell walls of the fibers and separate the nanosized fibrils.
- Separate the cellulose fibers by beating the mixture gently.
- Allow the fibers to form a thick paste of needle-like crystals or a spaghetti-like structure of cellulose fibrils.
- The thick paste that is obtained can be shaped and readily used to laminate surfaces.
Once it is completely separated from the wood pulp, the nanocellulose is in a water suspension. At this stage, care should be taken to prevent the formation of rough clumps in cases when the cellulose fibers stick together as the material dries.
Researchers have thus developed a process that allows nanocellulose to dry without the formation of rough clumps. This process thus prevents the cellulose fibrils from sticking together and enables the cellulose fibers to retain their mechanical properties.
Nanocellulose up-close: This TEM image of a nanocellulose membrane shows the individual cellulose nanofibers. Image Credits: Prof. Mohini Sain, University of Toronto
Applications of Nanocellulose
Nanocellulose has a wide range of applications, from cleaning of oil spills to usage in children’s toys. Nanocellulose can be used in pharmaceutical, food and medical industries. This new material can also replace some petrochemical-based products and is very likely to be cheaper than most other kinds of high-performance nanoscale materials. Given below are the key applications of nanocellulose:
- Nanocellulose sheets can be used for electronic displays and windows.
- Nanocellulose-based sensors could help in monitoring structures like bridges to detect their stress levels.
- Nanocellulose can be used as a food packaging material that prevents the spoiling of food contents and entry of oxygen in the food contents. This new material thus replaces the use of polystyrene-based foams.
- In food products, nanocellulose can be used as flavor carriers and suspension stabilizers.
- Nanocellulose is safe to be used as a food thickener.
- When used in paper products, nanocellulose helps to improve the fiber to fiber bond strength and acts as a barrier in grease-proof type papers.
- It can be used as wet-end additive to enhance retention, dry and wet strength in commodity type of board and paper products.
- Nanocelluose can be used to improve the mechanical properties of rubber latex, thermosetting resins, soy protein and starch-based matrixes.
- Nanocellulose can be used as fracturing fluid in oil recovery applications.
- In the medical field, nancellulose can be used for antimicrobial films and water absorbent pads. Nanocellulose can also be used in non-woven products or tissues.
Nanocellulose applications in cosmetic, pharmaceutical and medical products are listed below:
- Nanocellulose can be used in tampons, sanitary napkins or wound dressing in the form of freeze-dried nanocellulose aerogels.
- Intestinal disorders can be treated by tablets comprising dry solid nanocellulose.
- Nanocellulose can be used as a composite coating agent in cosmetics for nails, hair, eyebrows or eyelashes.
- Nanocellulose in a powdered form is used as an excipient in pharmaceutical formulations.
Nanocellulose with its lightweight, high strength and transparent properties is of great interest for many applications in a wide variety of areas. The material that is of immense significance in the ongoing commercialization of nanotechnologies, and researchers and industrialists are analyzing and exploring new manufacturing process and applications for nanocellulose.
Nanocellulose has been considered as a less expensive alternative to carbon fiber and glass fiber for some applications, and is also considered a useful material by the paper and pulp industries that use nanocellulose as an efficient means to increase absorbency in several products such as napkins, ketches towels, etc.
Nanocellulose thus plays a vital role in medical, food and pharmaceutical industries and also in several materials that are widely used commercially. It can also improve the environmental footprint of many of these industries by replacing synthetic or petrochemical-based materials.
Sources and Further Reading