Nanocellulose-based foam materials for water purification, smart packaging and green electronics

Nanocellulose is a renewable nanomaterial made from plant fibers, with unique properties including lightness, very high strength and large surface area. The doctoral dissertation of Mohammad Karzarjeddi from the University of Oulu, Finland, investigated nanocellulose-based porous foam materials in water purification, smart packaging and wireless communications. These advanced cellulose applications reduce dependence on fossil-based materials.

The new dissertation focused on a new generation of lightweight foams called aerogels which can contain air by more than 99% of their weight. The raw material for the foams is nanocellulose made of wood pulp.

“Cellulose is converted into hydrogels consisting of thin and strong cellulose nanofibers, which are then dried and then reassembled into aerogels: ultra-light, highly porous solids made mostly of air. Aerogels can be engineered for multiple high-end applications, such as removing pollutants from water, creating smart packaging that reacts to moisture or temperature, and serving as lightweight materials in wireless and radio-frequency telecommunication technologies,” Karzarjeddi explains.

For example, in the first part of the research, small, spherical, and extremely lightweight aerogel beads called superabsorbents were developed to effectively absorb oils and organic solvents from water. These beads were made hydrophobic (water-repellent) and embedded with magnetic nanoparticles, allowing them to be easily collected and reused. They were highly efficient, absorbing up to 280 times their own weight in substances like vegetable oil.

Nanocellulose was also used to create foam structures for 5G and 6G wireless telecommunications technologies, where they can be utilized to manipulate high-frequency radio signals. A particular advantage of nanocellulose foams is their low signal losses.

The majority of foams and porous materials in use today, such as polyurethane, are made from fossil raw materials and are difficult to recycle.

Professor Henrikki Liimatainen, Karzarjeddi’s doctoral thesis supervisor, emphasizes the importance of bio-based materials: “New materials that promote both general sustainability goals and enable novel future technologies, are widely needed,” Liimatainen states.

“Cellulose nanomaterials possess many unique properties and can be converted into various forms in addition to foams, such as transparent films. They enable the development of lighter, stronger, and more efficient materials that can be used in a wide range of industries,” Liimatainen continues.