Water-resistant nanocellulose films and coatings via deep eutectic solvent modifications

Thesis event information

Date and time of the thesis defence

Place of the thesis defence

University of Oulu, L5 (Linnanmaa)

Topic of the dissertation

Water-resistant nanocellulose films and coatings via deep eutectic solvent modifications

Doctoral candidate

Master of Science (tech.) Matias Lakovaara

Faculty and unit

University of Oulu Graduate School, Faculty of Technology, Fibre and Particle Engineering research unit

Subject of study

Process and environmental engineering

Opponent

Senior Researcher Gilberto Siqueira, Swiss Federal Laboratories for Materials Science and Technology - EMPA

Custos

Professor Henrikki Liimatainen, University of Oulu

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Water-resistant nanocellulose films and coatings for packaging and printed electronics applications

This doctoral thesis investigates the preparation of water-resistant nanocellulose (NC) films and coatings through modifications using deep eutectic solvent (DES). NC, a bio-based and renewable material derived from plant fibers (typically wood), forms films with high mechanical strength, flexibility, excellent oxygen and grease barrier properties, and high transparency, making it ideal for applications in packaging and printed electronics. DESs, novel solvents composed of inexpensive, low-toxicity, and biodegradable compounds, provide a sustainable alternative to traditional solvents for modifying cellulose and NC films.

In the first and second publications, NC films were chemically modified in DES using various reagents, resulting in films with enhanced water resistance, demonstrated by reduced water absorption and lower water vapor transmission rates. These films also exhibited improved mechanical strength under wet conditions.

In the third publication, cellulose nanomaterial was prepared by modifying cellulose fibers in DES and processed into transparent, heat-sealable, and water-resistant films using ethanol and ultrasonication. These films were successfully applied to create heat-sealable packaging for rice.

In the fourth publication, water-resistant cellulose nanomaterial from the third study was used to coat NC films, enabling their use as substrates for printed electronics. The coating significantly improved water resistance by reducing water absorption and protecting the printed electronic patterns from water-induced damage.

In conclusion, this research demonstrates that DES-based modifications offer a fast, simple, and sustainable method to enhance the water resistance of NC films and coatings, broadening their applicability in packaging and printed electronics.
Last updated: 28.8.2025