Cellulose Nanoworm Coatings for Enhancing the Water Resistance of Nanocellulose Film Substrates in Printed Electronics

Cellulose-nanomaterial-derived films are promising platforms for engineering advanced substrates for printed electronics. However, they are highly susceptible to water and humidity, which limit their wide application. To overcome these drawbacks, cellulose nanoworms (distinct hydrophobized cellulose nanomaterials) were introduced in this study as sustainable coatings to enhance the water resistance of cellulose nanofiber (CNF) films. Alcogels of nanoworms, produced via ethanol-induced swelling and ultrasonication of a cellulose pulp esterified in a deep eutectic solvent, form a dense and transparent coating on the CNF films, significantly inhibiting their water absorption and improving their surface smoothness. Furthermore, the resulting coated CNF films exhibited enhanced hydrophobicity with improved wet mechanical properties and lower water vapor permeability. In addition, the results of the ink-printing tests revealed that the coated films partially or completely inhibited ink removal. Thus, this study demonstrated that cellulose nanoworm coatings provide a promising approach to overcome the moisture sensitivity of CNF films.