Nanocellulose films exhibit excellent physical properties such as high strength and low oxygen permeability under dry conditions. However, these material properties become impaired drastically under humid conditions. In the present study, water-resistant nanocellulose films were prepared using TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl)-oxidized cellulose nanofibrils (TOCNs) with multivalent metal carboxylate groups. The counterions of carboxylate groups on the TOCN surfaces were exchanged to multivalent metal ions from the sodium ones in as-prepared TOCN films by immersing the films into multivalent metal chloride solutions. Wet, high-moisture-content (300–500%) films of TOCNs with aluminum or iron (III) carboxylates showed high Young’s moduli of about 3 GPa and tensile strength values of 30–40 MPa. Furthermore, TOCN films with aluminum or calcium carboxylates exhibited very low oxygen permeability of about 0.1 mL µm m–2 day–1 kPa–1 even at high relative humidity of 80% RH, which is an outstanding value compared with those for nanocellulose-based materials reported so far. These results are explained based on high densities of the films and the strong interactions between surface-carboxylated TOCNs via multivalent ions.

Water-resistant nanocellulose films with inter-fibrillar interactions via multivalent metal ions

253rd National Meeting (2017)

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