title: Strong, self-standing oxygen barrier films from nanocelluloses modified with regioselective oxidative treatments.
abstract: In this work, three self-standing nanocellulose films were produced from birch pulp using regioselective oxidation and further derivatization treatments. The modified celluloses were synthesized using periodate oxidation, followed by chlorite oxidation, bisulfite addition, or reductive amination with amino acid taurine, which resulted in dicarboxylic acid cellulose (DCC), α-hydroxy sulfonic acid cellulose (HSAC), and taurine-modified cellulose (TC), respectively. The nanocelluloses were fabricated by mechanical disintegration using high-pressure homogenization. Mechanical and barrier properties of the nanocellulose films were characterized. Two (2,2,6,6-tetramethyl-piperidin-1-yl)oxyl (TEMPO) oxidation-based nanocellulose films were also produced, and their properties were compared to the periodate-based nanocellulose films. All of the periodate-based nanocellulose films showed high tensile strength (130-163 MPa) and modulus (19-22 GPa). Oxygen barrier properties of the films were superior to many synthetic and composite materials; in particular, the nanofibrillated DCC films had oxygen permeability as low as 0.12 cm(3) μm/(m(2) d kPa) at 50% relative humidity. Compared to films of TEMPO-oxidized nanocelluloses, all of the periodate-based nanocellulose films had similar or even better mechanical and barrier properties, demonstrating versatility of periodate oxidation to obtain nanocellulose films with adjustable properties. Also, for the first time, amino-acid-based cellulose modification was used in the production of nanocellulose.
authors.affiliation: Fibre and Particle Engineering Laboratory & Thule Institute, University of Oulu , P.O. Box 4300, FI-90014 Oulu, Finland.
authors.forename: Juho Antti
authors.initials: JA
authors.lastname: Sirviö
authors.forename: Aleksi
authors.initials: A
authors.lastname: Kolehmainen
authors.forename: Miikka
authors.initials: M
authors.lastname: Visanko
authors.forename: Henrikki
authors.initials: H
authors.lastname: Liimatainen
authors.forename: Jouko
authors.initials: J
authors.lastname: Niinimäki
authors.forename: Osmo E O
authors.initials: OE
authors.lastname: Hormi