title: Low-birefringent and highly tough nanocellulose-reinforced cellulose triacetate.
abstract: Improvement of the mechanical and thermal properties of cellulose triacetate (CTA) films is required without sacrificing their optical properties. Here, poly(ethylene glycol) (PEG)-grafted cellulose nanofibril/CTA nanocomposite films were fabricated by casting and drying methods. The cellulose nanofibrils were prepared by 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation, and amine-terminated PEG chains were grafted onto the surfaces of the TEMPO-oxidized cellulose nanofibrils (TOCNs) by ionic bonds. Because of the nanosize effect of TOCNs with a uniform width of ∼3 nm, the PEG-TOCN/CTA nanocomposite films had high transparency and low birefringence. The grafted PEG chains enhanced the filler-matrix interactions and crystallization of matrix CTA molecules, resulting in the Young's modulus and toughness of CTA film being significantly improved by PEG-grafted TOCN addition. The coefficient of thermal expansion of the original CTA film was mostly preserved even with the addition of PEG-grafted TOCNs. These results suggest that PEG-TOCNs are applicable to the reinforcement for transparent optical films.
authors.affiliation: †Department of Biomaterials Science, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan.
authors.forename: Hiroto
authors.initials: H
authors.lastname: Soeta
authors.affiliation: ‡Department of Biomass Chemistry, Forestry and Forest Products Research Institute, 1 Matsuno-sato, Tsukuba, Ibaraki 305-8687, Japan.
authors.forename: Shuji
authors.initials: S
authors.lastname: Fujisawa
authors.affiliation: †Department of Biomaterials Science, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan.
authors.forename: Tsuguyuki
authors.initials: T
authors.lastname: Saito
authors.affiliation: §Fibre and Polymer Technology, School of Chemical Science and Engineering, Royal Institute of Technology, Teknikringen 56-58, SE-100 44, Stockholm, Sweden.
authors.forename: Lars
authors.initials: L
authors.lastname: Berglund
authors.affiliation: †Department of Biomaterials Science, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Isogai
keywords: TEMPO; birefringence; cellulose triacetate; nanocellulose; nanocomposite