title: Preparation of Transparent Bulk TiO2/PMMA Hybrids with Improved Refractive Indices via an in Situ Polymerization Process Using TiO2Nanoparticles Bearing PMMA Chains Grown by Surface-Initiated Atom Transfer Radical Polymerization.
abstract: Transparent TiO2/PMMA hybrids with a thickness of 5 mm and improved refractive indices were prepared by in situ polymerization of methyl methacrylate (MMA) in the presence of TiO2nanoparticles bearing poly(methyl methacrylate) (PMMA) chains grown using surface-initiated atom transfer radical polymerization (SI-ATRP), and the effect of the chain length of modified PMMA on the dispersibility of modified TiO2nanoparticles in the bulk hybrids was investigated. The surfaces of TiO2nanoparticles were modified with both m-(chloromethyl)phenylmethanoyloxymethylphosphonic acid bearing a terminal ATRP initiator and isodecyl phosphate with a high affinity for common organic solvents, leading to sufficient dispersibility of the surface-modified particles in toluene. Subsequently, SI-ATRP of MMA was achieved from the modified surfaces of the TiO2nanoparticles without aggregation of the nanoparticles in toluene. The molecular weights of the PMMA chains cleaved from the modified TiO2nanoparticles increased with increases in the prolonging of the polymerization period, and these exhibited a narrow distribution, indicating chain growth controlled by SI-ATRP. The nanoparticles bearing PMMA chains were well-dispersed in MMA regardless of the polymerization period. Bulk PMMA hybrids containing modified TiO2nanoparticles with a thickness of 5 mm were prepared by in situ polymerization of the MMA dispersion. The transparency of the hybrids depended significantly on the chain length of the modified PMMA on the nanoparticles, because the modified PMMA of low molecular weight induced aggregation of the TiO2nanoparticles during the in situ polymerization process. The refractive indices of the bulk hybrids could be controlled by adjusting the TiO2content and could be increased up to 1.566 for 6.3 vol % TiO2content (1.492 for pristine PMMA).
authors.affiliation: Department of Applied Chemistry, School of Science and Engineering, Waseda University , 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Maeda
authors.affiliation: Department of Applied Chemistry, School of Science and Engineering, Waseda University , 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Fujita
authors.affiliation: Kagami Memorial Research Institute for Materials Science and Technology, Waseda University , 2-8-26 Nishiwaseda, Shinjuku-ku, Tokyo 169-0051, Japan.
authors.forename: Naokazu
authors.identifier: http://orcid.org/0000-0001-6913-1787
authors.initials: N
authors.lastname: Idota
authors.affiliation: Kyoto Institute of Technology , Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan.
authors.forename: Kimihiro
authors.initials: K
authors.lastname: Matsukawa
authors.affiliation: Department of Applied Chemistry, School of Science and Engineering, Waseda University , 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan.|Kagami Memorial Research Institute for Materials Science and Technology, Waseda University , 2-8-26 Nishiwaseda, Shinjuku-ku, Tokyo 169-0051, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Sugahara
keywords: TiO2/PMMA hybrids; dispersibility; surface-initiated atom transfer radical polymerization; transparency