title: Modification of TiO2Nanoparticles with Oleyl Phosphate via Phase Transfer in the Toluene-Water System and Application of Modified Nanoparticles to Cyclo-Olefin-Polymer-Based Organic-Inorganic Hybrid Films Exhibiting High Refractive Indices.
abstract: Oleyl-phosphate-modified TiO2nanoparticles (OP_TiO2) were prepared via phase transfer from an aqueous phase containing dispersed TiO2nanoparticles to a toluene phase containing oleyl phosphate (OP, a mixture of monoester and diester), and employed for the preparation of OP_TiO2/cyclo-olefin polymer (COP) hybrid films with high-refractive indices. The modification of TiO2by OP was essentially completed by reaction at room temperature for 8 h, and essentially all the TiO2nanoparticles in the aqueous phase were transferred to the toluene phase. The infrared and solid-state13C cross-polarization and magic-angle spinning (CP/MAS) NMR spectrum of OP_TiO2showed the presence of oleyl groups originating from oleyl phosphate. The solid-state31P MAS NMR spectrum of OP_TiO2exhibited new signals at -1.4, 2.1, and 4.8 ppm, indicating the formation of Ti-O-P bonds. CHN and inductively coupled plasma analyses revealed that the major species bound to the TiO2surface was tridentate CH3(CH2)7CH═CH(CH2)8P(OTi)3. These results clearly indicate that the surfaces of the TiO2nanoparticles were modified by OP moieties via phase transfer. OP_TiO2/COP hybrid films exhibited excellent optical transparency up to 19.1 vol % TiO2loading, and the light transmittance of the hybrid films with 19.1 vol % TiO2loading was 99.8% at 633 nm. The refractive index of these hybrid films rose to 1.83.
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: Shiori
authors.initials: S
authors.lastname: Takahashi
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: Shuhei
authors.initials: S
authors.lastname: Hotta
authors.affiliation: Institute of Multidisciplinary Research for Advanced Materials, Tohoku University , 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Watanabe
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 nanoparticle; cyclo-olefin polymer; oleyl phosphate; organic−inorganic hybrid; phase transfer; refractive index; surface modification