Modification of TiO2 nanoparticles 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

Shiori Takahashi, Shuhei Hotta, Akira Watanabe, Naokazu Idota, Kimihiro Matsukawa, Yoshiyuki Sugahara

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Oleyl-phosphate-modified TiO2 nanoparticles (OP_TiO2) were prepared via phase transfer from an aqueous phase containing dispersed TiO2 nanoparticles 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 TiO2 by OP was essentially completed by reaction at room temperature for 8 h, and essentially all the TiO2 nanoparticles in the aqueous phase were transferred to the toluene phase. The infrared and solid-state 13C cross-polarization and magic-angle spinning (CP/ MAS) NMR spectrum of OP_TiO2 showed the presence of oleyl groups originating from oleyl phosphate. The solid-state 31P MAS NMR spectrum of OP_TiO2 exhibited 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 TiO2 surface was tridentate CH3(CH2)7CHCH(CH2)8P(OTi)3. These results clearly indicate that the surfaces of the TiO2 nanoparticles were modified by OP moieties via phase transfer. OP_TiO2/COP hybrid films exhibited excellent optical transparency up to 19.1 vol % TiO2 loading, and the light transmittance of the hybrid films with 19.1 vol % TiO2 loading was 99.8% at 633 nm. The refractive index of these hybrid films rose to 1.83.

Original languageEnglish
Pages (from-to)1907-1912
Number of pages6
JournalACS Applied Materials and Interfaces
Volume9
Issue number2
DOIs
Publication statusPublished - 2017 Jan 1

Keywords

  • Cyclo-olefin polymer
  • Oleyl phosphate
  • Organic−inorganic hybrid
  • Phase transfer
  • Refractive index
  • Surface modification
  • TiO2 nanoparticle

ASJC Scopus subject areas

  • Materials Science(all)

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