TiO2 nanocomposites with high refractive index and transparency

Abstract

Transparent polymer nanocomposites with high refractive index were prepared by grafting polymer chains onto anatase TiO 2 nanoparticles via a combination of phosphate ligand engineering and alkyneazide ''click'' chemistry. Highly crystalline TiO 2 nanoparticles with 5 nm diameter were synthesized by a solvothermal method and used as high refractive index filler. The synthesized phosphate-azide ligand anchors strongly onto the TiO 2 nanoparticle surface and the azide end group allows for attachment of poly(glycidyl methacrylate) (PGMA) polymer chains through an alkyne-azide ''click'' reaction. The refractive index of the composite material increased linearly from 1.5 up to 1.8 by increasing the loading of TiO 2 particles to 30 vol % (60 wt %). UV-vis spectra show that the nanocomposites exhibited a transparency around 90% throughout the visible light range. It was also found that the PGMAgrafted TiO 2 nanoparticles can be well dispersed into a commercial epoxy resin, forming transparent high refractive index TiO 2 -epxoy nanocomposites.

Dielectric performance of high permitivity nanocomposites: impact of polystyrene grafting on BaTiO3 and TiO2

“…[11][12][13][14] Recent advances in surface initiated ATRP and Cu-catalyzed "click" chemistry have led to an increasingly diverse group of polymer grafted, hairy nanoparticles (HNPs) that feature high ε r and refractive index core plus a polymer corona with tunable structure. [15][16][17] Solution cast films of these HNPs without an accompanying polymer matrix have recently been characterized for dielectric performance. Tchoul et al reported that hairy PS@TiO 2 matrix free assemblies at 27% v/v inorganic loading have a relative dielectric constant of 6.4, compared to 2.4 for neat PS, while maintaining low dielectric loss similar to PS (tan δ = 0.04 at 1 kHz).…”

Structural and Optical Properties of Smooth Surface TCO Thin Films Deposited on Different-Sized Staked Nanoparticle Layers for Window Electrode of Thin Film Si Solar Cells

“…Thus, the refractive index of the NP layers (n NP ) was lower than that of the bulk layers (n bulk ), and its value was determined by the volume fraction (x) of NPs in the NP layer. 23,24) We therefore calculated the refractive index of the NP layers from the optical interference between the single NP layer and the glass substrate in the low light-scattering wavelength rage of 1000 1500 nm using the equation as follows:…”

Dielectric breakdown strength of epoxy bimodal-polymer-brush-grafted core functionalized silica nanocomposites

“…Alkyne-terminated PGMA was received as a solution in tetrahydrofuran (THF) and synthesized as reported previously [21]. Alkyne functionalized oligothiophene was synthesized as follows.…”

“…This approach has been used for functionalization of silica [16][17][18][19] and also used as way to make "matrix free" silica polymer composite by using alkyne and azide modified polymer brushes on silica [20]. Polyglycidylmethacrylate (PGMA) has been "grafted to" TiO 2 nanoparticles and mixed into an epoxy matrix resulting in a composite with high refractive index and transparency [21]. Additionally, it has been shown to have minimal effects on the crosslinking density of epoxy composites as a whole when grafted to silica nanoparticles [22].…”