Fabrication of highly refractive, transparent BaTiO₃/poly(methyl methacrylate) composite films with high permittivities

Abstract

Incorporation of crystalline barium titanate (BT) nanoparticles into poly(methyl methacrylate) (PMMA) was carried out to prepare highly refractive polymer nanocomposite films that have transparency and high permittivities. The BT nanoparticles were prepared by hydrolysis of a barium/titanium complex alkoxide in 2-methoxyethanol, then surface-modified with a silane coupling agent (3-methacryloxypropyltrimethoxysilane) to improve their affinity for PMMA. The incorporation of the surface-modified nanoparticles into PMMA was performed up to a nanoparticle content almost equivalent to particle closepacking state. The refractive index of the composite films increased with nanoparticle incorporation, keeping the relative transmittance normalized with PMMA film above 90%. A high refractive index of 1.82 was reached at a nanoparticle content of 53 vol% with a dielectric constant as high as 36 and a dissipation factor as low as 0.05. The results demonstrate that the crystalline BT nanoparticles are useful fillers for effectively increasing both refractive index and dielectric constant of polymer nanocomposites.

Transparent, highly dielectric poly(vinylidene fluoride) nanocomposite film homogeneously incorporating BaTiO3 nanoparticles with fluoroalkylsilane surface modifier

“…In the development of dielectric films used as energy storage devices including capacitors [1][2][3], incorporation of barium titanate (BT) fillers has been extensively studied for a variety of polymeric matrices including polymethylmethacrylate (PMMA) [4,5], polyimides [6][7][8][9] and epoxy resins [10,11], because BT is one of the most commonly used high-κ materials. High loading of BT into polymer matrices is an essential technique for dielectric nanocomposite films with high permittivity.…”

“…The nanocomposite films, however, tend to form agglomeration of fillers when BT nanoparticles are loaded into polymer matrices around 60 vol% and more [12]. The filler agglomerations are accompanied by formation of pores or voids in nanocomposite films [4,13,14], resulting in low permittivity of the nanocomposite films.…”

“…Silane coupling agents and phosphoric acids can be effective surface-modifiers to improve the affinity between BT nanoparticles and polymers at high contents of BT fillers [10,15]. In our previous reports [4,6,7], surface modifiers having molecular structures similar to the one of polymer matrix were chosen to suppress both nanoparticle agglomeration and void formation in the nanocomposite films, leading to a success in highly dielectric and refractive nanocomposite films.…”

“…Optical properties of transmittance and haze were also characterized for the nanocomposite films highly loading BT nanoparticles. Thermal gravimetric analysis (TGA) was used at BT contents lower than 60 vol% to confirm that the amount of BT nanoparticles used in nanocomposite fabrication was almost equal to the BT content of nanocomposite film estimated by the TGA measurement [4]. …”

Fabrication of highly refractive barium‐titanate‐incorporated polyimide nanocomposite films with high permittivity and thermal stability

“…Recently we reported highly refractive, transparent nanocomposite films prepared by a blending route in which crystalline barium titanate (BT) nanoparticles with much less photocatalytic activity than titania were used as an RI filler . A high RI of 1.82 was attained by 53 vol% loading of the BT nanoparticles into poly(methyl methacrylate) (PMMA).…”