Covalently modified organic nanoplatelets and their use in polymer film capacitors with high dielectric breakdown and wide temperature operation

Organic-inorganic nanoplatelets in the form of nanoscale titanium phenyl phosphonate (nano-Ti(PPA)₂) were synthesized with dimensions of 100-250 nm by 5-10 nm. Upon incorporation into fluorene polyester (FPE) at low loadings (0.3 to 3 wt%), the resulting polymer nanocomposite film exhibited significant gains in breakdown field over the neat polymer film, with gains of 37% at 20°C, 39% at 150°C, and 18% at 275°C. The increase in breakdown field was much greater than expected based on previous literature reports for incorporation of spherical SiO₂ or TiO₂, and it is likely that these benefits arise from the high aspect ratio of the nano-Ti(PPA)₂ and the inherent organic functionalization of the material. Dielectric constant was unchanged within experimental error, and loss tangent decreased slightly at higher temperatures, upon the addition of the filler. Material energy densities of the resulting nanocomposite film were calculated to range from 3.6 J/cm³ at 150°C to 1.6 J/cm³ at 275°C, which are the highest known values obtained for a polymer-based capacitor material that can operate at these high temperatures.