Multiscale Interface Effect on Homogeneous Dielectric Structure of ZrO₂/Teflon Nanocomposite for Electrowetting...

Electrowetting-on-dielectric is a preferred option in practical applications of the electrowetting phenomenon but limited by dielectric and breakdown performances of the dielectric layer. In the present work, a ceramic/polymer nanocomposite as a novel dielectric layer is developed to intensify the overall electrowetting performances by multiscale interface effect. Hereinto, surface fluoro-modified ZrO₂ nanoparticles (mZrO₂) are dispersed well in AF 1600 matrix to form a mZrO₂@AF 1600 nanocomposite. The small addition of mZrO₂ improves the dielectric constant of the nanocomposite, and the experimental value is larger than the theoretical value calculated by Maxwell⁻Garnett model, but fits well with the Rahaman⁻Khastgir model. The molecular dynamics simulations with the explicit model further verify the interfacial effect. Meanwhile, double contact angle modulation and higher breakdown field strength (E_b) are obtained. For the three-layer sandwich structure, both the top and bottom AF 1600 layer decrease the surface roughness for better electrowetting reproducibility and wider wettability modulation. The Forlani⁻Minnaja theory related to the empirical relationship between E_b and thickness of dielectric layer fit well with the monolayer structure, but cannot be applied in multi-layer structures. A new relationship is proposed to guide the design of dielectric multi-layers with high breakdown field strength.