Controllable dielectric performance of polymer composites: Via the Coulomb-blockade effect with core-shell structured nano-particles

Designed core-shell structured titanium dioxide-poly(dopamine)-silver (TiO₂-PDA-Ag) particles were prepared via self-polymerization of poly(dopamine) and electroless plating of nano-silver particles. The poly(dopamine) layer was used not only to improve the interfacial interaction between TiO₂ and the nitrile-butadiene rubber (NBR) matrix but also as chemisorption sites for silver ions. Then the TiO₂-PDA-Ag particles were introduced into the NBR matrix to prepare dielectric composites. The effect of the nano-Ag content on morphology, dielectric properties, and electrical properties of the composites was thoroughly investigated. It was found that the Coulomb-blockade effect of nano-Ag particles led to the composites with relatively low dielectric loss and relatively high electrical breakdown strength. This simple and effective approach provides a promising route to adjust the dielectric properties of dielectric composites via the Coulomb-blockade effect.