Regulating dielectric performances of Poly(vinylidene fluoride) nanocomposites by individually controlling shell thickness of Core@Double-Shells structured nanowires

The synthesis of core@double-shells structured TiO₂@C@SiO₂ nanowires (NWs) with variable thickness of carbon inner shell and SiO₂ outer shell was achieved by individually controlling the chemical vapour deposition time and amount of silicon precursor added in the sol–gel synthesis. The resultant TiO₂@C@SiO₂ NWs filled nanocomposites exhibited an excellent dielectric performance with simultaneously improved dielectric constant and suppressed dielectric loss, which could be further regulated by individually controlling the carbon inner shell and SiO₂ outer shell thickness. More importantly, the influences of the conductive carbon inner shell and insulated SiO₂ outer shell thickness on the dielectric performance of nanocomposites were clearly revealed. The increase of the conductive carbon inner shell thickness would lead to an increase in dielectric constant and loss of nanocomposites, while the insulated SiO₂ outer shell exhibited a totally opposite law that the dielectric constant and loss of nanocomposites decrease with increasing SiO₂ outer shell thickness. Numerical simulations were also carried out to theoretically verify the relationship between the dielectric loss and SiO₂ outer shell thickness. This promising controllable multi-shell structure could be extended to a variety of hybrids to develop high-performance dielectric nanocomposites.