Dielectric performance of polymer-based composites containing core-shell Ag@TiO2 nanoparticle fillers

Abstract

This paper reports composites prepared by embedding core-shell Ag@TiO2 fillers into polytetrafluoroethylene. Ag nanoparticles were homogeneously coated with TiO2, to give a shell thickness of approximately ∼8–10 nm. The composite containing Ag@TiO2 nanoparticles with rutile shells exhibited better dielectric properties than the composite containing Ag@TiO2 nanoparticles with anatase shells. The relative permittivity (εr) of the composite containing 70 vol. % filler was approximately 240 at 100 Hz, which was more than 100 times higher than that of pure polytetrafluoroethylene (εr = 2.1). An effective medium percolation theory model is used to account for the dielectric constant of the composite.

Microstructure and Dielectric Properties of PTFE-Based Composites Filled by Micron/Submicron-Blended CCTO

“…At the third stage, from 560 • C to 700 • C, as the weightlessness of the CCTO precursor is about 2.17%, and the corresponding DSC curve appears to have a weak exothermic peak which may correspond to CCTO crystallization. Figure 2 shows the XRD pattern of CCTO powders calcined at 750 • C, 800 • C, and 850 • C. CCTO appears as the major phase, and small amounts of CaTiO 3 and CuO are also present in the three samples; however, TiO 2 is only present in the sample calcined at 750 • C.…”

“…Traditional polymer materials, such as polytetrafluoroethylene (PTFE) [2,3] and epoxy [4], are flexible and can be produced by a simple process. However, these materials cannot meet the developing trends of miniaturization and integration of electronic systems because of their low dielectric permittivity [5][6][7].…”

Core‐shell structured Al/PVDF nanocomposites with high dielectric permittivity but low loss and enhanced thermal conductivity

“…, to the electric modulus formalism. Large variations in the real and imaginary part of permittivity at low frequencies and high temperatures can be minimized in the electric modulus presentation, since electrode polarization, space charge injection and absorption of impurities can be neglected . Electric modulus is defined as the inverse quantity of complex permittivity: where ɛ' , M' , and ɛ'', M'' are the real and imaginary parts of dielectric permittivity and electric modulus, respectively.…”

“…Therefore, the preparation of percolative dielectrics with a threshold composition is difficult because of the abrupt variations in the dielectric constant and loss near f c , and the high‐k composite requires a uniform dispersion and precise control of the filler loading because of its percolative nature . So reducing the dielectric loss is the target of many investigations on preparing high‐k electric conductor/polymer composites because suffering from an abrupt variant in dielectric loss is a fatal disadvantage for its practical engineering applications . Up to now, many strategies have been designed and tried, such as the surface modification of conductors, the hybridization of conductors, to avoid the direct interconnection between conductors, however, reducing the tanδ into capacitor‐tolerated values (tan δ ≤ 1) while remaining high‐k is found to be still difficult .…”

Modulating and tuning relative permittivity of dielectric composites at metamaterial unit cell level for microwave applications

“…The composite matrix polymers under investigation are mainly polyolefins including polytetrafluoroethylene (PTFE) 4 , polypropylene (PP) 5,6 , polyethylene (PE) 7 , polystyrene (PS) 8,9 and thermoset resins such as bisphenol epoxy 10,11 . The high permittivity fillers could be inorganic micro/nanoparticles (BaTiO 3 , SiO 2 , SrTiO 3 , and TiO 2 ) 4, 12-16 , metallic nanoparticles (Ni, Fe, and Ag) 4,[17][18][19] and carbon-based materials (carbon nanotubes and graphene) 15,16,20 . The reported composite dielectrics offer a compromise of the best attributes between the fillers and the polymers.…”