Enhanced dielectric performance in flexible MWCNT/poly(vinylidene fluoride-co-hexafluoropropene)-based nanocomposites by designing a tri-layered structure

Polymer composites with high permittivity exhibit promising applications in advanced electronics. However, it remains a challenge to simultaneously achieve high permittivity, low dielectric loss, and high flexibility in single layer nanocomposites. In this work, a series of ternary tri-layered structure films is producedviaa facile solution-casting process. Two outer layers of a poly(vinylidene fluoride-co-hexafluoropropene) (P(VDF-HFP)) ferroelectric copolymer matrix are filled with acid-treated multi-walled carbon nanotubes (MWCNTs) to enhance permittivity, while the inner layer of P(VDF-HFP) blended with poly(methyl methacrylate) (PMMA) can effectively suppress the dielectric losses. The acid-treated MWCNT filler, organic-organic blend, and tri-layered structure contribute to the increase of permittivity, decrease of dielectric loss, and favorable mechanical reliability. As a result, the tri-layered composites with an optimized MWCNT content of 9 wt% at a test frequency of 1 kHz have been endowed with a maximized permittivity of 21 and low dielectric loss of 0.05. Specifically, excellent capacitive stability is demonstrated in these trilayered films over straight bending cycles (i.e.20?000 cycles) and winding (i.e.120 hours) tests. These attractive features of the designed tri-layered structure composites manifest that the facile approach proposed herein is scalable and can be extended to develop flexible composites with high permittivity and low dielectric loss for dielectric applications.