Search for: All records

Current research on ferroelectric polymers centers predominantly on poly(vinylidene fluoride) (PVDF)–based fluoropolymers because of their superior performance. However, they are considered “forever chemicals” with environmental concerns. We describe a family of rationally designed fluorine-free ferroelectric polymers, featuring a polyoxypropylene main chain and disulfonyl alkyl side chains with a C3 spacer: −SO₂CH₂CHRCH₂SO₂− (R = −H or −CH₃). Both experimental and simulation results demonstrate that strong dipole-dipole interactions between neighboring disulfonyl groups induce ferroelectric ordering in the condensed state, which can be tailored by changing the R group: ferroelectric for R = −H or relaxor ferroelectric for R = −CH₃. At low electric fields, the relaxor polymer exhibits electroactuation and electrocaloric performance comparable with those of state-of-the-art PVDF-based tetrapolymers. 

High performance polymer dielectrics are a key component for printed electronics. In this work, organo-soluble polymers of intrinsic microporosity (PIMs) are reported for the first time to demonstrate desirable dielectric properties with a high permittivity (or κ ), heat resistance, and low dielectric loss simultaneously. Due to the highly dipolar sulfonyl side groups (4.5 D) and rigid contorted polymer backbone, a sulfonylated PIM (SO 2 -PIM) enabled friction-free rotation of sulfonyl dipoles in the nanopores. As such, an optimal balance between relatively high κ and low dielectric loss is achieved in a broad temperature window (−50–200 °C). For example, the discharged energy density reached 17 J cm −3 with κ = 6.0. The discharge efficiency was 94% at 150 °C/300 MV m −1 and 88% at 200 °C/200 MV m −1 . Furthermore, its application as a high- κ gate dielectric in field effect transistors (FETs) is demonstrated. With the bilayer SO 2 -PIM/SiO 2 gate dielectric, InSe FETs exhibited a high electron mobility in the range of 200–400 cm 2 V −1 s −1 , as compared to 40 cm 2 V −1 s −1 for the bare SiO 2 -gated InSe FET. This study indicates that highly dipolar PIMs with a rigid polymer backbone and large free volume are promising as next generation gate dielectric materials for printed electronics.