Zwitterionic Polysiloxanes with Extreme Dielectric Permittivity

The design and synthesis of high permittivity polymers face a key challenge; namely, strong polarization requires concentrated dipoles that give rise to high thermal transition temperatures. The inverse relationship between permittivity and mobility limits the dielectric constant of all dipolar materials. Consequently, for pure polymers, the largest known dielectric constants are roughly 100 for vinylidene fluoride copolymers at the Curie temperature and 35 for room-temperature polymer melts. Here, we report the rational design and synthesis of a zwitterionic polysiloxane with a static dielectric constant of 420 at room temperature, the largest value achieved to date. This specific polysiloxane contains pendent zwitterionic dipoles with long, flexible spacers that simultaneously amplify dipole moment and dilute strong coulombic interactions, yielding a glass transition temperature Tg of-14 °C. This novel high-κ dielectric polymer overcomes the permittivity-mobility limitation thereby challenging the existing paradigm for dipolar polymer dielectrics.