Fluorine-free polymers set a new benchmark for ferroelectrics

• Fluorine-free disulfonyl polymers achieve high dipole moment (9 D) comparable to rod-like molecules, enabling ferroelectricity without fluoropolymers. • Simple R-group substitution (H to CH3) tunes normal ferroelectricity to relaxor ferroelectricity, demonstrating tunable FE properties. • Relaxor ferroelectric polymer exhibits exceptional electroactuation strain (-4%) and electrocaloric effect (ΔS = 14.8 J·kg⁻¹·K⁻¹) under low electric fields. • Performance matches state-of-the-art PVDF-based tetrapolymers, offering a sustainable alternative for flexible electronics and thermal management.