High-performance dielectric ionic ladderphane-derived triblock copolymer with a unique self-assembled nanostructure

Functional poly(bisnorbornene)-based ladderphanes, P1, P2, and P3, as well as the derived triblock copolymers containing two blocks of poly(N-3,5-difluorophenyl-norbornene pyrrolidine) (PFNP), PFNP-b-P2-b-PFNP and PFNP-b-P3-b-PFNP, were synthesized by ring-opening metathesis polymerization. The dielectric constants of the polymers were 5, 7, 21, 12, and 18 accompanied with the dielectric losses of 0.03, 0.03, 0.11, 0.02, and 0.04 at a frequency range of 100 Hz to 1 MHz, respectively. In particular, the ionic copolymer PFNP-b-P3-b-PFNP could self-assemble into a unique tree ring-like nanostructure, in which the ionic P3 blocks were isolated between the insulating PFNP blocks, and the long distance migration of ions was difficult to achieve, resulting in lower dielectric dissipation and higher charge-discharge efficiency than those of the ionic homopolymer P3. This research presented a practical way to effectively improve the dielectric properties by combining the ionic, dipolar, and nano-interfacial polarizations, as well as the stereoregular microstructure of the polymer chain.