Synthesis, characterization and thermoelectric properties of new non-conjugated nitroxide radical-containing metallopolymers

In the last decade, there is an intense interest in the study of conjugated organic polymers for thermoelectric (TE) application. Non-conjugated polymers are usually considered as the insulators with no or extremely low electrical conductivity. Nevertheless, non-conjugated radical polymers (NCRPs) are different from those polymers in which they can be widely applied in electronic technology, for example, as battery electrode materials, conductors in solid-state and memory devices, but they have not been used for the TE application. Here, three metal-containing NCRPs P1–P3 with different nitroxide radical moieties were synthesized and coated with single-walled carbon nanotubes (SWCNTs) to form various polymer composites. P2 exhibited the highest electrical conductivity of 1310.0 ± 3.92 S m⁻¹ when the SWCNT content reached 60%. P3 had the highest Seebeck coefficient of 62.5 ± 0.40 μV K⁻¹ when the SWCNT ratio reached 90%. The highest power factor of 130.1 ± 1.61 μW m⁻¹ K⁻² was achieved from the P3/SWCNT composite at the mass ratio of 90%. The results showed that the NCRPs could be one of the potential TE materials of further study.