Synthesis of thermally robust benzimidazolone-based wholly aromatic polyketones

Abstract

A series of wholly aromatic polyketones bearing benzimidazolone moieties (PK-BI) were synthesized via N–C coupling polycondensation. Calcium carbonate coupled with potassium carbonate was used for the first time to achieve a high molecular weight, with T_g of the polymer as high as 299 °C. The polymer structure was confirmed by solid state ¹³C NMR and FT-IR. The thermal stability of wholly aromatic polyketones with a benzimidazolone unit in the main chain was significantly improved, being higher than those of PEEKs and other amorphous PAEKs, proved by thermogravimetric analysis (TGA) and derivative thermogravimetric (DTG) analysis. The degradation activation energy (E_k) values estimated by Flynn–Wall–Ozawa (FWO) and Kissinger methods were 260.33 kJ mol⁻¹ and 282.57 kJ mol⁻¹, respectively, which are higher than those of PEEKs.