CS2-based one-pot multicomponent tandem polymerization toward functional polybenzothiazoles

Abstract

CS₂ is an attractive sulfur source in organic synthesis. The conversion of abundant, low-cost, sustainable and toxic CS₂ into sulfur-containing functional polymers is of great significance from the standpoints of both polymer synthesis and environmental protection. In this work, a robust one-pot multicomponent tandem polymerization of CS₂, amines and 2-iodoaniline was developed for efficient synthesis of sulfur-containing fused-heterocyclic polymers. The polymerizations were carried out in the presence of CuCl₂·2H₂O and K₂CO₃, and a series of polybenzothiazoles (PBTs) with multiple structures and high molecular weights (M_w up to 43 500) were generated in excellent yields (up to 94%). The PBTs exhibited high thermal stability with 5% weight loss temperatures ranging from 288 to 338 °C and could emit bright fluorescence in solution owing to the high contents of benzothiazole rings in the structures. In addition, the PBT films exhibited high refractive indices of up to 1.82 at 632.8 nm. This work not only establishes a readily accessible and efficient polymerization for direct CS₂ fixation, but also provides various functional polybenzothiazoles with potential applications in materials science and the biological field.