Tailor-made chalcogen-rich polycarbonates: experimental and computational insights into chalcogen group-dependent ring opening polymerization†
The critical role of abundant chalcogens (with variable types and valences) located in polymer backbones on the properties, functions and bioactivities of final materials underscores the pressing need for versatile and controlled synthetic platforms towards chalcogen-rich polymers. Herein, we reported a universal and robust approach to generate a poly(chalcogen-carbonate) library using commercially available organic base-catalyzed ring opening polymerization (ROP) of macrocarbonates containing chalcogen groups. Polymerizations have unique advantages including high control, fast kinetics, mild reaction conditions at room temperature and compatible operation for different monomers. Furthermore, ROP depends sensitively on chalcogen groups, where thioether (–S–), selenide (–Se–) and disulfide (–SS–)-substituted monomers polymerize readily, while the diselenide (–SeSe–) substituted one is difficult to polymerize. A density functional theory (DFT)-combined experimental study provided abundant mechanism insights and illuminated the structure/composition-kinetic relationships to rationalize the observed polymerization trends. Polymerization kinetics was gradually suppressed with chalcogen groups evolving from –S–, –Se–, –SS– to –SeSe–, which may offer a powerful support to forecast the polymerization behaviors of other chalcogen-based monomers. This work not only describes a convenient and efficient strategy for chalcogen-rich polymeric materials, but also provides important insights for understanding the influence of chalcogen groups on polymerization behaviors.