Green and Efficient Synthesis of Biobased Polycarbonates with Tunable Performance via Functionalized Ionic Liquid Catalysts Enhanced by Cation–π Interactions

The utilization of biomass to produce plastic is one of the key ways to minimize the negative impacts of climate change and alleviate the depletion of petroleum resources. However, there is still a lack of bioderived polymers with properties comparable to those of commercial petroleum-based polymers. Isosorbide-based polycarbonate (PIC) is the most promising substitute for traditional petroleum-derived polycarbonate, but its application is still limited by the low reactivity and poor ductility of isosorbide. In this study, we developed a new strategy for designing functionalized ionic liquid catalysts enhanced by the cation–π interactions, and high performance isosorbide-based copolycarbonate was prepared. On the one hand, PIC with high weight-average molecular weight of 126,000 g/mol was synthesized by using 1-benzyl-3-methylimidazolium acetate ([Bnmim][OAc]) as a catalyst. This was attributed to the formation of stronger π–π interactions between the benzyl group and the imidazolium cation, which promoted the activation of carbonyl groups and overcame the low activity of isosorbide. Furthermore, to overcome the brittleness of PIC, the introduction of 1,10-decanediol into PIC provided not only copolycarbonates with an adequate elongation at break (121%), which was better than bisphenol A polycarbonate, but also copolycarbonates with a wide range of glass transition temperature (Tg 20–168 °C), expanding the application of PIC. This study provides an avenue for the development of excellent performance biobased polycarbonates using ionic liquid catalysts.