Bio-based isosorbide is considered as an excellent candidate for replacing toxic bisphenol-A (BPA) in polycarbonate (PC) synthesis owing to its high rigidity, chirality and non-toxicity. The majority of present catalysts for high molecular weight (Mn) PC preparation are restricted to alkali-metal-based types. However, they are extremely difficult to be completely removed and the of deleterious metal residual may undermine the properties of the product and limit the application range of the material. Therefore, developing a complete metal-free and green catalytic system to synthesize poly(isosorbide carbonate) PIC bearing high Mn and high glass transition temperature (Tg) by melt polycondensation approach is meaningful and challenging. Ionic liquids (ILs) show outstanding performance in catalysis owing to tunability and low toxicity, which are promising alternative for traditional metal-based catalysts. In this work, thermal-stable PIC with high Mn of 61,700 g/mol, high Tg of 174 °C and isosorbide yield of 99 % was achieved in the presence of environmentally-friendly [Bmim][CH3CHOHCOO] under optimized reaction conditions (Fig. 1). To improve the flexibility of PIC, poly(aliphatic diol-co-isosorbide carbonate)s with Mn ranging from 34,000 to 75,700 g/mol were also prepared by incorporating with aliphatic diols. A possible cooperative nucleophilic–electrophilic mechanism was proposed based on experiment results (Fig. 2). It indicated that the bifunctional ILs, whose anions with stronger electronegativity and greater hydrogen bond formation ability, were more efficient.

Synthesis of high-molecular-weight polycarbonates from bio-based isosorbide catalyzed by metal-free ionic liquids

255th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.