High Thermal Stability of Bio-Based Polycarbonates Containing Cyclic Ketal Moieties

Bio-based polycarbonates containing cyclic ketal moieties were designed, and the bio-based diol monomer was synthesized by CQ with glycerol to improve their thermal properties and replace BPA in polymer industry. The molecular structure of the novel bio-based diol monomer 2,2:3,3-bis­(4′-hydroxy­methyl­ethylene­dioxy)-1,7,7-trimethyl­bicyclo[2.2.1]­heptane (abbreviated as CaG) was analyzed by ¹H, ¹³C, and 2D-COSY NMR techniques. GPC results show that CaG was reacted successfully and led to the high molecular weights for homopolycarbonate (M_w = 18 652) abbreviated as PCaGC and for copolycarbonate (M_w = 78 482) as PCaG₂₀BPA₈₀C. The high thermal stability (T_d value above 350 °C) and glass transition temperature (T_g value from 128 to 151 °C) of PCaGCs and PCaG_xBPA_yCs were studied by TGA and DSC, respectively. Given the sufficient reactivity and high thermal stability, CaG is a promising renewable building block for applicable polymers.