Mono- and bifunctional six-membered cyclic carbonates synthesized by diphenyl carbonate toward networked polycarbonate films

The synthesis of six-membered cyclic carbonates from diols utilizing less toxic and easily-handled diphenyl carbonate (DPC) is carried out based on the reactivity and selectivity at different conditions. Commercially-available neopentylglycol (NPG) or di(trimethylolproapane) (DTMP) react effectively with DPC at 140°C and converted to their corresponding monofunctional NPG-carbonate (NPGC) or bifunctional DTMPC-carboante (DTMPC), respectively. The selectivity of these carbonates changes depending on a feed ratio of DPC and these diols. After a NPG/DPC mixture with the DPC/NPG feed ratio of 4 was heated at 140°C for 48 h, the NPGC is isolated with a yield of 74%. A 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)-catalyzed ring-opening polymerization (ROP) of NPGC with DTMPC can form effectively networked structures. By only drying of THF solutions containing NPGC, DTMPC, and a catalytic amount of DBU at 60°C for 12 h, the ROP efficiently proceeds and networked polycarbonate films with well transparency and flexibility are easily obtained.