Degradation of waste polycarbonate via hydrolytic strategy to recover monomer (bisphenol A) catalyzed by DBU-based ionic liquids under metal- and solvent-free conditions

The application of ionic liquids in chemical recycling of waste polycarbonate (PC) via the simple hydrolytic strategy has shown great potential. Herein, a series of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) based ILs were facilely synthesized and characterized, and could efficiently catalyze the hydrolysis of PC in the absence of transition metal and solvent. The catalyst structures and reaction conditions were optimized, and 100% PC conversion with 97% bisphenol A (BPA) yield could be obtained under the conditions of n(H2O)/n(PC) = 3:1, n(Cat.)/n(PC) = 0.1:1, 140 °C for 3.0 h. Based on the experimental results and in-situ FT-IR analysis of the PC residues and BPA product, a feasible molecular activation and catalytic pathway for [HDBU][LAc] catalyzed hydrolysis of PC was proposed.