Copolymerization Of CO₂ With Cyclohexene Oxide Catalyzed By Aromatic Zinc Carboxylates

Aliphatic polycarbonate formated from copolymerization of CO₂ and epoxides has important industrial application value. Based on the review of CO₂ and epoxide copolymerization and the application of mass spectrometry in polymerization reaction mechanism, we investigated the reaction mechanism of copolymerization of CO₂ with cyclohexene?CHO? to prepare poly?cyclohexene carbonate??PCHC? catalyzed by two aromatic zinc carboxylate and determined the modification research program of two aromatic zinc carboxylate catalyst.Slected Zinc??? 2-[[?2,3-dihydro-1,5-dimethyl-3-oxo-2-phenyl-1H-pyrazol-4-yl?imino] methyl] benzoic acid complex?ZnPPBA? as catalyst, we proposed a possible reaction mechanism combined with electrospray ionization mass spectrometry?ESI-MS?, and then we introduced double metal cyanide?DMC? to prepare modified ZnPPBA catalyst. The results showed that compared with ZnPPBA or DMC, the catalytic efficiency was increased significantly. For example, at 110?, 4 MPa CO₂ presssure, catalytic efficiency of modified ZnPPBA catalyst was 476 g polymer /g catalyst?equivalent to 5520 g polymer /g DMC. 552 g /g ZnPPBA?, polycarbonate content was greater than 85%.We synthesized three zinc complexes based on diphenic acid scaffolds and tested their catalytic behaviour in the copolymerization of CO₂ with cyclohexene oxide. The structure and catalytic activity of zinc complexes were studied and the plausible reaction mechanism of the copolymerization reaction used [Zn?dpa?·H₂O]_n?H₂dpa=2,2'-biphenyldicarboxylate? as catalyst was proposed. We introduced DMC to prepare modified [Zn?dpa?·H₂O]_n catalyst. The results showed that compared with [Zn?dpa?·H₂O]_n or DMC, the catalytic efficiency was increased significantly. By way of illustration, at 110?, 4 MPa CO₂ presssure, the catalytic efficiency of modified catalyst was 675 g/g catalyst?equivalent to 5420 g polymer /g DMC, 774 g polymer /g [Zn?dpa?·H₂O]_n?, polycarbonate content was close to 87%.The successful preparation of the modified catalyst provides the possibility of industrial application for the PCHC which obtained from copolymerization of CHO and CO₂ catalyzed by aromatic zinc carboxylates.