Alternating Copolymerization of Carbon Dioxide and Cyclohexene Oxide Catalyzed by Silicon Dioxide/Zn-CoIII Double Metal Cyanide Complex Hybrid Catalysts with a Nanolamellar Structure
writer：Xue-Ke Sun, Xing-Hong Zhang*, Fei Liu, Shang Chen, Bin-Yang Du, Qi Wang, Zhi-Qiang Fan, Guo-Rong Qi
keywords：catalysts, carbon dioxide, copolymerization, double metal cyanide complex,polycarbonates
source：期刊
specific source：Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 46, 3128–3139 (2008)
Issue time：2008年
Air-stable hybrid catalysts of silicon dioxide/double metal cyanide complexes(Si-DMCCs) based on Zn3[Co(CN)6]2 (ZHCC) were prepared by an in situ sol–gel method. The Si-DMCCs showed low crystallinity and a nanolamellar structure with a thickness of 40–60 nm. In particular, a lamellar structure of regular hexagonal shape was observed for Si-DMCCs with low SiO2 content. These catalysts had very high catalytic activity for alternating copolymerization of cyclohexene oxide(CHO) and carbon dioxide. A turnover number of 11,444, turnover frequency of 3815 h-1, and apparent efficiency of 7.5 kg polymer/g ZHCC (24.0 kg polymer/g Zn) were achieved at 3.8 MPa and 100 oC. The poly(cyclohexenylene carbonate) (PCHC) polymers obtained were completely atactic with a molecular weight (Mn) of 10 kg/mol and polydispersity of 2.0–3.0. The PCHCs had a structure of nearly alternating CHO and CO2 units, with a molar fraction of carbonate units of 0.44–0.47. Preliminary investigations of the mechanism suggest that nucleophilic attack by neighboring oxygen atoms is involved in copolymerization initiation with ZnCoIII DMCCs.