The Effect of H2o in Zinc Glutarate and its Modification in the Synthesis of High Molecular Weight Poly(Propylene Carbonate)

Abstract

Zinc glutarate (ZnGA) is a prominent catalyst for the synthesis of CO2-based poly(propylene carbonate) by copolymerization of CO2 and propylene oxide. The original ZnGA catalyst synthesized from anhydrous zinc acetate (referred to as Cat 3) showed increased activity after H2O activation (referred to as Cat 4). Both catalysts were thoroughly investigated using XRD, SEM, EDS, FTIR, TGA, and XPS methods. The characterization results showed that H2O is a critical component that not only improves the crystallinity and surface area of ZnGA, but also increases the number of surface Zn-OH groups. Under optimized reaction conditions, the highest yield of 1729 g poly/g cat, 98.7% selectivity and 2.3×105 g/mol molecular weight were obtained after introducing a small amount of cyanide in Cat 4. The modified ZnGA catalyst (m-ZnGA) showed remarkable activity and selectivity for the copolymerization of CO2 and propylene oxide to produce high molecular weight alternating copolymers.

Keywords: CO2, Zinc glutarate, Copolymerization, Poly (propylene carbonate), Propylene oxide