From Table nbsp several conclusions can be deduced

The copolymerization of PO and CO2 using rare earth metal catalyst was first made possible by Chen et al. (1991). In the study, Yttrium is used to synthesize the rare earth metal catalyst Y(P204)3-Al(i-Bu)3-glycerin to produce copolymer with molecular weight as high as 476 kg mol−1 (Chen et al., 1991). Although this copolymerization method was able to produce higher copolymer yield within shorter ZCL278 of time, the copolymer obtained contain only about 10–30 % of carbonate linkages.