CO2-based polyols prepared from CO2 and propylene epoxide on double metal cyanide catalysts modified with various co-complexing agents and employed in polyurethanes

CO 2 -based poly(ether-carbonate) polyols (CO 2 -based PEC polyols), composed of carbonate and ether linkages, were synthesized by the copolymerization of CO 2 , chain transfer agent and propylene oxide (PO) in the presence of Zn–Co double metal cyanide (DMC) complex catalyst, and employed to prepare polyurethane elastomers (PUEs) successfully. To obtain high-quality poly(ether–carbonate) polyols, DMC catalysts were further modified by versatile low-molecule compounds and polymers including maleic acid, D-gluconate acid, ethylenediaminetetraacetic acid, polyacrylic acid, and polyacrylamide (PAM) as co-complexing agents (co-CAs). The catalysts bearing polymer co-CAs displayed much superior activity to those of low-molecule co-CAs counterparts. The best copolymerization activity was achieved by the DMC–PAM catalyst with a PO conversion of 86.9 % and a CO 2 incorporation of 23. 9 mol%. It was attributed to the low-symmetry crystal structure, high specific surface area, and strong acidity. Importantly, a conclusion concerning that N-containing polymers were highly effective co-CAs of the DMC catalysts was drawn. EXAFS analysis proved that various co-CAs caused changes in the coordination environment around Zn atoms. In addition, it was confirmed that the carbonate units in CO 2 -based polyols endowed PU−PEC with high tensile and tear strength, and strong water/toluene resistance, while the ether units in CO 2 -based polyols provided the advantages of high elongation at break, low viscosity, and low cost.