Block copolymerization of carbon dioxide with butylene oxide, propylene oxide and 4-vinyl-1-cyclohexene-1,2-epoxide in based poly(cyclohexene carbonate)

摘要

Poly(cyclohexene carbonate) (PCHC) resulting from the copolymerization of CO2 with cyclohexene oxide (CHO) could be effectively synthesized using the coordination system Y(CF3CO2)(3) (I) - diethyl zinc (II) - glycerine (III) and 1,3-dioxolane as the catalyst and solvent. It therefore was used as the base to synthesize block copolymers. Block copolymerization in the based PCHC was carried out by introducing an epoxide other than CHO right after the copolymerization of CO2 with CHO. The IR and H-1-NMR spectra as well as the glass transition temperatures indicated that the resultant copolymers from the block copolymerization of CO2 with butylene oxide (BO), propylene oxide (PO), and 4-vinyl-1-cyclohexene-1,2-epoxide (VCHO) in PCHC were indeed block copolymers. The epoxide activity followed the sequence VCHO > PO > BO at 353 K. While the most appropriate temperature regarding yield, molecular weight and the polydispersity index in the copolymerization of CO2 with PO was 333 K, it was found to be 353 K in the block copolymerization. The most appropriate temperatures for the block copolymerization of CO2 with BO as well as CO2 with VCHO in the based PCHC were 343 K and 353 K, respectively. The molecular weights of the resulting block copolymers were found to exceed 2x10(5), and the polydispersity indexes were in a range of 6.2 to 9.9. The carbonate contents (f(CO2)) were observed to be in the range of 86% to 100%. The thermal and mechanical properties of the resulting block copolymers lay between those of the copolymers resulting from CO2 with an individual epoxide, such as BO, PO, CHO and VCHO. These results indicated that block copolymerization was an effective means of generating a polymer with the desired thermal and mechanical properties. [References: 25]