A comparative study of the copolymerization of racemic propylene oxide (PO) with CO catalyzed by racemic (salcy)CoX (salcy = ,'-bis(3,5-di--butylsalicylidene)-1,2-diaminocyclohexane; X = perfluorobenzoate (OBzF) or 2,4-dinitrophenoxy (DNP)) in the presence of a [PPN]Cl ([PPN] = bis(triphenylphosphine)iminium) cocatalyst is performed in bulk at 21 °C and a 2.5 MPa pressure of CO. The increase in the nucleophilicity of an attacking anion results in the increase in the copolymerization rate. Racemic (salcy)CoX provides a high selectivity of the copolymerization, which can be higher than 99%, and the living polymerization mechanism. Poly(propylene carbonate) (PPC) with bimodal molecular weight distribution (MWD) is formed throughout copolymerization. Both modes are living and are characterized by low dispersity, while their contribution to MWD depends on the nature of the attacking anion. The racemic (salcy)CoDNP/[PPN]DNP system is found to be preferable for the production of PPC with a high yield and selectivity.
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| http://dx.doi.org/10.3390/ijms252010946 | DOI Listing |
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