Polymerization of Epoxides, Isocyanate, and Phthalic Anhydride or CO ₂ : Synthesis of Block Polymers

The synthesis of structurally diverse block polymers from mixed monomers is an appealing strategy in polymer science. However, the production of polyurethane-based block polymers has rarely been reported, primarily due to the strict requirements for compatible catalysts and monomers. In this contribution, we report an efficient approach for preparing polyurethane-based block polymers by one-pot multicomponent polymerization reactions of epoxides, p-tosyl isocyanate (TSI) with phthalic anhydride (PA), or/and CO2, mediated by salcyCo(III)NO3 (salcy = N,N′-bis(3,5-tert-butylsalicylidene)-1,2-diaminocyclohexane) and PPNNO3 (bis(triphenylphosphine)ammonium nitrate) under mild conditions. The binary catalyst system is capable of catalyzing the ring-opening copolymerization of epoxide with TSI, PA, or CO2 in different rates, affording the corresponding copolymers in a perfectly alternating structure. Notably, salcyCo(III)NO3/PPNNO3-mediated terpolymerization of epoxides, TSI, and PA or CO2 afforded polyurethane-b-polyester and polyurethane-b-polycarbonate block polymers, respectively. The multicomponent polymerization of a mixed-monomer feedstock of epoxides, TSI, PA, and CO2 produced novel polyurethane-b-poly(ester-g-carbonate) block polymers with adjustable properties by varying the experimental conditions.