A “Catalyst Switch” Strategy for the Sequential Metal-Free Polymerization of Epoxides and Cyclic Esters/Carbonate

• Published in: Macromolecules Vol. 47; no. 12; pp. 3814 - 3822
• Main Authors: Zhao, Junpeng, Pahovnik, David, Gnanou, Yves, Hadjichristidis, Nikos
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 24.06.2014
• Subjects: Applied sciences; biphenyl; catalysts; composite polymers; Copolymerization; epoxides; esters; Exact sciences and technology; Organic polymers; phosphates; Physicochemistry of polymers; polymerization; Preparation, kinetics, thermodynamics, mechanism and catalysts; Ring opening polymerization; Catalytic reaction; Lactone copolymer; Base catalysis; Molecular structure; Ethylene oxide copolymer; Experimental study; Superbase; Monodispersed polymer; Phosphoric acid esters; Caprolactone copolymer; Cyclic ether copolymer; Preparation; Diblock copolymer; Carbonate copolymer; Phosphorus compound; Aliphatic copolymer; Successive reaction
• DOI: 10.1021/ma500830v
• ISSN: 0024-9297; 1520-5835

A “catalyst switch” strategy was used to synthesize well-defined polyether–polyester/polycarbonate block copolymers. Epoxides (ethylene oxide and/or 1,2-butylene oxide) were first polymerized from a monoalcohol in the presence of a strong phosphazene base promoter (t-BuP4). Then an excess of diphenyl phosphate (DPP) was introduced, followed by the addition and polymerization of a cyclic ester (ε-caprolactone or δ-valerolactone) or a cyclic carbonate (trimethylene carbonate), where DPP acted as both the neutralizer of phosphazenium alkoxide (polyether chain end) and the activator of cyclic ester/carbonate. This work has provided a one-pot sequential polymerization method for the metal-free synthesis of block copolymers from monomers which are suited for different types of organic catalysts.