Phosphazene Bases: A New Category of Organocatalysts for the Living Ring-Opening Polymerization of Cyclic Esters
Macromolecules2007Vol. 40(12), pp. 4154–4158
Citations Over TimeTop 10% of 2007 papers
Lei Zhang, Fredrik Nederberg, Russell C. Pratt, Robert M. Waymouth, James L. Hedrick, Charles G. Wade
Abstract
We demonstrate that phosphazene bases, such as 2-tert-butylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2-diazaphosphorine (BEMP) and N‘-tert-butyl-N,N,N‘,N‘,N‘ ‘,N‘ ‘-hexamethylphosphorimidic triamide (P1-t-Bu), are active organocatalysts for the living ring-opening polymerization (ROP) of cyclic esters. Polyesters prepared through this organocatalytic route possess predictable molecular weights, narrow polydispersities, and high end-group fidelity. Mechanistic studies suggest that the intermolecular hydrogen bonding of the alcohol initiator to phosphazene bases activates the alcohol for ROP of cyclic esters.
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