Abstract
We report a new synthetic methodology for poly(ester amide)s by anionic ring‐opening copolymerization of N‐sulfonyl aziridines and cyclic anhydrides. Phosphazenes organocatalysts have been found to promote a highly‐active, controlled, and selective alternating copolymerization in the absence of any competitive side reaction (zwitterionic mechanism and exchange transacylations). Mechanistic studies have shown first‐order dependence of the copolymerization rate in N‐sulfonyl aziridines and phosphazenes, and zero‐order in cyclic anhydrides. This one‐pot methodology leads not only to homopolymers but also to poly(ester amide)‐based block copolymers. Two catalytic cycles involving ring‐opening alternating copolymerization of N‐sulfonyl aziridines with cyclic anhydrides and ring‐opening polymerization of N‐sulfonyl aziridines have been proposed to explain the one pot synthesis of poly(ester amide)‐based homo‐ and block copolymers.
Highlights
Poly(ester amide)s have gained an increasing interest in recent years as they combine, in the same macromolecule, the biodegradability/biocompatibility of polyesters with excellent thermal and mechanical properties of polyamides
Inspired by the rapid advancement in polyester synthesis by ring-opening alternating copolymerization (ROAP) of epoxides with cyclic anhydrides,[6] we thought that the ROAP of aziridines with cyclic anhydrides is a potential synthetic methodology for poly(ester amide)s
Aziridines have a similar chemical structure and ring strain to epoxides, the strong nucleophilic ring-nitrogen allows aziridines to act as nucleophilic monomers, in contrast to the electrophilic epoxide monomers
Summary
Well-defined poly(ester amide)-based homo- and block copolymers by one-pot organocatalytic anionic ring-opening copolymerization of Nsulfonyl aziridines and cyclic anhydrides.
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