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Keywords:

  • block copolymers;
  • N-carboxy anhydrides;
  • peptides;
  • poly(ethylene oxide);
  • ring-opening polymerization

Abstract

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Gel permeation chromatograms recorded for the diblock copolymers of poly(ethylene oxide)-block-poly(γ-benzyl-L-glutamate) prepared by N-carboxy anhydride polymerization initiated either by PEO-NH2 macroinitiator or PEO-NHmath imageCl macroinitiator.

Summary: The ring-opening polymerization of N-carboxy anhydrides (NCA) of γ-benzyl-L-glutamate and β-benzyl-L-aspartate was studied in the presence of an ammonium chloride-functionalized poly(ethylene oxide) macroinitiator, which possibly prevents side reactions such as NCA deprotonation. Although polymerization initiated by such macroinitiators was found to be quite slow, well-defined conjugates of poly(ethylene oxide)-block-poly(γ-benzyl-L-glutamate) and poly(ethylene oxide)-block-poly(β-benzyl-L-aspartate) with polydispersity indexes as low as 1.05 were prepared. Moreover, the presence of ammonium chloride chain ends significantly prevented end-group cyclization of poly(γ-benzyl-L-glutamate) after polymerization.