Amino end-functionalized poly(ethylene oxide)-block-poly(methylidene malonate 2.1.2) block copolymers: synthesis, characterization, and chemical modification for targeting purposes

Poly(ethylene oxide)-block-poly(methylidene malonate 2.1.2) block copolymers (PEO-b-PMM 2.1.2) bearing a primary amino group at the PEO chain end were synthesized by sequential anionic polymerization of ethylene oxide (EO) and methylidene malonate 2.1.2 (MM 2.1.2). It was demonstrated that the direct initiation with 2-aminoethanolate was the most efficient method in terms of simplicity and of α-end functionalization yield. In this one-step reaction, amino end-functionalization yields of 92 ± 4% could be obtained, in contrast to maximum yields of 60–80% for the two-step reactions, including the one performed with a protected 2-aminoethanolate initiator. The reactive amino end-group was subsequently modified by reaction with functional ligands such as mannose and fluorescein. The chemical modifications were performed as well in organic medium as in aqueous micellar solutions, with reaction yields varying between 21% and 88%.