Telechelic Triblock Poly(α-Amino Acid)-Poly(Tetrahydrofuran)-Poly(α-Amino Acid) Copolymers: Chain-End Transformation, Polymerization and pH-Responsive Hydrolysis^†

Block copolymers not only combine properties of different segments but also generate new application prospects. Poly(α-amino acid)-b-poly(tetrahydrofuran)-b-poly(α-amino acid) (PAA-PTHF-PAA) is one of the copolymers. In this contribution, di-hydroxyl-ended HO-PTHF-OH is transferred into di-oxyamino-ended H₂NO-PTHF-ONH₂ quantitatively, which is used as a macroinitiator to polymerize sarcosine N-thiocarboxyanhydride (Sar-NTA) and N-phenyoxycarbonyl N-ε-carbobenzyloxy-D-lysine (ZDL-NPC). Well-defined triblock PAA-NHO-PTHF-ONH-PAA is produced with high molecular weight (up to 25.3 kg/mol) and narrow dispersity. The amphiphilic PSar-NHO-PTHF-ONH-PSar (STS) self-assembles into micelles with uniform diameters of 30—40 nm according to DLS. Owing to oxygen amide groups inside the backbone of these copolymers, the polyether-poly(amino acid)s block copolymers are cleavable under an acidic environment and therefore have potential applications in smart biomedicine and engineering.