Poly( ε ‐caprolactone)–Poly(oxyethylene) Multiblock Copolymers Bearing Along the Chain Regularly Spaced Pendant Amino Groups

Poly( ε ‐caprolactone) (PCL) macromers ( $\overline M _{\rm n} $  = 1.7–3.8 kDa) which contain one Z‐protected NH 2 group per chain were synthesized by ring‐opening polymerization of ε ‐caprolactone in the presence of Sn(oct) 2 using as initiator a diamine prepared by condensation of N ‐Boc‐1,6‐hexanediamine and N α ‐Boc‐ N ε ‐Z‐ L ‐Lysine. The coupling of these macromers with COCl end‐capped poly(oxyethylene) (PEO), $\overline M _{\rm n} $  = 1.0 kDa, afforded amphiphilic multiblock poly(ether ester)s (PEEs) which have, along the chain, regularly spaced pendant protected amino groups. Deprotection, accomplished without chain degradation, yielded NH 2 groups available for further reactions. The molecular structure of macromers and PEEs was investigated by 1 H NMR and SEC. DSC and WAXS analyses showed that macromers and copolymers were semicrystalline and their T m increased with increase in the molecular weight of PCL segments. The inherent viscosity values (0.25–0.30 dL · g −1 ), together with SEC analysis results, indicated moderate polymerization degrees.