Poly(ε-caprolactone)-poly(oxyethylene) multiblock copolymers bearing along the chain regularly spaced pendant amino groups

Poly(epsilon-caprolactone) (PCL) macromers ((M) over bar (n) = 1.7-3.8 kDa) which contain one Z-protected -NH2 group per chain were synthesized by ring-opening polymerization of epsilon-caprolactone in the presence of Sn(oct)(2) using as initiator a diamine prepared by condensation of N-Boc-1,6-hexanediamine and N-alpha-Boc-N-epsilon-Z-L-Lysine. The coupling of these macromers with -COCl end-capped poly(oxyethylene) (PEO), (M) over bar (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 -NH2 groups available for further reactions. The molecular structure of macromers and PEEs was investigated by H-1 NMR and SEC. DSC and WAXS analyses showed, that macromers crystalline 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.