Synthesis and characterization of amine-functionalized amphiphilic block copolymers based on poly(ethylene glycol) and poly(caprolactone)

A series of amine-functionalized block copolymers, poly(caprolactone)-block-poly(ethylene glycol) (PCL-b-PEG), were synthesized by ring-opening bulk polymerization (ROP) of epsilon-caprolactone (epsilon-CL) initiated through the hydroxyl end of the amino poly(ethylene glycol) (PEG) used as a macroinitiator in the presence of stannous 2-ethylhexonoate [Sn(Oct)(2)]. The polymerization and end functionality of the polymer were studied by different physicochemical techniques (H-1 NMR, Fourier transform infrared and X-ray photoelectron spectroscopy, gel permeation chromatography and thermogravimetric analysis). Thermal, crystalline and mechanical properties of the polymer were thoroughly analyzed using differential scanning calorimetry, wide-angle X-ray diffractometry and tensile testing, respectively. The results showed a linear improvement in crystallinity and mechanical properties of the polymer with the content of PEG. Thus the synthesized functional polymers can be used as excellent biomaterials for the delivery of polyanions, as well as macroinitiators for the synthesis of A-B-C-type block copolymers. (C) 2006 Society of Chemical Industry.