A novel functional E-caprolactone monomer containing protected amino groups, gamma-(carbamic acid benzyl ester)-epsilon-caprolactone (gamma CAB epsilon CL), was successfully synthesized. A series of copolymers [poly(CL-co-CAB CL)] were prepared by ring-opening polymerization of epsilon-caprolactone (CL) and gamma CABECL in bulk using tin (II)-2-ethylhexanoate [Sn(Oct)(2)] as catalyst. The morphology of the copolymers changed from semi-crystalline to amorphous with increasing gamma CABECL monomer content. They were further converted into deprotected copolymers [poly(CL-co-ACL)] with free amino groups by hydrogenolysis in the presence of Pd/C. After deprotection, the free amino groups on the copolymer were further modified with biotin. The monomer and the corresponding copolymers were characterized by (1)H NMR, (13)C NMR, FT-IR, mass, GPC and DSC analysis. The obtained data have confirmed the desired monomer and copolymer structures. (C) 2010 Elsevier Ltd. All rights reserved.