DDS(drug delivery systems) based on polyester have been much investigated due to their biodegradability, biodegradability and nontoxicity. But there are still many problems to be resolved such as cell deformation and denaturation of the loading materials. It is known that the incorporation of PEG chain to copolymer brings the enhancement of hydrophilicity and prevents protein and peptide adsorption. The crystallinity of the matrix polymer influencing the cell deformation is usually dependent on the structure of the matrix polymer.
In this study, we prepared novel diblock copolymers based on the MPEG and random copolymers of L-lactide and ε-caprolactone and characterized their structures and properties by DSC, GPC, 1H NMR, 13C NMR, and FT-IR analysis. The degree of hydrophilicity of the diblock copolymers was determined by the water uptake test and water contact angle measurement. Diblock copolymers that consist of both part randomized with LLA and εCL segments and PEG units showed lower crystallinity and higher hydrophilicity than the conventional block copolymers based on the LLA and εCL. MPEG-b-P(LLA-ran-εCL) copolymer containing equal amount of LLA and εCL units was found to be most effective in the reduction of crystallinity and in the enhancement of hydrophilicity.