Two amphiphilic block copolymers using hydrophobic poly(ε-caprolactone) (PCL) and hydrophilic poly(ethylene glycol) (PEG) were successfully synthesized. One of them is an (A- b-B) 4 type star polymer [(PCL- b-PEG) 4] and the other one is a Y-shaped PEG–(PCL) 2. A star-shaped polymer (PCL- b-PEG) 4 was prepared by ring-opening polymerization (ROP) of ε-caprolactone continued by click reaction of (PCL-azide) 4 and PEG-alkyne. The synthesis of Y-shaped PEG–(PCL) 2 block copolymer was carried out via Diels-Alder click reaction of a furan protected maleimide end-functionalized PEG (PEG-MI) with an anthracene end-functionalized PCL following the ROP of ε-caprolactone. The characterization of micelles is carried out using both materials in aqueous media as drug delivery vehicles, which showed satisfying results and enhanced the cytotoxic effect of the anti-cancer drug vinorelbine (VLB). However, micelles consisted of Y-shaped unimers were found to be more convenient for delivery of hydrophobic drugs such as VLB because they formed in lower concentration, carrying a higher amount of drugs and owing a monomodal distribution. We concluded that the free tails of hydrophobic chains in Y-shaped block copolymer facilitate the assembly of amphiphilic material in water to form micelles.
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