Synthesis of Amphiphilic ABC 3-Miktoarm Star Terpolymer by Combination of Ring-Opening Polymerization and “Click” Chemistry

Novel biodegradable amphiphilic ABC 3-miktoarm star terpolymers composed of poly(ε-caprolactone) (PCL), monomethoxy poly(ethylene glycol) (MPEG), and polyphosphoester (PPE) were synthesized by a combination of ring-opening polymerization and “click” chemistry. MPEG was first end-capped by epoxide ring, which was opened by sodium azide in the presence of ammonium chloride to give modified MPEG bearing reactive azide and hydroxyl groups (MPEG(−OH,−N 3 )). “Click” chemistry was then applied to conjugate α-propargyl-ω-acetyl-poly(ε-caprolactone) and MPEG(−OH,−N 3 ), resulting in a diblock copolymer of MPEG and PCL with reactive hydroxyl groups at the junction point (MPEG(−OH)- b -PCL), which further initiated ring-opening polymerization of 2-ethoxy-2-oxo-1,3,2-dioxaphospholane (EEP) under the catalytic action of stannous octoate to obtain the desired well-defined (MPEG)(PCL)(PEEP) 3-miktoarm star terpolymers. Such terpolymers and their intermediates were characterized by 1 H NMR, FT-IR, and gel permeation chromatography. These polymers are expected to be promising vehicles for drug delivery applications.