Synthesis and characterization of resorcinarene-centered amphiphilic A8B4 miktoarm star copolymers based on poly(ε-caprolactone) and poly(ethylene glycol) by combination of CROP and “click” chemistry

Well-defined amphiphilic A8B4 miktoarm star copolymers with eight poly(ethylene glycol) chains and four poly(e-caprolactone) arms (R-8PEG-4PCL) were prepared using “click” reaction strategy and controlled ring-opening polymerization (CROP). First, multi-functional precursor (R-8N3-4OH) with eight azides and four hydroxyls was synthesized based on the derivatization of resorcinarene. Then eight-PEG-arm star polymer (R-8PEG-4OH) was prepared through “click” reaction of R-8N3-4OH with pre-synthesized alkyne-terminated monomethyl PEG (mPEG-A) in the presence of CuBr/N,N,N′,N″,N″′- pentamethyldiethylenetriamine (PMDETA) in DMF. Finally, R-8PEG-4OH was used as tetrafunctional macroinitiator to prepare resorcinarene-centered A8B4 miktoarm star copolymers via CROP of e-caprolactone utilizing Sn(Oct)2 as catalyst at 100 °C. These miktoarm star copolymers could self-assemble into spherical micelles in aqueous solution with resorcinarene moieties on the hydrophobic/hydrophilic interface, and the particle sizes could be controlled by the ratio of PCL to PEG. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2824–2833.