One-pot preparation of 3-miktoarm star terpolymers via click [3 + 2] reaction

The preparation of 3-miktoarm star terpolymers using nitroxide mediated radical polymerization (NMP), ring opening polymerization (ROP), and click reaction [3 + 2] are carried out by applying two types of one-pot technique. In the first one-pot technique, NMP of styrene (St), ROP of ε-caprolactone (ε-CL), and [3 + 2] click reaction (between azide end-functionalized poly(ethylene glycol) (PEG-N₃)/or azide end-functionalized poly(methyl methacrylate) (PMMA-N₃) and alkyne) are carried out in the presence of 2-(hydroxymethyl)-2-methyl-3-oxo-3-(2-phenyl-2-(2,2,6,6- tetramethylpiperidin-1-yloxy)ethoxy) propyl pent-4-ynoate, 2, as an initiator for 48 h at 125°C (one-pot/one-step). As a second technique, NMP of St and ROP of ε-CL were conducted using 2 as an initiator for 20 h at 125°C, and subsequently PEG-N₃ or azide end-functionalized poly(tert-butyl acrylate (PtBA-N₃) was added to the polymerization mixture, followed by a click reaction [3 + 2] for 24 h at room temperature (one-pot/two-step). The 3-miktoarm star terpolymers, PEG-poly(ε-caprolactone)(PCL)-PS, PtBA-PCL-PS and PMMA-PCL-PS, were recovered by a simple precipitation in methanol without further purification.