Degradable Linear and Bottlebrush Thioester-Functional Copolymers through Atom-Transfer Radical Ring-Opening Copolymerization of a Thionolactone

Polymers with tailored architectures and degradability were prepared through thiocarbonyl addition ring-opening (TARO) atom-transfer radical polymerization (ATRP) using dibenzo[c,e]oxepin-5(7H)-thione (DOT), Cu(I)Br, tris[2-(dimethylamino)ethyl]amine (Me6TREN) as the thionolactone, catalyst, ligand, respectively, in combination a selection of acrylic comonomers. Although copolymers selectively degradable backbone thioesters low dispersities (1.10 ? D? 1.26) achieved DMSO, acetonitrile, or toluene solvent, Cu(I)-catalyzed dethionation DOT to its (oxo)lactone analogue limited achievable copolymer content. Using anhydrous conditions minimized side reaction provided higher (?32 mol %) thioester Water-soluble molecular brushes by grafting poly(ethylene glycol) methyl ether acrylate–DOT from pre-made multi-ATRP initiator. Due copolymerization kinetics, installed close junctions enabled fast (<1 min) cleavage arms core give water-soluble products 10 mM oxone.