Well-Defined Linear and Grafted Poly(2-isopropenyl-2-oxazoline)s Prepared via Copper-Mediated Reversible-Deactivation Radical Polymerization Methods

2-Isopropenyl-2-oxazoline (IPOx) is an important double functional monomer with multiple potential applications. However, until now, the attempts at reversible-deactivation radical polymerization (RDRP) of IPOx via its double bond have met with little success, leading to low conversions and high-dispersity products. Here, we demonstrate that IPOx can be polymerized through aqueous Cu(0)-mediated RDRP in a controlled way using the 2-chloropropionitrile/CuCl(CuCl2)/TPMA initiation and catalytic system and 0.67 M NaCl as a solvent. It is shown that the polymerization is highly sensitive to the initiator concentration and the CuCl/CuCl2 ratio; however, with careful optimization of the polymerization parameters, low-dispersity products can be obtained at quantitative conversions. The synthesized poly(IPOx) polymers were subsequently transformed into different ATRP macroinitiators by the reaction of the pendant 2-oxazoline units with 2-bromoisobutyric or 2-chloropropionic acid under optimized reaction conditions. Styrene and methyl methacrylate were then grafted as model monomers from these macroinitiators under ATRP conditions, confirming that defined poly(IPOx)-based graft copolymers with controlled grafting density and molecular weights of the poly(IPOx) backbone and of the grafts are accessible by the presented method. This provides a straightforward route to a new class of 2-oxazoline-based materials.