Poly(2-oxazoline) with Pendant Hydroxyl Groups via a Silyl Ether-Based Protecting Group

Abstract

The introduction of a functionality onto a poly(2-oxazoline) (POx) chain has been widely explored, yet reports of POx bearing hydroxyl side chains in a well-defined manner have not. Here, we report a simple yet elegant approach for the synthesis of POx with pendant hydroxyl groups through use of silyl protecting groups. First, a hydroxyl group containing 2-oxazoline monomer was synthesized from ε-caprolactone, which on its own results in poorly defined polymers. Moreover, protecting the hydroxy group with silyl ether-based protecting group led to well-defined polymers with free hydroxyl groups on the side chains upon deprotection. Finally, copolymers with 2-ethyl-2-oxazoline resulted in polymers with tunable hydrophilicity, and copolymers with 2-n-propyl-2-oxazoline resulted in polymers with tunable thermoresponsive behavior in water.