Expanding the poly(2-oxazoline) block copolymer possibilities through nitroxide mediated polymerisation†

In recent years, poly(2-oxazoline)s (POx) have become a sought-after biomaterial to replace PEG. However, access to POx based block copolymers is rather limited and their combination with controlled radical polymerization (CRP) techniques is required. Herein, we report the combination of cationic ring opening polymerization (CROP) and nitroxide mediated radical polymerization (NMP) to enable block copolymerization of poly(2-oxazoline)s with styrenics, acrylics, 1,3-dienes, and acrylamides as the second block. A well-defined poly(2-ethyl-2-oxazoline) macroinitiator has been prepared via CROP and in situ termination via the carboxylic acid functional group of BlocBuilder alkoxyamine has been achieved with a functionalization efficiency of 78%. Four different monomers in each class have been copolymerized via NMP and gel permeation chromatography analysis allowed us to identify the suitable set of comonomers to be utilized in block copolymerization with POx in an efficient, facile, metal- and sulfur-free polymerization environment.