Precision PEGylated Polymers Obtained by Sequence-Controlled Copolymerization and Postpolymerization Modification

Copolymers containing water-soluble poly(ethylene glycol) (PEG) side chains and precisely controlled functional microstructures were synthesized by sequence-controlled copolymerization of donor and acceptor comonomers, that is, styrene derivatives and N-substituted maleimides. Two routes were compared for the preparation of these structures: a) the direct use of a PEG-styrene macromonomer as a donor comonomer, and b) the use of an alkyne-functionalized styrenic comonomer, which was PEGylated by copper-catalyzed alkyne-azide cycloaddition after polymerization. The latter method was found to be the most versatile and enabled the synthesis of high-precision copolymers. For example, PEGylated copolymers containing precisely positioned fluorescent (e. g. pyrene), switchable (e. g. azobenzene), and reactive functionalities (e. g. an activated ester) were prepared.