High-Order Multiblock Copolymers via Iterative Cu(0)-Mediated Radical Polymerizations (SET-LRP): Toward Biological Precision

We report a new approach for the facile synthesis of high-order multiblock copolymers comprising very short blocks. The approach entails sequential addition of different monomers via an iterative single electron transfer-living radical polymerization technique, allowing nearly perfect control of the copolymer microstructure. It is possible to synthesize high-order multiblock copolymers with unprecedented control, i.e., A-B-C-D-E-etc., without any need for purification between iterative 24 h block formation steps. To illustrate this concept, we report the synthesis of model P(MA-b-MA...) homopolymer and P(MA-b-nBuA-b-EA-b-2EHA-b-EA-b-nBuA) copolymer in extremely high yield. Finally, the halide end-group can be modified via "click chemistry", including thiol-bromide click chemistry, sodium methanethiosulfonate nucleophilic substitution, and atom transfer radical nitroxide coupling reaction, to yield functional, structurally complex macromolecules.