Synthesis of polymeric topological isomers based on sequential Ugi-4CR and thiol-yne click reactions with sequence-controlled amino-functionalized polymers

Abstract

Herein, sequence-controlled polymerization and sequential Ugi-4CR/thiol-yne click reactions inspired a novel synthetic strategy for preparing a well-defined multigraft polymer in which the sequence-controlled amino-functionalized backbones were converted to mono-or di-modular alkynyl-functionalized main chains via an Ugi-4CR and clicked with well-defined thiol end-functionalized polystyrene branches through the "graft-onto" method. The Ugi-4CR showed high conversions (above 91%), while the efficiencies for the thiol-yne click reaction were above 97%. Meanwhile, an innovative concept of "polymeric topological isomers" that had similar molecular weights but different grafted structures was proposed for the first time. These four well-defined multigraft isomeric polymers (mono-brush polymer, double-brush polymer, mono-comb polymer and double-comb polymer) provide a high-level platform for polymer physics studies. Through preliminary measurements, the dilute solution properties were found to be significantly different and to change regularly with variations in the grafted structures.