Radical Ring-Closing/Ring-Opening Cascade Polymerization

A novel strategy
for the synthesis of main-chain polymers through
radical ring-closing/ring-opening cascade polymerization is reported.
Efficient radical cyclopolymerization was achieved through systematic
optimization of the electronic properties of 1,6-diene structures.
Fusing 1,6-diene with allylic sulfide or allylic sulfone motifs enabled
a ring-closing/ring-opening cascade reaction that provides a strong
driving force for the ring-opening polymerization of large macrocyclic
monomers. The ability of 1,6-diene-fused allylic sulfone to undergo
efficient SO2 extrusion generated a propagating alkyl radical
capable of reversible deactivation. This strategy provides a general
platform for the synthesis of polymers incorporating complex main-chain
structures and degradable functionalities.