Radical Approach to Thioester-Containing Polymers

A new
approach to radical ring-opening polymerization is presented
that employs a new thionolactone monomer to generate polymers with
thioester-containing backbones. The use of a thiocarbonyl acceptor
overcomes longstanding reactivity problems in the field to give complete
ring-opening and quantitative incorporation into a variety of acrylate
polymers. The resulting copolymers readily degrade under hydrolytic
conditions, in addition to cysteine-mediated degradation through transthioesterification.
The strategy is compatible with reversible addition–fragmentation
chain transfer (RAFT) polymerization and permits the synthesis of
block polymers for the preparation of well-defined macromolecular
structures.