Expanding the Scope of RAFT Step-Growth Polymerization

This dissertation explores the development, mechanistic understanding, and application ofreversible addition–fragmentation chain transfer (RAFT) step-growth polymerization, a hybridstrategy that combines the control of RAFT polymerization with the structural diversity of stepgrowth processes. Initial chapters establish visible-light-mediated RAFT step-growthpolymerizations using both photo-iniferter and photoinduced electron/energy transfer (PETRAFT) mechanisms, demonstrating efficient synthesis of functional polymers under mild andoxygen tolerant conditions. These insights are extended to the synthesis of degradable graftcopolymers featuring dual stimuli–responsive backbones, illustrating the modularity of the RAFTstep-growth platform for constructing complex architectures. Furthermore, we exploremechanistic and kinetic modeling of thermally initiated RAFT step-growth polymerizations,revealing that monomer addition to the RAFT-derived radical is the rate-limiting step and thatpolymerization follows first-order kinetics. Complementary modeling of photo-mediated systemsuncovers distinct radical generation pathways and a three-half-order dependence on monomerconcentration, providing a unified kinetic framework across initiation modes. Collectively, thesestudies establish the mechanistic foundation and synthetic versatility of RAFT step-growthpolymerization. Lastly, we extend this platform toward biomedical applications, specificallyleveraging RAFT step-growth–enabled brush-like polymers as multifunctional carriers for drugdelivery.