Controlled polymerization techniques (e.g., reversible addition-fragmentation chain transfer (RAFT) polymerization) provide access to defined copolymer structures where block sequence, monomer composition, and architecture can be readily tuned. Herein, synthesis approaches that leverage photoinduced electron/energy transfer (PET) catalysis to control radical introduction mechanisms will be introduced. For example, we developed synthetic methods to yield polymers containing more precise control over monomer placement and sequence.