Photocontrolled Living Polymerization Systems with Reversible Deactivations through Electron and Energy Transfer

Recently, visible‐light‐regulated polymerization has been gaining popularity, as it opens a range of new opportunities for the synthesis of functional polymers and materials. Here, the most recent developments in this field are summarized, which is the use of photocatalysts and catalyst‐free approaches to mediate polymerization upon photoexcitation. These catalysts can transfer an electron or energy to activate an initiator. The recent achievements in light‐regulated atom‐transfer radical polymerization, reversible addition‐fragmentation chain‐transfer polymerization, ring‐opening metathesis polymerization, cobalt‐mediated radical polymerization, iodine‐mediated radical polymerization, and living cationic polymerization are reviewed. Recent development in these fields have solved important challenges in polymer chemistry, such as the development of oxygen‐tolerant polymerization, polymerization mediated by near‐infrared, metal‐free polymerization, and spatial‐, temporal‐, and sequence‐controlled polymerization. Some applications of these techniques will be discussed, such as adapting the current photocatalytic systems to synthesize heterogeneous photocatalysts that act as recyclable photocatalysts and novel light‐mediated approaches for surface functionalization of hybrid materials and living cells. Finally, the existing challenges in polymer chemistry that could be overcome by further development of light‐mediated polymerization techniques are highlighted along with the future directions of this field.