Photoinduced bulk polymerization strategy in melt state for recyclable polydiene derivatives.

Polydienes, particularly 1,3-butadiene derivatives, are integral to the chemical industry due to their widespread applications. However, current commercial production methods depend largely on gas- or solution-phase processes involving sophisticated initiators, catalysts and additives that require additional purification and cost. Here we introduce an ultraclean photo-melt-bulk polymerization strategy that enables the precise synthesis of high-molecular-weight polydienes without the need for solvents, catalysts or initiators. Using UV irradiation, we can generate long-lived biradicals in muconate derivatives that facilitate controlled chain propagation with minimal termination. This approach also simplifies the synthesis of ABA triblock co-polymers and allows for efficient random co-polymerization, yielding a plastic with excellent mechanical properties and processability. Furthermore, the inherently weaker carbon-carbon bonds in these polymers allow for facile depolymerization into monomers with high yields, providing an efficient pathway for chemical recycling. This work highlights a simple, yet effective polymerization method that aligns with the principles of green chemistry and advances the development of recyclable polymeric materials.