Photocontrolled Synthesis of Polyurethanes Enabled by Reversible Photoacid Catalysis under Visible Light

Photopolymerization is widely used across various fields, by virtue of its noninvasive and precise spatial regulation by light. Herein, we report the successful development of a photocontrolled polymerization of diisocyanate and diol monomers, which is enabled by employing merocyanine derivatives (MEH) as a reversible photoacid catalyst, thus allowing for an effective “on/off” control on the polyurethane chain growth by visible light. Structural modification on MEH unveils the reversibility and catalytic efficiency can be readily tuned by substituent variation and finally enables the success in the establishment of a strict temporal control. The utility of this photocontrolled polymerization method is further demonstrated in the synthesis of a series of polyurethanes from different monomers, as well as the development of a visible light-regulated polymer patterning approach on common papers.