On‐Demand Activation of Transesterification by Chemical Amplification in Dynamic Thiol‐Ene Photopolymers

Abstract Chemical amplification is a well‐established concept in photoresist technology, wherein one photochemical event leads to a cascade of follow‐up reactions that facilitate a controlled change in the solubility of a polymer. Herein, we transfer this concept to dynamic polymer networks to liberate both catalyst and functional groups required for bond exchange reactions under UV irradiation. For this, we exploit a photochemically generated acid to catalyse a deprotection reaction of an acid‐labile tert‐butoxycarbonyl group, which is employed to mask the hydroxy groups of a vinyl monomer. At the same time, the released acid serves as a catalyst for thermo‐activated transesterifications between the deprotected hydroxy and ester moieties. Introduced in an orthogonally cured (450 nm) thiol‐click photopolymer, this approach allows for a spatio‐temporally controlled activation of bond exchange reactions, which is crucial in light of the creep resistance versus reflow ability trade‐off of dynamic polymer networks.