ABSTRACT Harnessing the spatiotemporal precision of light, photo‐reversible chemistries offer an approach to move beyond static fabrication toward dynamic materials. This study reports the synthesis and characterization of coumarin end‐capped urethane based poly(ethylene glycol) (CUP) materials. The reversible 2+2 cycloaddition of coumarin allows for network formation within 5 min of 365 nm irradiation (max conversions ), while enabling cleaving after 30 s of <300 nm irradiation. Rheological assessment confirms the viscoelastic liquid precursor's suitability for extrusion‐based printing at ambient temperature, yielding high resolution prints with excellent shape fidelity. Finally, the CUP material is exploited as a strong, reversible and tunable light‐responsive adhesive for glass substrates, showing adhesive strengths between 53 15 and 1717 367 kPa depending on the irradiation time.
Parys et al. (2026) studied this question.