Dynamic Selenocarbamate Chemistry Enables Reconfigurable 3D-Printed Materials With Tunable Refractive Index

Dynamic covalent chemistry has emerged as a powerful strategy for imparting reprocessability and adaptability to polymer networks; however, the range of dynamic covalent bonds available for additive manufacturing remains limited. Herein, we integrate selenocarbamate linkages into photopolymerizable three-dimensional (3D) printing networks. Small-molecule studies reveal efficient selenocarbamate exchange with an activation energy of 44 kJ mol^-1, confirming its dynamic nature. A selenocarbamate-containing diacrylate crosslinker was synthesized via a click reaction between a diselenol and 2-isocyanatoethyl acrylate and subsequently incorporated into digital light processing (DLP) printable formulations. The resulting covalent adaptable networks (CANs) exhibit rapid stress relaxation, low topology-freezing temperatures, good thermal stability, and efficient hot-press reprocessability. Moreover, the printed objects display both shape memory behavior and shape reconfiguration, enabling 4D-printing functionality. In addition, incorporation of selenium imparts attractive optical properties, including high transparency (> 85% in the visible region) and tunable refractive indices ranging from 1.478 to 1.526. As a proof of concept, Fresnel lenses were 3D printed, demonstrating the potential of these materials for reconfigurable optical components. The combination of tunable refractive index, dynamic reconfigurability, and high optical transparency establishes selenocarbamate chemistry as a promising platform for adaptive optical materials and advanced additive manufacturing.