Orthogonal Photo-Click Reactions for Multimaterial Fabrication: Selectivity, Kinetics, Crosstalk and Network Compatibility

Orthogonal photo-click chemistry can assign different reactions to different chemical handles or optical triggers, creating routes to sequential functionalisation and multimaterial fabrication. The key engineering claim is selectivity: activating one reaction must not consume, deactivate or substantially perturb the handles reserved for another step. λ-Orthogonal photochemistry has enabled sequence-defined macromolecular synthesis, and tetrazole photoclick reactions have been used for spatial functionalisation of porous polymer networks. [1,2] Thiol-ene photochemistry additionally offers rapid, robust network formation and has demonstrated multimaterial printability across very broad mechanical-property ranges. [3] ER-419 focuses on chemical compatibility of orthogonal reaction pairs. In accordance with the corpus boundary, it does not take ownership of wavelength-addressed multimaterial patterning architecture itself. Qualification requires a selectivity matrix, kinetic separation, residual-handle analysis and proof that one reaction does not compromise the network state needed by the next.