Synergistic Two‐Color Photochemical Polymer Network Formation and Lithography

We introduce synergistic two‐color lithography as an advanced wavelength‐gated strategy for spatially and temporally controlling polymer network formation. Our photoresist entails two photoswitches, i.e., diarylindenone epoxide (DIO) and strained azobenzene (SA), each activated at a judiciously selected wavelength, i.e., 375 or 430 nm. Under specific conditions of photon flux, simultaneous irradiation at both wavelengths induces a (3 + 2) cycloaddition between the photoactivated DIO′ and SA′ species, generating covalently crosslinked networks, whereas under these specifically determined conditions, single‐wavelength exposure does not induce solidification. Kinetic analysis highlights the potential of synergistic activation to enable advanced additive manufacturing. We implemented the two‐color activated covalent bond forming system in a dual‐laser lithographic platform enabling the fabrication of well‐defined structures, including segmented ring and butterfly architectures by simply activating and deactivating one of the colors of light.