Volumetric Additive Manufacturing of Dormant Catalytic Chemistries to Generate Silicone Micro- and Millifluidic Devices and Instant Molds.

Tomographic volumetric additive manufacturing (T-VAM) rapidly prints solid objects within minutes, accessing photochemistries that are traditionally challenging for layer-based additive manufacturing methods. This includes high-viscosity materials, air-free chemistries, and solid-state systems. Catalytic chemistries are appealing as a pathway to engineering advanced materials, including tough thermosets, silicone elastomers, and complex block copolymers. However, photoactivated dormant catalytic chemistries, where the catalyst irreversibly activates upon exposure to light, are incompatible with typical tomographic VAM approaches. To address this limitation, a zero-dose optimization strategy is devised to preserve dormant catalysts in desired regions by keeping them unexposed to light. VAM printed micro- and millifluidic devices and instant molds are successfully produced within minutes in silicones polymerized using photoactivated dormant platinum photohydrosilylation catalysts. The printed channels are programmed to be 500  and 2500 µm for the micro- and millifluidic devices, and print fidelity is assessed by X-ray computed tomography. This work demonstrates the potential of zero-dose optimization to expand the range of chemistries accessible for VAM, enabling the rapid fabrication of complex devices.