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

## TL;DR

A new method enables fast 3D printing of silicone devices using dormant catalysts, which were previously incompatible with this type of manufacturing.

## Contribution

A zero-dose optimization strategy is introduced to enable dormant catalytic chemistries in tomographic volumetric additive manufacturing.

## Key findings

- Silicone micro- and millifluidic devices and instant molds were printed within minutes using the new method.
- Print fidelity was confirmed using X-ray computed tomography for programmed channel sizes.
- The approach expands the range of chemistries accessible for volumetric additive manufacturing.

## Abstract

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.

We describe use of a novel zero‐dose approach to tomographic volumetric additive manufacturing that has enabled us to print silicone micro‐ and millifluidic devices and instant molds within minutes. The silicones are polymerized using photoactivated dormant platinum photohydrosilylation catalysts that would traditionally be difficult to access in volumetric additive manufacturing.