Enhanced Volumetric Additive Manufacturing via Reversible Addition-Fragmentation Chain Transfer (RAFT) Polymerization

In this study, we introduce Reversible Addition-Fragmentation Chain Transfer (RAFT) polymerization into various (meth)acrylate-based polymer systems to effectively mitigate heat generation and expand the design space of CAL. RAFT also allows for post-printing-functionalization of the printed objects, expanding the potential application scope of CAL. The success of this approach to mitigate auto-acceleration is demonstrated through in-situ thermal monitoring. Computed Axial Lithography (CAL), the most widely adopted Volumetric Additive Manufacturing (VAM) technology, has shown great potential for manufacturing freeform geometries in seconds. In CAL, regions of photopolymer exposed to a threshold light dose level solidify rapidly and simultaneously through the superposition of projected light patterns from multiple angular positions. While free radical polymerization (FRP) has been the primary reaction mechanism enabling CAL’s rapid fabrication, its exothermic effects (ΔT > 60 °C) can trigger auto-acceleration, compromising print fidelity and limiting the scalability of VAM. The fabrication of novel structures that cannot be printed via FRP is enabled by RAFT both via direct VAM processing and post-polymerization.