Ultrafast and high-precision 3D printing via type-I-initiated xanthate-mediated RAFT polymerization.

Photopolymerization-based 3D printing offers outstanding spatial and temporal control; however, achieving high build speeds without sacrificing network precision remains challenging, particularly for living/controlled polymerization systems. Herein, we report an ultrafast, high-resolution photo-RAFT 3D printing platform enabled by xanthates in combination with a Norrish type I photoinitiator. This strategy allows practical build speeds (3-30 cm h-1) even at high RAFT concentrations. Through rational modification of the xanthate Z group and blending of xanthates with distinct controllability, the homogeneity and mechanical properties of the polymer networks can be continuously tuned without compromising printing fidelity. The printed objects retain active RAFT chain ends, enabling post-printing welding and multimaterial integration. This work establishes a versatile, application-oriented RAFT-based 3D printing framework that integrates ultrafast fabrication, precise network control, and programmable mechanical functionality.