Exploring inorganic particle-inclusive RAFT-controlled radical polymerization: Advancing precision in ceramic 3D printing

Stereolithography is a highly effective method for fabricating intricate ceramic parts, offering fast molding speeds and a diverse range of material options. However, it still faces significant precision challenges due to the incorporation of inorganic ceramic particles, which alters the propagation path of the incident light and affects the region where the polymerization reaction occurs. Herein, we regulate the polymerization reaction kinetics by introducing reversible addition-fragmentation chain transfer (RAFT) controlled radical polymerization into ceramic stereolithography, successfully reducing the minimum printable feature size of Al₂O₃ photosensitive slurry to 200 μm and achieving over 86.7 % fidelity across all tested feature sizes. The RAFT-based ceramic stereolithography system enhances the uniformity of the polymer network and reduces the formation of high cross-link density microgels with a high refractive index. Additionally, incorporating RAFT agents increases the critical energies in both depth and width directions, mitigating out-of-target area curing caused by radical diffusion. Furthermore, the RAFT formulation significantly reduces the attenuation length in the width direction, broadening the printing operational window and improving dimensional stability. Finally, the cross-section exposure distribution simulations under varying conditions suggest that RAFT-slurry reduces the broadening of the cure diameter caused by scattering effects and enhances inter-layer interactions during printing. This work presents a new technological approach for the advanced manufacturing of fine ceramic structures.