Versatile Sacrificial Mold-Assisted 3D Printing for High-Performance Mechanoluminescent Structures Toward Impact Protection and Visualization Monitoring.

Abstract

Mechanoluminescence (ML) materials exhibit significant potential for visual sensing and structural monitoring owing to their self-powered operation and capability for real-time stress mapping. However, the fabrication of complex and high-aspect-ratio 3D ML geometries remains challenging, primarily constrained by poor rheological control in direct ink writing and the limited adaptability of conventional demolding. Herein, this study proposes an indirect 3D printing strategy based on sacrificial molds to fabricate complex ZnS:Cu/polydimethylsiloxane (PDMS) structures with exceptional structural fidelity. By integrating digital image correlation (DIC) technology, a quantitative correlation between strain fields and ML intensity fields is successfully established. Furthermore, a 3D negative Poisson's ratio ML structure (NPR-ML/PDMS) filled with silicone is designed for complex service scenarios, enabling the synergistic integration of impact protection and real-time visualized impact sensing. NPR-ML/PDMS reduces peak impact force by 60% and enhances ML intensity by 89%, demonstrating its potential for intelligent protective systems. Finally, this sacrificial mold method is successfully extended to ZnS/CaZnOS:Mn2 +/epoxy resin and CaZnOS:Pr, Li-based composite systems to achieve stress visualization in rigid load-bearing structures, validating its broad universality across various polymer matrices. This work provides valuable guidance for the development and application of complex, high‑performance ML structures in impact protection and visualization monitoring fields.