Research on the morphology and mechanical property of bonding interfaces fabricated by multimaterial digital light processing

Multimaterial digital light processing (DLP) three-dimensional (3D) printing technology provides unique advantages in the field of multimaterial additive manufacturing (MMAM) with its high resolution and rapid shaping capabilities based on photopolymerization. However, owing to differences in the curing behavior and physical properties of different materials, multimaterial DLP 3D printing faces challenges such as insufficient interfacial bonding strength and unstable mechanical properties. In this study, two resins were integrated by multimaterial DLP 3D printing technology, and the effects of different layer thicknesses and exposure times on the interfacial bonding strength and morphology of the multimaterials were systematically investigated. The interfacial bonding mechanisms of the two resins was analyzed. It was found that increasing the exposure time can improve the interfacial bonding strength between materials, but certain limitations exist. A mathematical model relating the interfacial bonding strength to the exposure time and layer thickness was developed, and optimal process parameters were determined using optimization algorithms. A variable-parameter printing strategy for the interface was proposed to further improve the performance of printed parts. The maximum tensile strength of the multimaterial samples (44.43 MPa) using this strategy reached that of single-material parts (45 MPa), validating the feasibility of this strategy. This provides guidance for multimaterial DLP 3D printing processes and offers valuable insights for the future additive manufacturing of high-performance multimaterial components.