From Grayscale Photopolymerization 3D Printing to Functionally Graded Materials

Functionally graded materials (FGMs) have spatial variations in structure or composition that result in gradients in their mechanical, thermal, swelling, or other properties. FGMs have garnered significant research interest because of their extensive applications in areas such as biomedical implants, sensors, and soft robotics. Recently, grayscale photopolymerization 3D printing has emerged as a promising technology for crafting complex and high-resolution FGMs. This comprehensive work delves into various grayscale photopolymerization 3D printing techniques, offering insights into their ability to precisely control printing exposure energy and polymerization degree, which in turn influence material properties. Furthermore, this work highlights diverse applications of grayscale vat-photopolymerization 3D printing. Finally, it offers perspectives on ways to enhance grayscale photopolymerization 3D printing, with a focus on improving printing feedstocks and grayscale strategies. Based on various grayscale techniques, photopolymerization 3D printing provides nearly unlimited freedom in the design and fabrication of functionally graded materials with intricate structures and adjustable properties. This work comprehensively describes the use of grayscale photopolymerization 3D printing for producing functionally graded materials. In addition, it outlines the diverse applications of grayscale vat-polymerization 3D printing. image