The field of engineering materials has long faced the challenge of balancing mechanical properties, such as the mutual constraints between strength and toughness, stiffness and damping, which severely limits their high-end applications. Natural tooth enamel, with its multi-scale gradient structure, exhibits excellent comprehensive mechanical properties, providing a natural blueprint for solving this problem. Previously, the scientific research community has successfully synthesized various composite materials with enamel-inspired multi-scale structures, but the simulation of the gradient structure within the inner layer of tooth enamel has been difficult to achieve, becoming a key bottleneck restricting the performance enhancement of enamel-inspired materials.

To overcome this technical challenge, the author innovatively adopted a strategy combining magnetic field-assisted freezing with subsequent mechanical compression. Through the cross-assembly of oriented hybrid nanowires, a gradient enamel-mimicking composite material (GEMC) similar to the inner structure of tooth enamel was successfully prepared. This material not only simulates the amorphous grain boundary phase and parallel arrangement structure of nanocolumns in tooth enamel, but also precisely replicates the gradient structure of the inner layer of tooth enamel by changing the assembly direction of oriented nanowires. This is the first time in the research of enamel-mimicking materials.

Experimental tests have shown that this gradient enamel-mimicking composite material exhibits superior comprehensive mechanical properties beyond natural tooth enamel: its strength reaches 136.9 MPa, which is 1.93 times that of natural tooth enamel; its toughness is 9.5 MPa·m¹/², which is 2.43 times that of natural tooth enamel; it also possesses a stiffness of 71.3 GPa, a hardness of 4.2 GPa, and a damping coefficient of 0.063. Especially, it demonstrates outstanding fatigue resistance, withstanding more than 20,000 bending cycles under 50% stress, and only experiencing an 8.7% decrease in strength after cycling, exhibiting remarkable durability.

Yangbei Li, Junfeng Lu*, Qihan Zhao, Shaojia Liu, Tianqi Guo*, Hewei Zhao*, Lin Guo*. A Gradient Enamel‐Mimetic Composite via Crisscross Assembly of Aligned Hybrid Nanowires for Excellent Mechanical Performance[J]. Advanced Materials, 2025, 37(51): 2503537.

https://doi.org/10.1002/adma.202503537