Researchers have created a synthetic nacre remarkably similar to the natural material, which is also known as mother of pearl, though their synthetic version forms in weeks instead of months or years. Nacre is the shiny material found coating pearls and inside some mollusk shells. Its substantial strength and toughness make it an appealing material to synthesize, for various applications, yet its multifaceted and complex structure have made this process difficult. Current synthesis methods involve intricate layering and steps, as well as high degrees of heat, which limit the types of materials that can be used. In nature, nacre is produced using an organic matrix that acts as scaffolding. On the matrix, aragonite plates grow into one another through a mineralization process, in a brick-and-mortar fashion. Here, Li-Bo Mao and colleagues designed a similar matrix, and subjected it to a system that steadily pumps minerals and additives into the matrix. In this system, calcium carbonate is precipitated gradually across the matrix from a pool of calcium bicarbonate. The slow precipitation of the mineral offers a more uniform - and natural - formation of nacre than exists in current synthesis processes. Analysis of the final synthetic product reveals that is it slightly less dense than true nacre. As well, the aragonite platelets are slightly oversized, which means they can partially pop out of place, making the synthetic nacre slightly less crack-resistant. Regardless, the synthetic material maintains mechanical properties similar to its natural counterpart. The authors anticipate that this artificial mineralization method could be extended to produce other bio-inspired materials with unique or desirable properties.
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Science