Researchers have found the secret to a stronger, more lustrous, more resilient coating hiding in a shell.
Scientists at the University of Cambridge, in England, have successfully synthesized the strong, iridescent coating called nacre, or mother of pearl, found on the inside of some mollusks, according to a paper in the journal Nature Communications.
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|Iridescent nacre inside a Nautilus shell has inspired a synthetic coating with similar properties.|
Nacre is a composite material made of inorganic layers of calcium carbonate separated by organic polymers.
By recreating the biological steps that form nacre in mollusks, the scientists were able to manufacture a material that has a structure, mechanical behavior, and appearance similar to that found in nature, according to the report.
“Crystals have a characteristic shape that reflects their atomic structure, and it is very difficult to modify this shape,” said co-author Ullrich Steiner, a professor in the Department of Physics' Cavendish Laboratory.
“Nature is, however, able to do this, and through our research, we were able to gain insight into how it grows these materials. Essentially, we have created a new recipe for mother of pearl using nature’s cookbook.”
Following the Recipe
To create the artificial nacre, the scientists followed three steps.
First, they had to take preventive measures to ensure that the calcium carbonate (the primary component of nacre) did not crystallize when precipitating from the solution.
“This is done by using a mixture of ions and organic components in the solution that mimics how mollusks control this. The precipitate can then be adsorbed to surfaces, forming layers of well-defined thickness,” the researchers said.
Next, the precipitate layer was covered by an organic layer that has 10 nanometer-wide pores, which is done in a synthetic procedure invented by report co-author Alex Finnemore.
Finally, crystallization was induced and all steps repeated to create a stack of alternating crystalline and organic layers.
“While many composite engineering materials outperform nacre, its synthesis entirely at ambient temperatures in an aqueous environment, as well as its cheap ingredients, may make it interesting for coating applications,” said Finnemore.
“Once optimized, the process is simple and can easily be automated.”