It hasn’t slipped past material scientists that some of nature’s strongest materials, including bone and nacre/mother-of-pearl, are composed of layers of nanosized mineral platelets bonded by a flexible biopolymer matrix. But the complexity of these hierarchically ordered structures has made biomimetic production too expensive.
In 2020, in Nature Communications, a team led by Shu-Hong Yu detailed the rapid bulk-production of low-cost eco-friendly mimetic-nacre using a unidirectional pressing technique, cellulose nanofibers and mica micro-platelets. The material demonstrates better strength and thermal stability than petroleum-based plastics.
“We focused on the often overlooked processes of how organisms create these natural materials,” explains Yu. This approach was also behind a mineralization technique reported by the team in 2016 in Science. The method featured aragonite nanocrystals reminiscent of nacre’s aragonite platelets precipitated from a solution containing calcium bicarbonate, similar to the secretions of nacre-lined molluscs.
In 2017, the team used water-evaporation-aided lamination to form large nacre-mimetic composites of greater thickness.
“Ultimately, we would like to engineer more sustainable materials, and to also contribute to fields including tissue engineering and aerospace,” Yu says. His team are also investigating the twisted, layered structures found in the armour of some insects, and the unidirectionally porous structure of natural wood.