AsianScientist (Sep. 29, 2020) – Researchers in China have used bacteria to make an ultra-strong and transparent film that can replace plastic. Their findings have been published in Matter.
Although most plastic films—such as plastic bags and food wrappers—have a lifespan of mere minutes to hours, they persist in the environment for hundreds of years. Furthermore, exposure to sunlight, wind and wave action can cause a single plastic bag to be broken up into as many as 1.75 million microscopic fragments. These so-called microplastics have been found in every corner of the globe from Mount Everest to the Mariana Trench. Worryingly, they have been found in more than 100 species, including, fish, shrimp and birds.
To reduce the use of plastic, a team led by Professor Yu Shuhong from the University of Science and Technology of China (USTC) has developed a nanocomposite film inspired by mother of pearl that could one day replace many single-use plastics.
The researchers first allowed a thin layer of Gluconacetobacter xylinus bacteria to grow on an agar plate before spraying on a layer of nano-clay. The nano-clay particles became entangled in the cellulose nanofibers secreted by the bacteria, forming a uniform hydrogel. Multiple layers of this hydrogel were then pressed together to form a dense composite film that showed a ‘brick and fibre’ structure found in nacre.
When they tested the properties of the resulting film, the researchers found that it had a transmittance and haze of more than 73 percent and 80 percent respectively, suggesting that it could be useful for managing light in optoelectronic devices. The film was six times stronger than PET film and three times as stiff. It also was flexible enough to be folded and yet show no visible damage after unfolding.
“Compared to existing bio-based polymers, our nacre-inspired composite shows much better mechanical and thermal properties with good sustainability. Furthermore, given the intrinsic feature of fermentation, large-scale production of this sustainable nacre-inspired composite for commercial use can be expected in the near future,” the authors said.
Apart from replacing plastics, the film could also serve as a substrate for flexible electronics since it is not only transparent and flexible but also stable under thermal cycling.
The article can be found at: Guan et al. (2020) Nanocomposite Films for Plastic Substitute.
Source: University of Science and Technology China; Photo: Shutterstock.
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