Lotus effect: Self-cleaning bioplastics repel liquid and dirt
New bioinspired plastic is sturdy and compostable, ideal for eco-friendly
food packaging

Date:
February 8, 2022
Source:
RMIT University
Summary:
Inspired by the always immaculate lotus leaf, researchers have
developed a self-cleaning bioplastic that is sturdy, sustainable
and compostable.



FULL STORY ========================================================================== Inspired by the always immaculate lotus leaf, researchers have developed
a self-cleaning bioplastic that is sturdy, sustainable and compostable.


==========================================================================
The innovative plastic developed at RMIT University in Melbourne,
Australia, repels liquids and dirt -- just like a lotus leaf -- then
breaks down rapidly once in soil.

RMIT PhD researcher Mehran Ghasemlou, lead author of the study published
in Science of the Total Environment, said the new bioplastic was ideal
for fresh food and takeaway packaging.

"Plastic waste is one of our biggest environmental challenges but the alternatives we develop need to be both eco-friendly and cost-effective,
to have a chance of widespread use," Ghasemlou said.

"We designed this new bioplastic with large-scale fabrication in mind,
ensuring it was simple to make and could easily be integrated with
industrial manufacturing processes." Ghasemlou said nature was full of ingeniously-designed structures that could inspire researchers striving
to develop new high-performance and multifunctional materials.



========================================================================== "We've replicated the phenomenally water-repellent structure of lotus
leaves to deliver a unique type of bioplastic that precisely combines
both strength and degradability," he said.

The bioplastic is made from cheap and widely-available raw materials --
starch and cellulose -- to keep production costs low and support rapid biodegradability.

The fabrication process does not require heating or complicated equipment
and would be simple to upscale to a roll-to-roll production line,
Ghasemlou said.

Naturally compostable While biodegradable plastics are a growing market,
not all bioplastics are equal. Most biodegradable or compostable plastics require industrial processes and high temperatures to break them down.



==========================================================================
The new bioplastic does not need industrial intervention to biodegrade,
with trials showing it breaks down naturally and quickly in soil.

"There are big differences between plant-based materials -- just because something is made from green ingredients doesn't mean it will easily
degrade," Ghasemlou said.

"We carefully selected our raw materials for compostability and this
is reflected in the results from our soil studies, where we can see our bioplastic rapidly breaks down simply with exposure to the bacteria and
bugs in soil.

"Our ultimate aim is to deliver packaging that could be added to your
backyard compost or thrown into a green bin alongside other organic waste,
so that food waste can be composted together with the container it came
in, to help prevent food contamination of recycling." Lotus-inspired structures Lotus leaves are renowned for having some of the most water-repellent surfaces on earth and are almost impossible to get dirty.

The secret lies in the leaf's surface structure, which is composed of
tiny pillars topped with a waxy layer.

Any water that lands on the leaf remains a droplet, simply rolling off
with the help of gravity or wind. The droplets sweep up dirt as they
slide down, keeping the leaf clean.

To make their lotus-inspired material, the RMIT team of science and
engineering researchers first synthetically engineered a plastic made
of starch and cellulosic nanoparticles.

The surface of this bioplastic was imprinted with a pattern that mimics
the structure of lotus leaves, then coated with a protective layer of
PDMS, a silicon-based organic polymer.

Tests show the bioplastic not only repels liquids and dirt effectively,
but also retains its self-cleaning properties after being scratched with abrasives and exposed to heat, acid and ethanol.

Corresponding author, Professor Benu Adhikari, said the design overcomes
key challenges of starch-based materials.

"Starch is one of the most promising and versatile natural polymers,
but it is relatively fragile and highly susceptible to moisture,"
Adhikari said.

"Through our bio-inspired engineering that mimics the 'lotus effect',
we have delivered a highly-effective starch-based biodegradable
plastic." Ghasemlou is currently working with a bioplastic company,
which is evaluating further development of these novel water repellant materials. The RMIT research team is keen to collaborate with other
potential partners on commercial applications for the bioplastic.

Video: https://youtu.be/iryIxrMsiVI ========================================================================== Story Source: Materials provided by RMIT_University. Original written
by Gosia Kaszubska.

Note: Content may be edited for style and length.


========================================================================== Related Multimedia:
* Lotus_leaf_repelling_water ========================================================================== Journal References:
1. Mehran Ghasemlou, Fugen Daver, Billy J. Murdoch, Andrew S. Ball,
Elena P.

Ivanova, Benu Adhikari. Biodegradation of novel bioplastics made
of starch, polyhydroxyurethanes and cellulose nanocrystals in
soil environment. Science of The Total Environment, 2022; 815:
152684 DOI: 10.1016/j.scitotenv.2021.152684
2. Mehran Ghasemlou, Phuc H. Le, Fugen Daver, Billy J. Murdoch,
Elena P.

Ivanova, Benu Adhikari. Robust and Eco-Friendly Superhydrophobic
Starch Nanohybrid Materials with Engineered Lotus Leaf Mimetic
Multiscale Hierarchical Structures. ACS Applied Materials &
Interfaces, 2021; 13 (30): 36558 DOI: 10.1021/acsami.1c09959 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220208105204.htm
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