GERMANY – Scientists at the University of Konstanz, Germany, have developed bio-based and biodegradable next-generation mineral plastics that can regenerate after damage.
Created using a natural biopolymer – polyglutamic acid (PGlu) – the material was found to completely degrade after 32 days.
First developed in 2016, the mineral plastics’ shortcoming was difficulty in biodegrading. “Previously, we used polyacrylic acid to produce our mineral plastic,” explains project lead Helmut Cölfen.
“Chemically, this acid has the same backbone as PE, which is known to cause major problems in the environment because it is hardly biodegradable.
“Our new mineral plastic has the same positive properties as the previous one but has the decisive advantage that its basic building block – polyglutamic acid – can be produced with the help of microorganisms and is completely biodegradable.”
The Konstanz team mixed PGlu, calcium chloride and alcohol in water to form an environmentally safe alternative to conventional plastics.
The mineral plastic is described as “stretchable, deformable and reversibly swellable.” Additionally, in their study published in the journal Small Methods, the team states that mineral plastic exhibits self-healing properties.
The research team was looking for an alternative basic building block to develop an environmentally compatible mineral plastic that retains the intriguing properties of the original material.
They found the solution in PGlu, which is readily available in large quantities and can be obtained through biotechnological production using microorganisms.
Moreover, scientists state that various microorganisms in the environment can degrade the material.
“The biodegradability of PGlu-based mineral plastics, as confirmed in this study, makes it a very attractive polymer to be used for the development of environmentally safe materials,” they write.
“The elements [nitrogen, calcium and iron] present in the PGlu-based mineral plastics act as additional nutrients, supporting the growth of microorganisms and consequently, promoting the degradation process.”
The Konstanz chemists detail that easy tunability makes PGlu-based mineral plastics a “highly interesting” class of materials with numerous potential applications.
“They can effectively be used as adhesives, cell phone screen covers, non-flammable, insulating foams as opposed to styrofoams, parts in hot environments like in ovens and motors, since they are non-flammable.”
“Hence, the PGlu mineral plastics can be efficiently tailored for a number of applications with the valuable advantage of being biodegradable. Further, it also helps us ensure a rational, [environmentally] sustainable and eco-friendly approach to developing plastic alternatives,” concludes the chemists.
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