2D Plastic Ensures Pure Drinking Water
Scientists from the ETH Zürich in Switzerland have made ultrathin membranes which are only one molecule thick. Known as 2D membranes, they are structured, so tiny holes in the material are shaped exactly according to the molecules allowed to pass through.
molecules – or polymers – were formed by linking up many small molecules – or monomers. Staudinger was convinced that the polymer chains were the basic elements of plastic.
However, the leading chemists of the world were sceptical of the theory, maintaining that molecules of such size were chemically impossible. But over time, it became clear that the polymers did not only exist, rather the large molecules also existed anywhere in nature.
Among nature’s most sophisticated polymers are DNA molecules, which consist of two twisted chains composed of smaller molecules – nucleotides. The succession of nucleotides determines the genetic code, which forms the basis of our appearances and all bodily functions.
Though DNA is a polymer, it is not a type of plastic, as that designation is only used about synthetic polymers. But now, chemists have begun to copy nature. By controlling the molecular structure much more accurately, they can provide the new generation of plastic with customized properties.
PLASTIC BECOMES SENSITIVE
Chemists are particularly interested in developing plastic, which can react to external influences such as temperature, air moisture, or pH value. This type of plastic can be used to make clothes, which react to the surroundings, etc.
In 2017, scientists from the US University of California, San Diego, and the Harbin Institute of Technology in China showed how the nafion polymer can be used to make clothes that function in the same way as skin pores and are able to regulate body temperature according to the surroundings.
The scientists take advantage of the fact that nafion’s polymer chain has a side group of sulphur trioxide, which can easily react with water molecules. When the temperature rises, and the person begins to sweat, the polymer fibres on the inside of a sweater absorb some of the water. On the outside of the clothes, the air moisture level is lower, and so, the outside will not absorb as much water. The result is that the inside swells more, producing a slight bend, which makes flaps on the surface of the material open like tiny windows, letting in fresh air. The scientists imagine that plastic types
such as nafion will soon be used to make clothes with improved temperature regulation.
“CLICK CHEMISTRY” DRUG DOSAGE
Chemists have always tried to control the process by which monomers are linked into polymers: the very process in which the most important properties of the end product are determined. If the plastic is to be soft and flexible such as a plastic bag, other chemical bindings are required between the monomers than in hard plastic types such as Lego bricks. Today, scientists have taken one step further, trying to control the order and type of monomers in the polymer chain with complete accuracy. In the same way as DNA nucleotides ensure specific properties in the body, plastic molecules can be placed in specific sequences.
Using the “click chemistry” method, scientists can place molecules which normally have nothing to do with plastic in carefully selected places of the polymer chain via chemical reactions. Scientists from the University of Nottingham made plastic based on spider silk and clicked antibiotics molecules onto the chain. So, they could make a patch with integrated antibacterial qualities, which liberated the antibiotics little by little over five days. Such a patch could particularly benefit patients with diabetic ulcers, which heal slowly. The ulcers are difficult to treat efficiently with antibiotics pills, as the entire dose is liberated at the same time.
Together with other polymers, which help cardiac patients recover more quickly, etc., we can look forward to a new heyday for the wonder material of plastic. This time, plastic will not only ease our everyday lives, but also improve our health.