A new polymer extends the shelf life of food and pharmaceutical products

The finding resulted from a nanotechnology-based method designed to block the passage of harmful gases through a polymer, thereby helping to strengthen it while using less material

A new discovery from Case Western Reserve University may help extend the safety and freshness times of food products and drugs and the drying and safety of electronic equipment - all at low cost. The finding resulted from a nanotechnology-based method designed to block the passage of harmful gases through a polymer, thereby helping to strengthen it while using less material. The findings were published in the February issue of the scientific journal Science.

"This research takes us a big step toward developing more flexible and transparent polymeric barriers for a number of different applications," said Anne Hiltner, lead author of the paper and a professor of science and engineering at the university.

The discovery was a completely accidental finding, according to the researcher. The researchers discovered that when it is confined as nanolayers, the material polyethylene oxide (PEO) crystallizes as a monolayer, while organizing itself into large impermeable single crystals, which reduce up to a hundred times the amount of gas that is able to penetrate through them in all types of established applications on polymers. When the moldable polymer was limited to such tiny layers, the researchers were surprised to find that it self-organizes into an almost perfect crystalline packing of the polymer chains within each of these thin layers, explains the researcher.

Crystalline regions in polymers are complexes in which the atoms in the polymer chains are arranged side by side in an orderly, rigid and defined pattern, similar to water droplets that line up perfectly in ice (which is a crystal of water). Since the atoms are placed very close to each other in an ordered pattern, crystalline complexes of polymers do not allow the passage of gases, even the smallest of their kind, such as oxygen or carbon dioxide. Therefore, crystalline complexes of polymers reduce the permeability of gases through them - that is, these complexes improve the barrier properties of polymers.

This self-organization of the polymer melt into large, nearly perfect single crystals has never been observed before, the researchers note. "The ability to produce kilometers of layers containing polymer single crystals is unprecedented," said the lead researcher.

Crystalline polymers, such as polyethylene, polypropylene and nylon, are widely used as coatings against gases in the fields of food products, medicine and electronic component packaging and are common materials due to their low production cost, easy processing and mechanical strength.

Thanks to the use of an innovative and advanced process in which two polymers are fused together as layers and then multiplied into four layers and continue to be multiplied by whatever number we want later, the researchers were able to notice the emergence of a new structure in the form of defined polyethylene oxide layers that continue to become thinner and thinner while saving the amount of material.

Polymers are already used today in many applications where their ability to maintain a sealed package is essential to the performance of the application itself, such as in the packaging of medicines and food products. However, there are modern technologies, such as flexible electronic displays, in which the sealing of contemporary polymers does not satisfy the requirements of the application. The researchers hope that their new method can provide a suitable solution for these applications.

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