Tough, clear coating uses natural oils to kill viruses and bacteria

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Though there is are coatings that kill harmful microbes on frequently touched surfaces, most of these substances must be reapplied frequently or they take a long time to work. A new durable coating, however, is claimed to fill both gaps.

Developed at the University of Michigan, the material consists of commonly used polyurethane plastic combined with tea tree oil and cinnamon oil. All ingredients are already known to be safe for humans.

While still in liquid form, the substance is either brushed or sprayed onto objects such as doorknobs or touch screens. Once it dries, it forms a tough, transparent coating that is said to be very effective at killing bacteria and viruses.

Some of the tea tree and cinnamon molecules are cross-linked to the polyurethane molecules – holding them permanently in place within the plastic matrix – while others are free to move between this matrix and the coating surface. That said, the free molecules generally tend to stay with the cross-linked ones, reducing the rate at which the oils evaporate. When microbes come into contact with the coating, however, the free molecules kill them by penetrating their protective outer membranes – and they do so in about two minutes.

In tests conducted on surfaces such as keyboards, smartphone screens and cutting boards used to cut chicken, the coating remained effective for at least six months, killing 99.9% of pathogens, including E.coli, MRSA and the SARS-CoV-2 virus responsible for Covid-19. It did so even though those surfaces had been repeatedly cleaned and abraded.

As a bonus, once the effectiveness wanes as the oils begin to evaporate, the coating can be “recharged” simply by wiping it down with fresh tea tree and cinnamon oils – these are absorbed by the polyurethane matrix.

Examples of antimicrobial performance of the coating when applied to various surfaces

University of Michigan

“Disinfectant cleaners can kill germs in just a minute or two, but they dissipate quickly and leave surfaces vulnerable to reinfection,” said Professor Anish Tuteja, corresponding co-author of a paper on the research. “We have durable antibacterial surfaces made from metals like copper and zinc, but it takes hours to kill bacteria. This coating offers the best of both worlds.”

Spin-off company Hygratek is now commercializing the technology. The article was recently published in the journal Question.

Source: University of Michigan Going through Eurek Alert

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