COVID-19 Disinfectants: Pacific Northwest National Laboratory Invents Antiviral Superhydrophobic Coating For Healthcare Usage Such As On PPEs, Gloves Etc
: PNNL or Pacific Northwest National Laboratory has created a new superhydrophobic material, called ElastiDry that repels bacteria and viruses.
Water beads off ElastiDry due to the substance’s superhydrophobocity.
Image credit: Andrea Starr | PNNL
PPEs or personal protective equipment has been at the center of the fight against COVID-19. The unforgiving coronavirus has shown healthcare professionals the essential importance of top-of-line products.
As a result of the dire need, the super-liquid-repellent substance called ElastiDry may soon be entering the marketplace very shortly.
Materials scientist from PNNL, Dr Curtis Larimer and his co-workers spent two years researching, testing, and retesting potential coatings before developing the formula and process for application. As they planned, the non-toxic product shed liquids with ease. But to the researchers’ pleasant surprise, it did something completely unexpected: it retained its water-shedding properties, even when stretched. And now, ElastiDry is ready for market.
A microscopic silica plays a role in the ElastiDry formula.
Image credit: Andrea Starr | PNNL
Medical and surgical gloves are one of the primary uses Dr Larimer and colleagues envision for their superhydrophobic (“water fearing”) material. The liquid-shedding performance displayed in the laboratory could prevent an infection of a nurse, physician, and others in a health-care setting. Surgical gloves with ElastiDry could provide the extra protection that health-care professionals have sought while guarding themselves against the highly contagious virus.
Roughly about 28 billion disposable gloves are used globally each year, primarily in hospitals and medical settings, food preparation and service industries for chemical handling, and in laboratory research settings. Most of these gloves are used once, and only for a short period of time before disposal.
Dr Larimer told Thailand Medical News, “Dollar for dollar there’s no better, more valuable, infection control device than the latex glove. Medical staff interact with the world, and the patients, and everything with their hands. They are going to pick up viruses and bacteria and move them around with their hands. Gloves, especially gloves modified to shed liquids easily, are going to disrupt that mode of transport.”
From the start of ElastiDry’s development, Dr Larimer and colleagues saw other potential applications. ElastiDry could be applied on:
-Tyvek suits and head coverings, as well as boots or aprons made from rubber.
Medical devices, walls, or bedding in a health care setting.
at contact food in food preparation and service industries.
-Pipets, beakers, or tubing that transfer biomaterials and hazardous chemicals in industrial and scientific research settings.
When the Ebola virus was ravaging parts of West Africa and a handful of cases had been reported in the United States in October 2014, PNNL officials called an urgent meeting, canvassing researchers for ideas to respond to the often-fatal disease. Dr Larimer, who’d joined the laboratory as postdoctoral fellow, had been working with colleagues to develop slippery coatings.
ElastiDry’s developers believe the substance could be of help to
first responders. Image credit: Andrea Starr | PNNL
Using seed funding from PNNL’s Office of Technology Deployment and Outreach, Dr Larimer launched into the project in late 2014.
It was water repellent examples in nature influenced Dr Larimer, such as the back of the Namib Desert beetle, the legs of the Gerridae water strider and, most importantly, the nanoscale texture of a lotus leaf. Intrigued with the way water droplets beaded on its leaves, Larimer purchased a lotus plant at a local garden shop to assist in laboratory testing.
Dr Larimer built his water-shedding idea on previous theories of repellency. In 1805, Thomas Young explored the relationship between a liquid and flat surface; in 1936, Thomas Wenzel developed an equation illustrating the relationship between liquids and rough, flat surfaces; and in 1944, researchers A.B.D. Cassie and S. Baxter focused on liquid behavior on surfaces that were rough and had air gaps.
Dr Larimer was interested in creating a hybrid of the Wenzel and Cassie-Baxter formulas to create a material that retained its superhydrophobic properties even when stretched.
In order to create the new material, Larimer experimented with mixtures containing hydrophobic silica, a microscopic particle derived from sand that’s a common ingredient in a variety of products, including paints, plastics, and coatings.
Dr Larimer told Thailand Medical News, “We tested dozens of different particles over the course of a year,” We tested for particle size, for microscopic chain length, for surface chemistry for all these things.”
Since silica resisted mixing with water-based latex emulsions, the researchers instead applied the silica to drying latex with a high-velocity sprayer. They practiced on a latex glove they produced in the laboratory.
Dr Larimer said, “When the latex glove comes out of a vat, it’s essentially the film it’s going to end up being. But it’s still a canvas we can paint on. The idea is that exactly at that point, we step in, bombard the surface with fibers, embedding them. And then we let the whole glove dry and remove it from the mold.”
The team found that one of the time-consuming tasks was determining the amount of silica fibers to be dispensed and at what velocity.
Dr Larimer said,“That took a lot of time. We did a lot of studies where we varied how much time we waited from when we applied the liquid latex to when we applied the silica solution.”
Importantly, applying on a wet surface was too early; waiting five minutes or more was too much time.
Dr Larimer added, “But there was this sweet spot, in the one to two minutes after it’s been taken out. We figured out the timing. And then we did a lot of studies where we changed the concentration of the particles in a solvent.”
The team were surprised to find that the super hydrophobicity increased when the material was stretched, which wasn’t expected, and later discovered the increased repellency resulted from a change in the surface’s structure as it is stretched.
The Patent and Trademark Office in United States approved the ElastiDry patent at about the same time COVID-19 began claiming its first victims in the United States and Dr Larimer naturally thought of how the superhydrophobic substance could play a timely role in thwarting the pandemic’s impact.
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