Scientists, including one of Indian origin, have developed super slippery packaging that lets consumers squeeze out every last drop of a product, and could significantly cut down food wastage. Food left behind in plastic packaging contributes to the millions of pounds of perfectly edible products being wasted every year. These small, incremental amounts of sticky foods like condiments, dairy products, beverages, and some meat products that remain trapped in their packaging can add up to big numbers over time, even for a single household.
Researchers from Virginia Tech in the US aim to cut down on that waste with a novel approach to creating super slippery industrial packaging. The study, published in the journal Scientific Reports, establishes a method for wicking chemically compatible vegetable oils into the surfaces of common extruded plastics. Not only will the technique help sticky foods release from their packaging much more easily, but for the first time, it can also be applied to inexpensive and readily available plastics such as polyethylene and polypropylene.
These hydrocarbon-based polymers make up 55 per cent of the total demand for plastics in the world today, meaning potential applications for the research stretch far beyond just ketchup packets. They are also among the easiest plastics to recycle. “Previous SLIPS, or slippery liquid-infused porous surfaces, have been made using silicon- or fluorine-based polymers, which are very expensive,” said Ranit Mukherjee, a doctoral student at Virginia Tech.
“But we can make our SLIPS out of these hydrocarbon-based polymers, which are widely applicable to everyday packaged products,” said Mukherjee. First created by Harvard University researchers in 2011, SLIPS are porous surfaces or absorbent polymers that can hold a chemically compatible oil within their surfaces via the process of wicking. These surfaces are not only very slippery, but they’re also self-cleaning, self-healing, and more durable than traditional superhydrophobic surfaces.
In order for SLIPS to hold these oils, the surfaces must have some sort of nano- or micro-roughness, which keeps the oil in place by way of surface tension. However, current SLIPS that use silicone- and fluorine-based absorbent polymers are not attractive for industrial applications due to their high cost, while the method of adding roughness to surfaces can likewise be an expensive and complicated process.
“Not only are we using these hydrocarbon-based polymers that are cheap and in high demand, but we don’t have to add any surface roughness, either,” said said Jonathan Boreyko, an assistant professor at Virginia Tech. “We actually found oils that are naturally compatible with the plastics, so these oils are wicking into the plastic itself, not into a roughness we have to apply,” he said.
“We use natural oils like cottonseed oil, so there are no health concerns whatsoever,” he added. While the method has obvious implications for industrial food and product packaging, it could also find widespread use in the pharmaceutical industry. The oil-infused plastic surfaces are naturally anti-fouling, meaning they resist bacterial adhesion and growth.