The minute amounts of ketchup that won’t come out of its bottle, the last sips of a beverage that stubbornly cling to its container — these all contribute to the waste of plastic-packaged food waste.

Slippery liquid-infused porous surfaces (SLIPS) were engineered in 2011 by Harvard University researchers as inexpensive, super-repellent packaging materials to protect objects from liquids, excessive temperatures and bacteria. Building on this development, a team from Virginia Polytechnic Institute and State University established a method for wicking chemically compatible vegetable oils, such as cottonseed oil, into the surfacesOn dry films (top images), sliding ketchup leaves behind considerably more residue than on infused films (bottom). Source: Virginia Polytechnic Institute and State UniversityOn dry films (top images), sliding ketchup leaves behind considerably more residue than on infused films (bottom). Source: Virginia Polytechnic Institute and State University of common extruded plastics. The technology will help sticky foods release from their packaging much more easily, and is applicable to inexpensive and readily available plastics such as polyethylene and polypropylene.

SLIPS must have some sort of nano- or micro-roughness to keep the vegetable oils in place by way of surface tension. The required roughness can be achieved by texturizing the material with a type of applied coating, or by using an absorbent polymer to fabricate the surface material.

However, available SLIPS composed of silicone and fluorine-based absorbent polymers are not cost-competitive for industrial applications, and the method of adding roughness to surfaces also poses economic and process constraints.

By using low-cost hydrocarbon-based polymers, the researchers aren’t faced with the need to add any surface roughness. The oils wick into the plastic itself, negating the need for this extra process step.

Oil-impregnated films were observed to remain slippery even after several weeks of being submerged in ketchup, illustrating their extreme durability. The method has obvious implications for industrial food and product packaging, and the naturally anti-fouling oil-infused plastic could also find widespread use in the pharmaceutical industry.

Scientists from Bemis North America also contributed to this study, which is published in Scientific Reports.

To contact the author of this article, email shimmelstein@globalspec.com