Food-derived materials used to make safer, stickier glues

Mimicking materials found naturally in nuts and plants can create strong, non-toxic adhesives.

The Purdue University team chose compounds in foods, like plants, nuts and fruits – all of which might have similar chemistry to the adhesives seen in shellfish that stick to rock – to develop new, non-toxic adhesives for single-use applications.. (Image source: Purdue University)

A research team a Purdue University has taken inspiration from natural food sources to develop new, strong adhesive materials from compounds in nuts, fruits, and plants.

Gudrun Schmidt, an associate professor in Purdue’s College of Science, said the researchers hope their materials can replace the glues currently used in electronics and other consumer products, which are typically made from petroleum-based materials and are toxic to the environment.

“Adhesives are used in almost every consumer product that we touch each day,” Schmidt said in a press statement. “We would love to leave this planet a better place for the future generations. It turns out creating new adhesives is one way that we will get there.”

The team is especially interested in developing more eco-friendly adhesives for single-use products, which are those that produce the most waste and thus could significantly benefit from non-toxic adhesives, researchers said.

High performance without toxicity

The materials the researchers focused on are formed from corn zein protein and tannic acid, according to an abstract for a paper published about the work in the journal Advanced Sustainable Systems.

“High-strength adhesive bonding is found when the formulations are optimized with regard to composition, pH, and curing temperature,” the researchers explained in the abstract.

The team tested the bonding of their adhesive on aluminum substrates using lap shear configurations. In these tests, they reported that adhesives formed from these materials, at maximum adhesion, can be as strong as commercial Super Glue “when measured under similar conditions.”

“Adhesion strengths exceed the minimal bonding of zein‐only controls,” they wrote. “The system forms nanometer and micrometer-sized pores throughout the bulk adhesive.”

A low amount of tannic acid and neutral pH of the strongest adhesive make the materials based on corn zein–tannic acid “potentially appealing” for a number of commercial applications. Those include “adhesives used in packaging, cosmetics, and other single-use applications where biomedical grade purity is not required.”

“We found that some combinations of zein protein and tannic acid could be reacted together in order to generate high-performance adhesives that could be alternatives to carcinogenic formaldehyde used in the glues that hold lots of furniture and other household items together,” Schmidt said in a press statement. “It would be a big health benefit if we could switch over to bio-based or even food-based adhesives.”

Other potential applications for the adhesive materials developed by the team include cardboard packaging, cosmetics, and construction materials like plywood, she added.

Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco and New York City. In her free time she enjoys surfing, traveling, music, yoga and cooking. She currently resides in a village on the southwest coast of Portugal.

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