AWARDEES: Kaichang Li

SCIENCE: From Golden Fleece to Golden Glue: The Sea Soy Solution

FEDERAL FUNDING AGENCIES: U.S. Department of Agriculture

Like the Golden Fleece that gave Jason potency in the story of Jason and the Argonauts, the glue holding together the plywood in your kitchen cabinets has mussels to thank for its strength.

While out on the beach crabbing one day, Oregon State University wood chemist Kaichang Li admired the adhesive muscle of mussels, which inspired him to design a new, safer glue for plywood. At the time, nearly all of the plywood used for kitchen cabinets and furniture in homes around the world were made with a formaldehyde-based glue that released gasses that scientists were finding caused cancer. With support from the U.S. Department of Agriculture, Kaichang developed a cost-competitive, soy-based analog to the mussel’s natural glue that has found its way into homes and building material stores around the country.

Working with the largest domestic manufacturer of hardwood plywood panels, Kaichang and his students helped commercialize his bio-inspired invention. In 2006, Columbia Forest Products converted all of its manufacturing to the less harmful glue, and since then, some 60 percent of the plywood and veneer industry has followed suit.

We’re putting what down the drain?

As a young researcher working on a master’s degree in organic chemistry in China in the 1980s, Kaichang Li found some of the local lab practices disturbing. He’d work all day with hazardous organic solvents, and at the end of the day when he asked where to dispose of them, he was told to just pour them down the drain. At the same time, he saw rivers polluted with wastewater runoff. He knew then that he would dedicate his life to finding ways to make this kind of pollution unnecessary.

After doing scientific research in China for a few years, Kaichang came to the United States in 1993 to obtain a Ph.D. in wood chemistry at Virginia Tech and then went on to a postdoctoral position at the University of Georgia. It was at Georgia that his interest in formaldehyde and its use in wood glue was first piqued. Kaichang’s advisor there, while being flushed one day, said to Kaichang, “You think my face is red? Imagine if you were making plywood in the 1950s. All that formaldehyde, you’d be red as a beet.”

Supper or superglue?

One evening in 1999, Kaichang and a friend went out crabbing, looking forward to a tasty shellfish dinner. When they came up empty handed, Kaichang’s friend suggested they get some mussels instead. This was Kaichang’s first brush with the bivalves, and he was immediately struck by one thing: how tightly they clung to rough, unwashed surfaces with unmatched tenacity. He was so fascinated by their superpower, he nearly forgot to eat them for dinner. He did make sure to save some for his lab, where he dove into the existing literature on the mussel’s abilities.

In the literature on mussels, he found a deep well of existing knowledge about marine adhesive proteins (MAPs), the compounds at work in mussels’ super stickiness. Mussels weave these proteins into what are known as byssus threads that connect the mussels to whatever surface they take root on. The proteins have special amino acids on them that make them both sticky and water resistant, two keys to the species’ unique ability at adhesion.

Kaichang and his team knew that mass producing marine adhesive proteins (MAPs), by farming them from mussels or synthesizing them, would be incredibly expensive and never produce the volumes of adhesive at a reasonable cost that industrial producers would accept. They needed a more cost-effective solution, so Kaichang chewed over the problem … literally.

One day as he ate tofu at lunch, Kaichang realized the answer had been in front of him all along. Or at least, in his refrigerator. Soy is abundant – it is the second-most planted field crop in the United States – and made largely of proteins.

Proteins are fundamentally just chains of amino acids connected and folded together in different configurations. Kaichang and his team discovered that adding the distinct amino acids crucial to bonding and water resistance in MAP to soy protein converted the soy protein into a superior wood adhesive. Unfortunately, the conversion process was too costly to be commercially viable for making plywood. That did not deter Kaichang, who continued to ponder over how to take advantage of superior MAPs for developing a commercially viable, biologically inspired adhesive.

While teaching a course one day, a thought occurred to Kaichang that led to a central breakthrough: why does a piece of printing paper fall apart when wet, but a thin tissue paper can withstand repeated sneezes without losing all of its strength? The answer? Tissue paper producers add something they creatively call a “wet strength agent.” Kaichang and his students started with the most obvious formula: soy protein, water, and a common, commercially available wet strength agent—and it worked.

With some tinkering, Kaichang and his team perfected their mixture of simple, food grade ingredients and developed a perfectly capable soy-based, bio-inspired adhesive for wood. They filed a patent application in 2002 for their potentially game-changing product. But unless they could get a commercial company to take up the invention, this was little more than that: potential.

“I felt like he was speaking directly to me.”

In 2003, Columbia Forest Products had already spent years looking for a commercially viable alternative to formaldehyde-based glues. A body of evidence was steadily growing that emissions from the urea-formaldehyde glues they and their competitors used had the potential to cause cancer. Consumers wanted a more environmentally friendly product, but they weren’t willing to pay much extra for it.

When Kaichang presented his work at a conference in 2003 in Seattle, WA, the company’s Vice President for Technology, Steve Pung, felt like Kaichang was talking directly to him. Here was a researcher excitedly walking through a recipe for the solution to CFP’s conundrum. Steve approached Kaichang afterwards and basically said, “Can we follow your recipe and do this?”

By the time they left the conference, Kaichang and Steve had agreed to work together to commercialize this soy-based, mussel-inspired glue.

It took quite a bit more than just following the recipe to make Kaichang’s invention work. After all, the floor of a factory is quite a bit different from the lab bench. The factory is open to the outside elements with fluctuating temperatures and people moving in and out carrying potential contaminants. And of course, the processes are subject to human error.

The most obvious thing they had to overcome was the glue’s consistency, which is like peanut butter; the glues CFP had been using were more like water. The company ended up consulting with food companies – which have to move actual peanut butter around factories – and bringing equipment into their process that had never before been used in their industry. Every individual CFP plant presented its own challenges, with its own unique set of equipment and environmental conditions.

Within two years, CFP announced it would remove urea-formaldehyde glues from all of its plants and convert fully to soy-based glue. With over 40 percent of the market share in hardwood plywoods at the time, this move marked a sea change for the plywood panels used in kitchen cabinets and furniture in homes around the country.

For more than ten years, CFP has been formaldehyde-free, and much of the industry has followed suit. Today, as they will tell you, their process for producing formaldehyde-free plywood panels, which they call PureBond technology, is synonymous with CFP. It’s become their brand.

Kaichang and CFP showed that ridding hardwood plywood panels of formaldehyde was not only possible, but commercially viable. Shortly after CFP converted fully to formaldehyde-free production, the state of California put in place its first of a series of regulations on the emissions of formaldehyde gas from composite wood products. And in December 2018, a national standard will go into effect for the first time.

Kaichang and CFP have maintained their partnership since 2003, and today the company has agreed to invest R&D funding in anything Kaichang wants to do. A curious scientist with buckets of ideas—the ultimate golden goose.