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Fall 2018

Sticky Science: Turning Plant Waste into Tape’s Adhesive

Chemical engineers stick together to develop adhesive materials from waste wood pulp

Angela Norton

Chemical engineers combine their skill sets to convert lignin from biomass into sticky adhesives! Image: Nathan Johnson, Pacific Northwest National Lab

At the National Air and Space Museum in Washington, D.C., visitors have the unique opportunity to experience what it is like to live on the International Space Station through a motion-based virtual reality model. Similar to how we use models to mimic space, chemists and engineers use “model” compounds to mimic those found in complex feedstocks, such as waste wood pulp and other forms of biomass. These model compounds are well-developed and convenient, but they still leave us wondering: Can we make valuable products from actual biomass?

For the first time, chemical engineers at the Catalysis Center for Energy Innovation (CCEI) Energy Frontier Research Center have taken on this question. They designed a catalyst and created the right conditions to turn lignin from wood pulp into pressure-sensitive adhesives, or PSAs.

Defining PSAs and lignin

PSAs are the sticky materials that bind objects together, and they are often put to work in practical applications—labels, plastic wrap, even bandages. Lignin is a substance found in plants and trees. We usually discard it when processing wood in the pulp and paper industry.

From waste to adhesive

Lignin is an excellent starting material to make adhesive products. It is inexpensive, abundant, and renewable. In addition, lignin is a natural polymer, meaning it contains a large number of similar subunits, or monomers, bounded together. Because adhesives only require a specific subunit, lignin must be broken down through a process called depolymerization.

Depolymerization occurs much faster in the presence of a catalyst than without one. In fact, chemical engineers at CCEI with expertise in catalysis have determined that ruthenium metal supported on carbon (Ru/C) is suitable for lignin depolymerization. In addition, Ru/C is commercially available.

Once lignin has undergone depolymerization, another group of chemical engineers with expertise in studying materials adds designer molecules to give the depolymerized-lignin intermediate the appropriate structural properties found in adhesives. The engineers then “seal the deal” by stringing together the intermediate and creating a new solution.

Cast the solution onto a 50-micrometer-thick sheet, and the adhesive is almost ready to go!

All that’s left is to test adhesion performance. And as it turns out, these biomass-derived adhesives are just as competitive (and sticky!) as FisherbrandTM labeling tape and Scotch® MagicTM tape, demonstrating the practical significance of these biomass-derived adhesives.

Summing up a sticky science

Seemingly impossible problems, such as making valuable products from actual biomass, are, in fact, possible, especially when researchers with different expertise collaborate. Furthermore, this work just goes to show the breadth of chemical engineering. Bioengineering, catalysis, materials—these are just a few of the cool areas you can pursue as a chemical engineer!

More Information

Wang S, S Li, B Saha, VG Vlachos, and TH Epps III. 2018. “From Tree to Tape: Direct Synthesis of Pressure Sensitive Adhesives from Depolymerized Raw Lignocellulosic Biomass.” ACS Central Science 4(6):701. DOI: 10.1021/acscentsci.8b00140

Acknowledgments

The biomass deconstruction and monomer production work was conducted by L.S., B.S., and D.G.V. and was supported financially by the Catalysis Center for Energy Innovation, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences. The polymer synthesis and characterization work was performed by S.W. and T.H.E. and was supported financially by a National Science Foundation grant to T.H.E. The University of Delaware nuclear magnetic resonance facility and solids analyzer were supported by the Delaware Center of Biomedical Research Excellence program with a grant from the National Institutes of Health.

About the author(s):

  • Angela Norton is a Ph.D. candidate in chemical and biomolecular engineering at the University of Delaware. She is a member of the Catalysis Center for Energy Innovation (CCEI) Energy Frontier Research Center working under the advisement of Dionisios Vlachos, director of CCEI. Her research focuses on studying how catalysts play a role in converting biomass to fuels and chemicals.

Sealing the Deal on Wood Waste to Tape Adhesive

Researchers create the sticky side of tape from plant matter, potentially greening up tape

Chemical engineers combine their skill sets to convert lignin from biomass into sticky adhesives! Image: Joy Smoker, University of Delaware

Tape’s sticky adhesive is typically made from petroleum-derived chemicals. But what if there was a better way? What if the chemicals could come from industrial waste? Chemical engineers at the Catalysis Center for Energy Innovation (CCEI) Energy Frontier Research Center took on these questions. They showed, for the first time, a way of producing adhesives directly from lignin, part of wood pulp waste produced by the paper industry. The team’s method breaks apart the lignin into smaller units. They then added designer molecules to each unit. They attached the units together. Finally, they cast it onto sheets. Their plant-derived adhesive is just as competitive (and sticky!) as commercial tapes. The CCEI is led by the University of Delaware.

More Information

Wang S, S Li, B Saha, VG Vlachos, and TH Epps III. 2018. “From Tree to Tape: Direct Synthesis of Pressure Sensitive Adhesives from Depolymerized Raw Lignocellulosic Biomass.” ACS Central Science 4(6):701. DOI: 10.1021/acscentsci.8b00140

Disclaimer: The opinions in this newsletter are those of the individual authors and do not represent the views or position of the Department of Energy.