This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Mistletoe is best known from winter traditions as a symbol of luck and affection. For trees, however, the hemiparasitic plant can be a burden: It draws water and nutrients from its hosts.
Now the plant could provide a sustainable alternative to petroleum-based industrial adhesives. Researchers led by Oliver Lieleg, professor of biopolymer materials at TUM, have developed an adhesive based primarily on a natural sugar mixture from mistletoe berries. The fully bio-based glue, which is supplemented with tannic acid and malic acid, bonds various materials including wood, metal, glass and Teflon.
Of particular interest is its ability to be reactivated several times by applying heat after a bonded joint has been separated. In the future, this could make repairs and recycling easier, for example in electronic devices. The researchers were also able to avoid petrochemical components and synthetic pretreatments of the starting materials.
"Many bio-based adhesives are either not strong enough or require elaborate chemical processing," says Dr. Ufuk Gürer, first author of the study published in Advanced Materials. "Our approach uses a natural raw material with exceptional adhesive properties and works with comparatively simple ingredients." The inspiration came from nature itself: Mistletoe seeds use a sticky substance to attach to branches, allowing the plant to colonize new host trees.
In tests, the adhesive achieved high strength on a range of materials, including birch wood, stainless steel, aluminum and glass. Even on Teflon, which is difficult to bond because of its nonstick surface, the formulation produced load-bearing joints. The bio-based adhesive reached shear strengths of more than 10 megapascals in some tests, placing it within the range of technical structural adhesives.
The adhesive maintains bonding performance under extremely cold conditions at -150°C (-238°F) and can also be detached and reactivated by heating to around 90°C (194°F). According to the researchers, this could make the material useful for electronic devices in the long term. Displays, housings or other glued components could be replaced more easily without damaging the parts.
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