Plant-Based Protective Coating Provides Alternative to Synthetic Options

A chair applied with lignin. Photo courtesy of Fotoni Film & Communications.

Researchers from Alto University (Espoo, Finland) have developed a safe, high-performance coating made from lignin, a complex organic polymer found in the support tissues of most plants. According to the researchers, this bio-based coating outperforms traditional synthetic options in its ability to resist abrasion, stain, and sunlight.

The results of this research were published in the July 15 edition of ACS Applied Materials & Interfaces.

In order to meet global sustainability standards, many countries are looking to construct buildings that replace concrete with wood. Because wood is prone to degradation when exposed to sunlight and moisture, researchers like those at Alto University have been working to create protective coatings that can help bring wood into wider use.

“Our new coating has great potential to protect wood,” explains Alexander Henn, doctoral candidate at Aalto University, The School of Chemical Engineering. “It's more water repellent than a lot of commercial coatings because it retains the natural structure of wood and its micro-scaled roughness. Since it's hydrophobic, the coating is also quite resistant to stains, while lignin’s inherent structure resists colour changes from sunlight. It also does an excellent job of retaining wood’s breathability.”

Currently, many protective coatings options for materials such as wood, concrete, metals, and composites have deficiencies that limit their wide use. For instance, many petroleum-based coatings include substances that are harmful to the environment, while vegetable-oil coatings made from tall, linseed, coconut, soybean, and castor lack durability and are often combined with synthetic materials to improve their performance.

By contrast, more sustainable, non-toxic alternatives have the potential to be both effective and help meet safety and environmental regulations. While lignin is often regarded as a waste product of pulping and biorefinery processes, it has several beneficial properties. However, poor solubility and mediocre performance have limited its commercial applications thus far.

“Lignin as a coating material is actually very promising with its many benefits compared to the synthetic and bio-based coatings currently used,” says Monika Österberg, head of the Department of Bioproducts and Biosystems at Aalto University. “It has excellent anti-corrosion, anti-bacterial, anti-icing, and UV-shielding properties. Our future research will concentrate on developing characteristics like elasticity of the coating.”

Source: Alto University,