Wood is one of the earliest used construction materials in human history, and exhibits great strength in relation to its weight. However, such excellent material faces challenges in durability when it encounters moisture, heat, sunlight, various organisms, etc. (De Meijer 2001). One way to address this problem is to apply a layer of protective coating on the wood product, which is expected to insulate the wood from the surrounding environment, and further prolong the lifetime of related wood products. However, wood protective coatings are often dissolved or dispersed in organic solvents, some of which contain hazardous compounds like ethylbenzene, xylene, formaldehyde, and heavy metals, which can have a negative impact on human health and the surrounding environment (Teacă et al. 2019).
Inspired by the natural barrier properties of tree bark, we want to use it as a resource for developing a green wood-protective coating that can resist harsh conditions in outdoor environments(Garcia et al. 2014; Niu et al. 2022). Tree bark can be chemically fractionated into different compounds, here we mainly focus on the suberinic acids and polyphenols which were fractionated from birch outer bark and spruce bark respectively (Heinämäki et al. 2017)(Makars, Rizikovs, and Paze 2022; Rizhikovs et al. 2022). In this work, our approach to obtaining a stable waterborne coating is preparing hybrid particle dispersion of suberinic acids and condensed tannins through the solvent exchange method previously described with mixtures of lignin with fatty acids (Sipponen et al. 2020). By doing this, the relatively more hydrophilic tannins tend to form a hydrophilic shell around the more hydrophobic fatty acids in a core-shell structure, which helps prevent the phase separation of such oil-in-water emulsions. The resulting dispersion can be cured at a certain temperature to obtain a protective coating on wood substrates.
Keywords: wood coating, tree bark, suberinic acids
Authors
Fengyang Wang
Department of Materials and Environmental Chemistry, Stockholm University, SE-10691, Stockholm, Sweden
Mohammad Morsali
Department of Materials and Environmental Chemistry, Stockholm University, SE-10691, Stockholm, Sweden
Deparment of Materials and Environmental Chemistry, Wallenberg Wood Science Center, Stockholm University,
SE-10691, Stockholm, Sweden
Ievgen Pylypchuk
Department of Materials and Environmental Chemistry, Stockholm University, SE-10691, Stockholm, Sweden
Aji P. Mathew
Department of Materials and Environmental Chemistry, Stockholm University, SE-10691, Stockholm, Sweden
Mika Sipponen
Department of Materials and Environmental Chemistry, Stockholm University, SE-10691, Stockholm, Sweden
Deparment of Materials and Environmental Chemistry, Wallenberg Wood Science Center, Stockholm University,
SE-10691, Stockholm, Sweden
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