Valorization of Tree Bark-Derived Suberin in Applications for the Bio-Based Composites Industry–A Recent Review

Bark extracts are sustainable sources of biopolymers and hold great promise for replacing fossil fuel-based polymers, for example, in wood-based composites. In addition to primary and secondary metabolites, tree bark also contains suberin, which plays a major role in protecting the tree from environmental conditions. Suberin is a natural aliphatic-aromatic cross-linked polyester present in the cell walls of both normal and damaged external tissues, the main component of which are long-chain aliphatic acids. Its main role as a plant ingredient is to protect against microbiological factors and water loss. One of the most important suberin monomers are suberin fatty acids, known for their hydrophobic and barrier properties. Therefore, due to the diverse chemical composition of suberin, it is an attractive alternative to hydrocarbon-based materials. Although its potential is recognized, it is not widely used in biocomposites technology, including wood-based composites and the polymer industry. The article will discuss the current knowledge about the potential of suberin and its components in biocomposites technology, which will include surface finishes, composite adhesives and polymer blends.