Hydrophobization of lignocellulosic materials part II: chemical modification

Abstract Lignocellulosic materials with hydrophobic properties are of great interest for developing sustainable products that can be used in various applications such as packaging, water-repellent and self-cleaning materials, oil and water separation or as reinforcements in biocomposite materials. The hydroxyl functional groups present in cellulose provide the possibility to perform various chemical modifications to the cellulosic substrates that can increase their hydrophobicity. This review is the second part of a comprehensive review on hydrophobization of lignocellulosic materials and summarizes the recent advances in the chemical modification of such substrates. The methods described in this review can provide changes in the hydrophilicity of the materials that range from a small decrease in the initial hydrophilicity of the substrate (contact angles below 90°) to superhydrophobic properties (contact angles above 150°). Additional attention has been paid to whether the modification is limited to the surface of the substrate or if it occurs in the bulk of the material. We also discuss hydrophobized cellulose material applications in packing and oil/water purification. Graphical abstract