Enhanced hydrophobicity and thermal stability of hemicelluloses by butyrylation in [BMIM]Cl ionic liquid

Abstract

To enhance the hydrophobicity and thermal stability of hemicelluloses for the production of functional biopolymer, hemicelluloses was homogeneously butyrylated with butyryl chloride in 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) ionic liquid using triethylamine as a neutralizer. This efficient method to prepare butyrylated hemicelluloses was confirmed by FT-IR, 1H, and 13C NMR spectroscopies. The results showed that the biopolymers with degrees of substitution (DS) between 0.91 and 1.89 were accessible in this completely homogeneous system by changing reaction conditions. The preferred reaction parameters that resulted in the highest DS (1.89) were as follows: 2:1 molar ratio of butyryl chloride to hydroxyl groups, 90°C, and 120min. The hydrophobicity and thermal stability of the prepared hemicellulosic derivatives were investigated by thermogravimetric analysis (TGA). The results indicated that the hydrophobicity of the butyrylated hemicelluloses was increased by increasing the value of DS. The thermal stability of the butyrylated hemicelluloses was increased while the derivative with a high DS value and decreased with a low DS value. The enhanced hydrophobicity and thermal stability of the butyrylated hemicelluloses with a high DS value make it beneficial for the production of functional biopolymer.