Hydrophobic Surface Modification of SO42–/TiO2 Solid Acid for Enhanced Catalytic Cellulose Acetylation

The generally low reaction efficiency of solid-acid-catalyzed cellulose acetylation limits the development of green production technologies for cellulose acetate. Recognizing that the hydrophobicity of acetylated cellulose increases as hydroxyl groups are progressively substituted by acetyl groups, the preset work introduces a novel strategy to increase the contacts between SO₄^2–/TiO₂ solid acid and acetylated cellulose with a low degree of substitution (DS) by modulating the surface properties of the solid acid for an efficient acetylation reaction. Catalytic results indicate that surface modification using vinyltrimethoxysilane (VTMS) can significantly improve the catalytic performance of SO₄^2–/TiO₂ in cellulose acetylation, with both the DS value and yield of the resulting cellulose acetate surpassing those catalyzed by H₂SO₄ under equivalent acidic conditions. Systematic characterizations demonstrate that surface modification using VTMS can enhance the interaction strength between VTMS-SO₄^2–/TiO₂ and low-acetylated celluloses, thereby sustaining effective acetylation to achieve cellulose acetate with a high DS value.