Exploring the potential of gas-phase esterification to hydrophobize the surface of micrometric cellulose particles

• Gas-phase esterification was applied on a hundred grams of micrometric cellulose particles. • Cellulose particles were hydrophobized without degrading intrinsic cellulose structure. • A degree of substitution as low as 0.01 was enough to hydrophobize cellulose. In order to lift the barrier of a poor interfacial interaction between cellulosic plant fibers and polymeric matrices in biocomposites, an eco-friendly surface modification of fibers was explored. A solvent-free gas-phase esterification applied to cellulose particles allowed to graft palmitoyl moieties on their surface in order to make them more compatible with non-polar polymers for composite applications. The efficiency of the treatment was evidenced from FT-IR analysis, and the degree of substitution (DS) was quantified by solid-state 13 C NMR spectroscopy. The effect of surface grafting on resulting intrinsic characteristics of cellulose particles, i.e. crystallinity, thermal stability, morphology, surface free energy and water vapor sorption were investigated respectively by X-ray diffraction, thermogravimetric analysis, SEM observations coupled with image analysis, contact angle measurements and dynamic vapor sorption system (DVS). It was shown that a DS as low as 0.01 was enough to drastically increase the hydrophobicity of cellulose particles without affecting the inner properties of cellulose.