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

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 13C 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