In the current context of sustainability, there is a growing interest in developing novel functional materials based on sustainable bioresources. In particular, cellulose nanocrystals (CNC) are nanometer-sized particles, which can be easily recovered from cellulosic substrates (wood pulp, microcrystalline cellulose…) by sulfuric acid treatment. Because of their high specific strength, modulus and aspect ratio, CNC can significantly improve the mechanical performances of polymers, at low loading levels. They can also serve as stabilizing agents in Pickering emulsions, as matrix for the preparation of aerogels or foams, or as templating agents. But to realize the full potential of these applications, the CNC surface must be tuned by appropriate functions to control its dispersive, interfacial and self-assembling properties.<br/>In this context, a novel and straightforward method for the surface esterification of CNC by transesterification of vinyl esters is proposed. The reaction of vinyl esters with the CNC hydroxyl groups was examined in different solvents, with potassium carbonate as catalyst. Reactions were performed under microwave activation and monitored by Fourier transform infrared spectroscopy (FT-IR) and Nuclear Magnetic Resonance (NMR) spectroscopy. The supramolecular structure of the CNC before and after modification was characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM). The thermal stability was evaluated by thermogravimetric analysis (TGA). The dispersibility of the acetylated nanoparticles was examined in various solvents of different polarities, using dynamic light scattering (DLS). The impact of solvent and reaction time on the efficiency of the reaction and nanoparticles integrity will be particularly discussed.

Control of the surface properties of cellulose nanocystals by transesterification of vinyl esters

249th National Meeting (2015)

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