Cellulose nanocrystals (CNCs) are nanometer-sized rod-like particles, which are increasingly considered as nanoscale building blocks for the elaboration of functional materials with applications in areas as diverse as biotechnology, electronics, optics, energy, packaging or catalysis. The potential benefits of these nanoparticles rely in particular on their high strength, low abrasiveness, high aspect ratio, biocompatibility and inclination for chiral nematic ordering. The application field is a priori vast, but the engineering of innovative functional materials from CNCs requires a fine control of their self-assembling properties and interaction with surrounding materials or in-use environment. This control is generally achieved by chemical functionalization of the CNCs surface, in particular using reactions based on alcohol chemistry. In this context, we report a versatile method for the surface tailoring of CNCs building blocks by acylation with functional vinyl esters. CNCs decorated with different chemical functionalities were accordingly prepared by reacting the nanoparticles with a selection of vinyl esters bearing various functionalities. Reactions were performed in various solvents (DMF, DMSO or water) and monitored by FT-IR and 13C CP-MAS NMR spectroscopy. The impact of the treatment on the supramolecular structure of the CNCs was controlled by atomic force microscopy (AFM) and X-ray diffraction (XRD). The potential of acylated CNCs as nano-filler in PDMS matrices or Pickering surfactant was later investigated. For some of the surface treatments, the incorporation of low amounts of CNCs in PDMS aerospace coatings was found to improve significantly the thermal and photo-stability of the composites. The tuning of the hydrophilic/hydrophobic balance at the CNCs surface by the acylation method also allowed preparing stabilized monomer-in-water Pickering emulsions, which could be subsequently polymerized to form micro and nano polymer beads with low dispersity.

Control of the surface properties of cellulose nanocrystals by acylation with functional vinyl esters: Application to the design of innovative fillers or Pickering surfactants

253rd National Meeting (2017)

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