A versatile method for the surface tailoring of cellulose nanocrystal building blocks by acylation with functional vinyl esters

Herein we propose a versatile method for the surface tailoring of cellulose nanocrystals (CNCs) based on the reactivity of vinyl ester molecules toward the accessible hydroxyl groups located at the surface of the nanoparticles. CNCs produced from wood pulp were acylated in various conditions, with potassium carbonate as catalyst and under microwave activation. The impact of solvent, temperature and reagent concentration on the reaction efficiency and kinetics was then investigated, using vinyl acetate as a model vinyl ester. Results indicated that the chemical reactivity was significantly influenced by the quality of the CNCs dispersion in the solvent of reaction, the ratio of reagent relative to the CNCs surface OH groups, the diffusion of reagent and catalyst within the CNCs aggregates, and the different nucleophilic strengths of the surface hydroxyl groups. The versatility of the method was verified by extending the reaction to a selection of vinyl esters bearing various functionalities.