Preparation and characterization of functionalized cellulose nanocrystals.

•Functional cellulose nanocrystals were produced by combining acid hydrolysis and Fischer esterification with various organic acids.•Functionalities such as ATRP-initiator, allyl, alkyne and thiol groups were incorporated.•The degree of substitution varied between 0.06 and 0.27, depending on the organic acid utilized.•The ATRP-initiator functionalized cellulose nanocrystals were grafted by MMA with ATRP.•Characterization and efficiency of various functional cellulose nanocrystals were also investigated in this study.