The disclosure relates to a novel process for functionalizing NCC, a method for producing amine-cured epoxy-based nanocomposites through the use of said functionalized NCC, and nanocomposites thereof. The process for functionalizating NCC comprises providing a mixture of NCC and one or more monomers. The mixture is suitable for free radical polymerization and the monomer is cross-linkable with epoxy and is aqueous soluble. The polymerization takes place in the presence of a free radical initiator and oxygen is purged from the mixture and the initiator solution. The epoxy-based nanocomposite is produced by mixing the funtionalized NCC with an amine-curable epoxy resin and a hardener, in a solvent, and allowing the mixture to cure.