The creation of nanocomposites is one of the promising technologies for adapting the mechanical and barrier properties of biobased and biodegradable polymers to the requirements of commodity products such as food packaging.
The Panagro project aimed at the creation of fully organic nanocomposites by the distribution of cellulose nanocrystals (CNC) inside polylactide (PLA). Compatibility between nanocharges and polymer is one of the challenges in the development of nanocomposites. The Panagro project proposed rise to this challenge in designing the cellulose nanocrystals surface with a double functionality, insuring compatibility and modifying barrier properties of the nanocomposites towards organic vapours.
Two versatile surface grafting methods respecting the principles of green chemistry were developed and aromatic molecules were grafted using ozone activation, radical initiation and grafting of the surface in aqueous solvents, or using the reactants as solvents be in situ solvent exchange. The increase of compatibility of PLA and CNC was evidenced by the increase in rubbery storage modulus of nanocomposites and constant gas barrier properties. The permeability of the aromatic probe anisole was decreased due to the distribution of CNC inside PLA and was in addition decreased by the interaction with the aromatic surface grafts.