Cellulose nanocrystals: A layered host candidate for fabricating intercalated nanocomposites

The stacking of cellulose chains along planes and weak intersheet interactions make cellulose nanocrystals (CNCs) promising as a layered host candidate for fabricating intercalated nanocomposites. As a proof-of-concept, we demonstrate the intercalation of alkyls into CNCs through the in situ intercalative chemical reaction between terminal groups of N-octadecyl isocyanates and hydroxyl groups on the (200) planes in CNCs. Results showed that CNCs could intercalate alkyls in a high degree of substitution to form dense brushes on their (200) planes. After intercalation, a significant enlargement of interlayer spacing was observed. Moreover, alkyls were fully extended in all-trans configuration and crystallized in a co-existing organization of α_H, β_H and β_O crystalline forms. This meant that the molecular arrangement in CNCs/alkyl intercalated nanocomposites would involve a bilayer model in which alkyls were in the ordered packing and titled to (200) plane. Furthermore, CNCs/alkyl intercalated nanocomposites possessed increased thermal properties and decreased char residue.