Cellulose nanocrystals: A layered host candidate for fabricating intercalated nanocomposites

• Published in: Carbohydrate polymers 2017-02, Vol.157, p.79-85
• Main Authors: Guo, Juan, Du, Wenbo, Wang, Siqun, Yin, Yafang, Gao, Yong
• Format: Article
• Language: English
• Subjects: Cellulose nanocrystals; Intercalation; Molecular structure; Thermal properties; X-ray diffraction
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2016.09.065

•CNCs a layered host candidate for fabricating intercalated nanocomposites.•Alkyls are intercalated into CNCs through in situ intercalative chemical reaction.•The interlayer spacing in CNCs was enlarged significantly after intercalation.•Intercalated alkyls were fully extended in all-trans configuration and crystallized. 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 αH, βH and βO 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.