دانلود رایگان مقاله نانوبلورهای سلولزی کاندید میزبان لایه بندی شده برای ساخت نانوکامپوزیت

ABSTRACT

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 H, H and 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. ©

4. Conclusions

CNCs are an intercalated host candidate, due to their layered structure and the weak intersheet interactions. In this paper, CNCs/alkyl intercalated nanocomposites were fabricated through the in situ intercalative chemical reaction between the terminal groups of N-octadecyl isocyanate molecules and hydroxyl groups on the (200) lattice planes in CNCs. The intercalation of alkyls resulted in a significant enlargement of interlayer spacing, compared with the d-spacing of CNCs (0.39 nm). Moreover, intercalated alkyls were fully extended in the all-trans configuration and crystallized in a co-existing organization of H, H and O crystalline forms. Considering intercalated alkyls in a high degree of substitution at O(6)H and O(2)H hydroxyl groups in CNCs and their ordered packing, the molecular arrangement in the resultant intercalated nanocomposites would involve a bilayer model in which intercalated alkyls were ordered packing and titled to cellulose (200) lattice plane. Besides, the resultant intercalated nanocomposites displayed the increased thermal properties and decreased char residue.