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Free keywords:
acylation; cellulose; helical fibers; nanowhiskers; self-assembly
Abstract:
Many natural materials have helical or twisting shapes. In this work, we show the formation of helical fibers with the lengths of micrometers via evaporation-driven self-assembly of functionalized cellulose nanowhiskers (CNWs) with surface-attached acyl chains after drying on silicon wafers. The self-assembly process and the final helical structures were affected by a few critical parameters, which include the wettability of substrates, dispersing solvents, the amount of 10-undecenoyl groups, the crystallinity, the dimension of CNWs and the length of acyl chains. In particular, surface-acylated CNWs with the amount of 10-undecenoyl groups of a certain range (~3.52 mmol/g), an appropriate crystallinity (~40%), a length of ~135 nm and a diameter of around 4 nm preferentially self-assembled into explicit left-handed helical fibers from their THF suspensions on wafer. Thus, we showed on the one hand novel particular self-assembly behaviors of surface-acylated CNWs, and on the other hand we expanded the materials spectrum for the reconstruction of helical structures.
