Synthesis, characterization and hydrophobicity of esterified waxy potato starch nanocrystals.

Graphical abstract Highlights • Waxy potato starch nanocrystals (SNCs) were modified by octenyl succinic acid. • Crystalline structure of SNCs preserved after the esterification. • Hydrophobicity of SNCs was controlled by adjusting octenyl succinic acid content. • Prominent compatibility and stability of SNCs in chloroform were exhibited. Abstract Waxy potato starch nanocrystals (SNCs) were successfully modified through esterification by using octenyl succinic anhydride (OSA) aiming to improve its hydrophobicity. The SNCs were characterized by using 1H nuclear magnetic resonance (1H NMR) spectroscopy, X-ray diffraction (XRD), Fourier transformation infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), dispersion experiments and scanning electron microscopy (SEM). The degree of substitution (DS) was determined by means of 1H NMR revealed the upward trend with the increase of OSA dosage. XRD displayed the un-changed crystalline structure of SNCs but relative slight decrease of crystallinity. FT-IR spectroscopy showed characteristic absorption of the ester carbonyl groups and carboxylate RCOO− enclosed to 1732 cm-1, 1572 cm-1 respectively in OSA-SNCs. XPS confirmed the introduction of long chain hydrocarbon. The hydrophobicity of the modified SNCs increased with the increase of applied OSA contents. Dispersion experiments revealed the prominent compatibility and stability of nanocrystals in chloroform and acetone. SEM micrographs showed the serious aggregation of OSA-SNCs composed of smaller blocklets with 200–800 nm in size. [ABSTRACT FROM AUTHOR]