Phase transition identification of cellulose nanocrystal suspensions derived from various raw materials.

ABSTRACT: Cellulose nanocrystals (CNCs) as attractive nanomaterials are widely distributed in higher plants, algae, and marine animals. Herein, three kinds of CNCs were isolated by sulfuric acid hydrolysis from cotton pulp, algae, and tunicate cotton, respectively. Their morphologies and size were characterized by scanning electron microscope and atomic force microscope. The results showed that the aspect ratio of CNCs was in the order of CNCs from cotton pulp (CCNCs) (15 ± 10) < CNCs (ACNCs) from algae (ACNCs) (18 ± 12) < CNCs from tunicate (TCNCs) (75 ± 60). The phase transitions of CNC suspensions were also determined by phase diagram and rheological experiments. Two critical concentrations from isotropic to biphasic phase (<italic>C_i</italic>) and from biphasic to anisotropic phase (<italic>C_a</italic>) were measured and calculated, indicating that CNCs with higher aspect ratio reached <italic>C_i</italic> and <italic>C_a</italic> at lower concentration. Furthermore, the critical concentrations were also checked by polarized optical microscopy measurement. This work provided important information for construction of CNCs reinforced nanocomposites and investigation of CNCs chiral nematic liquid crystals. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. <bold>2018</bold>, <italic>135</italic>, 45702. [ABSTRACT FROM AUTHOR]