Electrostatic or Steric Stabilization of the Cellulose Nanostructures Using Different Modifying Agents

Cellulose nanostructures (CNSs) are nanoscale biomaterials that have an excellent reinforcing ability; however, due to their high hydrophilic nature, its functionalization is necessary to improve the compatibility between CNS and polymeric matrices. In this work, the CNS-functionalization with four different modifiers: cationic (CS), anionic (AS), and non-ionic (NS) surfactant, and GA (grafting agent) is proposed. The modification is conducted in aqueous solution, using three different modifiers contents: 1, 3, and 5 wt%. The modified-CNS are characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), zeta potential (zeta), dynamic light scattering (DLS), and thermogravimetric analysis (TGA). CS and AS modifiers acted as electrostatic stabilizers, through charges present in its functional groups (NH3+ and SO3-, respectively); in this case, zeta and XPS results investigated the stabilization. NS and GA modifiers acted as steric stabilizers, due to their polymeric chains, which induces the repulsion between the CNS; the stabilization is confirmed mainly by DLS and XPS. Regarding thermal stability, modified-CNS samples showed a slight decrease in thermal properties due to the presence of reactive groups in the modifiers. All the samples showed the potential to be applied as fillers in nanocomposites, with degradation temperatures above the biopolymers processing temperatures.