Cellulose Nanoparticles Prepared by Ionic Liquid-Assisted Method Improve the Properties of Bionanocomposite Films

Bionanocomposites have garnered wide interest from the packaging industry as a biocompatible alternative to non-biodegradable petroleum-based synthetic materials. This study presents a simple and eco-friendly alternative to produce cellulose nanoparticles using a protic ionic liquid, and the effects of their incorporation in cassava starch and chitosan films are evaluated. Bionanocomposite films are prepared using the solvent casting method and are characterized using X-ray diffraction, Fourier transform infrared spectroscopy, zeta potential, thermogravimetry analysis, and transmission electron microscopy. The achieved yield of cellulose nanoparticles is 27.82%, and the crystalline index is 67.66%. The nanoparticles’ incorporation (concentration from 0.2 to 0.3%) results in a progressive reduction of water vapor permeability up to 49.50% and 26.97% for starch and chitosan bionanocomposite films, respectively. The starch films with 0.1% cellulose nanoparticles exhibit significantly increased flexibility compared to those without any addition. The nanoparticles’ incorporation in chitosan films increases the thermal stability without affecting the mechanical properties. The study demonstrates that the use of cellulose nanoparticles obtained using protic ionic liquid can be a simple, sustainable, and viable method to produce bionanocomposites with tailored properties useful for applications in the packaging industry.

The Structure of the Electric Double Layer of the Protic Ionic Liquid [Dema][TfO] Analyzed by Atomic Force Spectroscopy

Protic ionic liquids are promising electrolytes for fuel cell applications. They would allow for an increase in operation temperatures to more than 100 °C, facilitating water and heat management and, thus, increasing overall efficiency. As ionic liquids consist of bulky charged molecules, the structure of the electric double layer significantly differs from that of aqueous electrolytes. In order to elucidate the nanoscale structure of the electrolyte–electrode interface, we employ atomic force spectroscopy, in conjunction with theoretical modeling using molecular dynamics. Investigations of the low-acidic protic ionic liquid diethylmethylammonium triflate, in contact with a platinum (100) single crystal, reveal a layered structure consisting of alternating anion and cation layers at the interface, as already described for aprotic ionic liquids. The structured double layer depends on the applied electrode potential and extends several nanometers into the liquid, whereby the stiffness decreases with increasing distance from the interface. The presence of water distorts the layering, which, in turn, significantly changes the system’s electrochemical performance. Our results indicate that for low-acidic ionic liquids, a careful adjustment of the water content is needed in order to enhance the proton transport to and from the catalytic electrode.