Applying a combination of physico-chemical techniques, the researchers have synthesized bionanocomposite IL/Na-Bent/MCC ionogels with different (up to 10%) cellulose concentrations. The prepared materials have high ionic conductivity within a wide temperature range (from -40 to +80оC) and can potentially be used in electrochemical devices (lithium chemical power sources, supercapacitors, and sensors), for environmental protection (in ion exchange devices, CO2 and organic pollutant absorbers) , in materials for biomedical purposes (antibacterial coatings, surface modifiers, and gels), etc.
By now science has accumulated a lot of knowledge for making new types of functional nanomaterials based on the use of clay minerals and ionic liquids. Such materials posses a combination of useful properties, such as high ionic conductivity, thermal stability, chemical inertness, low flammability, ion exchange ability, and affinity to polymers. The functional characteristics of such materials are determined by the nanostructure of the clay minerals, structure and physico-chemical propertires of liquid ionic conductors and are associated with spatial shielding effects and properties of clay surface. The materials in question can potentially be applied in practice both individually as in the form of nanocomposites with polymers. The most interesting is application of cellulose as a polymer filler fro ionogels because this natural polymer possesses excellent thermal stability, is biocompatible and environmentally safe. Cellulose is also attractive due to its high solubility in acetate ionic liquids, which makes it possible to combine the production technique of clay/cellulose ionogels.
ISC RAS researchers have synthesized and characterized bionanocomposite IL/Na-Bent/MCC ionogels with different (up to 10%) cellulose concentrations. The scanning electron microscopy data showed that the ionogels are a specific ionic liquid that is densely filled with clay particles. An increase in the cellulose concentration causes changes in the density of some parts of the ionogel. As the WAXS data show, the Na-bentonite interlayer space in the ionogels is bigger due to the IL molecule intercalation. The glass transition temperature of the BMImAc/Na-Bent ionogels turned out to be higher than that of pure BMImAc. This was also true for the other IL/clay ionogels studied earlier. TG analysis showed that MCC inclusion increased the thermal stability of the obtained IL/Na-Bent/MCC ionogels. The highest electric conductivity of triple IL/Na-Bent/MCC ionogels was achieved at a 2% cellulose concentration. Na-Bent/MCC достигнута при концентрации целлюлозы 2%. However, the mechanism and causes of this maximum are still unclear. The observed phenomena can be related to the strong dehydrating ability of BMImAc, which effectively absorbs the bound water from solid fillers. The obtained material is characterized by high plasticity and can be easily used to make goods by extrusion. Its ionic conductivity is comparable to that of the best ionic conductors. The material can work within a wide temperature range from -30 to + 80оC.
The results of the study are available at: https://www.mdpi.com/2079-6412/13/8/1475.
