Enhancing the Thermal Stability of Ionogels: Synthesis and Properties of Triple Ionic Liquid/Halloysite/MCC Ionogels

Abstract

In this study, an ionic liquid (IL), 1-butyl-3-methylimidazolium acetate, was used to prepare ionogels with microcrystalline cellulose (MCC) and halloysite (Hal). SEM, XRD, TG, DSC, FTIR spectroscopy, conductometry and mechanical tests were used to study the morphology, structure, thermal behaviour and electrophysical and mechanical characteristics of synthesised ionogels. XRD analysis showed a slight decrease in the interlayer space of halloysite in ionogels containing MCC, which may have been associated with the removal of residual water molecules resulting from hydrophilic IL anions and polymer macromolecules. A change in conductivity and glass-transition temperature of the ionic liquid was revealed due to intercalation into halloysite (a confinement effect) and modification with cellulose. For triple IL/Hal/MCC ionogels, the characteristic thermal degradation temperatures were higher than the corresponding values for IL/Hal composites. This indicates that the synthesised IL/Hal/MCC ionogels are characterised by a greater thermal stability than those of IL/Hal systems.

Ionic Liquid/Na-Bentonite/Microcrystalline Cellulose Ionogels as Conductive Multifunctional Materials

“…For example, the T g value became almost 12 • C higher compared to the ionic liquid. A similar conclusion concerning the influence of the clay mineral was made by us earlier for the BMImAc/Halloysite ionogels [26] as well as for the BMImNTf 2 /Bent and BMImNTf 2 /Na-MMT ionogels [36]. The presented data indicate the confinement in the IL/clay systems.…”

“…The presented data indicate that the interaction with bentonite nanoparticles hinders the decomposition of the IL molecules. It should be noted that earlier [26], when studying the thermal behavior of the BMI-mAc/Halloysite composites, we made the opposite conclusion. Namely, we reported that BMImAc confined in the halloysite nanotubes decomposed easier than bulk IL.…”

“…The electrical conductivity of both triple IL/Na-Bent/MCC and binary IL/MCC ionogels was non-monotonous. The present paper is a continuation of our studies of triple ionogels with halloysite as a clay filler [26]. Therefore, the information on the properties of triple ionogels (but with bentonite as a clay filler) obtained in the current study is new and can be used in describing the effect of the clay filler nature in such systems.…”

Earth-Abundant Kaolinite Nanoplatelet Gel Electrolytes for Solid-State Lithium Metal Batteries

“…Furthermore, when exfoliated, their structured aluminosilicate layers provide high gravimetric surface area that results in robust nanocomposite mechanical properties . The most common clays utilized are montmorillonite, vermiculite, and halloysite for nanofillers or matrices in polymer, − polymer gel, − and ionogel − electrolytes. In these cases, the nanoclay provides mechanical support, increasing the electrolyte mechanical modulus and decreasing polymer crystallinity that enhances ionic conductivity. , Despite the breadth of demonstrated clay nanocomposite electrolytes, the most naturally abundant clay variety, kaolinite, has rarely been utilized. , The 1:1 structure of silica and alumina layers within bulk kaolinite results in strong hydrogen bonding between the layers making exfoliation difficult relative to other clay varieties. , Although kaolinite nanocomposites produced through chemical intercalation have been demonstrated, this process is time-intensive and limited to a small subset of molecules, restricting potential applications. , Only one reported system to date has shown direct liquid-phase exfoliation of kaolinite, albeit with the assistance of a large fraction of graphene oxide (GO) dispersing agent (i.e., 5:1 GO/kaolinite) and no reported yield for the process. , Therefore, a need remains for a highly scalable kaolinite exfoliation process that will enable broader use of kaolinite in SSEs and related clay nanocomposite applications.…”