Abstract
Transforming potential waste materials into high-value-added sustainable materials with advanced properties is one of the key targets of the emerging green circular economy. Natural mica (muscovite) is abundant in the mining industry, which is commonly regarded as a byproduct and gangue mineral flowing to waste rock and mine tailings. Similarly, chitin is the second-most abundant biomass resource on Earth after cellulose, extracted as a byproduct from the exoskeleton of crustaceans, fungal mycelia, and mushroom wastes. In this study, exfoliated mica nanosheets were individualized using a mechanochemical process and incorporated into regenerated chitin matrix through an alkali dissolution system (KOH/urea) to result in a multifunctional, hybrid hydrogel, and film design. The hydrogels displayed a hierarchical and open nanoporous structure comprising an enhanced, load-bearing double-cross-linked polymeric chitin network strengthened by mica nanosheets possessing high stiffness after high-temperature curing, while the hybrid films (HFs) exhibited favorable UV-shielding properties, optical transparency, and dielectric properties. These hybrid designs derived from industrial residues pave the way toward sustainable applications for many future purposes, such as wearable devices and tissue engineering/drug delivery.
Highlights
Nanostructured composite and hybrid materials comprising nanoscale inorganic fillers and polymeric matrices have been investigated as wearable electronic devices or functional sensors.[1,2] For example, montmorillonite, vermiculite, saponite, and kaolinite[3,4] can be harnessed to fabricate layered silicate−polymer composites and to enhance polymer features without degrading its processability.[5]
Composites based on layered silicates and petroleum-derived polymeric derivatives have been revealed, such as poly(vinyl alcohol) (PVA),[6] poly(methyl methacrylate) (PMMA),[7] epoxy resin,[8] polystyrene (PS),[9] polyimide (PI),[10] and polypropylene (PP).[11]
We propose a facile exfoliation method combining mechanochemical treatment and ultrasonication to obtain crystalline-delaminated mica nanosheets from natural mica, which is a byproduct of mining sites
Summary
Nanostructured composite and hybrid materials comprising nanoscale inorganic fillers and polymeric matrices have been investigated as wearable electronic devices or functional sensors.[1,2] For example, montmorillonite, vermiculite, saponite, and kaolinite[3,4] can be harnessed to fabricate layered silicate−. Self-standing HF with different IPAMica contents from 0.1 to 1.6 wt % was prepared by dissolving chitin in alkaline dispersion of IPAMica nanosheets, followed by tape-casting, washing, and drying (Figure 3) This robust and straightforward approach can be adapted at larger-scale film fabrication, and the technique is more efficient than, for example, a typical layer-bylayer process in which hundreds of layers are typically required to reach a thickness above 1.5 μm.[32] The HFs possessed a transparent and yellowish appearance depending on the content of the IPAMica, and 1.6HF was highly flexible when bent (Figure 6a and Supporting Information Figure S10). 0.8HF exhibits a favorable dielectric performance regarding dielectric permittivity and loss at a relatively high frequency at 100 MHz
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