Nanostructured and Advanced Designs from Biomass and Mineral Residues: Multifunctional Biopolymer Hydrogels and Hybrid Films Reinforced with Exfoliated Mica Nanosheets

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.

Trends in Green Chemistry Research between 2012 and 2022: Current Trends and Research Agenda

“…The agro-industry constantly seeks to add value to its waste, for example, by producing edible and inedible oils [85,86]. The mining industry recovers mica from tailings to create mica nanosheets [87]. The textile industry improves process circularity and waste management through sustainable biotextile production [88].…”

Highly Sensitive and Stable Flexible Sensors Based on Antifreezing and Self-Healing Double-Network Composite Hydrogels for Human Motion Monitoring

“…Flexible wearable electronic devices have attracted tremendous attention in recent years. Furthermore, flexible strain sensors hold the ideal potential to be used in wearable devices, electronic skin, soft robots, motion detection, and health monitoring. − Flexible and stretchable strain sensors convert mechanical signals into electrical signals by utilizing the internal resistance/capacitance of the sensors. − Biomass hydrogels, one of the most essential materials in daily life, have attracted much attention in the field of stretchable/wearable sensors due to their inherent stretchability, flexibility, and biocompatibility. − For instance, Fei et al prepared a biomass-based hydrogel with excellent conductivity by incorporating modified starch into a poly­(acrylic acid) (PAA) hydrogel system, which enables accurately monitor the human motion . Gu et al introduced carbon nanotubes and gelatin into a poly­(vinyl alcohol) (PVA) system to design biobased hydrogel strain sensors, achieving response to human movement signals .…”