Stretchable, Biodegradable Dual Cross-Linked Chitin Hydrogels with High Strength and Toughness and their Potential Applications in Flexible Electronics

Abstract

Sensors, displays, and energy storage devices utilized in electronics are undergoing a rapid transition from rigid to flexible and stretchable materials. Traditional electronics-material substrates (metals and semiconductors) have several flaws, including insufficient softness and flexibility and high fragility, resulting in breakage upon stretching and folding. In addition, these materials have limited biodegradability for recycling. Thus, natural polymer hydrogels, with intrinsic biodegradability and biocompatibility, have been recently used to fabricate eco-friendly sensors and flexible energy storage devices. These hydrogels exhibit a vast range of tunable mechanical properties, making them suitable for the fabrication of flexible electronics. Here, dual cross-linked chitin hydrogels with high strength, flexibility, and biodegradability were synthesized using a sequential chemical and physical cross-linking strategy. The dual cross-linked chitin hydrogels exhibited a more comprehensive energy dissipation mechanism than hydrogels that were only physically or chemically cross-linked. Additionally, they could be used as flexible substrates for screen printing, with immense potential applications in the fields of wearable sensors and flexible supercapacitors. Furthermore, the hydrogel-based flexible electronics can be biodegraded in soil or easily recycled in Chitinase solution. This strategy provides a promising route for creating high strength, toughness, and biodegradable chitin hydrogels, which may contribute to the sustainable development of flexible electronics.

Current Trends and Promising Electrode Materials in Micro-Supercapacitor Printing

“…Wang et al [ 128 ] developed a method of sequential chemical and physical crosslinking to synthesize dual cross-linked chitin hydrogels with high strength, flexibility, and biodegradability. It was shown that the obtained hydrogels can be used directly as an electrode material and also as promising flexible substrates for screen printing of electrode structures of miniature supercapacitors on their surface.…”

Uniform Micronano Network Affords All-Chitin Films with Water Resistance, Biodegradability, and High Strength

“…With the formation of physical cross-linking bonds (hydrogen bonds) through the dissolution in potassium hydroxide (KOH)/urea solutions, the prepared chitin bioplastic exhibited an excellent tensile strength of ∼107.1 MPa . Moreover, chemical and physical cross-linking were incorporated, resulting in further enhanced strength and toughness . However, with desirable mechanical performance and thermal stability, these chitin nanofiber films still encounter poor water resistance due to the large number of hydroxyl groups on chitin molecular chains .…”

Dual-Network Conductive Hydrogels with Self-Healing, Ultrasensitive, and Antibacterial Activity toward Multifunctional Flexible Strain Sensor

“…Flexible electronic devices, including electronic skins, functional display, smart fabric, and implantable medical devices, hold significant importance in meeting the progressively intricate and diverse requirements of future electronic products. , To ensure the successful integration of flexible electronic products within the medical field for physiological signal collection and monitoring, they must possess commendable biocompatibility, flexibility, and mechanical performance . This necessitates the application of diverse assembly methods to incorporate these products with electronic components in order to achieve various functionalities .…”

“…1,2 To ensure the successful integration of flexible electronic products within the medical field for physiological signal collection and monitoring, they must possess commendable biocompatibility, flexibility, and mechanical performance. 3 This necessitates the application of diverse assembly methods to incorporate these products with electronic components in order to achieve various functionalities. 4 However, the most flexible sensors currently available are constructed via mixing functional fillers and flexible materials as substrates, resulting in a lack of ductility, mechanical flexibility, and sensitivity in these sensors, thus difficulty in accurately monitoring soft tissues.…”