Deep eutectic solvent-induced nanostructuring of cellulose gels: Review of mechanisms, properties, and applications

Cellulose, the most abundant natural polymer on Earth, combines renewability, biocompatibility, and rich surface chemistry in ways that make it exceptionally suited for next-generation functional gel materials, yet its extensive inter- and intramolecular hydrogen bonding network and semicrystalline architecture create persistent challenges in processing, dissolution, and integration into high-performance systems requiring precise mechanical and ionic properties. Deep eutectic solvents (DESs) offer a compelling solution to these limitations: their tunable physicochemical characteristics allow them to function as affordable, customizable media capable of disrupting cellulose's recalcitrant structure while simultaneously contributing functional properties to the resulting materials. The combination of DESs with supporting polymer networks yields eutectogels, a class of materials distinguished by negligible volatility, robust mechanical strength, high ionic conductivity, and remarkable thermal and electrochemical stability, that have attracted growing interest for applications in biomedicine, solid-state electrolytes, sensors, soft robotics, and advanced functional systems. This review systematically examines recent progress in cellulose-based eutectogels, with particular emphasis on molecular-level design strategies such as dynamic covalent and noncovalent bonding, hierarchical assembly, and switchable supramolecular architectures that collectively enhance mechanical toughness, ionic transport, and autonomous self-healing. These approaches are critically evaluated in the context of responsive sensors for human motion detection, energy storage devices, and emerging manufacturing platforms, while also addressing opportunities in flexible electronics, interactive technologies, and electronic skin systems. By mapping current performance benchmarks against developmental targets, this work underscores the transformative potential of cellulosic components in eutectogel design and outlines scalable, sustainable pathways for expanding their multifunctional capabilities across diverse technological domains.