Abstract: The development of lignin-based functional materials is a predictable boom. However, lignin is limited by its rigidity and brittleness, and difficult in material application requiring high elasticity. In this work, an effective innovative strategy was put forward to fabricate ultra-highly elastic conductive lignin-based porous system with flexible-rigid-flexible lamella topological structure for piezoresistive sensor. In the system, alkali lignin (AL) was utilized as the rigid skeleton and seriatim wrapped with polyvinyl alcohol (PVA) and flexible methyltrimethoxysilane (MTMS) as the flexible lamella to construct a structure like flexible-rigid sandwich lamella, where poly (3,4-ethylenedioxythiophene)@polystyrene sulfonate (PEDOT@PSS) are evenly fixed to form a conductive network by electrostatic adsorption with AL. Directional freezing makes the orderly flexible-rigid sandwich lamellas form a topological scaffold, whose orderly arrangement could effectively transfer and disperse pressure-induced stress, enhancing the structural ultra-high elasticity of system with a 98.6 %, 92.1 %, and 76.4 % compressive recovery rate (at 50 % strain) after compression of over 200 cycles, 1000 cycles, and 10,000 cycles, respectively. As the piezoresistive sensor, the system exhibits outstanding sensing capabilities up to 80 % strain, high fatigue resistance, and remarkable piezoresistive stability (with unchanging the curve of ΔR/R0 over 10,000 compressions at 50 % strain rate). In addition, the system displays super sensitive sensing performance for weak deformation (such as wrist pulse). Meanwhile, owing to the high porosity of its topological structure, the aerogel achieves an oil absorption efficiency of 19.1 to 51.5 g/g for various types of oils and demonstrates excellent reusability in oil absorption (with only a 6.96 % decrease after 10 cycles). The study advances the development and utilization of lignin, paving a new way for lignin-based smart sensing and adsorption applications.

Key words: Alkali lignin, Flexible-rigid sandwich lamella, Topological structure, Ultra-high elasticity, Piezoresistive sensor