The shape tunable gelatin/carbon nanotube wet-gels for complex three-dimensional cellular structures with high elasticity

Porous three-dimensional (3D) assemblies of nanocarbons with large surface areas and tunable physical properties are attractive for a wide range of applications, such as energy storage electrodes, pollution adsorption, and thermal insulators. However, the full utilization of these materials is impeded by two challenges: forming 3D robust porous network structures that retain the intrinsic properties of the nanocarbon and achieving high shape-tunability to create structures with desired shapes. To address these challenges, gelatins with zwitterionic and hydrogen-bonded helical structure were considered a bio-derived binder to modulate the structural integrity of carbon nanotube (CNT) network which consists of overlapping nanotubes held by weak van der Waals attraction. The resulting CNT/gelatin wet-gels have favorable rheological properties, enabling 3D printing into complex porous architectures. Moreover, the 3D-printed complex wet-gel structure was successfully transformed into elastic and hierarchical porous structures consisting of micro-, meso-, and macro-scale pores with large specific surface areas of ∼988 m2 g−1 and excellent mechanical stability without permanent deformation even at 85% compressive strain. The resulting high shape-tunability, high elasticity, and large surface area are attributed to the reinforcement of the existing nanotube cross-linking points strengthened by the gelatin-derived graphitic layer coating without deteriorating the intrinsic properties of CNTs. Thermosensitive gelatin association into carbon nanotube (CNT) dispersions strengthens the structural integrity of the nanotube network and achieves favorable rheological properties for transforming the wet-gels into complex porous architectures using 3D printing. Furthermore, the gelatin-derived graphene-coating around nanotube junctions transforms mechanically fragile carbon nanotube networks into ultra-compressible cellular structure. [Display omitted]