Ultralight and robust polyimide aerogels with tunable porous structures based on cation-π interactions for superior thermal insulation

•Cation-π interactions enabled well-organized pore structures in polyimide aerogels.•Shrinkage and density decreased, while porosity increased after cation-π bonding.•PIA’s yield strength rose by 344% and compressive modulus by 520% with cation-π bonds.•PIAs maintained ultra-low thermal conductivity across 25 °C to 180 °C. Polyimide (PI) aerogels, renowned for their ultra-low density and exceptional porosity, exhibit substantial potential for thermal insulation applications. However, conventional freeze-drying method often produces irregular and large pore structures, which compromise the mechanical properties of PI aerogels and limit their practical applications. In this work, the enhanced PI-Cu aerogels by cation-π interactions are fabricated through the introduction of Cu ions and benzimidazole. The findings reveal that cation-π interactions facilitate the transformation of PI aerogels from two-dimensional layered structure to three-dimensional honeycomb structure characterized by smaller and more uniform pores, significantly reducing shrinkage and leading to ultra-light properties. Remarkably, a significant improvement of mechanical performance is also achieved after introducing cation-π interactions, even at a decreased density (0.046 g/cm3). Specifically, for samples with 3.5 wt% solid content, the yield strength and modulus of PI-Cu aerogels increase to 0.71 MPa and 13.58 MPa, respectively, representing improvements of 344 % and 520 % over pristine PI aerogels, which are superior to those of many other previously reported PI aerogels/foams with similar or even higher densities. Additionally, the toughness is significantly elevated from 13.5 MPa to 48.8 MPa. More importantly, after introducing cation-π interactions, the thermal insulation of PI-Cu aerogels are also improved with thermal conductivity decreasing from 0.04214 to 0.03997 W/m·K in axial direction and from 0.0399 to 0.03688 W/m·K in radial direction at 25°C. Interestingly, the thermal conductivity show only a slight increase under 180°C less than 0.05741 W/m·K in axial direction and 0.04923 W/m·K in radial direction owning to their exceptional thermal stability (Tg = 404 °C, T5%=524 °C). These exceptional properties position PI-Cu aerogels as promising candidates for diverse functional applications in the field of energy conservation.