Self-Assembly of Nanoporous ZIF-8-Based Superstructures for Robust Chemical Sensing of Solvent Vapors

Self-assembly of metal-organic frameworks (MOFs) to construct optical sensors has been proposed to detect chemicals by acclimating colors in response to analytes that adsorbed on the surface of MOF nanoparticles and in the interspaces between particles. However, the instability of the weakly assembled optical structures held together by van der Waals forces limits their active sensing application. Here, we propose full-color tunable superstructures that are constructed by self-assembled ZIF-8 nanoparticles and postsynthetic poly(dimethylsiloxane) (PDMS) coating, which behave as robust optical sensors. The optical band was tuned by controlling the size of the ZIF-8 particles and also responded to the adsorption of chemicals with different refractive indexes in the micropores of the ZIF-8 particles. In addition, PDMS-coated ZIF-8 superstructures (ZIF-8@PDMS) were fabricated by thermal evaporation to optimize the optical quality and improve the robustness and solvent resistance during chemical sensing. Static and dynamic sensing results showed that the hierarchical porous structures endow the ZIF-8@PDMS superstructure with higher optical saturation and faster response in comparison to their counterparts configured with a ZIF-8 superstructure.