Multifunctional Integrated Superhydrophobic Coatings with Unique Fluorescence and Micro/Micro/Nano-Hierarchical Structures Enabled by In Situ Self-Assembly

Abstract

Conferring versatility to superhydrophobic materials is extremely desirable to advance their utility. Herein, we have developed a superhydrophobic material with montmorillonite as microskeleton supports and in situ grown ZIF-8 nanoparticles and loaded them with newly developed fluorescent carbon dots. In situ growth of the ZIF-8 on OMMT constructs a dense nanoscale rough structure and meanwhile self-assembly generates abundant microporous, thus forming unique hierarchical microporous/microsheet/nanoparticle tri-tier micro and nano structures. Then the multifunctional superhydrophobic coating is fabricated by a facile spraying technique using polydimethylsiloxane (PDMS) as a multifunctional polymer binder. The PDMS/RB-CDs/ZIF-8@OMMT exhibits superhydrophobicity with a water contact angle of 164.7° and a water sliding angle of 1.4°, which also possesses good self-cleaning performance. Moreover, novel carbon dots are developed in this work which can confer unique fluorescent properties and photothermal properties to materials. Fluorescence characterization reveals the multiple emission peaks among 300-800 nm and excitation wavelength dependence and independence. Photothermal experiments unveil an efficient light-to-heat conversion caused by the light traps and absorption wavelengths associated with photothermal heating. Benefiting from the dense microporous/microsheet/nanoparticle structures, the superhydrophobicity is still maintained after 120 cycles of abrasion. Moreover, electrochemical impedance spectroscopy (EIS) reveals a significant increase in impedance, which is associated with excellent corrosion resistance. The superhydrophobic coating also exhibits superior UV resistance and good thermal stability. Multifunctional fluorescent superhydrophobic materials will enable the development of various and potential applications in different fields.