Alkene-modified Fe3O4 nanoparticle-mediated construction of functionalized mesoporous poly(ionic liquid)s: Synergistic catalysis of mesoporous confinement effect and hydrogen proton for organic transformations

Abstract

Abstract The preparation of mesoporous poly(ionic liquid)s (MPILs) is critically fundamental for the design of heterogeneous catalysts, whereas traditional methods are difficult to obtain these materials with both well-defined mesoporous structure and unique functionality. Here, HClO4-functionalized MPILs with well-defined mesoporous structure were successfully fabricated, in which the alkene-modified Fe3O4 nanoparticles as structural reinforcer play a vital role for mesoporous structure formation. The MPILs were characterized by N2 adsorption/desorption, scanning electron microscope (SEM), transmission Electron Microscope (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and vibration sample magnetometry (VSM), and the results confirm that MPILs possess moderate surface area, well-defined mesoporosity, abundant active ionic centers, as well as efficient magnetic recovery. The resulting MPILs show excellent catalytic activity for condensation reaction and Knoevenagel condensation. The kinetic study reveals that the excellent catalytic activity of MPILs is attributed to the synergistic catalysis of mesoporous confinement effect and hydrogen proton from MPILs, albeit with mass transfer resistance produced by mesoporous channels. Further, the catalyst can be recovered using an external magnetic field and reused at least 10 times without a considerable decrease in its catalytic activity. Finally, alkene-modified Fe3O4 nanoparticle-mediated mesoporous construction promotes a textural engineering approach to the development of novel mesoporous materials for other applications.