After a brief introduction to the sol-gel process, this lecture will present the concept of Electrochemically Assisted Self-Assembly (EASA), as a versatile route to generate ordered and functionalized mesoporous silica films, and illustrate its potential for applications in various fields [1]. EASA is now a well-established versatile method to generate highly ordered mesoporous silica thin films onto conductive substrates, with vertically aligned nanochannels normal to the electrode surface. The EASA method involves the electro-induced condensation of silica precursors (e.g., tetraethoxysilane, TEOS) around tubular micelles (e.g., made of cetyltrimethylammonium bromide, CTAB), leading to the vertical growth of silica channels oriented orthogonally to the underlying support. Such oriented nanoporous membranes are easily modified with pendent organo-functional groups covalently attached to the inner walls of the silica nanochannels, by combining the EASA generation of azide- or thiol-functionalized films with click chemistry. The nanopores can be also filled with conducting polymers (e.g., polyaniline), which are produced by electropolymerization through the vertically oriented mesopores, leading to 1D nanofilament arrays. Both filled and open-pore nanochannel membranes, as well as organically functionalized mesoporous films, offer opportunities for advanced applications as sensors and biosensors, permselective membranes, and electrocatalysts, but also for surface protection, energy storage, and electrochromic.
Reference:
[1] A. Walcarius, Acc. Chem. Res. 2021, 54, 3563–3575.