A Comparative Study of PMETAC-Modified Mesoporous Silica and Titania Thin Films for Molecular Transport Manipulation

• Published in: Polymers Vol. 14; no. 22; p. 4823
• Main Authors: Alberti, Sebastian, Giussi, Juan, Azzaroni, Omar, Soler-Illia, Galo J A A
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 09.11.2022; MDPI
• Subjects: Chloride; Comparative analysis; Comparative studies; Confined spaces; Design; Dielectric films; Ellipsometry; Fourier transforms; Humidity; hybrid materials; Infrared spectroscopy; Membranes; mesoporous thin films; molecular brushes; Nitrogen; permselective membranes; Polyelectrolytes; Polymerization; Polymers; Pore size; Porous materials; Silica; Silicon dioxide; Thin films; zwitterionic; Argentina; molecular brushes; hybrid materials; zwitterionic; mesoporous thin films; permselective membranes
• ISSN: 2073-4360; 2073-4360
• DOI: 10.3390/polym14224823

The manipulation and understanding of molecular transport across functionalized nanopores will take us closer to mimicking biological membranes and thus to design high-performance permselective separation systems. In this work, Surface-initiated atom transfer radical polymerization (SI-ATRP) of (2-methacryloyloxy)-ethyltrimethylammonium chloride (METAC) was performed on both mesoporous silica and mesoporous titania thin films. Pores were proven to be filled using ellipsometry and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Furthermore, the employed method leads to a polymer overlayer, whose thickness could be discriminated using a double-layer ellipsometry model. Cyclic voltammetry experiments reveal that the transport of electrochemically active probes is affected by the PMETAC presence, both due to the polymer overlayer and the confined charge of the pore-tethered PMETAC. A more detailed study demonstrates that ion permeability depends on the combined role of the inorganic scaffolds' (titania and silica) surface chemistry and the steric and charge exclusion properties of the polyelectrolyte. Interestingly, highly charged negative walls with positively charged polymers may resemble zwitterionic polymer behavior in confined environments.