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

Abstract

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.

Design, synthesis and characterization of hierarchical porous stacked thin films based on MOFs and ordered mesoporous oxides

“…Aer reaction, the lms were placed for 15 minutes in an oven at 60 °C for thermal annealing. 52 2.1.2 Synthesis of ZIF-8 lms by liquid-phase epitaxy (LPE). Substrate preparation of silicon wafers of 95 mm diameter cut into 1.5 × 1.5 cm slides was carried out as follows: a cleaning step with acid piranha 1(H 2 SO 4 98%) : 1(H 2 O 2 30%) volume ratio until bubbling stopped, followed by Milli-Q water rinsing and drying with air.…”

Recent developments in visible light induced polymerization towards its application to nanopores

“…The group of Scho ¨nherr 65 recently analyzed the confinement effects in anodic alumina nanopores and demonstrated the effect of curvature and pore diameter effect on the polymerization kinetics using SI-ATRP. ATRP was as well used to functionalize mesoporous silica [66][67][68][69][70] and ion track etched pores [71][72][73] with different polyelectrolytes to study e.g. the resulting permselective ion transport in such polyelectrolyte functionalized mesoporous thin films.…”

Large-pore mesoporous silica: template design, thin film preparation and biomolecule infiltration

“…2), and surface modification permits to create hybrid interfacial nanoarchitectures where chemical functions can be precisely located in space. [19][20][21][22][23] Nevertheless, the most common polymers used as porogenic agents limit the preparation of MTF to pore sizes below 10 nm in diameter and rather narrow connecting necks below 5 nm in diameter. 24 In this regard, most reports rely on commercial templating agents such as CTAB, the diblock co-polymer Brij family, and the triblock co-polymer pluronic family.…”