Solvent Vapor Annealing for Controlled Pore Expansion of Block Copolymer-Assembled Inorganic Mesoporous Films

Abstract

Mesoporous inorganic thin films are promising materials architectures for a variety of high-value applications, ranging from optical coatings and purification membranes to sensing and energy storage devices. Having precise control over the structural parameters of the porous network is crucial for broadening their applicability. To this end, the use of block copolymers (BCP) as sacrificial structure-directing agents via micelle coassembly is a particularly attractive route, since the resultant pore size is directly related to scaling laws for the radius of gyration of the pore-forming macromolecule. However, tailoring the molecular weight of the BCP via bespoke synthesis is an elaborate process that requires precise control over highly sensitive reactions conditions. Alternative methods have emerged, based on supramolecular assembly or the addition of different swelling agents. Nevertheleses, to date, these present a negative impact on the structural order and pore size dispersity of the final inorganic mesoporous films. In this work, we propose a novel and effective method for control over pore size, porosity, and structural order, which relies on a synergistic combination of BCP selective swelling via solvent vapor annealing (SVA) and locking of the structure by condensation of the inorganic sol–gel precursors. The results obtained in this work for TiO 2 establish SVA as a new, straightforward, simple, and powerful route for the fabrication of mesoporous thin-film materials with controllable structural characteristics.

Enhanced Mechanical Stability and Scratch Resistance of Mesoporous Aluminosilicate Thin Films

“…[68,74] Contrary to more commonly used techniques to study the surface morphology (like scanning electron or atomic force microscopy), EP probes the accessible porosity across the entire film thickness and for a representative sample volume. [66,67,75] Moreover, EP provides also information about pore size distribution and the Youngs modulus. [71] As shown in the Supporting Information (Figure S2), some changes were also observed with the modification over the O:I ratio: 7.2±0.1 nm (AlSi-20); 8.2±0.3 nm (AlSi-30) and 10.0±0.1 nm (AlSi-40), which is in agreement with previous studies, [73] Young's modulus (E) values were obtained from the fitting of the EP measurements (Figure 2D).…”

“…Aluminosilicate sol was prepared as described in previous studies. [66][67][68][69] In short, 2.8 g of (3glycidyloxypropyl)trimethoxysilane (GLYMO, ≥ 98 %, Sigma Aldrich) was mixed with 0.32 g of aluminium tri-sec-butoxide (ALTSB, 97 %, Sigma Aldrich) (molar ratio 9:1) and 20 mg of KCl (≥ 99.9 %, Sigma Aldrich). The solution was then stirred vigorously in an ice batch for 15 min.…”

Silica Inverse Opal Nanostructured Sensors for Enhanced Immunodetection of Extracellular Vesicles by Quartz Crystal Microbalance with Dissipation Monitoring

“… 27 , 38 While colloids offer precise control over porous networks on the 100 nm to micrometer length scale, co-assembly techniques involving block copolymer micelles are particularly suited for pore diameters below 100 nm. 39 − 43 …”

“…These properties make them ideal candidates for a myriad of applications, such as in catalytic systems, , photonics, , electrochemistry, and energy devices. − 3D inverse opals (3D IOs) may be fabricated using top-down techniques such as photo- and electron beam lithography or nanoimprinting, , or via bottom-up techniques such as colloidal assembly with sacrificial spheres. , One particularly attractive route is by co-assembly, where an inorganic sol–gel precursor is added to a colloidal suspension and therefore participates in an evaporative self-assembly process at the meniscus of a substrate. The result is minimized cracking and inhomogeneities associated with the multistep process of standard colloidal assembly. , While colloids offer precise control over porous networks on the 100 nm to micrometer length scale, co-assembly techniques involving block copolymer micelles are particularly suited for pore diameters below 100 nm. − …”

Enhanced Exosome Immunodetection by Integration of Silica Inverse Opal Architectures as Nanostructured Sensors in Quartz Crystal Microbalance with Dissipation Monitoring

“…31,32 While colloids offer precise control over porous networks on the 100 nm to micrometres length scale, co-assembly techniques involving block copolymer micelles are particularly suited for pore diameters below 100 nm. [33][34][35][36][37] The establishment of such precise and facile manufacturing methods for 3D IOs has facilitated their integration into biosensing. 38 The enhanced surface area offered by the incorporation of 3D IO structures, in combination with their optical properties, has been successfully exploited for improving the analytical performance of multiple sensing platforms.…”