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Fractionation of block copolymers for pore size control and reduced dispersity in mesoporous inorganic thin films

Alvarez-Fernandez, A; Reid, B; Suthar, J; Choy, SY; Jara Fornerod, M; Mac Fhionnlaoich, N; Yang, L; ... Guldin, S; + view all (2020) Fractionation of block copolymers for pore size control and reduced dispersity in mesoporous inorganic thin films. Nanoscale 10.1039/d0nr05132b. (In press). Green open access

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Abstract

Mesoporous inorganic thin films are promising materials architectures for a variety of applications, including sensing, catalysis, protective coatings, energy generation and storage. In many cases, precise control over a bicontinuous porous network on the 10 nm length scale is crucial for their operation. A particularly promising route for structure formation utilizes block copolymer (BCP) micelles in solution as sacrificial structure-directing agents for the co-assembly of inorganic precursors. This method offers pore size control via the molecular weight of the pore forming block and is compatible with a broad materials library. On the other hand, the molecular weight dependence impedes continuous pore tuning and the intrinsic polymer dispersity presents challenges to the pore size homogeneity. To this end, we demonstrate how chromatographic fractionation of BCPs provides a powerful method to control the pore size and dispersity of the resulting mesoporous thin films. We apply a semi-preparative size exclusion chromatographic fractionation to a polydisperse poly(isobutylene)-block-poly(ethylene oxide) (PIB-b-PEO) BCP obtained from scaled-up synthesis. The isolation of BCP fractions with distinct molecular weight and narrowed dispersity allowed us to not only tune the characteristic pore size from 9.1 ± 1.5 to 14.1 ± 2.1 nm with the identical BCP source material, but also significantly reduce the pore size dispersity compared to the non-fractionated BCP. Our findings offer a route to obtain a library of monodisperse BCPs from a polydisperse feedstock and provide important insights on the direct relationship between macromolecular characteristics and the resulting structure-directed mesopores, in particular related to dispersity

Type: Article
Title: Fractionation of block copolymers for pore size control and reduced dispersity in mesoporous inorganic thin films
Open access status: An open access version is available from UCL Discovery
DOI: 10.1039/d0nr05132b
Publisher version: https://doi.org/10.1039/d0nr05132b
Language: English
Additional information: This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. http://creativecommons.org/licenses/by/3.0/
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Chemical Engineering
URI: https://discovery.ucl.ac.uk/id/eprint/10109287
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