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

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Inorganic mesoporous coatings find widespread application in fields ranging from photovoltaics, supercapacitors and other electrochemical applications to optical coatings, chemo- and biosensing. In many cases, control over the pore dimensions is of paramount importance. The use of block copolymers as sacrificial structure directing agent has proven a particular attractive method for solution-based material deposition, since the resulting pore sizes can be adjusted through the molecular weight of the pore forming block. On the other hand, bespoke block copolymer synthesis remains a considerable effort, thus impeding continuous pore tuning for nanostructure optimisation. Furthermore, the intrinsic polymer dispersity presents challenges to the pore size homogeneity.

To this end, we establish a powerful route to pore size and dispersity control of mesoporous inorganic thin films via size exclusion chromatographic fractionation of BCPs. We provide a reliable experimental protocol and extensive materials characterisation. Furthermore, we present important fundamental insights on the direct relationship between macromolecular characteristics and the resulting structure-directed mesopores, in particular related to dispersity This approach represents a versatile approach for structure-function screening and applicationspecific optimisation of structural parameters.

The article published in Nanoscale (10.1039/D0NR05132B) is freely available as gold open access here:!divAbstract

Stefan Guldin

Associate Professor and Head of Adaptive & Responsive Nanomaterials Group, University College London