Porous metal oxides are enabling materials for a wide range of applications. Much work has focused on the cooperative assembly of precursors with block copolymers to synthesize a wide variety of metal oxides, but sizes of the pores are generally mesoporous due to the scaling of template dimensions with molecular weight (N<sup>1/2</sup>). In this work, we demonstrate a route to overcome this intrinsic limitation for block copolymer templates through the use of block bottlebrush copolymers. A generalizable approach to macroporous metal oxide films is demonstrated through the cooperative assembly of metal nitrates, citric acid, and a norbornene-based block bottlebrush copolymer containing poly(ethylene oxide) and poly(t-butyl acrylate) side chains. After calcination, ellipsoidal pores (~200 nm in long axis) are generated even when the framework is highly crystalline. Interestingly, the porosity of these metal oxide films reaches as high as ~65%, which is double the maximum porosity achieved in analogous porous films templated by linear block copolymers with similar polymer chemistry. Additionally, the spectrum from evaporation induced self-assembly (EISA) to persistent micelle templating is probed using mixed solvents to determine the impact of the solvent selectivity on the porous metal oxide morphology (size, porosity, and structure). Insights into how to control structure and properties of macroporous films templated by block bottlebrush copolymers will be discussed.<br/>

Soft-templating of ultra-large pores using block bottlebrush copolymer via a cooperative assembly approach

256th National Meeting (2018)

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