Towards mesoporous Keggin-type polyoxometalates – systematic study on organic template removal

Abstract

Here, we present systematic studies on the removal of the polymer template from inverse hexagonally ordered poly(butadiene-block-2-dimethylaminoethyl methacrylate)–phosphomolybdic acid (H₃PMo₁₂O₄₀) nanocomposites. Highly ordered mesophases are obtained via an evaporation-induced self-assembly process. Different techniques are used to remove the organic template: direct calcination in air, a two-step heat treatment ((1) argon atmosphere and (2) oxidative atmosphere), and a combination of heat and plasma treatment. Our studies show that direct calcination in air and two-step heat treatment lead to a collapse of mesostructure before complete carbon removal is accomplished. In contrast, plasma etching of heat treated ultra-microtomed samples results in hexagonally ordered porous nanofilms.