Ordered Mesoporous Carbons via Self-Assembly of Tailored\nBlock Copolyethers for Pore Size-Dependent Applications

Abstract

Using an organocatalytic\npolymerization method for the preparation\nof well-defined, amphiphilic block copolyethers of the type PPO_<i>n</i>/2-PEO_<i>m</i>-PPO_<i>n</i>/2 (“Reverse Pluronics”, <i>M</i>_n up to 50 000 g/mol, <i>Đ</i>_M = 1.01–1.08, >100 examples), it is demonstrated\nthat the application of these polymers as structure-directing agents\n(SDAs) in a standard soft-templating process delivers ordered mesoporous\ncarbons (OMCs), whereby the resulting pore diameters are monomodal\nand narrowly distributed. Moreover, by the judicious choice of the\nSDA properties (total molar mass, ratio of <i>n</i> and <i>m</i>, and PPO block length), pore diameters in the range of\n6–18 nm can be selectively addressed, notably within the same\narrangement pattern (2D hexagonal, <i>p</i>6<i>mm</i>). This provides a rational, operationally simple method to tailor\npore properties of otherwise uniform carbons, also significantly reducing\nthe effort necessary to obtain systematically altered materials. Ready\naccess to such quick screenings is assumed to be immensely useful\nfor pore size-dependent applications from numerous disciplines such\nas sensing, catalysis, or energy storage and conversion. Surprisingly,\nit is not only found that a minimum of <i>M</i>_n = 13 000 g/mol is required to deliver ordered (nondistorted)\nmaterials under these conditions but also that very high-molar-mass\nSDAs are best suited to achieve optimum results, potentially providing\nan explanation for why “Reverse Pluronics” are frequently,\nand wrongly, thought to be per se unsuitable for the preparation of\nwell-ordered mesoporous carbons.