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Design of Amphiphilic ABC Triblock Copolymer for Templating Synthesis of Large-Pore Ordered Mesoporous Carbons with Tunable Pore Wall Thickness

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journal contribution
posted on 08.09.2009, 00:00 by Junyong Zhang, Yonghui Deng, Jing Wei, Zhenkun Sun, Dong Gu, Hans Bongard, Chong Liu, Haihong Wu, Bo Tu, Ferdi Schüth, Dongyuan Zhao
In this paper, we demonstrate a successful synthesis of highly ordered mesoporous carbons with large pores and tunable pore walls by using a home-designed ABC amphiphilic triblock copolymer poly(ethylene oxide)-block-poly(methyl methacrylate)-block-polystyrene (PEO-b-PMMA-b-PS) with gradient hydrophilicity as a template and resol as a carbon source via the solvent evaporation induced self-assembly (EISA) strategy. SAXS, TEM, HRSEM, and N2 sorption characterizations show that the obtained carbon products possess ordered face-centered cubic (fcc) close-packed (Fmm) mesostructure with large pores of about 20.0 nm. By simply adjusting the resol/template ratios, the wall thickness of products can easily be tuned in the range of 10−19 nm. For the first time, we observed numerous large micro/mesopores in the carbon pore walls, originating from the removal of PMMA segment during the pyrolysis. The obtained mesoporous carbons have an extra-large lattice constant of up to 55.0 nm, high surface areas of ∼ 900 m2/g, and pore volume of ∼ 0.6 cm3/g, as well as high stability even in concentrated KOH solution. The gradient hydrophilicity of the ABC triblock copolymer template facilitates the continuous invasion of resol precursor molecules along the PEO to PMMA segments of the spherical PEO-PMMA-PS micelles, tuning the pore wall thickness. The rationally designed ABC-type triblock copolymers make it possible to synthesize ordered mesoporous carbons with ultrathick pore walls as well as excellent chemical and thermal stability.