Ultra-Large-Pore Mesoporous Carbons Templated from Poly(ethylene oxide)-b-Polystyrene Diblock Copolymer by Adding Polystyrene Homopolymer as a Pore Expander
journal contributionposted on 09.12.2008, 00:00 by Yonghui Deng, Jia Liu, Chong Liu, Dong Gu, Zhenkun Sun, Jing Wei, Junyong Zhang, Lijuan Zhang, Bo Tu, Dongyuan Zhao
A pore swelling approach was developed for the synthesis of ultralarge mesoporous carbons by using diblock copolymer PEO125-b-PS230 as a template, homopolystyrene (h-PS49) as a pore expander, resol as a carbon source, and THF as a solvent through solvent evaporation induced self-assembly (EISA). Small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) characterizations show that when h-PS94 amount is lower than 20 wt% relative to PEO125-b-PS230, highly ordered face-center cubic (fcc) mesoporous carbon structure (space group Fm3̅m) with ultralarge cell parameter of 46.4−58.0 nm can be obtained. Nitrogen sorption measurements reveal that the obtained LP-FDU-18s possess high surface area of about 1210 m2/g and large pore volume of 1.10 cm3/g. Because of adding pore swelling agent h-PS49, the mesostructural shrinkage is restrained, the pore wall thickness becomes very thin (3.6 nm). With the increase of h-PS49 addition amount from 0 to 20 wt%, the pore size can be continuously tuned in the range of 22.9−37.4 nm. Excess h-PS49 addition can lead to foamlike disordered porous carbons with multimodal pore size distribution (40−90 nm). A continuous solubilizing process is proposed to explain the expansion of pore size and cell parameter. This approach could be extended to the synthesis of other large-pore mesoporous materials with different frameworks such as silica, silica-carbon composite, and metal oxides.