261760 Small-Angle X-Ray Scattering (SAXS) Investigation of Porous Monolithic Carbons From Phenolic Precursor

Monday, October 29, 2012: 5:21 PM
405 (Convention Center )
Dipendu Saha, Andrew E. Payzant and Amit K. Naskar, Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN

In this work, we have synthesized monolithic carbonaceous materials from varieties of synthetic and natural phenolic precursors upon bulk-polymerization with and without the presence of surfactants. A series of carbon monoliths were synthesized with varying surfactant concentration from each of the precursors and it was observed that nonporous to nanoporous morphologies vary with the surfactant concentration and leave their fingerprints in small-angle X-ray scattering (SAXS) patterns. The understanding of evolution of pore structures in bulk carbon materials is important for its applications. The pore textural properties and surface fractality of the porous carbons were investigated by analyzing the SAXS patterns and compared with the results of nitrogen adsorption-desorption studies. The inherent advantage of SAXS analysis is the identification of closed or impenetrable pores in these carbons that cannot be characterized by any adsorption studies. Micropores and macropores leave very prominent and distinct fingerprint in the SAXS patterns that can be readily identified from their scattering patterns. All the SAXS patterns were modeled with a suitable equation that identifies the contribution from micropore, external surface or macropore and background and hence can be compared with adsorption studies. The distance distribution functions were also calculated from the SAXS patterns and a comparison is made with the pore widths obtained from the adsorption data. The effect of degree of interfacial tension varied by surfactant doping on the structure of carbons is also investigated by wide angle X-ray scattering (WAXS) analysis.

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