An advanced structural characterization of templated meso-macroporous carbon monoliths by small- and wide-angle scattering techniques

• Felix M. Badaczewski,
• Marc O. Loeh,
• Torben Pfaff,
• Dirk Wallacher,
• Daniel Clemens and
• Bernd M. Smarsly

Beilstein J. Nanotechnol. 2020, 11, 310–322, doi:10.3762/bjnano.11.23

• physisorption was applied, using deuterated p-xylene (DPX) as a contrast-matching agent in the neutron scattering process. The impact of the carbon precursor on the structural order on an atomic scale in terms of size and disorder of the carbon microstructure, on the nanopore structure, and on the template

• neutron scattering (SANS) combined with in situ physisorption were the methods of choice. Deuterated p-xylene (DPX) acts as a contrast-matching agent in the neutron scattering process. In a perfect case, that is if DPX filled all pores, the scattering contrast would be zero and the SANS intensity would

• scattering length densities with respect to neutrons, thereby enabling the principle of “contrast matching”, i.e., micro- and mesopores filled with p-xylene no longer contribute to the SANS pattern, and the filling process can thereby be studied by comparing the SANS patterns of the filled material and the

Distribution of functional groups in periodic mesoporous organosilica materials studied by small-angle neutron scattering with in situ adsorption of nitrogen

• Monir Sharifi,
• Dirk Wallacher and
• Michael Wark

Beilstein J. Nanotechnol. 2012, 3, 428–437, doi:10.3762/bjnano.3.49

• functionalization (0.81 mmol SO3H·g−1) and/or an inhomogeneous distribution of the SO3H-groups, the SLD changes only negligibly, and thus, complete contrast matching is still found. However, for higher amounts of SO3H-groups (1.65 mmol SO3H·g−1) being present in the mesopores, complete matching of the neutron

• diffraction signals is no longer observed proving that homogeneously distributed SO3H-groups on the inner pore walls of the benzene-PMO alter the SLD in a way that it no longer fits to the SLD of the condensed N2. Keywords: contrast matching; crystal-like periodicity; distribution of functional groups; PMO

• gas adsorption [19]. Based on contrast matching, which was introduced by Bragg et al. in 1952 [20], the intensities of the X-ray or neutron scattering reflections of the ordered porous solids are altered if the pores are filled with suitable gases. The degree of matching, however, depends strongly on