SMALL-ANGLE NEUTRON-SCATTERING STUDIES ON THE MESOPOROUS MOLECULAR-SIEVE MCM-41

A pure silica MCM-41 preparation with high crystalline order perpendic ular to the channels has been examined using small-angle neutron scatt ering and the contrast variation method in both the calcined and templ ate-containing forms. This defines various structural features such as template and water distributions and content, local silica density, a nd surface properties. Adsorption isotherm data, NMR, previous neutron scattering data, and the SANS data allow a choice between proposed mo dels for the channel structure of MCM-41, in terms of the straightness of the channels and their surface roughness.