title: Porosity of silica Stöber particles determined by spin-echo small angle neutron scattering.
abstract: Stöber silica particles are used in a diverse range of applications. Despite their widespread industrial and scientific uses, information on the internal structure of the particles is non-trivial to obtain and is not often reported. In this work we have used spin-echo small angle neutron scattering (SESANS) in conjunction with ultra small angle X-ray scattering (USAXS) and pycnometry to study an aqueous dispersion of Stöber particles. Our results are in agreement with models which propose that Stöber particles have a porous core, with a significant fraction of the pores inaccessible to solvent. For samples prepared from the same master sample in a range of H2O : D2O ratio solutions we were able to model the SESANS results for the solution series assuming monodisperse, smooth surfaced spheres of radius 83 nm with an internal open pore volume fraction of 32% and a closed pore fraction of 10%. Our results are consistent with USAXS measurements. The protocol developed and discussed here shows that the SESANS technique is a powerful way to investigate particles much larger than those studied using conventional small angle scattering methods.
authors.affiliation: Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, 2629 JB Delft, The Netherlands. S.R.Parnell@tudelft.nl and Centre for Exploration of Energy and Matter, Indiana University, Bloomington, 47408, USA.
authors.forename: S R
authors.initials: SR
authors.lastname: Parnell
authors.affiliation: Department of Physics and Astronomy, The University of Sheffield, Sheffield, S3 7RH, UK and Department of Mechanical Engineering, The University of Sheffield, Sheffield, S1 3DJ, UK.
authors.forename: A L
authors.initials: AL
authors.lastname: Washington
authors.affiliation: Department of Physics and Astronomy, The University of Sheffield, Sheffield, S3 7RH, UK.
authors.forename: A J
authors.initials: AJ
authors.lastname: Parnell
authors.affiliation: Department of Chemistry, The University of Sheffield, Sheffield, S3 7HF, UK.
authors.forename: A
authors.initials: A
authors.lastname: Walsh
authors.affiliation: ISIS, Rutherford Appleton Laboratory, Chilton, Oxfordshire, OX11 0QX, UK.
authors.forename: R M
authors.initials: RM
authors.lastname: Dalgliesh
authors.affiliation: Centre for Exploration of Energy and Matter, Indiana University, Bloomington, 47408, USA.
authors.forename: F
authors.initials: F
authors.lastname: Li
authors.affiliation: Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, 37831, USA.
authors.forename: W A
authors.initials: WA
authors.lastname: Hamilton
authors.affiliation: ID02 Beamline, European Synchrotron Radiation Facility, F38043, Grenoble, France.
authors.forename: S
authors.initials: S
authors.lastname: Prevost
authors.affiliation: Department of Mechanical Engineering, The University of Sheffield, Sheffield, S1 3DJ, UK.
authors.forename: J P A
authors.initials: JP
authors.lastname: Fairclough
authors.affiliation: Centre for Exploration of Energy and Matter, Indiana University, Bloomington, 47408, USA and Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, 37831, USA.
authors.forename: R
authors.initials: R
authors.lastname: Pynn