title: Spatial distribution of organic functional groups supported on mesoporous silica nanoparticles: a study by conventional and DNP-enhanced29Si solid-state NMR.
abstract: Solid-state NMR spectroscopy, both conventional and dynamic nuclear polarization (DNP)-enhanced, was employed to study the spatial distribution of organic functional groups attached to the surface of mesoporous silica nanoparticles via co-condensation and grafting. The most revealing information was provided by DNP-enhanced two-dimensional29Si-29Si correlation measurements, which unambiguously showed that post-synthesis grafting leads to a more homogeneous dispersion of propyl and mercaptopropyl functionalities than co-condensation. During the anhydrous grafting process, the organosilane precursors do not self-condense and are unlikely to bond to the silica surface in close proximity (less than 4 Å) due to the limited availability of suitably arranged hydroxyl groups.
authors.affiliation: U.S. DOE Ames Laboratory, Iowa State University, Ames, Iowa 50011-3020, USA. mpruski@iastate.edu.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kobayashi
authors.affiliation: U.S. DOE Ames Laboratory, Iowa State University, Ames, Iowa 50011-3020, USA. mpruski@iastate.edu and Department of Chemistry, Iowa State University, Ames, Iowa 50011-3020, USA.
authors.forename: Dilini
authors.initials: D
authors.lastname: Singappuli-Arachchige
authors.affiliation: U.S. DOE Ames Laboratory, Iowa State University, Ames, Iowa 50011-3020, USA. mpruski@iastate.edu and Department of Chemistry, Iowa State University, Ames, Iowa 50011-3020, USA.
authors.forename: Zhuoran
authors.initials: Z
authors.lastname: Wang
authors.affiliation: U.S. DOE Ames Laboratory, Iowa State University, Ames, Iowa 50011-3020, USA. mpruski@iastate.edu and Department of Chemistry, Iowa State University, Ames, Iowa 50011-3020, USA.
authors.forename: Igor I
authors.identifier: http://orcid.org/0000-0002-9319-8639
authors.initials: II
authors.lastname: Slowing
authors.affiliation: U.S. DOE Ames Laboratory, Iowa State University, Ames, Iowa 50011-3020, USA. mpruski@iastate.edu and Department of Chemistry, Iowa State University, Ames, Iowa 50011-3020, USA.
authors.forename: Marek
authors.identifier: http://orcid.org/0000-0001-7800-5336
authors.initials: M
authors.lastname: Pruski