title: 29Si NMR and SAXS investigation of the hybrid organic-inorganic glasses obtained by consolidation of the melting gels.
abstract: This study is focused on structural characterization of hybrid glasses obtained by consolidation of melting gels. The melting gels were prepared in molar ratios of methyltriethoxysilane (MTES) and dimethyldiethoxysilane (DMDES) of 75%MTES-25%DMDES and 65%MTES-35%DMDES. Following consolidation, the hybrid glasses were characterized using Raman,29Si and13C Nuclear Magnetic Resonance (NMR) spectroscopies, synchrotron Small Angle X-Ray Scattering (SAXS) and scanning electron microscopy (SEM). Raman spectroscopy revealed the presence of Si-C bonds in the hybrid glasses and 8-membered ring structures in the Si-O-Si network. Qualitative NMR spectroscopy identified the main molecular species, while quantitative NMR data showed that the ratio of trimers (T) to dimers (D) varied between 4.6 and 3.8. Two-dimensional29Si NMR data were used to identify two distinct types of T3environments. SAXS data showed that the glasses are homogeneous across the nm to micrometer length scales. The scattering cross section was one thousand times lower than what is expected when phase separation occurs. The SEM images show a uniform surface without defects, in agreement with the SAXS results, which further supports that the hybrid glasses are nonporous.
authors.affiliation: Department of Chemistry, Lehman College, CUNY, Davis Hall, 250 Bedford Park Boulevard West, Bronx, New York 10468, USA. andrei.jitianu@lehman.cuny.edu and Ph.D. Program in Chemistry and Biochemistry, The Graduate Center of the City University of New York, New York, NY 10016, USA.
authors.forename: Andrei
authors.identifier: http://orcid.org/0000-0001-6111-531X
authors.initials: A
authors.lastname: Jitianu
authors.affiliation: Institut des Matériaux Jean Rouxel (IMN), Université de Nantes, CNRS, 2 rue de la Houssinière, BP32229, 44322 Nantes Cedex 3, France and CEMHTI CNRS UPR3079, Université d'Orléans, France.
authors.forename: Sylvian
authors.initials: S
authors.lastname: Cadars
authors.affiliation: National Institute of Standards and Technology (NIST) 100 Bureau Drive, Stop 8520, Gaithersburg, MD 20899-8520, USA.
authors.forename: Fan
authors.initials: F
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, Lehman College, CUNY, Davis Hall, 250 Bedford Park Boulevard West, Bronx, New York 10468, USA. andrei.jitianu@lehman.cuny.edu.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Rodriguez
authors.affiliation: Department of Chemistry, Lehman College, CUNY, Davis Hall, 250 Bedford Park Boulevard West, Bronx, New York 10468, USA. andrei.jitianu@lehman.cuny.edu.
authors.forename: Quentin
authors.initials: Q
authors.lastname: Picard
authors.affiliation: Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas (CSIC), Kelsen 5, 28049 Madrid, Spain.
authors.forename: Mario
authors.initials: M
authors.lastname: Aparicio
authors.affiliation: Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas (CSIC), Kelsen 5, 28049 Madrid, Spain.
authors.forename: Jadra
authors.initials: J
authors.lastname: Mosa
authors.affiliation: Department of Materials Science and Engineering, Rutgers University, 607 Taylor Road, Piscataway, New Jersey 08854, USA.
authors.forename: Lisa C
authors.initials: LC
authors.lastname: Klein