29Si NMR and SAXS investigation of the hybrid organic-inorganic glasses obtained by consolidation of the melting gels

Authors

Andrei Jitianu, CUNY Lehman CollegeFollow
Sylvian Cadars, Université de Nantes
Fan Zhang, National Institute of Standards and Technology
Gabriela Rodriguez, CUNY Lehman CollegeFollow
Quentin Picard, CUNY Lehman CollegeFollow
Mario Aparicio, Instituto de Cerámica y Vidrio
Jadra Mosa, Instituto de Cerámica y Vidrio
Lisa C. Klein, Rutgers University - New Brunswick/Piscataway

Document Type

Article

Publication Date

Spring 5-2017

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 and ¹³C 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-dimensional ²⁹Si NMR data were used to identify two distinct types of T3 environments. 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.

Comments

This article was originally published in Dalton Transactions, available at DOI: 10.1039/c6dt04394a.