Accession Number : ADA266999


Title :   NMR and Theoretical Investigation of Cation Binding With Sol-Gel Silicates


Descriptive Note : Technical rept.,


Corporate Author : MINNESOTA UNIV MINNEAPOLIS DEPT OF CHEMICAL ENGINEERING AND MATERIALS SCIENCE


Personal Author(s) : Sanchez, J ; McCormick, A V


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a266999.pdf


Report Date : 12 Jul 1993


Pagination or Media Count : 7


Abstract : Previous reports suggest that the choice of base catalyst affects both the kinetics and structural evolution of SiO2 gelation from tetraethoxysilane (TEOS). Furthermore, these effects have been attributed to the interaction of the alkaline cations with charged silicate fragments. In this study, NMR analysis of alkali-metal nuclei and of 29Si directly shows that during the condensation of silicon alkoxides in basic alcohol solutions, cations form ion-pair complexes with negatively charged silicate groups. It is determined that the ion pair is formed most favorably with potassium. In seeking a predictive model of complex stability, we found it most successful to use a bond orbital electronegativity equalization model developed by Bergman and Hinze.... SiO 2, Sol/gel, NMR, Electronegativity equalization, Cation


Descriptors :   *CATIONS , *NUCLEAR MAGNETIC RESONANCE , *SILICATES , *ALKALI METALS , *SILICON DIOXIDE , IONS , MODELS , CHEMICAL BONDS , SILANES , KINETICS , EQUALIZATION , COMPLEX IONS , GELATION , BASES(CHEMISTRY) , ALCOHOLS , CONDENSATION , NUCLEI , FRAGMENTS , POTASSIUM , GELS , CATALYSTS , SILICON , ATOMIC ORBITALS , INTERACTIONS , STABILITY , REPRINTS


Subject Categories : Inorganic Chemistry
      Physical Chemistry
      Atomic and Molecular Physics and Spectroscopy


Distribution Statement : APPROVED FOR PUBLIC RELEASE