<i>n</i>-Octadecyltriethoxysilane (C<sub>18</sub>-TEOS) and tetraethoxysilane (TEOS) were used as the precursors to fabricate an organic-inorganic hybrid composite by sol-gel processing. The hydrolysis and initial condensation reactions of TEOS and C<sub>18</sub>-TEOS/TEOS mixtures were studied by <sup>29</sup>Si-NMR spectroscopy. The rate of disappearance of the silane precursors and the evolution of the various silicon species during the reaction indicate that TEOS hydrolyzes and condenses faster than C<sub>18</sub>-TEOS. The rate of hydrolysis for C<sub>18</sub>-TEOS, however, increases when reacting in the C<sub>18</sub>-TEOS/TEOS hybrid mixture, indicating that the condensation reactions involving TEOS species drive the reaction of C<sub>18</sub>-TEOS. The formation of cross-condensed products leads to the composite with octadecyl groups incorporated into the final glass material. The maximum degree of condensation in the C<sub>18</sub>-TEOS/TEOS mixture was observed after 2 h of reaction. Fused-silica capillary columns were coated with the C<sub>18</sub>-TEOS/TEOS mixture while in its liquid-like stage. After drying, the columns were tested for open tubular capillary electrochromatography (OT-CEC). Coating of the columns was performed after the maximum degree of condensation was achieved, which has been shown to correlate with maximum chromatographic retention.
You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.
Contact your librarian or system administrator
Login to access OSA Member Subscription