Modification of Quartz Surfaces via Thiol-Disulfide Interchange
Technical rept. no. 14, Jul 1988-Jul 1989
UTAH UNIV SALT LAKE CITY DEPT OF CHEMISTRY
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The present investigation focuses on procedures for silica modification by 3-mercaptopropyltrimethoxysilane MPS as studied by attenuated total reflection-fourier transform infrared ATRFTIR and X-ray photoelectron spectroscopies XPS, along with energy dispersive analysis of X-rays EDAX. Particular emphasis is given to the accessibility of the surface-attached thiol groups and means for enhancing this accessibility. From the ATR-FTIR studies, the surface coverage of MPS Silanization A and protected-MPS Silanization B appears to reach a steady state in about 17 minutes. The elemental composition given by XPS verifies both the presence of MPS on the surface and the stability of the conjugate in alkaline solutions. The possibility of interactions by the thiol group with the surface or other parts of the silane molecule is suggested by XPS and molecular modeling. An alternate way of producing thiol-containing quartz surfaces is suggested where the mercaptosilane is initially protected by reacting its thiol group with 22 dithiodipyridine prior to silanization and subsequently reduced to yield the free thiol group. By silver-staining the product of silanization B, it is possible to use both the XPS and SEMEDAX techniques to assess the fraction of thiol groups which is accessible to a hydrophilic probe.
- Organic Chemistry
- Physical Chemistry