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Surface characterization of chemically modified (trimethylsily) silicas by 29 Si solid state NMR, XPS, and IR photoacoustic spectroscopy
Author(s) -
Linton R. W.,
Miller M. L.,
Maciel G. E.,
Hawkins B. L.
Publication year - 1985
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.740070407
Subject(s) - geminal , vicinal , reactivity (psychology) , chemistry , x ray photoelectron spectroscopy , monolayer , steric effects , fourier transform infrared spectroscopy , solid state nuclear magnetic resonance , nuclear magnetic resonance spectroscopy , organic chemistry , nuclear magnetic resonance , chemical engineering , medicine , biochemistry , physics , alternative medicine , pathology , engineering
The surface reactivity of hydroxyl groups on silica with trimethylchlorosilane (TMCS) is examined using XPS, FTIR‐PAS, and solid state NMR. All techniques give responses give responses which can be correlated with increasing TMS surface coverages on Lichrosorb Si 60 silica and provide detection limits of ⩽10% of a TMS monolayer. Solid state NMR is particularly suited to examining reactivity differences between geminal and single silanols. Geminal hydroxyl groups are found to be much more reactive. At higher TMS coverages approaching steric limitations (0.5 TMS monolayer), nearly 100% of the geminal sites are reacted as opposed to only 20% of the single sites. The reactive subset of single silanols appears to include hydrogen‐bonded (vicinal) groups. A mechanism is postulated to explain the apparent enhanced reactivity of geminal and vicinal silanols.