Functionalization of Deuterium- and Hydrogen-Terminated Diamond Particles with Mono- and Multilayers using Di-tert-Amyl Peroxide and Their Use in Solid Phase Extraction

Abstract

In spite of an earlier report to the contrary and a different attempt that appears to have been unsuccessful, here we show an improved method that allows functionalization of hydrogen- and deuterium-terminated diamond with a dialkyl peroxide. In particular, hydrogen-/deuterium-terminated diamond particles were treated with neat di-tert-amyl peroxide (DTAP, C2H5C(CH3)2OOC(CH3)2C2H5) at elevated temperature. Surface changes were followed by X-ray photoelectron spectroscopy (XPS), diffuse reflectance Fourier transform infrared spectroscopy (DRIFT), and time-of-flight secondary ion mass spectroscopy (ToF-SIMS). After these reactions, the oxygen signal in the XPS spectra increased, the deuterium peak in the negative ToF-SIMS spectra decreased, and DRIFT showed C−H stretches, which were not previously present and which were similar to those of the precursor. In the C−H stretching region, the IR spectrum of adsorbed di-tert-amyl peroxide shows features that are red-shifted with respect to the IR spectrum of the precursor molecule. These trends are supported by density functional theory (DFT) calculations. These data are consistent with the chemisorption of fragments of di-tert-amyl peroxide primarily through ether linkages. The threshold for this reaction was determined by DRIFT to be ca. 95 °C. Multilayers of DTAP could be prepared by repeated exposure of the substrate to this reagent. Functionalized diamond particles were used in solid phase extraction.

Direct modification of hydrogen/deuterium-terminated diamond particles with polymers to form reversed and strong cation exchange solid phase extraction sorbents

“…Condensation of surface radicals with peroxy radicals could also take place to terminate reactive surface sites, as has previously been proposed on diamond surfaces [24]:…”

“…This primary amine modified diamond could then be further functionalized with hydrophobic isocyanates, and the resulting C 18 SPE adsorbate would extract pesticides from water [23]. A different hydrophobic SPE adsorbate could also be prepared by reacting di-tert-amyl peroxide (DTAP) with hydrogen-and deuteriumterminated diamond [24].…”

“…The presence of a crosslinking agent, such as divinylbenzene (DVB), appears to enhance polymer growth. This work follows a careful study of the reaction of DTAP alone with HTD and DTD [24]. There is also a report of nanodiamond incorporation into bulk polymers via radical polymerization [41].…”

“…Radicals are created by the thermal decomposition of DTAP at its relatively weak O-O bond. Because the O-H bond is stronger than the C-H bond [42], these oxygencentered radicals are believed to abstract hydrogen or deuterium from diamond surfaces, yielding carbon-centered radicals [24]:…”

Optical spectroscopy of the surface of nanoporous diamond films

“…The band for the stretching vibrations of the CH x groups consists of five individual lines with half-widths in the range 15-30 cm are typical of nanoporous diamond films [26] and nanosized diamond particles [30]. According to [31], CH 2 and CH 3 groups are characteristic respectively for the (100) and (111) faces of diamond.…”