Phosphonic acid based initiator for Atom Transfer Radical Polymerization on metal oxide surfaces : Application to Solid Phase Microextraction (SPME)

Abstract

The aim of the SPME-GC project was the creation of new metallic SPME fibers to be used for the detection and identification of small amounts of polluting substances in the environment (water, air, soil), in urines (medical application) as well as in food and beverages (food industry). To reach this goal, we have worked out a “grafting from” method for the bonding of a layer of polymer, copolymer or composite materials onto the stainless steel wires. The advantages of our method are twofold: the use of stainless steel as support ensures much greater mechanical robustness of the title objects and the onsite polymerization technique allows for the synthesis of coating layers exhibiting a wide range of affinity towards the compounds to be extracted from various samples (SPME) and/or to be separated and identified (GC). A new ATRP initiator, 11-(2-bromoisobutyrate)-undecyl-1-phosphonic acid, has been synthesized and grafted as a film on a mechanically polished stainless steel substrate. Molecular integrity of the grafted initiator in the film, alkyl chain ordering, wettability were determined by X-ray photoelectron spectroscopy, polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS) and water contact angles. Homopolymer and diblock copolymer brushes as well as the same “doped” by carbon nanotubes have been grafted from the flat stainless steel surfaces and characterized to check the effectiveness of the new initiator. The extraction performances of the fibers (made as previously described) were assessed on different classes of compounds (polar, non-polar, aromatic, etc.) by headspace extraction. The optimization of the parameters affecting the extraction efficiency of the target compounds was studied as well as the reproducibility and the repeatability of the fiber. The fibers sustain more than 200 extractions during which they remain chemically stable and maintain good performances (detection limits lower than 2µg/l, repeatability, etc.). Considering their robustness together with their easy and inexpensive fabrication, these fibers could constitute promising alternatives to existing products.

Date of Award	16 Dec 2011
Original language	French
Awarding Institution	University of Namur
Supervisor	Zineb Mekhalif (Supervisor), Laszlo HEVESI (Co-Supervisor), Joseph DELHALLE (President), Manuel Azenha (Jury), Jean-Yves Hihn (Jury) & Marc TERMONIA (Jury)