PhD thesis defense of William RENE
William RENE, PhD student at MAPIEM lab, under the supervision of:
- Catherine BRANGER
- Véronique LENOBLE (MIO laboratory)
will defend his PhD thesis in Polymer Chemistry, on the topic:
on October 4th,2019, at 9:30AM, in the Amphitheatre M-001, Building M, University of Toulon.
Ion imprinted polymers (IIP) are highly cross-linked porous materials with specific recognition cavities of a target ion. Thus, this kind of materials shows high selectivity. This work focuses on the preparation of fluorescent ion-imprinted polymers specific to lead (II), i.e. capable of transforming the ion recognition into a fluorescence signal, for the detection of this contaminant in marine environment.
In a first step, the strategy adopted was to select and synthesise a fluorescent ligand, specific to lead (II) and to study and use it for the preparation of the polymers. This ligand was modified to produce a styrene type fluorescent monomer (ANQ-ST). An exaltation of the fluorescence signal of ANQ-ST was observed along with lead (II) addition. The second step was dedicated to the development of the lead (II) ion-imprinted polymers. Various parameters were tested: polymerization solvents, nature of crosslinking agent (EGDMA and DVB) and ANQ-ST/crosslinker ratio (2 % and 5% molar). A diversified panel of characterization techniques allowed to study the polymer structures and to evidence the integration of the functional monomer ANQ-ST inside the polymer matrix. The last step consisted in evaluating the performances of the IIPs for the detection of lead (II) by fluorescence. The polymers prepared with EGDMA and 5 % of functional monomer showed the best results. For these polymers, IIPs’ fluorescence intensity in the presence of lead (II) was almost not impacted by the addition of interfering ion species, unlike their non-imprinted analogs. These results highlight the effectiveness of the imprinting effect. Calibration curves were established in aqueous media at different pH and in different matrices. Those parameters did not have major influences. The limits of detection obtained are below the World Health Organization recommendation (10 µg.L-1). These results were successfully validated by the detection of lead in natural samples, including tests in marine media.
Keywords: Ion imprinted polymers, fluorescence, lead, precipitation polymerisation, seawater