Ingénierie macromoléculaire appliquée à l'étude de nano-objets à base de nanoparticules inorganiques greffées de polymères.
Jeudi 12/07/2007, 11:00
NIMBE Bât 125, p.157, CEA-Saclay
Nanohybrid objects based on polymer and inorganic nanoparticles are of great interest for different reasons. Indeed, the polymer part can help first for the stability and the organization of the particles, second to increase the amount of chemical functions available in the organic corona and finally to improve or to mask the properties of the particles. SANS is a well-suited technique for the study of these objects particularly due to the possibility to use contrast matching to see either the particle or the polymer corona. Here we are interested in the synthesis of both silica and platinum nanoparticles grafted with polymers or biological molecules which may be used first as models or as probes for biological detection. The method to introduce the polymer consists in using both the “grafting from” technique and controlled radical polymerisation. These systems (mainly in aqueous media) are exempt of free polymers so the characterization via SANS can lead to quantitative data such as the amount of chains in the polymer corona and the chains molecular weight. Contrast matching has been used to see only the polymer chains. Platinum particles have been characterized previously using X-ray diffraction and silica particles are studied in H2O or in the polymer matching index. In both cases, polymerization kinetics was followed by SANS and the polymer corona spectra show a plateau at small q which attests that the objects are individual and well-dispersed. Results obtained from SANS have been compared to other techniques such as NMR or TEM measurements. A good correlation has also been observed with the compression isotherms of Langmuir films obtained directly from the polymer-grafted nanoparticles.