Bertrand Pavageau

Organic semiconductor core–shell nanoparticles designed through successive solvent displacements

This study reports for the first time the elaboration of core–shell organic nanoparticles through successive solvent displacements. The concept has been applied to generate donor–acceptor nanoparticles with the commonly used organic semiconductors P3HT and PCBM. The strategy is based on the sequential nanoprecipitation of P3HT and PCBM. Starting from a P3HT:PCBM solution in THF, the first solvent displacement with DMSO triggers the formation of the P3HT core while the second displacement with water generates the PCBM shell. The core–shell morphology is evidenced by both DLS and TEM. Efficient quenching of the P3HT photoluminescence is observed after the second solvent displacement procedure, confirming the formation of a well-defined PCBM shell around the P3HT core. Studying the emission of such core–shell nanoparticles leads to an estimation of the diffusion length of photogenerated excitons in P3HT of around ∼14 nm.

Time-resolved IR thermographic detection of gaseous molecules adsorption on oxide supports

High throughput characterization of materials was based on the thermal effect due to the reaction between a solid material and specific gas phase molecules. A dedicated cell was built (9-wells cell) to record by mean of an infrared camera the surface temperature of the material when it was contacted with a specific molecule. The design of the cell allows combining the infrared measurements of temperature with several other techniques like video camera, Raman spectroscopy or mass spectrometry. Catalytic activity, reducibility, basicity of solids and specific surface area have been successfully determined by this technique.

MADIX polymerization follow-up by viscosity sensing using Love-wave devices

Love wave sensors are highly sensitive microacoustic devices which are especially suited for sensing in liquids due to the shear polarized wave. In this contribution, a Love-wave device is used to follow the xanthate-mediated controlled free radical homopolymerization (MADIX technology) of butyl acrylate and acrylic acid. During the polymerization, using an automated synthesis workstation, a sample of the solution is taken into the reactors and deposited on the Love-wave sensor. Velocity changes of the Love-wave due to the liquid properties (e.g. viscosity) allowed to determine in real time the component fractions (e.g. monomer and polymer fractions) and give indications about the advance of the polymerization