Synthesis of conducting poly(3,4-ethylenedioxythiophene), PEDOT, is achieved through an original reductionpolymerization route: γ-radiolysis of aqueous solutions containing EDOT monomers under N 2 atmosphere. According to UV-vis absorption spectrophotometry and ATR-FTIR spectroscopy, reduction of EDOT is initiated by hydrated electrons produced by water radiolysis and leads to PEDOT polymers through coupling reactions. The morphology of PEDOT is characterized by Cryo-TEM microscopy in aqueous solution and by SEM after deposition. In an original way, high resolution AFM microscopy, coupled with infrared nanospectroscopy, is used to probe the local chemical composition of PEDOT nanostructures. The results demonstrate that spherical self-assembled PEDOT nanostructures are formed. TGA analysis and four point probe measurements demonstrate that thermal stability and electrical conductivity of PEDOT polymers obtained by the present original reduction-polymerization method are close to those of PEDOT we previously prepared by radiolysis according to an oxidation-polymerization route.

International audienceThe use of dynamic seals to reduce the rotor/stator dynamic clearance in jet engine compressor stages leads to a higher rubbing occurrence between each blade and the coated inside of the casing. This article describes the development of a test rig capable to investigate forces and wear at the dynamic blade/seal interaction, in conjunction with blade kinetics. Testing conditions are consistent with those of low-pressure compressor stages of jet engines: high-speed rubbing occurs between a TA6V blade substitute and an aluminium-silicon/boron nitride abradable seal. The platform is instrumented to allow a dynamic measurement of forces and displacements as well as high-speed imaging of the blade/seal interaction zone throughout the experiment. The experiments showed that the blade incursion speed and penetration depth in the abradable seal both affect the amplitude and frequency of blade vibration. The amount and severity of blade incursions into the abradable seal have an impact on seal wear type and intensity, which can in turn increase blade excitation