Catalytic activity of a soft composite material: Nanoparticle location-activity relationship

A nanostructure, fiber-shaped morphology of a conjugated polymer (poly-5 amono-ortho-cresol, PAOC) has been synthesized using palladium acetate as the oxidizing agent. A one pot, in situ chemical synthesis approach has been utilized in which palladium acetate was reduced during the polymerization process of 5-amono-o-cresol (AOC) and formed well dispersed palladium nanoparticles in the polymer fibers. The resultant composite material was characterized by means of optical, thermo and micro-analytical techniques. The elemental identity of the nanoparticles was determined by means of electron energy loss spectroscopy (EELS) mapping using analytical transmission electron microscopy (TEM). Subsequently, the sample was used as a catalyst for a model gas-phase hydrogenation reaction. The activation and deactivation behaviour of the catalyst as a function of temperature is discussed in the light of different phase transition points of the polymer as well as the orientation of the palladium nanoparticles. The fact that palladium nanoparticles (∼2 nm) were uniformly distributed throughout the polymer matrix makes the composite material an excellent hybrid structure.