A unique path to reach thermostable polypyrrole/Pd microfibers via chemical oxidative polymerization

Polypyrrole/palladium (PPy/Pd) nanocomposites, labeled by PPy/Pd-2/1-0, PPy/Pd-2/1-25, and PPy/Pd-3/1-0, are synthesized via a direct redox reaction between pyrrole monomer and PdCl₂ in the presence of sodium dodecyl sulfate (SDS) stabilizer in chloroform (CHCl₃)/acetonitrile (CH₃CN) binary organic solvents with 2:1 and 3:1 volume ratios at two temperatures involving 0 and 25 °C. A Pd-unloaded polypyrrole (PPy-2/1-0) is also synthesized similarly using iron(III) chloride (FeCl₃) oxidant for comparison purposes. The volume ratio of the solvents used as well as the temperature at which the oxidative polymerization takes place affects significantly the thermostability of the resulting nanocomposites. According to the thermogravimetric analyses, the stability order towards heat is found to be PPy/Pd-2/1-25 > PPy/Pd-2/1-0 > PPy/Pd-3/1-0 > PPy-2/1-0. The nanocomposite PPy/Pd-2/1-25 shows clearly more thermostability compared to PPy/Pd-2/1-0 analog at temperatures above 400 °C. Furthermore, whereas three discrete maxima can be obviously found in the differential thermal analysis (DTA) thermogram of PPy-2/1-0 pure sample, no distinctive exothermic peak is observed in the curves of the three Pd-loaded nanocomposites.