Thermooxidative degradation of poly(3-alkyltirophenes)

Summary form only given. Poly(3-alkylthiophenes), containing alkyl side chains with more than four carbon atoms, are meltable and soluble in common solvents which make them possible to process with conventional techniques such as injection moulding and solution casting. However, these techniques may introduce new problems. During processing, polymers are exposed to high temperatures, shear forces and often also to oxygen. This may initiate different degradation reactions, ultimately leading to chain scission or crosslinking, and thus impaired properties. In this investigation, thin films of undoped poly(3-octylthiophene), POT, have been exposed to temperatures and atmospheres similar to processing conditions. Low molecular weight compounds and chemical treatment have been used for identification of the degradation products. The results show that the alpha-carbon position of the alkyl side chain is very sensitive to oxidation yielding carbonyl groups and crosslinks. Attempts to stabilize POT have also been carried out.