Conductive composite films of polyimide and poly(3-dodecylthiophene)

A new method of making polymer films with conductive surfaces by permeation of the conducting guest species into the host is reported. A layer of poly(3-dodecyl thiophene) (p3ddt) is embedded at the surface of polyimide by permeation of the polythiophene (in solution in tetrahydrofuran (THF)) into a solution of polyamic acid in n-methyl pyrrolidinone (NMP) or dimethyl acetamide (DMAc). The resulting composite could be imidised chemically and the conducting polymer was stable in the composite even after solvent extraction. The sheet resistance of the composite decreased rapidly upon exposure to iodine; this effect was similar to, though slower than that observed for pure dodedcyl thiophene. Also, the composite recovered conductivity after a few hours of exposure to the dopant subsequent to de-doping. The higher mobility afforded by contact in the liquid state may contribute to the entanglement between the constituents leading to greater thermal and solvent resistance of the conducting constituent.