The direct electrochemical copolymerization of pyrrole and caprolactam on an Indium-tin oxide (ITO) electrode was carried out by potentiostatic methods. The polymerization reaction was controled under the applied potential over 1.2 V vs. Ag/AgCl (saturated KCl) electrode in the nitromethane solution containing 0.05 M tetrabutyl ammonium tetrafluoroborate (Bu4NBF4)

0.1 M pyrrole and 1.5 M caprolactam. The composition of polypyrrole and polycaprolactam chain in the obtained products can be adjusted by controling the synthesis potential in the process of polymerization. Characterizations in the structure

morphology

and thermal properties of the novel copolymer were based on scanning electron microscopy (SEM)

thermal gravimetrical analysis (TGA)

Fourier transform infrared (FT-IR) spectra studies. The results showed that the electrochemical oxidation of pyrrole and caprolactam comonomers generates true copolymers rather than blends of the two homopolymers. The copolymer of pyrrole and caprolactam showed a better flexibility than pure polypyrrole obtained under the same polymerization condition. A probable mechanism of the copolymerization of pyrrole and caprolactam was proposed. The existence of polycaprolactam matrix in copolymer was desired to improve the hydrophilic characteristic and the biocompatibility of polymer film

and thus the copolymer film can be used for a good immobilization material of protein in the construction of electrochemical biosensors.