Polymerization of pyrrole in intracrystalline tunnels of sepiolite

Polymerization of pyrrole was carried out in the intracrystalline tunnels of sepiolite adsorbing I2 to obtain a linear polymer of pyrrole in the limited space of the tunnel. The composites of polypyrrole, sepiolite and I2 (I2-SPy) were obtained. The polymerization of pyrrole took place in the inner space of the tunnels of sepiolite adsorbing a small amount of I2. On the other hand, using the sepiolite adsorbing a large amount of I2, the polypyrrole was formed on the surface of the sepiolite. Electrical conductivities of the resulting composites (I2-SPy) increased with an increase of the I2 content. The existence of a polaron and a bipolaron in the composites was confirmed by EPR signals at g = 2.00 and strong absorption bands above 450 nm, respectively. The electric conductivity of the I2-SPy composites is attributed to the polaron and bipolaron in the sample.