Polycrystalline polyaniline with strong infrared absorption

Orthorhombic polycrystals of polyaniline with regular low-dimensional nanostructures are successfully fabricated by using a simultaneous redoping–reprecipitation approach. The protonation reaction happening at the same time with the reprecipitation is confirmed to be the key point for the formation of the special polycrystalline nanostructures. Experimental results indicate that the obtained polycrystals are composed of microcrystalline domains with ordered structures and amorphous matrix with disordered molecular arrangements, and as a result, exhibit an unusual strong infrared absorption over the entire infrared region. In addition, with the help of the special characteristics of the simultaneous redoping–reprecipitation process, d-camphorsulfonic acid-doped polyaniline polycrystals are prepared and show an exceptional optical property without chirality of the main chains.