Polypyrrole

Polypyrrole (PPy) is a type of organic polymer formed by the polymerization of pyrrole. It is a solid with the formula H(C4H2NH)nH. Upon oxidation, polypyrrole converts to a conducting polymer.Some of the first examples of polypyrroles were reported in 1963 by Weiss and coworkers. These workers described the pyrolysis of tetraiodopyrrole to produce highly conductive materials.Polypyrrole is prepared by oxidation of pyrrole:Films of PPy are yellow but darken in air due to some oxidation. Doped films are blue or black depending on the degree of polymerization and film thickness. They are amorphous, showing only weak diffraction. PPy is described as 'quasi-unidimensional' vs one-dimensional since there is some crosslinking and chain hopping. Undoped and doped films are insoluble in solvents but swellable. Doping makes the materials brittle. They are stable in air up to 150 °C at which temperature the dopant starts to evolve (e.g., as HCl).PPy and related conductive polymers have two main application in electronic devices and for chemical sensors.PPy is a potential vehicle for drug delivery. The polymer matrix serves as a container for proteins.