Polypyrrole-Coated Melamine Sponge as a Precursor for Conducting Macroporous Nitrogen-Containing Carbons

Macroporous open-cell melamine sponges were coated with a conducting polymer, polypyrrole, during in-situ oxidative polymerization of pyrrole. Two samples, differing in polypyrrole content, 8.2 and 27.4 wt%, were prepared. They were exposed to various temperatures up to 700 degrees C in an inert atmosphere. The macroporous structure and mechanical integrity were preserved after this process. This converted both the polypyrrole coating and the melamine sponge to macroporous nitrogen-containing carbons. The changes in molecular structure in the course of carbonization were followed by elemental analysis and FTIR and Raman spectra. The specific surface area of polypyrrole-coated sponge increased from ca. 90 to ca. 300 m(2) g(-1) along with accompanying increase in the porosity. The conductivity of the sponges was recorded as a function of compression in a newly developed apparatus. The sponge containing 27.4 wt% pyrrole had conductivity of the order of 10(-2) S center dot cm(-1) at 0.1 MPa pressure, which was reduced by four orders of magnitude when exposed to 400-500 degrees C and nearly recovered after the temperature reached 700 degrees C. The sponges were tested in electromagnetic radiation shielding and displayed both radiation absorption and, to a lower extent, radiation reflection proportional mainly to the samples' conductivity.

Automated summary

Macroporous melamine sponges were coated with polypyrrole conducting polymer. After high-temperature treatment, both the coating and the sponge were converted to macroporous nitrogen-containing carbons. Changes in molecular structure were observed during carbonization. The specific surface area and porosity of the coated sponge increased, and the conductivity was affected by compression. The coated sponges showed radiation absorption and reflection during shielding tests.