Melamine Sponges Decorated with Polypyrrole Nanotubes as Macroporous Conducting Pressure Sensors

The macropores of melamine sponges were coated in situ during the polymerization of pyrrole with either polypyrrole globules or nanotubes and tested as pressure-sensing materials. The dependence of the conductivity of this compressible material on pressure was determined by the four-point van der Pauw method. The conductivity increased from the order of 10–2 S cm–1 to units of S cm–1 at 10 MPa, and it was higher for nanotubes. The pressure dependence of sponge resistance was also recorded in another experimental setup in the design of a simple low-pressure sensor. The information on electrical properties obtained by both methods is discussed. In addition, the use of the melamine sponge decorated with polypyrrole in fields that do not directly exploit conductivity, such as electromagnetic radiation shielding and/or adsorption of organic dye, is also demonstrated. The study proves the superior performance of polypyrrole nanotubes in all applications.