The development of sophisticated telecommunication equipment and other electro-electronic devices resulted in a kind of electromagnetic pollution that affects the performance of other equipment as well as the health of human beings. Intrinsically conducting polymers (ICP), mainly polyaniline and polypyrrole, have been considered as promising candidates for applications in efficient electromagnetic interference shielding (EMI) due to their ease of preparation, light weight, good conductivity and corrosion resistance. One of the important advantages of these materials is the capability to interact with the EM radiation through both absorption and reflection mechanisms thus enlarging the field of application. In this context, this review article describes a recent overview of the existing methods to produce intrinsically conducting polymers and their blends for electromagnetic shielding application. Additionally, it highlights the relationship between preparation methods reported in the literature with the structure and properties, such as electrical conductivity, electromagnetic shielding effectiveness (EMI SE), complex permittivity and permeability of these materials. Furthermore, a brief theory related to the electromagnetic mechanism and techniques for measuring the microwave absorbing properties are also discussed.

Conducting composite materials based on epoxy matrix loaded with graphene nanoplatelets (GNP) were prepared by different procedures using ultrasonication. The dispersions of GNP in a mixture of epoxy/methyl-tetrahydrophthalic anhydride without solvent, resulted in composites with better conductivity, higher storage modulus and higher glass transition temperature than those prepared with solvent assisted procedure, indicating better filler dispersion. The non-covalent functionalization of GNP with the ionic liquid, 1-butyl-3-methyl-imidazolium bis(trifluorosulfonyl) imide (bmim.TFSI) contributed for an increase of the modulus for the systems containing low amount of filler. The electrical conductivity was not influenced by the presence of ionic liquid. Nevertheless, the micro-wave absorption effectiveness in the frequency range of 8-12 GHz (X-band frequency) was improved by the presence of IL mainly for the composites containing 0.9 and 1.5 vol.% of filler. All systems were characterized by low viscosity, comparable to that of neat epoxy resin, thus making easier their application on the development of coatings, conducting adhesives, etc.