Graphene/polymer nanocomposites as microwave absorbers

Abstract

A major application identified for graphene/polymer nanocomposites is as electromagnetic (EM) wave absorbers in high frequency electronics which is the backbone of present day communication systems. In this application area, thin and flexible absorbers are essential for ensuring electromagnetic interference (EMI)/EM compatibility standards. Presently, communication modes are primarily mobile in nature and inherently light weight and small in size. In this context, there is a great demand for high performance novel absorbing materials that can offer required solutions. The properties of graphene-filled polymer nanocomposites clearly make them outstanding candidates for microwave absorption. Graphene as a filler is quite unique as it offers the highest surface-to-volume ratio and hence once it is incorporated inside a polymer matrix it offers increased conductive and dielectric loss without a large increase in impedance mismatch. It is possible to disperse graphene in some polymers uniformly and hence their large surface-to-volume ratio becomes advantageous. Once they are well dispersed in the host, the composite can be imagined as a kind of distributed capacitors combining in series and parallel resulting in reduced capacitance but increased dissipation, yielding impedance-matched absorber. Graphene can be functionalized with various functional groups giving an additional degree of freedom to fine-tune its properties. This in turn increases the flexibility in designing novel graphene-based materials. For an absorber, not only its EM response but its mechanical, adhesive, and weatherability characteristics are also important. Since meeting the EM absorption requirement over a range of frequencies by a single material is difficult, the possibility of functionalization of graphene opens up many opportunities and hence raphene/polymer nanocomposites open up scope for a wide. spectrum of combinatorial 1investigations that are able to give solutions for the emerging scenario where in the sage of microwave spectrum is becoming more widespread, rather than not merely confined to the strategic sector as it used to be.