Tough Graphene−Polymer Microcellular Foams for Electromagnetic Interference Shielding

Abstract

Functional polymethylmethacrylate (PMMA)/graphene nanocomposite microcellular foams were prepared by blending of PMMA with graphene sheets followed by foaming with subcritical CO(2) as an environmentally benign foaming agent. The addition of graphene sheets endows the insulating PMMA foams with high electrical conductivity and improved electromagnetic interference (EMI) shielding efficiency with microwave absorption as the dominant EMI shielding mechanism. Interestingly, because of the presence of the numerous microcellular cells, the graphene-PMMA foam exhibits greatly improved ductility and tensile toughness compared to its bulk counterpart. This work provides a promising methodology to fabricate tough and lightweight graphene-PMMA nanocomposite microcellular foams with superior electrical and EMI shielding properties by simultaneously combining the functionality and reinforcement of the graphene sheets and the toughening effect of the microcellular cells.

Effects of graphene nanoplatelets on the morphology of polycarbonate–graphene composite foams prepared by supercritical carbon dioxide two-step foaming

“…Graphene-filled polymer foams have recently aroused a great interest in the scientific and industry communities [1][2][3][4], as the incorporation of graphene can dramatically enhance the electrical, physical, mechanical and barrier properties of polymers at extremely low loadings and, as a consequence, extend their potential applications to fields such as electronics, aerospace, automotive, green energy, among others [5]. The use of supercritical carbon dioxide (scCO 2 ) dissolved into a given polymer has become one of the most common strategies used to prepare graphene-filled polymer foams [2][3][4]6].…”

“…The use of supercritical carbon dioxide (scCO 2 ) dissolved into a given polymer has become one of the most common strategies used to prepare graphene-filled polymer foams [2][3][4]6]. Carbon dioxide acts as polymer plasticizer, decreasing its glass transition temperature and facilitating expansion due to decreased polymer viscosity [7], in some cases even leading to cell coalescence and as a result to a decrease in cell density [8].…”

“…Thus, foaming processing conditions play an essential role in the final morphological/microstructural characteristics of the resulting foams. On the other hand, several studies have indicated that a small amount of well-dispersed nanoparticles can act as cell nucleation sites and that nucleation efficiency is dependent on particle size, shape, surface properties and dispersion quality [2,4,9]. In addition, it has been shown that the combination of graphene nanoplatelets and scCO 2 during foaming may have remarkable effects on the microstructure of the developed foams [10].…”

Foam injection molding of polypropylene/stainless steel fiber composites for efficient EMI shielding

“…Therefore, inducing a cellular structure can resolve the shortcomings of injection-molded CPCs, while resulting in lightweight products. Recently, some researchers have tried to develop CPC foams for EMI shielding applications [12,16,[26][27][28][29][30][31][32]. However, most of these efforts have been focused on batch-scale systems, and very little attention has been paid to the foam injection molding.…”

Ultra-light carbon nanotube sponge as an efficient electromagnetic shielding material in the GHz range

“…These architectures can be subsequently infiltrated with polymers in order to increase their robustness while the conducting paths through the entire composite remain unaltered, thus maintaining high values of SE even for low filler loadings. Some examples of composite foams can be found in the literature using microcellular foams of graphene (5 wt%) with electrical conductivities of 3.11 S/m and SE values of 15 dB [16], ultra-light MWCNTs aerogels (>1 wt%) with electrical conductivities of ca. 3.2 S/m [17], or CNTs and CNFs polystyrene composite foams in which SE values of 19 dB and 9 dB were achieved with loadings close to 7 wt% of CNTs and CNFs, respectively [18].…”