Preparation of polysiloxane foam with graphene for promoting electromagnetic interference shielding performance and thermal stability

Mechanical exfoliation of graphene (MEG) and reduced graphene oxide (RGO) are fabricated with using graphite and they are used as fillers to improve the electromagnetic interference (EMI) shielding performance and thermal stability of polysiloxane composite foam. Since graphene builds a conductive network in the matrix and at the same time enhances the impedance mismatch between the syntactic foam and the external free space, the total shielding effectiveness (SEtotal) of the composite foam can reach up to 4.74 dB, which is 500% higher than that of pure foam. Moreover, the layered structure of graphene can restrict the small molecules generated during the foam pyrolysis process from leaving the system, and also increases the maximum decomposition temperature of the composite foam (increased from 431.8 to about 500 degrees C), which improves the thermal stability of the foam. These results indicate that the combination of graphene in polysiloxane foams produces composite foams with multifunctional properties, suitable for applications requiring EMI shielding and thermal performance.