Heterogeneous nucleation promoting formation and enhancing microwave absorption properties in hierarchical sandwich-like polyaniline/graphene oxide induced by mechanical agitation

In this paper, polyaniline/graphene oxide composites were prepared by a one-step intercalation polymerization of aniline in the presence of GO layers under different mechanical agitation duration period, and the formation mechanism and microwave absorbing mechanism were investigated for an entire hierarchical sandwich-like structured polyaniline/graphene oxide composites. The morphology and structure were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, Brunauer-Emmett-Teller (BET) nitrogen sorption-desorption measurement and vector network analysis (VNA). The results revealed that mechanical agitation duration promoted the heterogeneous nucleation of aniline on graphene oxide layers and induced the formation of PANI-GO-PANI sandwich-like microstructure. The minimum reflection loss of entire sandwich-like structure reaches −28.12 dB at 5.675 GHz and an ultra-wide effective absorbing bandwidth (RL < −10 dB) over 13.175 GHz from 4.825 GHz to 18 GHz with the thickness varies from 2 mm to 5.5 mm, performing much better than pristine PANI and mixtures of PANI nanorods and sandwich-like structure. This paper reveals that constructing a hierarchical microstructure can be a promising method for developing novel microwave absorbing materials.