Multifunctional nanocomposites reinforced by aligned graphene network via a low-cost lyophilization-free method

Compared with a disordered network, the ordered framework is more beneficial to improving the multifunctional properties (including thermal, electrical, and mechanical properties) of epoxy-based composites. However, current methods for building aligned structures are both energy and time-consuming on account of the tedious and lengthy lyophilization process. Herein, a new strategy is proposed to obtain low-density graphene aerogels (GAs) with long-range oriented structures through a lyophilization-free processes. Due to the minimum thermal boundary resistance, the prepared aligned graphene/epoxy composite exhibits an ultrahigh thermal conductivity of ∼11.6 W/(m·K) at a graphene content of 1.84 vol%, i.e., an enhancement efficiency of 3640% per 1 vol%. In addition, the compressive strength of the composite is increased by 2.6 times compared to epoxy (from 0.29 MPa to 0.76 MPa). Because the composite shows a modulus as low as 0.5–1.0 MPa, it has excellent deformability and compression performance. Moreover, the obtained 3-mm-thick composite achieves an electromagnetic interference shielding effectiveness (EMI SE) of 40 dB due to the interconnected graphene network structure, which meets the requirements of commercial EMI shielding applications. Hence, this strategy can be used to synthesize aligned graphene/epoxy composites with excellent multifunctional performances, which can be simultaneously used as elastic thermal interface materials (TIMs) and EMI shielding materials in the fields of advanced electronic packaging.