Embedded 3D printing of RGO frameworks with mechanical strength, and electrical and electromagnetic interference shielding properties

The three-dimensional (3D) printing technique is used to efficiently design the structure of 3D graphene assemblies and give them extraordinary properties. However, directly constructing 3D graphene assemblies with complex structures using direct ink writing (DIW) 3D printing is still limited. Herein, we demonstrate a strategy for directly constructing microstructurally porous or dense 3D reduced graphene oxide (RGO) frameworks with an octet-truss structure using embedded 3D printing combined with freeze-drying or capillary-drying, respectively. Reasonable structural design and self-assembled RGO sheets contribute to endowing RGO frameworks with mechanical strength and electrical properties. The freeze-dried RGO framework (F-RGF) has an electrical conductivity of 131.85 S m-1 and a compressive strength of 35.42 kPa at 50% strain. Moreover, the properties of the RGO framework are changed by altering its drying method. Compared with F-RGF, the capillary-dried RGO framework (C-RGF) has a higher electrical conductivity of 863.77 S m-1 and a higher compressive strength of 3.23 MPa. At a thickness of 2.8 mm, low-conducting F-RGF and high-conducting C-RGF exhibit good electromagnetic interference shielding effectiveness (EMI SE) in the frequency range of 18-40 GHz, with total SE (SET) values up to 72.87 dB and 63.48 dB, respectively. This work provides a reference for constructing 3D assemblies with multi-level structures and exhibits the possibility of structural changes for different applications. Micro-porous and micro-dense 3D RGO frameworks prepared by embedded 3D printing are reported, and the 3D RGO frameworks exhibit high electrical conductivity, high mechanical strength, and excellent electromagnetic interference shielding properties.