Kexia Jin, Jianxiong Xing, Xinge Liu, Zehui Jiang, Shumin Yang, Xuan Yang, Jianfeng Ma*a

Chemistry A, 2021, 9(47): 26999-27009

To achieve high mechanical strength electromagnetic interference (EMI) shielding materials for practical application, cellulose nanocrystals (CNC), as a reinforcing and dispersing agent, are intercalated into reduced graphene oxide (RGO) layers, forming an ultrathin, robust, flexible, and hydrophobic CNC/RGO film with a highly ordered nacre-like layered structure via a self-assembly process.

The layered structure significantly shortens the reduction time and improves the mechanical strength and shielding effectiveness (SE) of the resultant CNC/RGO composite film. The controlled preparation of CNC with different aspect ratios is realized by using separated bamboo fiber and parenchyma. The CNC of the fiber with a higher aspect ratio and lower diameter results in a lower porosity, denser structure, and more uniform distribution in the composites, and therefore a higher electrical conductivity and SE. The highest SE (39.1 dB) and specific SE (11 367 dB cm2 g−1) with a high tensile strength (179 MPa) and water contact angle (106°) of the CNC/RGO film are obtained at 10 wt% CNC loading with a film thickness of 12 μm. The maximum tensile strength of the composite film reaches 227 MPa with 30–50% CNC. The ultrathin high-performance CNC/RGO film shows significant potential as an EMI shielding material in the aerospace and flexible electronics fields.

Fig. 1 (a) Illustration of the preparation process of the CNC/GO composite film; (b) digital image of the CNC/RGO film exhibits excellent mechanical flexibility; (c, d and e) cross-sectional SEM micrographs of the FCNC/RGO and PCNC/RGO films with different magnifications; (f and g) schematic representation of the FCNC/RGO (f) and PCNC/RGO (g) composite films with a nacre-like layered structure.