Design of PDMS/SiO2@MXene composites with “Floatable Interlayer” structure for the electromagnetic shielding behavior improvement

Designing inhomogeneous structure is an efficient method to prepare polymer composites with electromagnetic interference (EMI) shielding. According to principle of phase separation induced by volatilizing solvent, herein, sandwich structure with a SiO2@MXene "floatable interlayer" is designed by regulating the affinity of mixed solvents (dimethylbenzene and tetrahydrofuran) and SiO2@MXene, and then compounded with poly(dimethylsiloxane) (PDMS). The interactions among SiO2@MXene, PDMS and mixed solvents can be dynamically adjusted during solvents evaporation via controlling the nano-SiO2 in/on MXene, which accurately regulates the dispersion of SiO2@MXene in PDMS for further forming floatable conductive interlayer. The composite PDMS/SiO2@MXene-0.25 (SiO2: MXene = 0.25) containing 10 wt% of MXene exhibits typical sandwich structure owing to the opportune specific surface area (545.42 m2 g−1) and surface-loaded SiO2 of the SiO2@MXene-0.25 nanohybrids. The special sandwich structure brings superior performances to the PDMS/SiO2@MXene composites including an average EMI shielding effectiveness of 43.3 dB (0.2 mm in thickness) in X-band, stable mechanical property (remain > 97% after 150 cycles of stretch testing) and wide temperature window in application (-50 ∼ 200 °C). Thus, this study provides a novel method for designing sandwich-like heterostructure of PDMS/SiO2@MXene composites that can be used for EMI shielding in a wide temperature range.