MoS2 Lubricate-Toughened MXene/ANF Composites for Multifunctional Electromagnetic Interference Shielding

Abstract

The design and fabrication of high toughness electromagnetic interference (EMI) shielding composite films with diminished reflection are an imperative task to solve electromagnetic pollution problem. Ternary MXene/ANF (aramid nanofibers)–MoS2 composite films with nacre-like layered structure here are fabricated after the introduction of MoS2 into binary MXene/ANF composite system. The introduction of MoS2 fulfills an impressive “kill three birds with one stone” improvement effect: lubrication toughening mechanical performance, reduction in secondary reflection pollution of electromagnetic wave, and improvement in the performance of photothermal conversion. After the introduction of MoS2 into binary MXene/ANF (mass ratio of 50:50), the strain to failure and tensile strength increase from 22.1 ± 1.7% and 105.7 ± 6.4 MPa and to 25.8 ± 0.7% and 167.3 ± 9.1 MPa, respectively. The toughness elevates from 13.0 ± 4.1 to 26.3 ± 0.8 MJ m−3 (~102.3%) simultaneously. And the reflection shielding effectiveness (SER) of MXene/ANF (mass ratio of 50:50) decreases ~10.8%. EMI shielding effectiveness (EMI SE) elevates to 41.0 dB (8.2–12.4 GHz); After the introduction of MoS2 into binary MXene/ANF (mass ratio of 60:40), the strain to failure increases from 18.3 ± 1.9% to 28.1 ± 0.7% (~53.5%), the SER decreases ~22.2%, and the corresponding EMI SE is 43.9 dB. The MoS2 also leads to a more efficient photothermal conversion performance (~45 to ~55 °C). Additionally, MXene/ANF–MoS2 composite films exhibit excellent electric heating performance, quick temperature elevation (15 s), excellent cycle stability (2, 2.5, and 3 V), and long-term stability (2520 s). Combining with excellent mechanical performance with high MXene content, electric heating performance, and photothermal conversion performance, EMI shielding ternary MXene/ANF–MoS2 composite films could be applied in many industrial areas. This work broadens how to achieve a balance between mechanical properties and versatility of composites in the case of high-function fillers.

1. Introduction

In recent years, the renewals of communication technology and flexible electronic devices lead to electromagnetic pollution risk [1–3]. Electromagnetic pollution has negative effects on other devices [4, 5] and human health [6–8]. The preparation of high toughness electromagnetic interference (EMI) shielding composite films becomes a major task to avoid the EM pollution problem. MXene has been utilized extensively as conductivity fillers in polymers-based EMI shielding composite films owing to its superior electrical conductivity [9–12], EMI shielding performance [13–15], mechanical performance [16, 17], electric heating performance [18–20], and photothermal conversion performance [21]. In addition, MXene could form interface interaction with soft polymers chains owing to the mass of functional groups on its surface [22–24].

In this background, substantial numbers of multilayer MXene/soft polymer chains composite films were prepared. Liu et al. [25] produced bacterial cellulose/MXene films via filtration method, the strain to failure was 17.3% with 20 wt% MXene, the corresponding EMI shielding effectiveness (EMI SE) was 18 dB, and the reflection shielding effectiveness (SER) values are at a relatively high level. Peng et al. [26] fabricated reflection-dominated MXene/heterocyclic aramid nanocomposite films, the strain to failure was 16.2% and 3.5% with 20 and 60 wt% MXene, respectively, EMI SE value reaches 8.7 and 34.2 dB, respectively, and the reflectional coefficient values are larger than the absorption coefficients values. Nan et al. [27] adopted intermittent filtration method to realize the compound of MXene and aramid nanofibers (ANF); when the MXene content elevated from 20 to 60 wt%, the strain to failure decreased from 12.5 ± 0.8