Hierarchically porous polyimide/Ti ₃ C ₂ T _x film with stable electromagnetic interference shielding after resisting harsh conditions

Abstract

Polymer-based conductive nanocomposites are promising for electromagnetic interference (EMI) shielding to ensure stable operations of electronic devices and protect humans from electromagnetic radiation. Although MXenes have shown high EMI shielding performances, it remains a great challenge to construct highly efficient EMI shielding polymer/MXene composite films with minimal MXene content and high durability to harsh conditions. Here, hierarchically porous polyimide (PI)/Ti 3 C 2 T x films with consecutively conductive pathways have been constructed via a unidirectional PI aerogel-assisted immersion and hot-pressing strategy. Contributed by special architectures and high conductivities, PI/Ti 3 C 2 T x films with 2.0 volume % Ti 3 C 2 T x have high absolute EMI shielding effectiveness up to 15,527 dB cm 2 g −1 at the thickness of 90 μm. Superior EMI shielding performance can be retained even after being subjected to hygrothermal or combustion environments, cryogenic (−196°C) or high (250°C) temperatures, and rapid thermal shock (∆T = 446°C), demonstrating high potential as high-performance EMI shielding materials resisting harsh conditions.

Ultralight, highly compressible, thermally stable MXene/aramid nanofiber anisotropic aerogels for electromagnetic interference shielding

“…With the rapid development of information technology and portable wearable devices, small volume and lightweight electromagnetic interference (EMI) shielding materials are urgently needed to cope with the complex electromagnetic wave (EMWs) environment, to ensure the stable operation of equipment and protect human health. 1–4 Different from the fatal weakness of traditional metal materials with a high density and ease of corrosion, transition-metal carbon/nitride (MXene), as an emerging two-dimensional sheet material, exhibits great potential in the field of electromagnetic shielding due to its excellent electrical conductivity and abundant interface groups. 5–10 It is urgent to overcome the weak interaction between MXene nanosheets, for the better usage of their unique 3D structural advantages, thus improving their mechanical properties and oxidation resistance.…”

A Flexible, Mechanically Strong, and Anti‐Corrosion Electromagnetic Wave Absorption Composite Film with Periodic Electroconductive Patterns

“…The characteristic peaks at 1775 (imide v as (CO)), 1714 (imide v s (CO)), 1374 (v(CN)), and 739 cm −1 (δ(CO)) were assigned to pure PI, and no additional peaks were observed after etching treatment. [3,40] In addition, our films offered outstanding features such as facile synthesis, low-cost, and environmental friendliness, making them feasible for mass production. The prepared films (3 × 3 cm), with a thickness of 0.14 mm, are shown in Figure 1c and Figure S9, Supporting Information.…”

“…In recent years, flexible and stable electromagnetic (EM) responsive films that can selectively reflect, absorb, or transmit an electromagnetic wave (EMW), have been extensively developed for EM pollution, radar stealth, and other specific applications. [1][2][3][4][5][6][7] Among the various responsive films, highefficiency EMW absorption films have become more important due to less secondary pollution and better stealth performance; however, their design remains a challenge owing to impedance mismatch, insufficient attenuation, and instability at small thicknesses. [8] In extreme conditions-such as acid/alkali and it was reduced to Cu 2 S, the valence band was mainly from the 3d orbital of Cu and 3p orbital of S, while the main component of the conduction band was the 3p orbital of S. Concurrently, the bandgap increased to 2.5 eV compared to CuS (0.75 eV).…”

“…The simple manipulation of absorbent constitutions and their concentrations in the framework offers limited improvement of absorption properties due to mass agglomeration and insulated polymer barriers. [3,[30][31][32][33] Therefore, structural designs such as periodic electroconductive patterns, multilayer architectures, and circuit-analog laminates must be introduced to optimize absorption performance. In particular, by interacting with a local EM field, according to generalized Snell's law, periodic electroconductive patterns can improve EMW control in terms of amplitude, phase, dispersion, momentum, and polarization.…”

“…In this case, the construction of absorbent-polymer composite films with combined features of both organic polymers and effective absorbent is regarded as a promising approach toward obtaining highly efficient EMW absorption films that meet the expected requirements. [3,13] Specifically, traditional polymers, such as polyimide (PI), polystyrene (PS), epoxy, and polyethylene terephthalate (PET), offer a proper framework because of their collective characteristics, including low dielectric constant, excellent physical/chemical properties, and easy processability. [14][15][16] Of these, PI, which has hightemperature resistance (>400 °C), low-temperature tolerance (<−270 °C), outstanding mechanical properties, chemical resistance, flexibility, and excellent dielectric properties (ε r < 3.4), is highly desirable as a framework.…”