Synergistic Manipulation of Zero-Dimension and One-Dimension Hybrid Nanofillers in Multi-Layer Two-Dimension Thin Films to Construct Light Weight Electromagnetic Interference Material

Abstract

Nanocomposite foam with a large expansion ratio and thin cell walls is promising for electromagnetic interference (EMI) shielding materials, due to the low electromagnetic (EM) reflection and high EM absorption. To overcome the dimensional limitation from two-dimension (2D) thin walls on the construction of conductive network, a strategy combining hybrid conductive nanofillers in semi-crystalline matrix together with supercritical CO2 (scCO2) foaming was applied: (1) one-dimension (1D) CNTs with moderate aspect ratio was used to minimize the dimensional confinement from 2D thin walls while constructing the main EM absorbing network; (2) zero-dimension (0D) carbon black (CB) with no dimensional confinement was used to connect the separated CNTs in thin walls and to expand the EM absorbing network; (3) scCO2 foaming was applied to obtain a cellular structure with multi-layer thin walls and a large amount of air cells to reduce the reflected EM; (4) semi-crystalline polymer was selected so that the rheological behavior could be adjusted by optimizing crystallization and filler content to regulate the cellular structure. Consequently, an advanced material featured as lightweight, high EM absorption and low EM reflection was obtained at 0.48 vol.% hybrid nanofillers and a density of 0.067 g/cm3, whose specific EMI shielding performance was 183 dB cm3/g.

Facile in situ construction of a covalent adaptable network polyester vitrimer with advanced performance in repairability, foamability and recyclability

“…As expected, the 0 BT sample does not have foamability due to the extremely low melt strength. 44 On the contrary, the PET-based vitrimer possessed excellent foamability. With the help of crosslinked structures, PET-based vitrimer foams were successfully fabricated, which had an extremely low density of 0.039 g cm −3 and could be easily supported by hairs, as presented in Fig.…”

Using a Supercritical Fluid-Assisted Thin Cell Wall Stretching–Defoaming Method to Enhance the Nanofiller Dispersion, EMI Shielding, and Thermal Conduction Property of CNF/PVDF Nanocomposites

“…A polyhedron model − (containing the air phase and solid phase of nanocomposite foams) based on the Voronoi method , and the Monte Carlo method , (the detailed model information could be found in the Supporting Information) was used to quantitatively analyze the relationship between the cell wall stretching and the average shortest nanofiber distance. Figure a shows different nanocomposite cell growth processes [Figure b for 1D growth (similar to 1D stretching of solid nanocomposites), Figure c for 2D growth, and Figure d for 3D growth].…”

Construction of a Two-Dimensional Response Network in Three-Dimensional Composites to Dramatically Enhance Sensor Sensitivity: A Simple, Feasible, and Green Regulating Strategy

“…Quantitative Study of the Nanofiber Network in the Cell Wall. A 3D cell is essentially composed of continuous 2D thin cell walls, 38,55 so foam stretching can be regarded as massive cell walls being stretched. A cell wall model was then established to quantitatively study the effects of fiber content and aspect ratio on the variation of d average and average orientation angle during dynamic stretching.…”

“…Environmentally friendly supercritical CO 2 (scCO 2 ) foaming technology enables the polymeric matrix to be filled with bubbles, and the obtained foams are supported by cell walls. In the scCO 2 foaming process, cell walls are subjected to biaxial stretching, leading to the orientation of fibers in cell walls, thus obtaining a confined conductive network. , Second, it easily acquires the foam material near the percolation threshold by adjusting the cellular structure . Third, it improves filler dispersion and decreases aggregation. ,, Hence, the scCO 2 foaming strategy combining the above merits is an effective method to enhance sensor sensitivity.…”

“…In the scCO 2 foaming process, cell walls are subjected to biaxial stretching, leading to the orientation of fibers in cell walls, thus obtaining a confined conductive network. 38,39 Second, it easily acquires the foam material near the percolation threshold by adjusting the cellular structure. 40 Third, it improves filler dispersion and decreases aggregation.…”