Cotton-based sandwich architectures for flexible electromagnetic interference shielding materials with superior flame retardancy
image: The multi-layer TPU/P-APP/MOF/C-nPM composite were successfully fabricated by using air-assisted hot-pressing technique and melt blending technique. The obtained composites demonstrate excellent fire safety and superior EMI shielding properties.
Credit: Nano Research, Tsinghua University Press
Electromagnetic waves are extensively utilized in many fields such as communication and medicine. Excessive electromagnetic waves will cause electromagnetic pollution. Electromagnetic pollution may lead to electromagnetic interference (EMI), which will interfere sensitive electronic devices. Furthermore, electromagnetic pollution is harmful to human health and may potentially cause information leakage. The development of lightweight and flexible EMI shielding materials with high mechanical strength and excellent flame retardant properties is currently a hot and difficult research topic.
A research team of led by Yongqian Shi from Fuzhou University in Fuzhou, China recently proposed a novel strategy for preparing flexible electromagnetic interference shielding materials with superior flame retardant performance. This work successfully prepared cotton-based composite materials (TPU/P-APP/MOF/C-nPM) with sandwich architectures through innovative material combination and integrated structural and functional design. This work promotes the development and application of high-performance flexible EMI shielding materials.
The team published their research work in Nano Research on November 27, 2025.
In this work, the copper-based metal-organic framework (MOF-Cu) and polyethyleneimine-modified ammonium polyphosphate (PEI-APP) were successfully synthesized. The flame-retardant thermoplastic polyurethane (TPU) composite was successfully prepared by compounding MOF-Cu and PEI-APP. The Cotton@PDA@MXene composite was fabricated via a sequential loading process of polydopamine (PDA) and MXene onto cotton fabric. Then, the multilayer TPU composites (TPU/P-APP/MOF/C-nPM) were prepared by layer-by-layer hot-pressing.
In the cone calorimeter test, the peak heat release rate (PHRR) and total heat release (THR) values of the TPU/C composite were 290 kW/m² and 12.2 MJ/m², respectively. Compared with pure TPU/cotton sample, the peak heat release rate, total heat release and total smoke release of TPU/9P-APP/1MOF/C-3PM composite decreased by 40.7%, 31.1% and 33.3%, respectively. The increased PDA@MXene loading contributed significantly to heat value reduction, thereby enhancing the composite's fire safety. TPU/9P-APP/1MOF/C-3PM exhibited excellent flame-retardant performance.
The TPU/9P-APP/1MOF/C-3PM composite exhibited exceptional EMI shielding effectiveness of 20.5 dB in X-band and 23.0 dB in K-band, exceeding commercial standards. The EMI shielding mechanism of the TPU/9P-APP/1MOF/C-3PM composite is attributed to the reflection and absorption of electromagnetic waves. On the one hand, the P-APP molecules in the TPU matrix reflect a portion of the electromagnetic waves, while the MOF metallic conductive network absorbs another portion. On the other hand, the remaining electromagnetic waves penetrating the cotton fabric composites undergo multiple internal reflections between MXene nano-layers, thereby prolonging their propagation path and dissipating them as thermal energy.
Furthermore, the thickness of the multilayer TPU composites was only 1 mm, demonstrating excellent flexibility. As the outer encapsulation material, TPU endowed the multilayer TPU composites outstanding durability and effectively addressed the common issues of fabric abrasion and conductive filler detachment. This work provides a novel strategy for preparing flexible electromagnetic interference shielding materials with superior flame retardancy.
Other contributors include Longcheng Tang from the College of Material at Hangzhou Normal University in Hangzhou, China; Jiefeng Gao from School of Chemistry and Chemical Engineering at Yangzhou University in Yangzhou, China; Pingan Song from School of Agriculture and Environmental Science at University of Southern Queensland in Australia; Libi Fu from College of Civil Engineering at Fuzhou University in Fuzhou, China.
This work was financially supported by the National Natural Science Foundation of China (Grant No. 52173070).
About Nano Research
Nano Research is a peer-reviewed, open access, international and interdisciplinary research journal, sponsored by Tsinghua University and the Chinese Chemical Society, published by Tsinghua University Press on the platform SciOpen. It publishes original high-quality research and significant review articles on all aspects of nanoscience and nanotechnology, ranging from basic aspects of the science of nanoscale materials to practical applications of such materials. After 18 years of development, it has become one of the most influential academic journals in the nano field. Nano Research has published more than 1,000 papers every year from 2022, with its cumulative count surpassing 7,000 articles. In 2024 InCites Journal Citation Reports, its 2024 IF is 9.0 (8.7, 5 years), and it continues to be the Q1 area among the four subject classifications. Nano Research Award, established by Nano Research together with TUP and Springer Nature in 2013, and Nano Research Young Innovators (NR45) Awards, established by Nano Research in 2018, have become international academic awards with global influence.