Mukun He, Jinwen Hu, Han Yan, Xiao Zhong, Yali Zhang*, Panbo Liu, Jie Kong, Junwei Gu*. Shape Anisotropic Chain-like CoNi/Polydimethylsiloxane Composite Films with Excellent Low-frequency Microwave Absorption and High Thermal Conductivity. Advanced Functional Materials, 2024, 10.1002/adfm.202316691. 2022IF=19.0.（1區材料科學Top期刊）
https://doi.org/10.1002/adfm.202316691
Abstract
The demand for low-frequency microwave absorption materials is becoming more and more urgent. Novel shape anisotropy chain-like CoNi is fabricated using polyvinylpyrrolidone as a shape-directing agent via solvothermal method, which is then mixed with polydimethylsiloxane (PDMS) to prepare corresponding multifunctional chain-like CoNi/PDMS composite films. Shape anisotropy and strong magnetic coupling effect of chain-like CoNi enhance natural resonance and magnetic loss capability. The minimum reflection loss (RLmin) is -50.5 dB and low-frequency effective absorption bandwidth (EAB) is 1.04 GHz (2.64~3.68 GHz) at 3.9 mm for chain-like CoNi. The corresponding 18 vol% chain-like CoNi/PDMS composite films present optimal low-frequency microwave absorption performance with RLmin of -56.7 dB and low-frequency EAB of 1.04 GHz (2.96~4.00 GHz) at 4.1 mm, which is far superior to 18 vol% spherical CoNi/PDMS composite films with RLmin of -9.5 dB. Meantime, the in-plane and inter-planethermal conductivity coefficients of 18 vol% chain-like CoNi/PDMS composite films are 2.05 W/(m·K) and 0.61 W/(m·K), about 1.5 times higher than 18 vol% spherical CoNi/PDMS composite films (1.36 W/(m·K) and 0.42 W/(m·K)), also 220% and 190% higher than pure PDMS (0.64 W/(m·K) and 0.21 W/(m·K)). This composite films with low-frequency microwave absorption and thermal conductivity can broaden applications in 5G communications and flexible electronics.
5G通信和柔性電子技術快速發展帶來的低頻（S和C波段）電磁干擾和輻射污染問題使其對低頻微波吸收材料的需求愈發迫切。本文以聚乙烯吡咯烷酮（PVP）為形狀導向劑，通過溶劑熱還原法制備形狀各向異性的鏈狀CoNi低頻微波吸收材料，再將其與聚二甲基硅氧烷（PDMS）基體復合制備多功能CoNi/PDMS復合膜。鏈狀CoNi優異的形狀各向異性和強烈的磁耦合效應使其在S和C波段的自然共振增強以及磁損耗能力提升。當鏈狀CoNi低頻微波吸收材料厚度為3.9 mm時，其最小反射損耗（RLmin）為-50.5 dB、低頻有效吸收帶寬（EAB）為1.04 GHz（2.64~3.68 GHz）。當鏈狀CoNi的體積分數為18 vol%時，厚度為4.1 mm的鏈狀CoNi/PDMS復合膜具有最優的低頻吸波性能，其RLmin為-56.7 dB、低頻EAB為1.04 GHz（2.96~4.00 GHz），遠優于相同用量顆粒狀CoNi/PDMS復合膜的RLmin（-9.5 dB）。同時，18 vol%鏈狀CoNi/PDMS復合膜的面內導熱系數和面間導熱系數分別為2.05 W/(m·K)和0.61W/(m·K)，約為18 vol%顆粒狀CoNi/PDMS復合膜（1.36 W/(m·K)和0.42 W/(m·K)）的1.5倍，比純PDMS（0.64 W/(m·K)和0.21 W/(m·K)）高220%和190%。這種兼具優異低頻吸波性能和導熱性能的多功能PDMS復合膜在5G通訊以及柔性電子設備領域具有廣闊的應用前景。
論文亮點
1. 鏈狀CoNi優異的形狀各向異性和強烈的磁耦合效應使其在S和C波段的自然共振增強以及磁損耗能力提升。當鏈狀CoNi低頻微波吸收材料厚度為3.9 mm時，RLmin為-50.5 dB、低頻EAB為1.04 GHz（2.64~3.68 GHz）。
2. 當鏈狀CoNi的體積分數為18 vol%時，厚度為4.1 mm的鏈狀CoNi/PDMS復合膜具有最優的低頻吸波性能，其RLmin為-56.7 dB、低頻EAB為1.04 GHz（2.96~4.00 GHz），遠優于相同用量顆粒狀CoNi/PDMS復合膜的RLmin（-9.5 dB）。
3. 18 vol% 鏈狀CoNi/PDMS復合膜的λ∥為2.05 W/(m·K)，分別為18 vol% 顆粒狀CoNi/PDMS復合膜（1.36 W/(m·K)）和純PDMS（0.64 W/(m·K)）的1.5倍和3.2倍。
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