Yongqiang Guo, Shuangshuang Wang, Haitian Zhang, Hua Guo,  Mukun He, Kunpeng Ruan, Ze Yu, Guang-sheng Wang*, Hua Qiu and Junwei Gu*. Consistent Thermal Conductivities of Spring-like Structured Polydimethylsiloxane  Composites under Large Deformation. Advanced Materials,  2024, 36: 2404648. 2023IF=27.4

https://doi.org/10.1002/adma.202404648

Abstract

Flexible and highly thermally conductive materials with consistent thermal conductivity (λ) during large deformation are urgently required to address the heat accumulation in flexible electronics. In this study, spring-like  thermal conduction pathways of silver nanowire (S-AgNW) fabricated by 3D printing are compounded with polydimethylsiloxane (PDMS) to prepare S-AgNW/PDMS composites  with excellent and consistent λ during deformation. The S-AgNW/PDMS composites exhibit a λ of 7.63 W m?1 K?1 at an AgNW amount of 20 vol%, which is ≈42 times that  of PDMS (0.18 W m?1 K?1) and higher than that of AgNW/PDMS composites with  the same amount and random dispersion of AgNW (R-AgNW/PDMS) (5.37 W m?1 K?1). Variations in the λ of 20 vol% S-AgNW/PDMS composites are less than 2% under a deformation of 200% elongation, 50% compression, or 180° bending, which benefits from the large  deformation characteristics of S-AgNW. The heat-transfer coefficient (0.29 W cm?2 K?1) of 20 vol% S-AgNW/PDMS composites is ≈1.3 times that  of the 20 vol% R-AgNW/PDMS composites, which reduces the temperature of a full-stressed  central processing unit by 6.8 °C compared to that using the 20 vol% R-AgNW/PDMS  composites as a thermally conductive material in the central processing unit.柔性电子领域的热量积聚问题使其对大形变下导热稳定的柔性高导热材料需求迫切。本文采用3D打印技术制备具有大形变能力的银纳米线螺旋导热通路（S-AgNW），将其与聚二甲基硅氧烷（PDMS）复合制备大形变下具有优异和稳定导热性能的S-AgNW/PDMS复合材料。AgNW体积分数为20 vol%的S-AgNW/PDMS复合材料的导热系数（λ）达7.63 W m-1 K-1，约为纯PDMS的λ（0.18 W m-1K-1）的42倍，也远高于相同体积分数AgNW在PDMS基体中随机分散的R-AgNW/PDMS复合材料的λ（5.37 W m-1 K-1）。得益于AgNW螺旋导热通路的大形变特性，20 vol% S-AgNW/PDMS导热复合材料在200%伸长率、50%压缩率和180°弯曲角度等形变下的λ变化率均小于2%。此外，20 vol% S-AgNW/PDMS导热复合材料的传热系数（0.29 W cm-2 K-1）约为20 vol% R-AgNW/PDMS导热复合材料传热系数（0.22 W cm-2 K-1）的1.3倍，用于CPU散热时可使其满功率工作温度较20 vol% R-AgNW/PDMS复合材料作为散热材料时的CPU温度降低6.8oC。

论文亮点

1. 采用3D打印技术制备具有大形变能力的银纳米线（AgNW）螺旋导热通路，将其与PDMS复合制备大形变下具有优异和稳定导热性能的S-AgNW/PDMS复合材料。

2. AgNW体积分数为20 vol%的S-AgNW/PDMS复合材料的λ达7.63 W m-1 K-1，约为纯PDMS的λ（0.18 W m-1 K-1）的42倍，其在200%伸长率、50%压缩率和180°弯曲角度等形变下的λ变化率均小于2%。

3. 扫描电子显微镜和微纳尺度热传导模拟表明，AgNW螺旋导热通路的大形变特性使AgNW在S-AgNW/PDMS导热复合材料形变时发生的位移变化很小，不影响整体的热传导过程。

作者：郭永强邮件地址：gyqnpu@nwpu.edu.cn

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