Hartquist Chase M, Li Buxuan, Zhang James H, Yu Zhaohan, Lv Guangxin, Shin Jungwoo, Boriskina Svetlana V, Chen Gang, Zhao Xuanhe, Lin Shaoting
Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
Department of Mechanical Engineering, Michigan State University, East Lansing, MI, USA.
Nat Commun. 2024 Jul 3;15(1):5590. doi: 10.1038/s41467-024-49354-2.
Polymeric thermal switches that can reversibly tune and significantly enhance their thermal conductivities are desirable for diverse applications in electronics, aerospace, automotives, and medicine; however, they are rarely achieved. Here, we report a polymer-based thermal switch consisting of an end-linked star-shaped thermoset with two independent thermal conductivity tuning mechanisms-strain and temperature modulation-that rapidly, reversibly, and cyclically modulate thermal conductivity. The end-linked star-shaped thermoset exhibits a strain-modulated thermal conductivity enhancement up to 11.5 at a fixed temperature of 60 °C (increasing from 0.15 to 2.1 W m K). Additionally, it demonstrates a temperature-modulated thermal conductivity tuning ratio up to 2.3 at a fixed stretch of 2.5 (increasing from 0.17 to 0.39 W m K). When combined, these two effects collectively enable the end-linked star-shaped thermoset to achieve a thermal conductivity tuning ratio up to 14.2. Moreover, the end-linked star-shaped thermoset demonstrates reversible tuning for over 1000 cycles. The reversible two-way tuning of thermal conductivity is attributed to the synergy of aligned amorphous chains, oriented crystalline domains, and increased crystallinity by elastically deforming the end-linked star-shaped thermoset.
对于电子、航空航天、汽车和医学等多种应用而言，能够可逆地调节并显著提高其热导率的聚合物热开关是非常理想的；然而，此类热开关却很少能够实现。在此，我们报道了一种基于聚合物的热开关，它由一种端链星形热固性材料组成，具有两种独立的热导率调节机制——应变和温度调制——能够快速、可逆且循环地调节热导率。在60°C的固定温度下，端链星形热固性材料表现出高达11.5的应变调制热导率增强（从0.15增加到2.1 W m⁻¹ K⁻¹）。此外，在2.5的固定拉伸量下，它展示出高达2.3的温度调制热导率调节比（从0.17增加到0.39 W m⁻¹ K⁻¹）。当这两种效应结合时，这两种效应共同使端链星形热固性材料能够实现高达14.2的热导率调节比。此外，端链星形热固性材料展示出超过1000次循环的可逆调节。热导率的可逆双向调节归因于通过对端链星形热固性材料进行弹性变形，使取向的非晶链、定向的结晶域以及结晶度增加之间的协同作用。
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