High-contrast and reversible polymer thermal regulator by structural phase transition

作者：Ramesh Shrestha, Yuxuan Luan, Sunmi Shin, Teng Zhang, Xiao Luo, James Spencer Lundh, Wei Gong, Michael R. Bockstaller, Sukwon Choi, Tengfei Luo, Renkun Chen, Kedar Hippalgaonkar, Sheng Shen · 发表于：Science Advances · 年份：2019 · DOI：10.1126/sciadv.aax3777 · 被引用次数：78 · 研究领域：Thermal properties of materials、Thermal Radiation and Cooling Technologies、Heat Transfer and Optimization

In comparison with the advancement of switchable, nonlinear, and active components in electronics, solid-state thermal components for actively controlling heat flow have been extremely rare. We demonstrate a high-contrast and reversible polymer thermal regulator based on the structural phase transition in crystalline polyethylene nanofibers. This structural phase transition represents a dramatic change in morphology from a highly ordered all-trans conformation to a combined trans and gauche conformation with rotational disorder, leading to an abrupt change in phonon transport along the molecular chains. For five nanofiber samples measured here, we observe an average thermal switching ratio of ~8× and maximum switching ratio of ~10×, which occurs in a narrow temperature range of 10 K across the structural phase transition. To the best of our knowledge, the ~10× switching ratio exceeds any reported experimental values for solid-solid and solid-liquid phase transitions of materials. There is no thermal hysteresis observed upon heating/cooling cycles.