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标题：Light-triggered thermal conductivity switching in azobenzene polymers
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作者：Jungwoo Shin ; Jaeuk Sung ; Minjee Kang 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2019
卷号：116
期号：13
页码：5973-5978
DOI：10.1073/pnas.1817082116
出版社：The National Academy of Sciences of the United States of America
摘要：Materials that can be switched between low and high thermal conductivity states would advance the control and conversion of thermal energy. Employing in situ time-domain thermoreflectance (TDTR) and in situ synchrotron X-ray scattering, we report a reversible, light-responsive azobenzene polymer that switches between high (0.35 W m−1 K−1) and low thermal conductivity (0.10 W m−1 K−1) states. This threefold change in the thermal conductivity is achieved by modulation of chain alignment resulted from the conformational transition between planar ( trans ) and nonplanar ( cis ) azobenzene groups under UV and green light illumination. This conformational transition leads to changes in the π-π stacking geometry and drives the crystal-to-liquid transition, which is fully reversible and occurs on a time scale of tens of seconds at room temperature. This result demonstrates an effective control of the thermophysical properties of polymers by modulating interchain π-π networks by light.
关键词：polymer ; thermal conductivity ; phase transition ; thermal switch ; azobenzene