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Title: Light-triggered thermal conductivity switching in azobenzene polymers

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 –1K –1) and low thermal conductivity (0.10 W m –1K –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. Furthermore this result demonstrates an effective control of the thermophysical properties of polymers by modulating interchain π-π networks by light.
Authors:
ORCiD logo [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [3] ;  [1] ;  [1] ;  [1] ;  [1]
  1. Univ. of Illinois at Urbana-Champaign, Urbana, IL (United States)
  2. Argonne National Lab. (ANL), Argonne, IL (United States)
  3. Air Force Research Lab, Wright Patterson Air Force Base, OH (United States)
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 116; Journal Issue: 13; Journal ID: ISSN 0027-8424
Publisher:
National Academy of Sciences, Washington, DC (United States)
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
Air Force Research Laboratory (AFRL). Air Force Office of Scientific Research (AFOSR); National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Scientific User Facilities Division
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; azobenzene; phase transition; polymer; thermal conductivity; thermal switch
OSTI Identifier:
1504273

Shin, Jungwoo, Sung, Jaeuk, Kang, Minjee, Xie, Xu, Lee, Byeongdu, Lee, Kyung Min, White, Timothy J., Leal, Cecilia, Sottos, Nancy R., Braun, Paul V., and Cahill, David G.. Light-triggered thermal conductivity switching in azobenzene polymers. United States: N. p., Web. doi:10.1073/pnas.1817082116.
Shin, Jungwoo, Sung, Jaeuk, Kang, Minjee, Xie, Xu, Lee, Byeongdu, Lee, Kyung Min, White, Timothy J., Leal, Cecilia, Sottos, Nancy R., Braun, Paul V., & Cahill, David G.. Light-triggered thermal conductivity switching in azobenzene polymers. United States. doi:10.1073/pnas.1817082116.
Shin, Jungwoo, Sung, Jaeuk, Kang, Minjee, Xie, Xu, Lee, Byeongdu, Lee, Kyung Min, White, Timothy J., Leal, Cecilia, Sottos, Nancy R., Braun, Paul V., and Cahill, David G.. 2019. "Light-triggered thermal conductivity switching in azobenzene polymers". United States. doi:10.1073/pnas.1817082116.
@article{osti_1504273,
title = {Light-triggered thermal conductivity switching in azobenzene polymers},
author = {Shin, Jungwoo and Sung, Jaeuk and Kang, Minjee and Xie, Xu and Lee, Byeongdu and Lee, Kyung Min and White, Timothy J. and Leal, Cecilia and Sottos, Nancy R. and Braun, Paul V. and Cahill, David G.},
abstractNote = {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–1K–1) and low thermal conductivity (0.10 W m–1K–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. Furthermore this result demonstrates an effective control of the thermophysical properties of polymers by modulating interchain π-π networks by light.},
doi = {10.1073/pnas.1817082116},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
number = 13,
volume = 116,
place = {United States},
year = {2019},
month = {3}
}

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