Light-triggered thermal conductivity switching in azobenzene polymers
Abstract
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.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Mar 08, 2019
- Source ID
- 10.1073/pnas.1817082116
Entities
People
- Byeongdu Lee
- Cecilia Leal
- David G. Cahill
- Jaeuk Sung
- Jungwoo Shin
- Kyung Min Lee
- Minjee Kang
- Nancy Sottos
- Paul V Braun
- Timothy White
- Xu Xie
Organizations
- Air Force Office of Scientific Research
- Air Force Research Laboratory
- Argonne National Laboratory
- National Science Foundation
- University of Illinois Urbana–Champaign