Ultrathin polymers have recently been shown to exhibit different chain dynamics and physical properties, as compared to their bulk counterparts. In this work, we measure the effective cross-plane thermal conductivity of polystyrene (PS) thin films using the ultrafast laser-based frequency-dependent time-domain thermoreflectance method. The effective thermal conductivity of PS films is found to increase with decreasing film thickness when the thickness of the PS film is comparable to or smaller than the radius of gyration of bulk PS. By correlating the effective thermal conductivity with the ratio of the film thickness to radius of gyration, we find that this increase is mainly due to the increase of interfacial thermal conductance between PS thin film and the substrate, which likely results from the changing chain structure near the PS/substrate interface.
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14 April 2014
Research Article|
April 16 2014
Size effect on the thermal conductivity of ultrathin polystyrene films
Jun Liu;
Jun Liu
1Department of Mechanical Engineering,
University of Colorado, Boulder
, Colorado 80309, USA
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Shenghong Ju;
Shenghong Ju
1Department of Mechanical Engineering,
University of Colorado, Boulder
, Colorado 80309, USA
2Department of Engineering Mechanics,
Tsinghua University
, Beijing 100084, China
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Yifu Ding;
Yifu Ding
1Department of Mechanical Engineering,
University of Colorado, Boulder
, Colorado 80309, USA
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Ronggui Yang
Ronggui Yang
a)
1Department of Mechanical Engineering,
University of Colorado, Boulder
, Colorado 80309, USA
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a)
Electronic mail: Ronggui.Yang@Colorado.Edu. Tel.: +1-303-735-1003. Fax: +1-303-492-3498.
Appl. Phys. Lett. 104, 153110 (2014)
Article history
Received:
March 01 2014
Accepted:
April 07 2014
Citation
Jun Liu, Shenghong Ju, Yifu Ding, Ronggui Yang; Size effect on the thermal conductivity of ultrathin polystyrene films. Appl. Phys. Lett. 14 April 2014; 104 (15): 153110. https://doi.org/10.1063/1.4871737
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