High thermal conductivity in electrostatically engineered amorphous polymers

Apoorv Shanker; Chen Li; Gun-Ho Kim; David Gidley; Kevin P Pipe; Jinsang Kim

doi:10.1126/sciadv.1700342

High thermal conductivity in electrostatically engineered amorphous polymers

Sci Adv. 2017 Jul 28;3(7):e1700342. doi: 10.1126/sciadv.1700342. eCollection 2017 Jul.

Authors

Apoorv Shanker¹, Chen Li², Gun-Ho Kim^{2

3

4}, David Gidley⁵, Kevin P Pipe^{2

6}, Jinsang Kim^{1

4

7

8}

Affiliations

¹ Department of Macromolecular Science and Engineering, University of Michigan, Ann Arbor, MI 48109-2800, USA.
² Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109-2125, USA.
³ Department of Mechanical and Nuclear Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea.
⁴ Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109-2117, USA.
⁵ Department of Physics, University of Michigan, Ann Arbor, MI 48109-1040, USA.
⁶ Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI 48109-2122, USA.
⁷ Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA.
⁸ Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109-2136, USA.

Abstract

High thermal conductivity is critical for many applications of polymers (for example, packaging of light-emitting diodes), in which heat must be dissipated efficiently to maintain the functionality and reliability of a system. Whereas uniaxially extended chain morphology has been shown to significantly enhance thermal conductivity in individual polymer chains and fibers, bulk polymers with coiled and entangled chains have low thermal conductivities (0.1 to 0.4 W m^-1 K^-1). We demonstrate that systematic ionization of a weak anionic polyelectrolyte, polyacrylic acid (PAA), resulting in extended and stiffened polymer chains with superior packing, can significantly enhance its thermal conductivity. Cross-plane thermal conductivity in spin-cast amorphous films steadily grows with PAA degree of ionization, reaching up to ~1.2 W m^-1 K^-1, which is on par with that of glass and about six times higher than that of most amorphous polymers, suggesting a new unexplored molecular engineering strategy to achieve high thermal conductivities in amorphous bulk polymers.

Publication types

Research Support, Non-U.S. Gov't