Thermal Transport in Polymers: A Review

Abstract

In this article, we review thermal transport in polymers with different morphologies from aligned fibers to bulk amorphous states. We survey early and recent efforts in engineering polymers with high thermal conductivity by fabricating polymers with large-scale molecular alignments. The experimentally realized extremely high thermal conductivity of polymer nanofibers are highlighted, and understanding of thermal transport physics from molecular simulations are discussed. We then transition to the discussion of bulk amorphous polymers with an emphasize on the physics of thermal transport and its relation with the conformation of molecular chains in polymers. We also discuss the current understanding of how the chemistry of polymers would influence thermal transport in amorphous polymers and some limited, but important chemistry-structural-property relationships. Lastly, challenges, perspectives and outlook of this field are presented. We hope this review will inspire more fundamental and applied research in the polymer thermal transport field to advance scientific understanding and engineering applications.

Perspectives on Molecular-Level Understanding of Thermophysics of Liquids and Future Research Directions

“…Molecular Dynamics Simulations. Molecular dynamics simulations have been increasingly used in simulating thermal conductivity, especially in amorphous materials that cannot be dealt with by first-principles simulations [116][117][118][119]. Ohara and co-workers carried out extensive molecular dynamics simulations on a variety of liquids and developed decomposition techniques to gain insights on heat conduction mechanisms in liquids.…”

Improving thermal conductivities of textile materials by nanohybrid approaches

“…It is a simple and low-cost method, with the advantage of being suitable to a broad diversity of polymer types. However, the process depends on many variables, and thermal conductivity of the as-spun fibers may differ due to the whipping instability ( Wei et al., 2021 ). Moreover, the solvents used in solvent electrospinning can be toxic, and scale-up production may not be feasible.…”

“…These filaments also displayed superior hydrophilic property and stable hygroscopic performance as well as good mechanical properties and high heat radiation emittance, which are suitable for applications of personal cooling in the case of sporting. Wet spinning has the advantage of suitability to a wide range of polymers with continuity and offers scalability; however, it can suffer from the use of volatile and cytotoxic solvents, as well as low production rate, higher manufacturing costs, and difficulty in scaling-up ( Wei et al., 2021 ). Moreover, if the drawing process cannot be well controlled, the fibers can dry too quickly at room temperature, leading to defects in molecular orientation.…”

Thermal Conductivity of Pentiptycene-Based Poly(o-hydroxyimide) Copolymers: A Study via Integrated Experiments and Simulations

“…In general, heat transfer in polymers is dominated by the strong bonding interactions, and if a polymer chain is more spatially extended, its thermal conductivity will be higher. , A spatially extended chain can be achieved by many means, such as mechanically stretching the polymer chain, chemically synthesizing a rigid rodlike backbone, or engineering proper sidechains. ,, Polymers with a conjugated backbone are expected to be more thermally conductive since they tend to be stiffer. For example, it is reported that nanofibers of conjugated polymer have more rigid backbones and thus higher thermal conductivity. − It is also reported that due to the molecular level chain alignment, amorphous polythiophene nanofibers, which are conjugated polymers, fabricated by nanotemplating can reach ∼4.4 W/m·K .…”